All EyeLink Publications
All 12,000+ peer-reviewed EyeLink research publications up until 2023 (with some early 2024s) are listed below by year. You can search the publications library using keywords such as Visual Search, Smooth Pursuit, Parkinson’s, etc. You can also search for individual author names. Eye-tracking studies grouped by research area can be found on the solutions pages. If we missed any EyeLink eye-tracking papers, please email us!
2014 |
Tomohiro Ishizu; Semir Zeki Varieties of perceptual instability and their neural correlates Journal Article In: NeuroImage, vol. 91, pp. 203–209, 2014. @article{Ishizu2014, We report experiments designed to learn whether different kinds of perceptually unstable visual images engage different neural mechanisms. 21 subjects viewed two types of bi-stable images while we scanned the activity in their brains with functional magnetic resonance imaging (fMRI); in one (intra-categorical type) the two percepts remained within the same category (e.g. face-face) while in the other (cross-categorical type) they crossed categorical boundaries (e.g. face-body). The results showed that cross- and intra-categorical reversals share a common reversal-related neural circuitry, which includes fronto-parietal cortex and primary visual cortex (area V1). Cross-categorical reversals alone engaged additional areas, notably anterior cingulate cortex and superior temporal gyrus, which have been posited to be involved in conflict resolution. |
Leyla Isik; Ethan M. Meyers; Joel Z. Leibo; Tomaso Poggio The dynamics of invariant object recognition in the human visual system Journal Article In: Journal of Neurophysiology, vol. 111, no. 1, pp. 91–102, 2014. @article{Isik2014, The human visual system can rapidly recognize objects despite transformations that alter their appearance. The precise timing of when the brain computes neural representations that are invariant to particular transformations, however, has not been mapped in humans. Here we employ magnetoencephalography decoding analysis to measure the dynamics of size- and position-invariant visual information development in the ventral visual stream. With this method we can read out the identity of objects beginning as early as 60 ms. Size- and position-invariant visual information appear around 125 ms and 150 ms, respectively, and both develop in stages, with invariance to smaller transformations arising before invariance to larger transformations. Additionally, the magnetoencephalography sensor activity localizes to neural sources that are in the most posterior occipital regions at the early decoding times and then move temporally as invariant information develops. These results provide previously unknown latencies for key stages of human-invariant object recognition, as well as new and compelling evidence for a feed-forward hierarchical model of invariant object recognition where invariance increases at each successive visual area along the ventral stream. |
Elena I. Ivleva; Amanda F. Moates; Jordan P. Hamm; Ira H. Bernstein; Hugh B. O'Neill; Darwynn Cole; Brett A. Clementz; Gunvant K. Thaker; Carol A. Tamminga In: Schizophrenia Bulletin, vol. 40, no. 3, pp. 642–652, 2014. @article{Ivleva2014, BACKGROUND: This study examined smooth pursuit eye movement (SPEM), prepulse inhibition (PPI), and auditory event-related potentials (ERP) to paired stimuli as putative endophenotypes of psychosis across the schizophrenia-bipolar disorder dimension. METHODS: Sixty-four schizophrenia probands (SZP), 40 psychotic bipolar I disorder probands (BDP), 31 relatives of SZP (SZR), 26 relatives of BDP (BDR), and 53 healthy controls (HC) were tested. Standard clinical characterization, SPEM, PPI, and ERP measures were administered. RESULTS: There were no differences between either SZP and BDP or SZR and BDR on any of the SPEM, PPI, or ERP measure. Compared with HC, SZP and BDP had lower SPEM maintenance and predictive pursuit gain and ERP theta/alpha and beta magnitudes to the initial stimulus. PPI did not differ between the psychosis probands and HC. Compared with HC, SZR and BDR had lower predictive pursuit gain and ERP theta/alpha and beta magnitudes to the first stimulus with differences ranging from a significant to a trend level. Neither active symptoms severity nor concomitant medications were associated with neurophysiological outcomes. SPEM, PPI, and ERP scores had low intercorrelations. CONCLUSION: These findings support SPEM predictive pursuit and lower frequency auditory ERP activity in a paired stimuli paradigm as putative endophenotypes of psychosis common to SZ and BD probands and relatives. PPI did not differ between the psychosis probands and HC. Future studies in larger scale psychosis family samples targeting putative psychosis endophenotypes and underlying molecular and genetic mediators may aid in the development of biology-based diagnostic definitions. |
Anshul Jain; Stuart Fuller; Benjamin T. Backus Cue-recruitment for extrinsic signals after training with low information stimuli Journal Article In: PLoS ONE, vol. 9, no. 5, pp. e96383, 2014. @article{Jain2014, Cue-recruitment occurs when a previously ineffective signal comes to affect the perceptual appearance of a target object, in a manner similar to the trusted cues with which the signal was put into correlation during training. Jain, Fuller and Backus reported that extrinsic signals, those not carried by the target object itself, were not recruited even after extensive training. However, recent studies have shown that training using weakened trusted cues can facilitate recruitment of intrinsic signals. The current study was designed to examine whether extrinsic signals can be recruited by putting them in correlation with weakened trusted cues. Specifically, we tested whether an extrinsic visual signal, the rotary motion direction of an annulus of random dots, and an extrinsic auditory signal, direction of an auditory pitch glide, can be recruited as cues for the rotation direction of a Necker cube. We found learning, albeit weak, for visual but not for auditory signals. These results extend the generality of the cue-recruitment phenomenon to an extrinsic signal and provide further evidence that the visual system learns to use new signals most quickly when other, long-trusted cues are unavailable or unreliable. |
Yoshiko Yabe; Melvyn A. Goodale; Hiroaki Shigemasu Temporal order judgments are disrupted more by reflexive than by voluntary saccades Journal Article In: Journal of Neurophysiology, vol. 111, no. 10, pp. 2103–2108, 2014. @article{Yabe2014, We do not always perceive the sequence of events as they actually unfold. For example, when two events occur before a rapid eye movement (saccade), the interval between them is often perceived as shorter than it really is and the order of those events can be sometimes reversed (Morrone MC, Ross J, Burr DC. Nat Neurosci 8: 950-954, 2005). In the present article we show that these misperceptions of the temporal order of events critically depend on whether the saccade is reflexive or voluntary. In the first experiment, participants judged the temporal order of two visual stimuli that were presented one after the other just before a reflexive or voluntary saccadic eye movement. In the reflexive saccade condition, participants moved their eyes to a target that suddenly appeared. In the voluntary saccade condition, participants moved their eyes to a target that was present already. Similarly to the above-cited study, we found that the temporal order of events was often misjudged just before a reflexive saccade to a suddenly appearing target. However, when people made a voluntary saccade to a target that was already present, there was a significant reduction in the probability of misjudging the temporal order of the same events. In the second experiment, the reduction was seen in a memory-delay task. It is likely that the nature of the motor command and its origin determine how time is perceived during the moments preceding the motor act. |
Daniel L. K. Yamins; Ha Hong; Charles F. Cadieu; Ethan A. Solomon; Darren Seibert; James J. DiCarlo Performance-optimized hierarchical models predict neural responses in higher visual cortex Journal Article In: Proceedings of the National Academy of Sciences, vol. 111, no. 23, pp. 8619–8624, 2014. @article{Yamins2014, The ventral visual stream underlies key human visual object recognition abilities. However, neural encoding in the higher areas of the ventral stream remains poorly understood. Here, we describe a modeling approach that yields a quantitatively accurate model of inferior temporal (IT) cortex, the highest ventral cortical area. Using high-throughput computational techniques, we discovered that, within a class of biologically plausible hierarchical neural network models, there is a strong correlation between a model's categorization performance and its ability to predict individual IT neural unit response data. To pursue this idea, we then identified a high-performing neural network that matches human performance on a range of recognition tasks. Critically, even though we did not constrain this model to match neural data, its top output layer turns out to be highly predictive of IT spiking responses to complex naturalistic images at both the single site and population levels. Moreover, the model's intermediate layers are highly predictive of neural responses in the V4 cortex, a midlevel visual area that provides the dominant cortical input to IT. These results show that performance optimization - applied in a biologically appropriate model class - can be used to build quantitative predictive models of neural processing. |
Ming Yan; Yingyi Luo; Albrecht W. Inhoff Syllable articulation influences foveal and parafoveal processing of words during the silent reading of Chinese sentences Journal Article In: Journal of Memory and Language, vol. 75, pp. 93–103, 2014. @article{Yan2014, The current study examined effects of syllable articulation on eye movements during the silent reading of Chinese sentences, which contained two types of two-character target words whose second characters were subject to dialect-specific variation. In one condition the second syllable was articulated with a neutral tone for northern-dialect Chinese speakers and with a full tone for southern-dialect Chinese speakers (neutral-tone target words) and in the other condition the second syllable was articulated with a full tone irrespective of readers' dialect type (full-tone target words). Native speakers of northern and southern Chinese dialects were recruited in Experiment 1 to examine the effect of dialect-specific articulation on silent reading. Recordings of their eye movements revealed shorter viewing durations for neutral- than for full-tone target words only for speakers of northern but not for southern dialects, indicating that dialect-specific articulation of syllabic tone influenced visual word recognition. Experiment 2 replicated the syllabic tone effect for speakers of northern dialects, and the use of gaze-contingent display changes further revealed that these readers processed an upcoming parafoveal word less effectively when a neutral- than when a full-tone target was fixated. Shorter viewing duration for neutral-tone words thus cannot be attributed to their easier lexical processing; instead, tonal effects appear to reflect Chinese readers' simulated articulation of to-be-recognized words during silent reading. |
Ming Yan; Wei Zhou; Hua Shu; Rizwangul Yusupu; Dongxia Miao; André Krügel; Reinhold Kliegl Eye movements guided by morphological structure: Evidence from the Uighur language Journal Article In: Cognition, vol. 132, no. 2, pp. 181–215, 2014. @article{Yan2014a, It is generally accepted that low-level features (e.g., inter-word spaces) are responsible for saccade-target selection in eye-movement control during reading. In two experiments using Uighur script known for its rich suffixes, we demonstrate that, in addition to word length and launch site, the number of suffixes influences initial landing positions. We also demonstrate an influence of word frequency. These results are difficult to explain purely by low-level guidance of eye movements and indicate that due to properties specific to Uighur script low-level visual information and high-level information such as morphological structure of parafoveal words jointly influence saccade programming. |
Jingwen Yang; Frederic Hamelin; Dominique Sauter Fault detection observer design using time and frequency domain specifications Journal Article In: IFAC Proceedings Volumes, vol. 19, no. 1, pp. 8564–8569, 2014. @article{Yang2014, Several scholars have proposed personalization models based on product variety breadth and the intensity of customer-firm interaction with a focus on marketing strategies ranging from basic product versioning to customerization and reverse marketing. However, some studies have shown that the explosion of product variety may generate information overload. Moreover, customers are highly heterogeneous in willingness and ability to interact with firms in personalization processes. This often results in consumer confusion and wasteful investments. To address this problem, we propose a conceptual framework of e-customer profiling for interactive personalization by distinguishing content (that is, expected customer benefits) and process (that is, expected degree of interaction) issues. The framework focuses on four general dimensions suggested by previous research as significant drivers of online customer heterogeneity: VALUE, KNOWLEDGE, ORIENTATION, and RELATIONSHIP QUALITY. We also present a preliminary test of the framework and derive directions for customer relationship management and future research. |
Jinmian Yang; Nan Li; Suiping Wang; Timothy J. Slattery; Keith Rayner Encoding the target or the plausible preview word? The nature of the plausibility preview benefit in reading Chinese Journal Article In: Visual Cognition, vol. 22, no. 2, pp. 193–213, 2014. @article{Yang2014a, Previous studies have shown that a plausible preview word can facilitate the processing of a target word as compared to an implausible preview word (a plausibility preview benefit effect) when reading Chinese (Yang, Wang, Tong, & Rayner, 2012; Yang, 2013). Regarding the nature of this effect, it is possible that readers processed the meaning of the plausible preview word and did not actually encode the target word (given that the parafoveal preview word lies close to the fovea). The current experiment examined this possibility with three conditions wherein readers received a preview of a target word that was either (1) identical to the target word (identical preview), (2) a plausible continuation of the pre-target text, but the post-target text in the sentence was incompatible with it (initially plausible preview), or (3) not a plausible continuation of the pre-target text, nor compatible with the post-target text (implausible preview). Gaze durations on target words were longer in the initially plausible condition than the identical condition. Overall, the results showed a typical preview benefit, but also implied that readers did not encode the initially plausible preview. Also, a plausibility preview benefit was replicated: gaze durations were longer with implausible previews than the initially plausible ones. Furthermore, late eye movement measures did not reveal differences between the initially plausible and the implausible preview conditions, which argues against the possibility of misreading the plausible preview word as the target word. In sum, these results suggest that a plausible preview word provides benefit in processing the target word as compared to an implausible preview word, and this benefit is only present in early but not late eye movement measures. |
Xiaohong Yang; Lijing Chen; Yufang Yang The effect of discourse structure on depth of semantic integration in reading Journal Article In: Memory & Cognition, vol. 42, no. 2, pp. 325–339, 2014. @article{Yang2014b, A coherent discourse exhibits certain structures in that subunits of discourses are related to one another in various ways and in that subunits that contribute to the same discourse purpose are joined to create a larger unit so as to produce an effect on the reader. To date, this crucial aspect of discourse has been largely neglected in the psycholinguistic literature. In two experiments, we examined whether semantic integration in discourse context was influenced by the difference of discourse structure. Readers read discourses in which the last sentence was locally congruent but either semantically congruent or incongruent when interpreted with the preceding sentence. Furthermore, the last sentence was either in the same discourse unit or not in the same discourse unit as the preceding sentence, depending on whether they shared the same discourse purpose. Results from self-paced reading (Experiment 1) and eye tracking (Experiment 2) showed that discourse-incongruous words were read longer than discourse-congruous words only when the critical sentence and the preceding sentence were in the same discourse unit, but not when they belonged to different discourse units. These results establish discourse structure as a new factor in semantic integration and suggest that discourse effects depend both on the content of what is being said and on the way that the contents are organized. |
Shanna C. Yeung; Cristina Rubino; Jaya Viswanathan; Jason J. S. Barton The inter-trial effect of prepared but not executed antisaccades Journal Article In: Experimental Brain Research, vol. 232, no. 12, pp. 3699–3705, 2014. @article{Yeung2014, A preceding antisaccade increases the latency of the saccade in the next trial. Whether this inter-trial effect is generated by the preparation or the execution of the antisaccade is not certain. Our goal was to examine the inter-trial effects from trials on which subjects prepared an antisaccade but did not make one. We tested 15 subjects on blocks of randomly ordered prosaccades and antisaccades. An instructional cue at fixation indicated whether a prosaccade or antisaccade was required, with the target appearing 2 s later. On 20 % of antisaccade trials, the target did not appear (prepared-only antisaccade trials). We analyzed the latencies of all correct prosaccades or antisaccades preceded by correctly executed trials. The latencies of prosaccade trials were 15 ms shorter if they were preceded by prosaccades than if the prior trial was an antisaccade. Prosaccades preceded by trials on which antisaccades were cued but not executed also showed prolonged latencies that were equivalent to those preceded by executed antisaccades. We conclude that the inter-trial effects from a prior antisaccade are generated by its preparation rather than its execution. This may reflect persistence of pre-target preparatory activity from the prior trial to affect that of the next trial in structures like the superior colliculus and frontal eye field. |
Luming Zhang; Yue Gao; Rongrong Ji; Yingjie Xia; Qionghai Dai; Xuelong Li Actively learning human gaze shifting paths for semantics-aware photo cropping Journal Article In: IEEE Transactions on Image Processing, vol. 23, no. 5, pp. 2235–2245, 2014. @article{Zhang2014, Photo cropping is a widely used tool in printing industry, photography, and cinematography. Conventional cropping models suffer from the following three challenges. First, the deemphasized role of semantic contents that are many times more important than low-level features in photo aesthetics. Second, the absence of a sequential ordering in the existing models. In contrast, humans look at semantically important regions sequentially when viewing a photo. Third, the difficulty of leveraging inputs from multiple users. Experience from multiple users is particularly critical in cropping as photo assessment is quite a subjective task. To address these challenges, this paper proposes semantics-aware photo cropping, which crops a photo by simulating the process of humans sequentially perceiving semantically important regions of a photo. We first project the local features (graphlets in this paper) onto the semantic space, which is constructed based on the category information of the training photos. An efficient learning algorithm is then derived to sequentially select semantically representative graphlets of a photo, and the selecting process can be interpreted by a path, which simulates humans actively perceiving semantics in a photo. Furthermore, we learn a prior distribution of such active graphlet paths from training photos that are marked as aesthetically pleasing by multiple users. The learned priors enforce the corresponding active graphlet path of a test photo to be maximally similar to those from the training photos. Experimental results show that: 1) the active graphlet path accurately predicts human gaze shifting, and thus is more indicative for photo aesthetics than conventional saliency maps and 2) the cropped photos produced by our approach outperform its competitors in both qualitative and quantitative comparisons. |
Peng Zhou; Stephen Crain; Likan Zhan Grammatical aspect and event recognition in children's online sentence comprehension Journal Article In: Cognition, vol. 133, no. 1, pp. 262–276, 2014. @article{Zhou2014, This study investigated whether or not the temporal information encoded in aspectual morphemes can be used immediately by young children to facilitate event recognition during online sentence comprehension. We focused on the contrast between two grammatical aspectual morphemes in Mandarin Chinese, the perfective morpheme -le and the (imperfective) durative morpheme -zhe. The perfective morpheme -le is often used to indicate that an event has been completed, whereas the durative morpheme -zhe indicates that an event is still in progress or continuing. We were interested to see whether young children are able to use the temporal reference encoded in the two aspectual morphemes (i.e., completed versus ongoing) as rapidly as adults to facilitate event recognition during online sentence comprehension. Using the visual world eye-tracking paradigm, we tested 34 Mandarin-speaking adults and 99 Mandarin-speaking children (35 three-year-olds, 32 four-year-olds and 32 five-year-olds). On each trial, participants were presented with spoken sentences containing either of the two aspectual morphemes while viewing a visual image containing two pictures, one representing a completed event and one representing an ongoing event. Participants' eye movements were recorded from the onset of the spoken sentences. The results show that both the adults and the three age groups of children exhibited a facilitatory effect trigged by the aspectual morpheme: hearing the perfective morpheme -le triggered more eye movements to the completed event area, whereas hearing the durative morpheme -zhe triggered more eye movements to the ongoing event area. This effect occurred immediately after the onset of the aspectual morpheme, both for the adults and the three groups of children. This is evidence that young children are able to use the temporal information encoded in aspectual morphemes as rapidly as adults to facilitate event recognition. Children's eye movement patterns reflect a rapid mapping of grammatical aspect onto the temporal structures of events depicted in the visual scene. |
Eckart Zimmermann; S. Born; Gereon R. Fink; P. Cavanagh Masking produces compression of space and time in the absence of eye movements Journal Article In: Journal of Neurophysiology, vol. 112, no. 12, pp. 3066–3076, 2014. @article{Zimmermann2014a, Whenever the visual stream is abruptly disturbed by eye movements, blinks, masks, or flashes of light, the visual system needs to retrieve the new locations of current targets and to reconstruct the timing of events to straddle the interruption. This process may introduce position and timing errors. We here report that very similar errors are seen in human subjects across three different paradigms when disturbances are caused by either eye movements, as is well known, or, as we now show, masking. We suggest that the characteristic effects of eye movements on position and time, spatial and temporal compression and saccadic suppression of displacement, are consequences of the interruption and the subsequent reconnection and are seen also when visual input is masked without any eye movements. Our data show that compression and suppression effects are not solely a product of ocular motor activity but instead can be properties of a correspondence process that links the targets of interest across interruptions in visual input, no matter what their source. |
Eckart Zimmermann; M. Concetta Morrone; David C. Burr The visual component to saccadic compression Journal Article In: Journal of Vision, vol. 14, no. 12, pp. 13–, 2014. @article{Zimmermann2014, Visual objects presented around the time of saccadic eye movements are strongly mislocalized towards the saccadic target, a phenomenon known as "saccadic compression." Here we show that perisaccadic compression is modulated by the presence of a visual saccadic target. When subjects saccaded to the center of the screen with no visible target, perisaccadic localization was more veridical than when tested with a target. Presenting a saccadic target sometime before saccade initiation was sufficient to induce mislocalization. When we systematically varied the onset of the saccade target, we found that it had to be presented around 100 ms before saccade execution to cause strong mislocalization: saccadic targets presented after this time caused progressively less mislocalization. When subjects made a saccade to screen center with a reference object placed at various positions, mislocalization was focused towards the position of the reference object. The results suggest that saccadic compression is a signature of a mechanism attempting to match objects seen before the saccade with those seen after. |
Benjamin A. Wolfe; David Whitney Facilitating recognition of crowded faces with presaccadic attention Journal Article In: Frontiers in Human Neuroscience, vol. 8, pp. 103, 2014. @article{Wolfe2014, In daily life, we make several saccades per second to objects we cannot normally recognize in the periphery due to visual crowding. While we are aware of the presence of these objects, we cannot identify them and may, at best, only know that an object is present at a particular location. The process of planning a saccade involves a presaccadic attentional component known to be critical for saccadic accuracy, but whether this or other presaccadic processes facilitate object identification as opposed to object detection-especially with high level natural objects like faces-is less clear. In the following experiments, we show that presaccadic information about a crowded face reduces the deleterious effect of crowding, facilitating discrimination of two emotional faces, even when the target face is never foveated. While accurate identification of crowded objects is possible in the absence of a saccade, accurate identification of a crowded object is considerably facilitated by presaccadic attention. Our results provide converging evidence for a selective increase in available information about high level objects, such as faces, at a presaccadic stage. |
Schnotz Wolfgang; Ludewig Ulrich; Ullrich Mark; Horz Holger; McElvany Nele; Baumert Jürgen Strategy shifts during learning from texts and pictures Journal Article In: Journal of Educational Psychology, vol. 106, no. 4, pp. 974, 2014. @article{Wolfgang2014, Reading for learning frequently requires integrating text and picture information into coherent knowledge structures. This article presents an experimental study aimed at analyzing the strategies used by students for integrating text and picture information. Four combinations of texts and pictures (text–picture units) were selected from textbooks on biology and geography, each combined with 3 comprehension test items of different complexity. Item difficulties were assessed in terms of item-response theory and through a cognitive task analysis. The texts, pictures, and items were presented to 40 students from Grades 5 and 8 from the higher tier and the lower tier of the German school system. Participants were asked to process the material and answer the items. Students' eye movements were recorded and analyzed in terms of number of fixations on different areas of interest as well as eye-movement transitions between these areas. Results suggest that text and pictures serve fundamentally different functions associated with different processing strategies in goal-directed knowledge acquisition. Texts are more likely to be used for coherence-oriented general processing. They guide the learner's conceptual analysis of the subject matter, which results in a coherent semantic network and initial mental model. Pictures are used as scaffolds for the initial mental model construction. Afterward, however, they are more likely to be used for task-driven selective processing serving as easily accessible visual representations on demand for item-specific mental model updates. |
Caitlin A. Wright; Keith S. Dobson; Christopher R. Sears Does a high working memory capacity attenuate the negative impact of trait anxiety on attentional control? Evidence from the antisaccade task Journal Article In: Journal of Cognitive Psychology, vol. 26, no. 4, pp. 400–412, 2014. @article{Wright2014, According to attentional control theory, high trait anxious individuals experience reduced attentional control as compared to low trait anxious individuals due to the imbalance between goal-directed and stimulus-driven attentional systems. One consequence is that high trait anxious individuals have difficulty resisting distraction, as compared to low trait anxious individuals. A separate line of research on individual differences in working memory capacity (WMC) has shown that individuals with higher WMC have better attentional control and thus are better able to resist distraction. The present study investigated the hypothesis that high WMC compensates for high trait anxiety in a task that evaluates the ability to resist distraction, the antisaccade task. Participants completed the State-Trait Anxiety Inventory to measure trait anxiety and the Operation Span and Reading Span tasks to measure WMC. As hypothesised, individuals who were high trait anxious exhibited increased attentional control on the antisaccade task when they had high WMC. Theoretical implications and directions for future research are discussed. |
Jessica M. Wright; Bart Krekelberg Transcranial direct current stimulation over posterior parietal cortex modulates visuospatial localization Journal Article In: Journal of Vision, vol. 14, no. 9, pp. 5–5, 2014. @article{Wright2014a, Visual localization is based on the complex interplay of bottom-up and top-down processing. Based on previous work, the posterior parietal cortex (PPC) is assumed to play an essential role in this interplay. In this study, we investigated the causal role of the PPC in visual localization. Specifically, our goal was to determine whether modulation of the PPC via transcranial direct current stimulation (tDCS) could induce visual mislocalization similar to that induced by an exogenous attentional cue (Wright, Morris, & Krekelberg, 2011). We placed one stimulation electrode over the right PPC and the other over the left PPC (dual tDCS) and varied the polarity of the stimulation. We found that this manipulation altered visual localization; this supports the causal involvement of the PPC in visual localization. Notably, mislocalization was more rightward when the cathode was placed over the right PPC than when the anode was placed over the right PPC. This mislocalization was found within a few minutes of stimulation onset, it dissipated during stimulation, but then resurfaced after stimulation offset and lasted for another 10-15 min. On the assumption that excitability is reduced beneath the cathode and increased beneath the anode, these findings support the view that each hemisphere biases processing to the contralateral hemifield and that the balance of activation between the hemispheres contributes to position perception (Kinsbourne, 1977; Szczepanski, Konen, & Kastner, 2010). |
Chia-Chien Wu; Hsueh-Cheng Wang; Marc Pomplun The roles of scene gist and spatial dependency among objects in the semantic guidance of attention in real-world scenes Journal Article In: Vision Research, vol. 105, pp. 10–20, 2014. @article{Wu2014, A previous study (Vision Research 51 (2011) 1192-1205) found evidence for semantic guidance of visual attention during the inspection of real-world scenes, i.e., an influence of semantic relationships among scene objects on overt shifts of attention. In particular, the results revealed an observer bias toward gaze transitions between semantically similar objects. However, this effect is not necessarily indicative of semantic processing of individual objects but may be mediated by knowledge of the scene gist, which does not require object recognition, or by known spatial dependency among objects. To examine the mechanisms underlying semantic guidance, in the present study, participants were asked to view a series of displays with the scene gist excluded and spatial dependency varied. Our results show that spatial dependency among objects seems to be sufficient to induce semantic guidance. Scene gist, on the other hand, does not seem to affect how observers use semantic information to guide attention while viewing natural scenes. Extracting semantic information mainly based on spatial dependency may be an efficient strategy of the visual system that only adds little cognitive load to the viewing task. |
David W. -L. Wu; Nicola C. Anderson; Walter F. Bischof; Alan Kingstone Temporal dynamics of eye movements are related to differences in scene complexity and clutter Journal Article In: Journal of Vision, vol. 14, no. 9, pp. 8–8, 2014. @article{Wu2014a, Recent research has begun to explore not just the spatial distribution of eye fixations but also the temporal dynamics of how we look at the world. In this investigation, we assess how scene characteristics contribute to these fixation dynamics. In a free-viewing task, participants viewed three scene types: fractal, landscape, and social scenes. We used a relatively new method, recurrence quantification analysis (RQA), to quantify eye movement dynamics. RQA revealed that eye movement dynamics were dependent on the scene type viewed. To understand the underlying cause for these differences we applied a technique known as fractal analysis and discovered that complexity and clutter are two scene characteristics that affect fixation dynamics, but only in scenes with meaningful content. Critically, scene primitives—revealed by saliency analysis—had no impact on performance. In addition, we explored how RQA differs from the first half of the trial to the second half, as well as the potential to investigate the precision of fixation targeting by changing RQA radius values. Collectively, our results suggest that eye movement dynamics result from top- down viewing strategies that vary according to the meaning of a scene and its associated visual complexity and clutter. |
David W. -L. Wu; Walter F. Bischof; Nicola C. Anderson; Tanya Jakobsen; Alan Kingstone The influence of personality on social attention Journal Article In: Personality and Individual Differences, vol. 60, pp. 25–29, 2014. @article{Wu2014b, The intersection between personality psychology and the study of social attention has been relatively untouched. We present an initial study that investigates the influence of the Big Five personality traits on eye movement behaviour towards social stimuli. By combining a free-viewing eye-tracking paradigm with canonical correlation and regression analyses, we discover that personality relates to fixations towards eye regions. Specifically, Extraversion and Agreeableness were related to greater gaze selection, while Openness to Experience was related to diminished gaze selection. The results demonstrate that who a person is affects how they move their eyes to social stimuli. The results also indicate that personality is a stronger factor in predicting social attention than past studies have suggested. Critical to the influence of personality on attention is the social situations viewers are placed in. |
Fuyun Wu; Yingyi Luo; Xiaolin Zhou Building Chinese relative clause structures with lexical and syntactic cues: Evidence from visual world eye-tracking and reading times Journal Article In: Language, Cognition and Neuroscience, vol. 29, no. 10, pp. 1205–1226, 2014. @article{Wu2014c, Relative clauses (RCs) in Chinese are prenominal. In object-modifying, object-extracted RCs (e.g. Click on [RC the ball broke] window, meaning 'Click on the window [RC that the ball broke]), the ambiguous status of the local noun ball and the long-distance attachment of the head noun window into the main verb appear to make online parsing of Chinese RCs particularly difficult. By interposing mismatching classifiers and the passive marker BEI into the RC sentences, we investigated whether the presence of incomplete heads would add storage costs, as predicted by the Dependency Locality Theory (DLT), or would serve as retrieval cues to help pre-build the RC structure, as predicted by the cue-based retrieval theory. Results from a visual world eye-tracking experiment and a self-paced reading showed that Chinese comprehenders are able to use BEI cues and the mismatching classifier (albeit to a less extent) to pre-build RC structure, providing support for the cue-based retrieval theory. |
Jianbo Xiao; Yu-Qiong Niu; Steven Wiesner; Xin Huang Normalization of neuronal responses in cortical area MT across signal strengths and motion directions Journal Article In: Journal of Neurophysiology, vol. 112, no. 6, pp. 1291–1306, 2014. @article{Xiao2014, Multiple visual stimuli are common in natural scenes, yet it remains unclear how multiple stimuli interact to influence neuronal responses. We investigated this question by manipulating relative signal strengths of two stimuli moving simultaneously within the receptive fields (RFs) of neurons in the extrastriate middle temporal (MT) cortex. Visual stimuli were overlapping random-dot patterns moving in two directions separated by 90°. We first varied the motion coherence of each random-dot pattern and characterized, across the direction tuning curve, the relationship between neuronal responses elicited by bidirectional stimuli and by the constituent motion components. The tuning curve for bidirectional stimuli showed response normalization and can be accounted for by a weighted sum of the responses to the motion components. Allowing nonlinear, multiplicative interaction between the two component responses significantly improved the data fit for some neurons, and the interaction mainly had a suppressive effect on the neuronal response. The weighting of the component responses was not fixed but dependent on relative signal strengths. When two stimulus components moved at different coherence levels, the response weight for the higher-coherence component was significantly greater than that for the lower-coherence component. We also varied relative luminance levels of two coherently moving stimuli and found that MT response weight for the higher-luminance component was also greater. These results suggest that competition between multiple stimuli within a neuron's RF depends on relative signal strengths of the stimuli and that multiplicative nonlinearity may play an important role in shaping the response tuning for multiple stimuli. |
Juan Xu; Ming Jiang; Shuo Wang; Mohan S. Kankanhalli; Qi Zhao Predicting human gaze beyond pixels Journal Article In: Journal of Vision, vol. 14, no. 1, pp. 1–20, 2014. @article{Xu2014, A large body of previous models to predict where people look in natural scenes focused on pixel-level image attributes. To bridge the semantic gap between the predictive power of computational saliency models and human behavior, we propose a new saliency architecture that incorporates information at three layers: pixel-level image attributes, object-level attributes, and semantic- level attributes. Object- and semantic-level information is frequently ignored, or only a few sample object categories are discussed where scaling to a large number of object categories is not feasible nor neurally plausible. To address this problem, this work constructs a principled vocabulary of basic attributes to describe object- and semantic-level information thus not restricting to a limited number of object categories. We build a new dataset of 700 images with eye-tracking data of 15 viewers and annotation data of 5,551 segmented objects with fine contours and 12 semantic attributes (publicly available with the paper). Experimental results demonstrate the importance of the object- and semantic-level information in the prediction of visual attention. |
Keir X. X. Yong; Timothy J. Shakespeare; Dave Cash; Susie M. D. Henley; Jennifer M. Nicholas; Gerard R. Ridgway; Hannah L. Golden; Elizabeth K. Warrington; Amelia M. Carton; Diego Kaski; Jonathan M. Schott; Jason D. Warren; Sebastian J. Crutch Prominent effects and neural correlates of visual crowding in a neurodegenerative disease population Journal Article In: Brain, vol. 137, no. 12, pp. 3284–3299, 2014. @article{Yong2014, Crowding is a breakdown in the ability to identify objects in clutter, and is a major constraint on object recognition. Crowding particularly impairs object perception in peripheral, amblyopic and possibly developing vision. Here we argue that crowding is also a critical factor limiting object perception in central vision of individuals with neurodegeneration of the occipital cortices. In the current study, individuals with posterior cortical atrophy (n=26), typical Alzheimer's disease (n=17) and healthy control subjects (n=14) completed centrally-presented tests of letter identification under six different flanking conditions (unflanked, and with letter, shape, number, same polarity and reverse polarity flankers) with two different target-flanker spacings (condensed, spaced). Patients with posterior cortical atrophy were significantly less accurate and slower to identify targets in the condensed than spaced condition even when the target letters were surrounded by flankers of a different category. Importantly, this spacing effect was observed for same, but not reverse, polarity flankers. The difference in accuracy between spaced and condensed stimuli was significantly associated with lower grey matter volume in the right collateral sulcus, in a region lying between the fusiform and lingual gyri. Detailed error analysis also revealed that similarity between the error response and the averaged target and flanker stimuli (but not individual target or flanker stimuli) was a significant predictor of error rate, more consistent with averaging than substitution accounts of crowding. Our findings suggest that crowding in posterior cortical atrophy can be regarded as a pre-attentive process that uses averaging to regularize the pathologically noisy representation of letter feature position in central vision. These results also help to clarify the cortical localization of feature integration components of crowding. More broadly, we suggest that posterior cortical atrophy provides a neurodegenerative disease model for exploring the basis of crowding. These data have significant implications for patients with, or who will go on to develop, dementia-related visual impairment, in whom acquired excessive crowding likely contributes to deficits in word, object, face and scene perception. |
Si On Yoon; Sarah Brown-Schmidt Adjusting conceptual pacts in three-party conversation Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 40, no. 4, pp. 919–937, 2014. @article{Yoon2014, During conversation, partners develop representations of jointly known information-the common ground-and use this knowledge to guide subsequent linguistic exchanges. Extensive research on 2-party conversation has offered key insights into this process, in particular, its partner-specificity: Common ground that is shared with 1 partner is not always assumed to be shared with other partners. Conversation often involves multiple pairs of individuals who differ in common ground. Yet, little is known about common ground processes in multi-party conversation. Here, we take a 1st step toward understanding this problem by examining situations in which simple dyadic representations of common ground might cause difficulty-situations in which dialogue partners develop shared labels (entrained terms), and then a 3rd (naïve) party joins the conversation. Experiment 1 examined unscripted, task-based conversation in which 2 partners entrained on terms. At test, speakers referenced game-pieces in a dialogue with their partner, or in a 3-party conversation including a new, naïve listener. Speakers were sensitive to the 3rd party, using longer, disfluent expressions when additionally addressing the new partner. By contrast, analysis of listener eye-fixations did not suggest sensitivity. Experiment 2 provided a stronger test of sensitivity and revealed that listeners do cancel expectations for terms that had been entrained before when a 3rd, naïve party joins the conversation. These findings shed light on the mechanisms underlying common ground, showing that rather than a unitary construct, common ground is flexibly adapted to the needs of a naïve 3rd party. |
Angela J. Yu; He Huang; Pradeep Shenoy Maximizing masquerading as matching in human visuosaccadic choice Journal Article In: Cognitive Science, vol. 1, no. 4, pp. 1–23, 2014. @article{Yu2014, There has been a long-running debate over whether humans match or maximize when faced with differentially rewarding options under conditions of uncertainty. While maximizing, that is, consistently choosing the most rewarding option, is theoretically optimal, humans have often been observed to match, that is, allocating choices stochastically in proportion to the underlying reward rates. Previous models assumed matching behavior to arise from biological limitations or heuristic decision strategies; this, however, would stand in curious contrast to the accumulating evidence that humans have sophisticated machinery for tracking environmental statistics. It begs the questions of why the brain would build sophisticated representations of environmental statistics, only then to adopt a heuristic decision policy that fails to take full advantage of that information. Here, we revisit this debate by presenting data from a novel visual search task, which are shown to favor a particular Bayesian inference and decision- making account over other heuristic and normative models. Specifically, while sub- jects' first-fixation strategy appears to indicate matching in aggregate data, they actually maximize on a finer, trial-by-trial timescale, based on continuously updated internal beliefs about the spatial distribution of potential target locations. In other words, matching-like stochasticity in human visual search is neither random nor heuristics- based, but attributable specifically to fluctuating beliefs about stimulus statistics. These results not only shed light on the matching versus maximizing debate, but also more broadly on human decision-making strategies under conditions of uncertainty. |
Shlomit Yuval-Greenberg; Elisha P. Merriam; David J. Heeger Spontaneous microsaccades reflect shifts in covert attention Journal Article In: Journal of Neuroscience, vol. 34, no. 41, pp. 13693–13700, 2014. @article{YuvalGreenberg2014, Microsaccade rate during fixation is modulated by the presentation of a visual stimulus. When the stimulus is an endogenous attention cue, the ensuing microsaccades tend to be directed toward the cue. This finding has been taken as evidence that microsaccades index the locus of spatial attention. But the vast majority of microsaccades that subjects make are not triggered by visual stimuli. Under natural viewing conditions, spontaneous microsaccades occur frequently (2-3 Hz), even in the absence of a stimulus or a task. While spontaneous microsaccades may depend on low-level visual demands, such as retinal fatigue, image fading, or fixation shifts, it is unknown whether their occurrence corresponds to changes in the attentional state. We developed a protocol to measure whether spontaneous microsaccades reflect shifts in spatial attention. Human subjects fixated a cross while microsaccades were detected from streaming eye-position data. Detection of a microsaccade triggered the appearance of a peripheral ring of grating patches, which were followed by an arrow (a postcue) indicating one of them as the target. The target was either congruent or incongruent (opposite) with respect to the direction of the microsaccade (which preceded the stimulus). Subjects reported the tilt of the target (clockwise or counterclockwise relative to vertical). We found that accuracy was higher for congruent than for incongruent trials. We conclude that the direction of spontaneous microsaccades is inherently linked to shifts in spatial attention. |
A. Zenon; M. Sidibe; Etienne Olivier Pupil size variations correlate with physical effort perception Journal Article In: Frontiers in Behavioral Neuroscience, vol. 8, pp. 286, 2014. @article{Zenon2014, It has long been established that the pupil diameter increases during mental activities in proportion to the difficulty of the task at hand. However, it is still unclear whether this relationship between the pupil size and effort applies also to physical effort. In order to address this issue, we asked healthy volunteers to perform a power grip task, at varied intensity, while evaluating their effort both implicitly and explicitly, and while concurrently monitoring their pupil size. Each trial started with a contraction of imposed intensity, under the control of a continuous visual feedback. Upon completion of the contraction, participants had to choose whether to replicate, without feedback, the first contraction for a variable monetary reward, or whether to skip this step and go directly to the next trial. The rate of acceptance of effort replication and the amount of force exerted during the replication were used as implicit measures of the perception of the effort exerted during the first contraction. In addition, the participants were asked to rate on an analog scale, their explicit perception of the effort for each intensity condition. We found that pupil diameter increased during physical effort and that the magnitude of this response reflected not only the actual intensity of the contraction but also the subjects' perception of the effort. This finding indicates that the pupil size signals the level of effort invested in a task, irrespective of whether it is physical or mental. It also helps refining the potential brain circuits involved since the results of the current study imply a convergence of mental and physical effort information at some level along this pathway. |
Alexandre Zénon; Brian D. Corneil; Andrea Alamia; Nabil Filali-Sadouk; Etienne Olivier Counterproductive effect of saccadic suppression during attention shifts Journal Article In: PLoS ONE, vol. 9, no. 1, pp. e86633, 2014. @article{Zenon2014a, During saccadic eye movements, the processing of visual information is transiently interrupted by a mechanism known as "saccadic suppression" [1] that is thought to ensure perceptual stability [2]. If, as proposed in the premotor theory of attention [3], covert shifts of attention rely on sub-threshold recruitment of oculomotor circuits, then saccadic suppression should also occur during covert shifts. In order to test this prediction, we designed two experiments in which participants had to orient towards a cued letter, with or without saccades. We analyzed the time course of letter identification score in an "attention" task performed without saccades, using the saccadic latencies measured in the "saccade" task as a marker of covert saccadic preparation. Visual conditions were identical in all tasks. In the "attention" task, we found a drop in perceptual performance around the predicted onset time of saccades that were never performed. Importantly, this decrease in letter identification score cannot be explained by any known mechanism aligned on cue onset such as inhibition of return, masking, or microsaccades. These results show that attentional allocation triggers the same suppression mechanisms as during saccades, which is relevant during eye movements but detrimental in the context of covert orienting. |
Simona Mancini; Nicola Molinaro; Douglas J. Davidson; Alberto Avilés; Manuel Carreiras Person and the syntax-discourse interface: An eye-tracking study of agreement Journal Article In: Journal of Memory and Language, vol. 76, pp. 141–157, 2014. @article{Mancini2014, The time-course of agreement processing was investigated through three eye-tracking experiments and one grammaticality judgment task by making use of the Spanish Unagreement pattern, which allows the presence of a 3rd person plural subject followed by a 1st person plural verb, as in Los manifestantes anunciamos una huelga (The protesters3.plannounced1.pla strike). Grammaticality is ensured by re-interpreting the subject as 1st person plural, thereby changing the underlying discourse composition of the sentence (We protesters announced a strike). The comparison of Unagreement with structurally similar sentences (Experiment 1), truly person-anomalous sentences (Experiments 2 and 3) and discourse-incongruent sentences (Experiment 4) revealed a clear dissociation between morphosyntactic-related and discourse-related analysis in agreement comprehension. The constant first-pass effect elicited by Unagreement with respect to structurally similar (grammatical and ungrammatical) sentences across the four experiments evidences the sensitivity of early stages to morphosyntactic evaluation, while the differential effect for discourse-congruous and discourse-incongruous sentences in later measures suggests that discourse-related analyses are dealt with by the parser in subsequent stages of processing. |
Anne Mandel; Siiri Helokunnas; Elina Pihko; Riitta Hari Neuromagnetic brain responses to other person's eye blinks seen on video Journal Article In: European Journal of Neuroscience, vol. 40, pp. 2576–2580, 2014. @article{Mandel2014, Eye blinks, typically occurring 15–20 times per minute, rarely capture attention during face-to-face interaction. To determine the extent to which eye blinks affect the viewer's brain activity, we recorded magnetoencephalographic brain responses to natural blinks, and to the same blinks slowed down to 38% of the original speed. The stimuli were presented on video once every 2.3–6.2 s. As a control, we presented two horizontal black bars moving with the same time courses and the same extent as the eyelids in the blink video. Both types of blinks and bars elicited clear responses peaking at about 200 ms in the occipital areas, with no systematic differences between hemispheres. For the bars, these main responses were (as expected) weaker (by 24%) and later (by 33 ms) to slowmotion than normal-speed stimuli. For blinks, however, the responses to both normal-speed and slow-motion stimuli were of the same amplitude and latency. Our results demonstrate that the brain not only responds to other persons' eye blinks, but that the responses are as fast and of equal size even when the blinks are considerably slowed down. We interpret this finding to reflect the increased social salience of the slowed-down blinks that counteracted the general tendency of the brain to react more weakly and more slowly to slowly- vs. quickly-changing stimuli. This finding may relate to the social importance of facial gestures, including eye blinks. |
Klara Marečková; Jennifer S. Perrin; Irum Nawaz Khan; Claire Lawrence; Erin Dickie; Douglas A. McQuiggan; Tomáš Paus Hormonal contraceptives, menstrual cycle and brain response to faces Journal Article In: Social Cognitive and Affective Neuroscience, vol. 9, no. 2, pp. 191–200, 2014. @article{Mareckova2014, Both behavioral and neuroimaging evidence support a female advantage in the perception of human faces. Here we explored the possibility that this relationship may be partially mediated by female sex hormones by investigating the relationship between the brain's response to faces and the use of oral contraceptives, as well as the phase of the menstrual cycle. First, functional magnetic resonance images were acquired in 20 young women [10 freely cycling and 10 taking oral contraception (OC)] during two phases of their cycle: mid-cycle and menstruation. We found stronger neural responses to faces in the right fusiform face area (FFA) in women taking oral contraceptives (vs freely cycling women) and during mid-cycle (vs menstruation) in both groups. Mean blood oxygenation level-dependent response in both left and right FFA increased as function of the duration of OC use. Next, this relationship between the use of OC and FFA response was replicated in an independent sample of 110 adolescent girls. Finally in a parallel behavioral study carried out in another sample of women, we found no evidence of differences in the pattern of eye movements while viewing faces between freely cycling women vs those taking oral contraceptives. The imaging findings might indicate enhanced processing of social cues in women taking OC and women during mid-cycle. |
Jun Maruta; Kristin J. Heaton; Alexis L. Maule; Jamshid Ghajar Predictive visual tracking: Specificity in nild traumatic brain injury and sleep deprivation Journal Article In: Military Medicine, vol. 179, no. 6, pp. 619–625, 2014. @article{Maruta2014, We tested whether reduced cognitive function associated with mild traumatic brain injury (mTBI) and sleep deprivation can be detected and distinguished using indices of predictive visual tracking. A circular visual tracking test was given to 13 patients with acute mTBI (recruited within 2 weeks of injury), 127 normal control subjects, and 43 healthy subjects who were fatigued by 26-hour sleep deprivation. Eye movement was monitored with video-oculography. In the mTBI-related portion of the study, visual tracking performance of acute mTBI patients was significantly worse than normal subjects (p < 0.001). In the sleep-deprivation-related portion of the study, no change was detected between the two baseline measures separated by 2 to 3 weeks, but the 26-hour sleep deprivation significantly degraded the visual tracking performance (p < 0.001). The mTBI subjects had substantially worse visual tracking than sleep-deprived subjects that could also be identified with different visual tracking indices, indicating possible different neurophysiological mechanisms. Results suggest that cognitive impairment associated with mTBI and fatigue may be triaged with the aid of visual tracking measures. |
Heath Matheson; Aaron J. Newman; Jason Satel; Patricia A. McMullen Handles of manipulable objects attract covert visual attention: ERP evidence Journal Article In: Brain and Cognition, vol. 86, no. 1, pp. 17–23, 2014. @article{Matheson2014, Previous research has demonstrated that people are faster at making a manual response with the hand that is aligned with the handle of a manipulable object compared to its functional end. According to theories of embodied cognition (ETC), the presentation of a manipulable object automatically elicits sensorimotor simulations of the respective hand and these simulations facilitate the response. However, an alternative interpretation of these data is that handles preferentially attract visual attention, since attended stimuli and locations typically elicit faster responses. We investigated attentional biases elicited by manipulable and non-manipulable objects using event-related-potentials (ERPs). On each trial, a picture of a manipulable object was followed by a target dot that participants had to make a button-press to. The dot was located at either the handle or functional end of the object. Consistent with previous attentional cuing paradigms, we showed that the P1 ERP component was greater in response to targets cued by handles than by functional ends. These results suggest that object handles automatically bias covert attentional processes. These attentional biases may account for earlier behavioural findings, without any recourse to ETC. |
Sebastiaan Mathot; Edwin S. Dalmaijer; Jonathan Grainger; Stefan Van der Stigchel The pupillary light response reflects exogenous attention and inhibition of return Journal Article In: Journal of Vision, vol. 14, no. 14, pp. 1–9, 2014. @article{Mathot2014, Here we show that the pupillary light response reflects exogenous (involuntary) shifts of attention and inhibition of return. Participants fixated in the center of a display that was divided into a bright and a dark half. An exogenous cue attracted attention to the bright or dark side of the display. Initially, the pupil constricted when the bright, as compared to the dark, side of the display was cued, reflecting a shift of attention toward the exogenous cue. Crucially, this pattern reversed about 1 s after cue presentation. This later-occurring, relative dilation (when the bright side was cued) reflected disengagement from the previously attended location, analogous to the behavioral phenomenon of inhibition of return. Indeed, we observed a reliable correlation between ‘‘pupillary inhibition'' and behavioral inhibition of return. Our results support the view that inhibition of return results from habituation to (or short-term depression of) visual input. We conclude that the pupillary light response is a complex eye movement that reflects how we selectively parse and interpret visual input. |
Shunichi Matsuda; Hideyuki Matsumoto; Toshiaki Furubayashi; Hideki Fukuda; Masaki Emoto; Ritsuko Hanajima; Shoji Tsuji; Yoshikazu Ugawa; Yasuo Terao Top-down but not bottom-up visual scanning is affected in hereditary pure cerebellar ataxia Journal Article In: PLoS ONE, vol. 9, no. 12, pp. e116181, 2014. @article{Matsuda2014, The aim of this study was to clarify the nature of visual processing deficits caused by cerebellar disorders. We studied the performance of two types of visual search (top-down visual scanning and bottom-up visual scanning) in 18 patients with pure cerebellar types of spinocerebellar degeneration (SCA6: 11; SCA31: 7). The gaze fixation position was recorded with an eye-tracking device while the subjects performed two visual search tasks in which they looked for a target Landolt figure among distractors. In the serial search task, the target was similar to the distractors and the subject had to search for the target by processing each item with top-down visual scanning. In the pop-out search task, the target and distractor were clearly discernible and the visual salience of the target allowed the subjects to detect it by bottom-up visual scanning. The saliency maps clearly showed that the serial search task required top-down visual attention and the pop-out search task required bottom-up visual attention. In the serial search task, the search time to detect the target was significantly longer in SCA patients than in normal subjects, whereas the search time in the pop-out search task was comparable between the two groups. These findings suggested that SCA patients cannot efficiently scan a target using a top-down attentional process, whereas scanning with a bottom-up attentional process is not affected. In the serial search task, the amplitude of saccades was significantly smaller in SCA patients than in normal subjects. The variability of saccade amplitude (saccadic dysmetria), number of re-fixations, and unstable fixation (nystagmus) were larger in SCA patients than in normal subjects, accounting for a substantial proportion of scattered fixations around the items. Saccadic dysmetria, re-fixation, and nystagmus may play important roles in the Impaired top-down visual scanning in SCA, hampering precise visual processing of individual items. |
Angelina Paolozza; Carmen Rasmussen; Jacqueline Pei; Ana Hanlon-Dearman; Sarah M. Nikkel; Gail Andrew; Audrey McFarlane; Dawa Samdup; James N. Reynolds Working memory and visuospatial deficits correlate with oculomotor control in children with fetal alcohol spectrum disorder Journal Article In: Behavioural Brain Research, vol. 263, pp. 70–79, 2014. @article{Paolozza2014a, Previous studies have demonstrated that children with Fetal Alcohol Spectrum Disorder (FASD) exhibit deficits in measures of eye movement control that probe aspects of visuospatial processing and working memory. The goal of the present study was to examine, in a large cohort of children with FASD, prenatal alcohol exposure (PAE) but not FASD, and typically developing control children, the relationship between performance in eye movement tasks and standardized psychometric tests that assess visuospatial processing and working memory. Participants for this dataset were drawn from a large, multi-site investigation, and included children and adolescents aged 5-17 years diagnosed with an FASD (n=71), those with PAE but no clinical FASD diagnosis (n=20), and typically developing controls (n=111). Participants completed a neurobehavioral test battery and a series of saccadic eye movement tasks. The FASD group performed worse than controls on the psychometric and eye movement measures of working memory and visuospatial skills. Within the FASD group, digit recall, block recall, and animal sorting were negatively correlated with sequence errors on the memory-guided task, and arrows was negatively correlated with prosaccade endpoint error. There were no significant correlations in the control group. These data suggest that psychometric tests and eye movement control tasks may assess similar domains of cognitive function, and these assessment tools may be measuring overlapping brain regions damaged due to prenatal alcohol exposure. The results of this study demonstrate that eye movement control tasks directly relate to outcome measures obtained with psychometric tests and are able to assess multiple domains of cognition simultaneously, thereby allowing for an efficient and accurate assessment. |
Angelina Paolozza; Carmen Rasmussen; Jacqueline Pei; Ana Hanlon-Dearman; Sarah M. Nikkel; Gail Andrew; Audrey McFarlane; Dawa Samdup; James N. Reynolds Deficits in response inhibition correlate with oculomotor control in children with fetal alcohol spectrum disorder and prenatal alcohol exposure Journal Article In: Behavioural Brain Research, vol. 259, pp. 97–105, 2014. @article{Paolozza2014, Children with fetal alcohol spectrum disorder (FASD) or prenatal alcohol exposure (PAE) frequently exhibit impairment on tasks measuring inhibition. The objective of this study was to determine if a performance-based relationship exists between psychometric tests and eye movement tasks in children with FASD. Participants for this dataset were aged 5-17 years and included those diagnosed with an FASD (n= 72), those with PAE but no clinical FASD diagnosis (n= 21), and typically developing controls (n= 139). Participants completed a neurobehavioral test battery, which included the NEPSY-II subtests of auditory attention, response set, and inhibition. Each participant completed a series of saccadic eye movement tasks, which included the antisaccade and memory-guided tasks. Both the FASD and the PAE groups performed worse than controls on the subtest measures of attention and inhibition. Compared with controls, the FASD group made more errors on the antisaccade and memory-guided tasks. Among the combined FASD/PAE group, inhibition and switching errors were negatively correlated with direction errors on the antisaccade task but not on the memory-guided task. There were no significant correlations in the control group. These data suggests that response inhibition deficits in children with FASD/PAE are associated with difficulty controlling saccadic eye movements which may point to overlapping brain regions damaged by prenatal alcohol exposure. The results of this study demonstrate that eye movement control tasks directly relate to outcome measures obtained with psychometric tests that are used during FASD diagnosis, and may therefore help with early identification of children who would benefit from a multidisciplinary diagnostic assessment. |
Angelina Paolozza; Sarah Treit; Christian Beaulieu; James N. Reynolds In: NeuroImage: Clinical, vol. 5, pp. 53–61, 2014. @article{Paolozza2014b, Response inhibition is the ability to suppress irrelevant impulses to enable goal-directed behavior. The underlying neural mechanisms of inhibition deficits are not clearly understood, but may be related to white matter connectivity, which can be assessed using diffusion tensor imaging (DTI). The goal of this study was to investigate the relationship between response inhibition during the performance of saccadic eye movement tasks and DTI measures of the corpus callosum in children with or without Fetal Alcohol Spectrum Disorder (FASD). Participants included 43 children with an FASD diagnosis (12.3 ± 3.1 years old) and 35 typically developing children (12.5 ± 3.0 years old) both aged 7-18, assessed at three sites across Canada. Response inhibition was measured by direction errors in an antisaccade task and timing errors in a delayed memory-guided saccade task. Manual deterministic tractography was used to delineate six regions of the corpus callosum and calculate fractional anisotropy (FA), mean diffusivity (MD), parallel diffusivity, and perpendicular diffusivity. Group differences in saccade measures were assessed using t-tests, followed by partial correlations between eye movement inhibition scores and corpus callosum FA and MD, controlling for age. Children with FASD made more saccade direction errors and more timing errors, which indicates a deficit in response inhibition. The only group difference in DTI metrics was significantly higher MD of the splenium in FASD compared to controls. Notably, direction errors in the antisaccade task were correlated negatively to FA and positively to MD of the splenium in the control, but not the FASD group, which suggests that alterations in connectivity between the two hemispheres of the brain may contribute to inhibition deficits in children with FASD. |
Eleni Papageorgiou; Rebecca J. McLean; Irene Gottlob Nystagmus in childhood Journal Article In: Pediatrics and Neonatology, vol. 55, no. 5, pp. 341–351, 2014. @article{Papageorgiou2014, Nystagmus is an involuntary rhythmic oscillation of the eyes, which leads to reduced visual acuity due to the excessive motion of images on the retina. Nystagmus can be grouped into infantile nystagmus (IN), which usually appears in the first 3-6 months of life, and acquired nystagmus (AN), which appears later. IN can be idiopathic or associated to albinism, retinal disease, low vision, or visual deprivation in early life, for example due to congenital cataracts, optic nerve hypoplasia, and retinal dystrophies, or it can be part of neurological syndromes and neurologic diseases. It is important to differentiate between infantile and acquired nystagmus. This can be achieved by considering not only the time of onset of the nystagmus, but also the waveform characteristics of the nystagmus. Neurological disease should be suspected when the nystagmus is asymmetrical or unilateral. Electrophysiology, laboratory tests, neurological, and imaging work-up may be necessary, in order to exclude any underlying ocular or systemic pathology in a child with nystagmus. Furthermore, the recent introduction of hand-held spectral domain optical coherence tomography (HH SD-OCT) provides detailed assessment of foveal structure in several pediatric eye conditions associated with nystagmus and it can been used to determine the underlying cause of infantile nystagmus. Additionally, the development of novel methods to record eye movements can help to obtain more detailed information and assist the diagnosis. Recent advances in the field of genetics have identified the FRMD7 gene as the major cause of hereditary X-linked nystagmus, which will possibly guide research towards gene therapy in the future. Treatment options for nystagmus involve pharmacological and surgical interventions. Clinically proven pharmacological treatments for nystagmus, such as gabapentin and memantine, are now beginning to emerge. In cases of obvious head posture, eye muscle surgery can be performed to shift the null zone of the nystagmus into the primary position, and also to alleviate neck problems that can arise due to an abnormal head posture. |
Cheolsoo Park; Markus Plank; Joseph Snider; Sanggyun Kim; He Crane Huang; Sergei Gepshtein; Todd P. Coleman; Howard Poizner In: IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol. 22, no. 5, pp. 1083–1096, 2014. @article{Park2014, The neural dynamics underlying the coordination of spatially-directed limb and eye movements in humans is not well understood. Part of the difficulty has been a lack of signal processing tools suitable for the analysis of non-stationary electroencephalographic (EEG) signals. Here we use multivariate empirical mode decomposition (MEMD), a data-driven approach that does not employ predefined basis functions. High-density EEG, and arm and eye movements were synchronously recorded in 10 subjects performing time-constrained reaching and/or eye movements. Subjects were allowed to move both the hand and the eyes, only the hand, or only the eyes following a 500-700 ms delay interval where the hand and gaze remained on a central fixation cross. An additional condition involved a non-spatially-directed "lift" movement of the hand. The neural activity during a 500 ms delay interval was decomposed into intrinsic mode functions (IMFs) usingMEMD. Classification analysis revealed that gamma band (30 Hz <) IMFs produced more classifiable features differentiating the EEG according to the different upcoming movements. A benchmark test using conventional algorithms demonstrated that MEMD was the best algorithm for extracting oscillatory bands from EEG, yielding the best classification of the different movement conditions. The gamma rhythm decomposed using MEMD showed a higher correlation with the eventual movement accuracy than any other band rhythm and than any other algorithm. |
Hyeong Dong Park; Stéphanie Correia; Antoine Ducorps; Catherine Tallon-Baudry Spontaneous fluctuations in neural responses to heartbeats predict visual detection Journal Article In: Nature Neuroscience, vol. 17, no. 4, pp. 612–618, 2014. @article{Park2014a, Spontaneous fluctuations of ongoing neural activity substantially affect sensory and cognitive performance. Because bodily signals are constantly relayed up to the neocortex, neural responses to bodily signals are likely to shape ongoing activity. Here, using magnetoencephalography, we show that in humans, neural events locked to heartbeats before stimulus onset predict the detection of a faint visual grating in the posterior right inferior parietal lobule and the ventral anterior cingulate cortex, two regions that have multiple functional correlates and that belong to the same resting-state network. Neither fluctuations in measured bodily parameters nor overall cortical excitability could account for this finding. Neural events locked to heartbeats therefore shape visual conscious experience, potentially by contributing to the neural maps of the organism that might underlie subjectivity. Beyond conscious vision, our results show that neural events locked to a basic physiological input such as heartbeats underlie behaviorally relevant differential activation in multifunctional cortical areas. |
Benjamin A. Parris Task conflict in the Stroop task: When Stroop interference decreases as Stroop facilitation increases in a low task conflict context Journal Article In: Frontiers in Psychology, vol. 5, pp. 1182, 2014. @article{Parris2014, In the present study participants completed two blocks of the Stroop task, one in which the response-stimulus interval (RSI) was 3500 ms and one in which RSI was 200 ms. It was expected that, in line with previous research, the shorter RSI would induce a low Task Conflict context by increasing focus on the color identification goal in the Stroop task and lead to a novel finding of an increase in facilitation and simultaneous decrease in interference. Such a finding would be problematic for models of Stroop effects that predict these indices of performance should be affected in tandem. A crossover interaction is reported supporting these predictions. As predicted, the shorter RSI resulted in incongruent and congruent trial reaction times (RTs) decreasing relative to a static neutral baseline condition; hence interference decreased as facilitation increased. An explanatory model (expanding on the work of Goldfarb and Henik, 2007) is presented that: (1) Shows how under certain conditions the predictions from single mechanism models hold true (i.e., when Task conflict is held constant); (2) Shows how it is possible that interference can be affected by an experimental manipulation that leaves facilitation apparently untouched; and (3) Predicts that facilitation cannot be independently affected by an experimental manipulation. |
Kevin B. Paterson; Victoria A. McGowan; Sarah J. White; Sameen Malik; Lily Abedipour; Timothy R. Jordan Reading direction and the central perceptual span in Urdu and English Journal Article In: PLoS ONE, vol. 9, no. 2, pp. e88358, 2014. @article{Paterson2014, BACKGROUND: Normal reading relies on the reader making a series of saccadic eye movements along lines of text, separated by brief fixational pauses during which visual information is acquired from a region of text. In English and other alphabetic languages read from left to right, the region from which useful information is acquired during each fixational pause is generally reported to extend further to the right of each fixation than to the left. However, the asymmetry of the perceptual span for alphabetic languages read in the opposite direction (i.e., from right to left) has received much less attention. Accordingly, in order to more fully investigate the asymmetry in the perceptual span for these languages, the present research assessed the influence of reading direction on the perceptual span for bilingual readers of Urdu and English. METHODS AND FINDINGS: Text in Urdu and English was presented either entirely as normal or in a gaze-contingent moving-window paradigm in which a region of text was displayed as normal at the reader's point of fixation and text outside this region was obscured. The windows of normal text extended symmetrically 0.5° of visual angle to the left and right of fixation, or asymmetrically by increasing the size of each window to 1.5° or 2.5° to either the left or right of fixation. When participants read English, performance for the window conditions was superior when windows extended to the right. However, when reading Urdu, performance was superior when windows extended to the left, and was essentially the reverse of that observed for English. CONCLUSION: These findings provide a novel indication that the perceptual span is modified by the language being read to produce an asymmetry in the direction of reading and show for the first time that such an asymmetry occurs for reading Urdu. |
C. A. Patterson; Jacob Duijnhouwer; S. C. Wissig; B. Krekelberg; Adam Kohn Similar adaptation effects in primary visual cortex and area MT of the macaque monkey under matched stimulus conditions Journal Article In: Journal of Neurophysiology, vol. 111, no. 6, pp. 1203–1213, 2014. @article{Patterson2014, Recent stimulus history, or adaptation, can alter neuronal response properties. Adaptation effects have been characterized in a number of visually responsive structures, from the retina to higher visual cortex. However, it remains unclear whether adaptation effects across stages of the visual system take a similar form in response to a particular sensory event. This is because studies typically probe a single structure or cortical area, using a stimulus ensemble chosen to provide potent drive to the cells of interest. Here we adopt an alternative approach and compare adaptation effects in primary visual cortex (V1) and area MT using identical stimulus ensembles. Previous work has suggested these areas adjust to recent stimulus drive in distinct ways. We show that this is not the case: adaptation effects in V1 and MT can involve weak or strong loss of responsivity and shifts in neuronal preference toward or away from the adapter, depending on stimulus size and adaptation duration. For a particular stimulus size and adaptation duration, however, effects are similar in nature and magnitude in V1 and MT. We also show that adaptation effects in MT of awake animals depend strongly on stimulus size. Our results suggest that the strategies for adjusting to recent stimulus history depend more strongly on adaptation duration and stimulus size than on the cortical area. Moreover, they indicate that different levels of the visual system adapt similarly to recent sensory experience. |
Clare Patterson; Helena Trompelt; Claudia Felser The online application of binding condition B in native and non-native pronoun resolution Journal Article In: Frontiers in Psychology, vol. 5, pp. 147, 2014. @article{Patterson2014a, Previous research has shown that anaphor resolution in a non-native language may be more vulnerable to interference from structurally inappropriate antecedents compared to native anaphor resolution. To test whether previous findings on reflexive anaphors generalize to non-reflexive pronouns, we carried out an eye-movement monitoring study investigating the application of binding condition B during native and non-native sentence processing. In two online reading experiments we examined when during processing local and/or non-local antecedents for pronouns were considered in different types of syntactic environment. Our results demonstrate that both native English speakers and native German-speaking learners of English showed online sensitivity to binding condition B in that they did not consider syntactically inappropriate antecedents. For pronouns thought to be exempt from condition B (so-called "short-distance pronouns"), the native readers showed a weak preference for the local antecedent during processing. The non-native readers, on the other hand, showed a preference for the matrix subject even where local coreference was permitted, and despite demonstrating awareness of short-distance pronouns' referential ambiguity in a complementary offline task. This indicates that non-native comprehenders are less sensitive during processing to structural cues that render pronouns exempt from condition B, and prefer to link a pronoun to a salient subject antecedent instead. |
David A. Paul; Elon Gaffin-Cahn; Eric B. Hintz; Giscard J. Adeclat; Tong Zhu; Zoë R. Williams; G. Edward Vates; Bradford Z. Mahon White matter changes linked to visual recovery after nerve decompression Journal Article In: Science Translational Medicine, vol. 6, no. 266, pp. 266ra173, 2014. @article{Paul2014, The relationship between the integrity of white matter tracts and cortical function in the human brain remains poorly understood. We investigate reversible white matter injury, in this case patients with compression of the optic chiasm by pituitary gland tumors, to study the structural and functional changes that attend spontaneous recovery of cortical function and visual abilities after surgical removal of the tumor and subsequent decompression of the nerves. We show that compression of the optic chiasm led to demyelination of the optic tracts, which reversed as quickly as 4 weeks after nerve decompression. Furthermore, variability across patients in the severity of demyelination in the optic tracts predicted visual ability and functional activity in early cortical visual areas. Preoperative measurements of myelination in the optic tracts predicted the magnitude of visual recovery after surgery. These data indicate that rapid regeneration of myelin in the human brain is a component of the normalization of cortical activity, and ultimately the recovery of sensory and cognitive function, after nerve decompression. More generally, our findings demonstrate the use of diffusion tensor imaging as an in vivo measure of myelination in the human brain. |
Angela M. Pazzaglia; Adrian Staub; Caren M. Rotello Encoding time and the mirror effect in recognition memory: Evidence from eyetracking Journal Article In: Journal of Memory and Language, vol. 75, pp. 77–92, 2014. @article{Pazzaglia2014, Low-frequency (LF) words have higher hit rates and lower false alarm rates than high-frequency (HF) words in recognition memory, a phenomenon termed the mirror effect. Visual word recognition latencies are longer for LF words. We examined the relationship between eye fixation durations during study and later recognition memory for individual words to test whether (1) increased fixation time on a word is associated with better memory, and (2) increased fixation times on LF words can account for their hit rate advantage. In Experiments 1 and 2, words of various frequencies were presented in lists in an intentional study design. In Experiment 3, HF and LF critical words were presented in matched sentence frames in an incidental study design. In all cases, the standard frequency effect on eye movements emerged, with longer reading times for lower frequency words. At test, studied words and new words from each frequency class were presented. The hit rate portion of the mirror effect was evident in all experiments. The time spent fixating a word did predict memory performance in the intentional encoding experiments, but critically, the frequency effect on hit rates was independent of this effect. Time spent fixating a word during incidental encoding did not predict later memory performance. These results suggest that the hit rate advantage for LF words is not due to the additional time spent on these words at encoding, which is consistent with retrieval-stage models of the mirror effect. |
Benjamin Pearson; Julius Raskevicius; Paul M. Bays; Yoni Pertzov; Masud Husain Working memory retrieval as a decision process Journal Article In: Journal of Vision, vol. 14, no. 2, pp. 1–15, 2014. @article{Pearson2014, Working memory (WM) is a core cognitive process fundamental to human behavior, yet the mechanisms underlying it remain highly controversial. Here we provide a new framework for understanding retrieval of information from WM, conceptualizing it as a decision based on the quality of internal evidence. Recent findings have demonstrated that precision of WM decreases with memory load. IfWMretrieval uses a decision process that depends on memory quality, systematic changes in response time distribution should occur as a function of WM precision.We asked participants to view sample arrays and, after a delay, report the direction of change in location or orientation of a probe. As WM precision deteriorated with increasing memory load, retrieval time increased systematically. Crucially, the shape of reaction time distributions was consistent with a linear accumulator decision process. Varying either task relevance of items or maintenance duration influenced memory precision, with corresponding shifts in retrieval time. These results provide strong support for a decision-making account ofWMretrieval based on noisy storage of items. Furthermore, they show that encoding, maintenance, and retrieval in WM need not be considered as separate processes, but may instead be conceptually unified as operations on the same noise- limited, neural representation. |
Maria Matziridi; Mijke O. Hartendorp; Eli Brenner; Jeroen B. J. Smeets Does perisaccadic compression require foveal vision? Journal Article In: Perception, vol. 43, no. 11, pp. 1214–1224, 2014. @article{Matziridi2014, People make systematic errors when localizing a stimulus that is presented briefly near the time of a saccade. These errors have been interpreted as compression towards the position that is fixated after the saccade. Normally, fixating a position means that its image falls on the fovea. Macular degeneration (MD) damages the central retina, obliterating foveal vision. Many people with MD adopt a new retinal locus for fixation, called the preferred retinal locus (PRL). If the compression of space during the saccade is a special characteristic of the fovea, possibly due to the high density of cones that is found in the fovea, one might expect people lacking central vision to show no compression of space around the time of a saccade. If the compression of space during the saccade is related to the position that is fixated after the saccade, one would expect compression towards the PRL, despite the lack of a high density of cones in this area. We found that a person with MD showed a clear compression towards her PRL. We conclude that perisaccadic compression is related to the position that is fixated after the saccade rather than to the high density of receptors in the fovea. |
Justin T. Maxfield; Westri D. Stalder; Gregory J. Zelinsky Effects of target typicality on categorical search Journal Article In: Journal of Vision, vol. 14, no. 12, pp. 1–11, 2014. @article{Maxfield2014, The role of target typicality in a categorical visual search task was investigated by cueing observers with a target name, followed by a five-item target present/absent search array in which the target images were rated in a pretest to be high, medium, or low in typicality with respect to the basic-level target cue. Contrary to previous work, we found that search guidance was better for high-typicality targets compared to low-typicality targets, as measured by both the proportion of immediate target fixations and the time to fixate the target. Consistent with previous work, we also found an effect of typicality on target verification times, the time between target fixation and the search judgment; as target typicality decreased, verification times increased. To model these typicality effects, we trained Support Vector Machine (SVM) classifiers on the target categories, and tested these on the corresponding specific targets used in the search task. This analysis revealed significant differences in classifier confidence between the high-, medium-, and low-typicality groups, paralleling the behavioral results. Collectively, these findings suggest that target typicality broadly affects both search guidance and verification, and that differences in typicality can be predicted by distance from an SVM classification boundary. |
Olivia M. Maynard; Angela Attwood; Laura O'Brien; Sabrina Brooks; Craig Hedge; Ute Leonards; Marcus R. Munafò Avoidance of cigarette pack health warnings among regular cigarette smokers Journal Article In: Drug and Alcohol Dependence, vol. 136, no. 1, pp. 170–174, 2014. @article{Maynard2014, Background: Previous research with adults and adolescents indicates that plain cigarette packs increase visual attention to health warnings among non-smokers and non-regular smokers, but not among regular smokers. This may be because regular smokers: (1) are familiar with the health warnings, (2) preferentially attend to branding, or (3) actively avoid health warnings. We sought to distinguish between these explanations using eye-tracking technology. Method: A convenience sample of 30 adult dependent smokers participated in an eye-tracking study. Participants viewed branded, plain and blank packs of cigarettes with familiar and unfamiliar health warnings. The number of fixations to health warnings and branding on the different pack types were recorded. Results: Analysis of variance indicated that regular smokers were biased towards fixating the branding rather than the health warning on all three pack types. This bias was smaller, but still evident, for blank packs, where smokers preferentially attended the blank region over the health warnings. Time-course analysis showed that for branded and plain packs, attention was preferentially directed to the branding location for the entire 10. s of the stimulus presentation, while for blank packs this occurred for the last 8. s of the stimulus presentation. Familiarity with health warnings had no effect on eye gaze location. Conclusion: Smokers actively avoid cigarette pack health warnings, and this remains the case even in the absence of salient branding information. Smokers may have learned to divert their attention away from cigarette pack health warnings. These findings have implications for cigarette packaging and health warning policy. |
Kathryn Louise McCabe; Rebbekah Josephine Atkinson; Gavin Cooper; Jessica Lauren Melville; Jill Harris; Ulrich Schall; Carmel M. Loughland; Renate Thienel; Linda E. Campbell In: Journal of Neurodevelopmental Disorders, vol. 6, no. 1, pp. 1–8, 2014. @article{McCabe2014, BACKGROUND: 22q11.2 deletion syndrome (22q11DS) is associated with a number of physical anomalies and neuropsychological deficits including impairments in executive and sensorimotor function. It is estimated that 25% of children with 22q11DS will develop schizophrenia and other psychotic disorders later in life. Evidence of genetic transmission of information processing deficits in schizophrenia suggests performance in 22q11DS individuals will enhance understanding of the neurobiological and genetic substrates associated with information processing. In this report, we examine information processing in 22q11DS using measures of startle eyeblink modification and antisaccade inhibition to explore similarities with schizophrenia and associations with neurocognitive performance.$backslash$n$backslash$nMETHODS: Startle modification (passive and active tasks; 120- and 480-ms pre-pulse intervals) and antisaccade inhibition were measured in 25 individuals with genetically confirmed 22q11DS and 30 healthy control subjects.$backslash$n$backslash$nRESULTS: Individuals with 22q11DS exhibited increased antisaccade error as well as some evidence (trend-level effect) of impaired sensorimotor gating during the active condition, suggesting a dysfunction in controlled attentional processing, rather than a pre-attentive dysfunction using this paradigm.$backslash$n$backslash$nCONCLUSIONS: The findings from the present study show similarities with previous studies in clinical populations associated with 22q11DS such as schizophrenia that may indicate shared dysfunction of inhibition pathways in these groups. |
Michael B. McCamy; Stephen L. Macknik; Susana Martinez-Conde Different fixational eye movements mediate the prevention and the reversal of visual fading Journal Article In: Journal of Physiology, vol. 592, no. 19, pp. 4381–4394, 2014. @article{McCamy2014, Fixational eye movements (FEMs; including microsaccades, drift and tremor) are thought to improve visibility during fixation by thwarting neural adaptation to unchanging stimuli, but how the different FEM types influence this process is a matter of debate. Attempts to answer this question have been hampered by the failure to distinguish between the prevention of fading (where fading is blocked before it happens in the first place) and the reversal of fading (where vision is restored after fading has already occurred). Because fading during fixation is a detriment to clear vision, the prevention of fading, which avoids visual degradation before it happens, is a more desirable scenario than improving visibility after fading has occurred. Yet previous studies have not examined the role of FEMs in the prevention of fading, but have focused on visual restoration instead. Here we set out to determine the differential contributions and efficacies of microsaccades and drift to preventing fading in human vision. Our results indicate that both microsaccades and drift mediate the prevention of visual fading. We also found that drift is a potentially larger contributor to preventing fading than microsaccades, although microsaccades are more effective than drift. Microsaccades moreover prevented foveal and peripheral fading in an equivalent fashion, and their efficacy was independent of their size, number, and direction. Our data also suggest that faster drift may prevent fading better than slower drift. These findings may help to reconcile the long-standing controversy concerning the comparative roles of microsaccades and drift in visibility during fixation |
Michael B. McCamy; Jorge Otero-Millan; Leandro Luigi Di Stasi; Stephen L. Macknik; Susana Martinez-Conde Highly informative natural scene regions increase microsaccade production during visual scanning Journal Article In: Journal of Neuroscience, vol. 34, no. 8, pp. 2956–2966, 2014. @article{McCamy2014a, Classical image statistics, such as contrast, entropy, and the correlation between central and nearby pixel intensities, are thought to guide ocular fixation targeting. However, these statistics are not necessarily task relevant and therefore do not provide a complete picture of the relationship between informativeness and ocular targeting. Moreover, it is not known whether either informativeness or classical image statistics affect microsaccade production; thus, the role of microsaccades in information acquisition is also unknown. The objective quantification of the informativeness of a scene region is a major challenge, because it can vary with both image features and the task of the viewer. Thus, previous definitions of informativeness suffered from subjectivity and inconsistency across studies. Here we developed an objective measure of informativeness based on fixation consistency across human observers, which accounts for both bottom-up and top-down influences in ocular targeting. We then analyzed fixations in more versus less informative image regions in relation to classical statistics. Observers generated more microsaccades on more informative than less informative image regions, and such regions also exhibited low redundancy in their classical statistics. Increased microsaccade production was not explained by increased fixation duration, suggesting that the visual system specifically uses microsaccades to heighten information acquisition from informative regions. |
Gerald P. McDonnell; Brian H. Bornstein; Cindy E. Laub; Mark Mills; Michael D. Dodd Perceptual processes in the cross-race effect: Evidence from eyetracking Journal Article In: Basic and Applied Social Psychology, vol. 36, no. 6, pp. 478–493, 2014. @article{McDonnell2014, The cross-race effect (CRE) is the tendency to have better recognition accuracy for same-race than for other-race faces due to differential encoding strategies. Research exploring the nature of encoding differences has yielded few definitive conclusions. The present experiments explored this issue using an eyetracker during a recognition task involving White participants viewing White and African American faces. Participants fixated faster and longer on the upper features of White faces and the lower features of African American faces. When instructing participants to attend to certain features in African American faces, this pattern was exaggerated. Gaze patterns were related to improved recognition accuracy. |
Victoria A. McGowan; Sarah J. White; Timothy R. Jordan; Kevin B. Paterson Aging and the use of interword spaces during reading: Evidence from eye movements Journal Article In: Psychonomic Bulletin & Review, vol. 21, no. 3, pp. 740–747, 2014. @article{McGowan2014, In an eye movement experiment, we assessed the performance of young (18-30 years) and older (65 + years) adult readers when sentences contained conventional interword spaces, when interword spaces were removed, or when interword spaces were replaced by nonlinguistic symbols. The replacement symbol was either a closed square (■) that provided a salient (low-spatial-frequency) cue to word boundaries, or an open square (□) that provided a less salient cue and included features (vertical and horizontal lines) similar to those found in letters. Removing or replacing interword spaces slowed reading times and impaired normal eye movement behavior for both age groups. However, this disruption was greater for the older readers, particularly when the replacement symbol did not provide a salient cue as to word boundaries. Specific influences of this manipulation on word identification during reading were assessed by examining eye movements for a high- or low-frequency target word in each sentence. Standard word frequency effects were obtained for both age groups when text was spaced normally, and although the word frequency effect was larger when spaces were removed or filled, the increases were similar across age groups. Therefore, whereas older adults' normal eye movements were substantially disrupted when text lacked conventional interword spaces, the process of lexical access associated with the word frequency effect was no more difficult for older than for young adults. The indication, therefore, is that although older adults struggle from the loss of conventional cues to word boundaries, this is not due to additional difficulties in word recognition. |
David B. T. McMahon; Igor V. Bondar; Olusoji A. T. Afuwape; David C. Ide; David A. Leopold One month in the life of a neuron: longitudinal single-unit electrophysiology in the monkey visual system Journal Article In: Journal of Neurophysiology, vol. 112, no. 7, pp. 1748–1762, 2014. @article{McMahon2014, Conventional recording methods generally preclude following the activity of the same neurons in awake animals across days. This limits our ability to systematically investigate the principles of neuronal specialization, or to study phenomena that evolve over multiple days such as experience-dependent plasticity. To redress this shortcoming, we developed a drivable, chronically implanted microwire recording preparation that allowed us to follow visual responses in inferotemporal (IT) cortex in awake behaving monkeys across multiple days, and in many cases across months. The microwire bundle and other implanted components were MRI compatible and thus permitted in the same animals both functional imaging and long-term recording from multiple neurons in deep structures within a region the approximate size of one voxel (<1 mm). The distinct patterns of stimulus selectivity observed in IT neurons, together with stable features in spike waveforms and interspike interval distributions, allowed us to track individual neurons across weeks and sometimes months. The long-term consistency of visual responses shown here permits large-scale mappings of neuronal properties using massive image libraries presented over the course of days. We demonstrate this possibility by screening the visual responses of single neurons to a set of 10,000 stimuli. |
David B. T. McMahon; Adam P. Jones; Igor V. Bondar; David A. Leopold Face-selective neurons maintain consistent visual responses across months Journal Article In: Proceedings of the National Academy of Sciences, vol. 111, no. 22, pp. 8251–8256, 2014. @article{McMahon2014a, Face perception in both humans and monkeys is thought to depend on neurons clustered in discrete, specialized brain regions. Because primates are frequently called upon to recognize and remember new individuals, the neuronal representation of faces in the brain might be expected to change over time. The functional properties of neurons in behaving animals are typically assessed over time periods ranging from minutes to hours, which amounts to a snapshot compared to a lifespan of a neuron. It therefore remains unclear how neuronal properties observed on a given day predict that same neuron's activity months or years later. Here we show that the macaque inferotemporal cortex contains face-selective cells that show virtually no change in their patterns of visual responses over time periods as long as one year. Using chronically implanted microwire electrodes guided by functional MRI targeting, we obtained distinct profiles of selectivity for face and nonface stimuli that served as fingerprints for individual neurons in the anterior fundus (AF) face patch within the superior temporal sulcus. Longitudinal tracking over a series of daily recording sessions revealed that face-selective neurons maintain consistent visual response profiles across months-long time spans despite the influence of ongoing daily experience. We propose that neurons in the AF face patch are specialized for aspects of face perception that demand stability as opposed to plasticity. |
Bob McMurray; Cheyenne Munson; J. Bruce Tomblin Individual differences in language ability are related to variation in word recognition, not speech perception: Evidence from eye movements Journal Article In: Journal of Speech, Language, and Hearing Research, vol. 57, no. 4, pp. 1344–1362, 2014. @article{McMurray2014, Purpose: The authors examined speech perception deficits associated with individual differences in language ability, contrasting auditory, phonological, or lexical accounts by asking whether lexical competition is differentially sensitive to fine-grained acoustic variation. Method: Adolescents with a range of language abilities (N = 74, including 35 impaired) participated in an experiment based on McMurray, Tanenhaus, and Aslin (2002). Participants heard tokens from six 9-step voice onset time (VOT) continua spanning 2 words (beach/peach, beak/peak, etc.) while viewing a screen containing pictures of those words and 2 unrelated objects. Participants selected the referent while eye movements to each picture were monitored as a measure of lexical activation. Fixations were examined as a function of both VOT and language ability. Results: Eye movements were sensitive to within-category VOT differences: As VOT approached the boundary, listeners made more fixations to the competing word. This did not interact with language ability, suggesting that language impairment is not associated with differential auditory sensitivity or phonetic categorization. Listeners with poorer language skills showed heightened competitors fixations overall, suggesting a deficit in lexical processes. Conclusion: Language impairment may be better characterized by a deficit in lexical competition (inability to suppress competing words), rather than differences in phonological categorization or auditory abilities. |
Eugene McSorley; Clare Lyne; Rachel McCloy Dissociation between the impact of evidence on eye movement target choice and confidence judgements Journal Article In: Experimental Brain Research, vol. 232, no. 6, pp. 1927–1940, 2014. @article{McSorley2014, It has been suggested that the evidence used to support a decision to move our eyes and the confidence we have in that decision are derived from a common source. Alternatively, confidence may be based on further post-decisional processes. In three experiments, we examined this. In Experiment 1, participants chose between two targets on the basis of varying levels of evidence (i.e., the direction of motion coherence in a random dot kinematogram). They indicated this choice by making a saccade to one of two targets and then indicated their confidence. Saccade trajectory deviation was taken as a measure of the inhibition of the non-selected target. We found that as evidence increased so did confidence and deviations of saccade trajectory away from the non-selected target. However, a correlational analysis suggested they were not related. In Experiment 2, an option to opt-out of the choice was offered on some trials if choice proved too difficult. In this way, we isolated trials on which confidence in target selection was high (i.e., when the option to opt-out was available but not taken). Again saccade trajectory deviations were found not to differ in relation to confidence. In Experiment 3, we directly manipulated confidence, such that participants had high or low task confidence. They showed no differences in saccade trajectory deviations. These results support post-decisional accounts of confidence: evidence supporting the decision to move the eyes is reflected in saccade control, but the confidence that we have in that choice is subject to further post-decisional processes. |
Tyler R. Peel; Kevin D. Johnston; Stephen G. Lomber; Brian D. Corneil Bilateral saccadic deficits following large and reversible inactivation of unilateral frontal eye field Journal Article In: Journal of Neurophysiology, vol. 111, no. 2, pp. 415–433, 2014. @article{Peel2014, Inactivation permits direct assessment of the functional contribution of a given brain area to behavior. Previous inactivation studies of the frontal eye field (FEF) have either used large permanent ablations or reversible pharmacological techniques that only inactivate a small volume of tissue. Here we evaluated the impact of large, yet reversible, FEF inactivation on visually guided, delayed, and memory-guided saccades, using cryoloops implanted in the arcuate sulcus. While FEF inactivation produced the expected triad of contralateral saccadic deficits (increased reaction time, decreased accuracy and peak velocity) and performance errors (neglect or misdirected saccades), we also found consistent increases in reaction times of ipsiversive saccades in all three tasks. In addition, FEF inactivation did not increase the proportion of premature saccades to ipsilateral targets, as was predicted on the basis of pharmacological studies. Consistent with previous studies, greater deficits accompanied saccades toward extinguished visual cues. Our results attest to the functional contribution of the FEF to saccades in both directions. We speculate that the comparative effects of different inactivation techniques relate to the volume of inactivated tissue within the FEF. Larger inactivation volumes may reveal the functional contribution of more sparsely distributed neurons within the FEF, such as those related to ipsiversive saccades. Furthermore, while focal FEF inactivation may disinhibit the mirroring site in the other FEF, larger inactivation volumes may induce broad disinhibition in the other FEF that paradoxically prolongs oculomotor processing via increased competitive interactions. |
Didem Pehlivanoglu; Shivangi Jain; Robert Ariel; Paul Verhaeghen The ties to unbind: Age-related differences in feature (un)binding in working memory for emotional faces Journal Article In: Frontiers in Psychology, vol. 5, pp. 253, 2014. @article{Pehlivanoglu2014, In the present study, we investigated age-related differences in the processing of emotional stimuli. Specifically, we were interested in whether older adults would show deficits in unbinding emotional expression (i.e., either no emotion, happiness, anger, or disgust) from bound stimuli (i.e., photographs of faces expressing these emotions), as a hyper-binding account of age-related differences in working memory would predict. Younger and older adults completed different N-Back tasks (side-by-side 0-Back, 1-Back, 2-Back) under three conditions: match/mismatch judgments based on either the identity of the face (identity condition), the face's emotional expression (expression condition), or both identity and expression of the face (both condition). The two age groups performed more slowly and with lower accuracy in the expression condition than in the both condition, indicating the presence of an unbinding process. This unbinding effect was more pronounced in older adults than in younger adults, but only in the 2-Back task. Thus, older adults seemed to have a specific deficit in unbinding in working memory. Additionally, no age-related differences were found in accuracy in the 0-Back task, but such differences emerged in the 1-Back task, and were further magnified in the 2-Back task, indicating independent age-related differences in attention/STM and working memory. Pupil dilation data confirmed that the attention/STM version of the task (1-Back) is more effortful for older adults than younger adults. |
Florian Perdreau; Patrick Cavanagh Drawing skill is related to the efficiency of encoding object structure Journal Article In: i-Perception, vol. 5, no. 2, pp. 101–119, 2014. @article{Perdreau2014, Accurate drawing calls on many skills beyond simple motor coordination. A good internal representation of the target object's structure is necessary to capture its proportion and shape in the drawing. Here, we assess two aspects of the perception of object structure and relate them to participants' drawing accuracy. First, we assessed drawing accuracy by computing the geometrical dissimilarity of their drawing to the target object. We then used two tasks to evaluate the efficiency of encoding object structure. First, to examine the rate of temporal encoding, we varied presentation duration of a possible versus impossible test object in the fovea using two different test sizes (8° and 28°). More skilled participants were faster at encoding an object's structure, but this difference was not affected by image size. A control experiment showed that participants skilled in drawing did not have a general advantage that might have explained their faster processing for object structure. Second, to measure the critical image size for accurate classification in the periphery, we varied image size with possible versus impossible object tests centered at two different eccentricities (3° and 8°). More skilled participants were able to categorise object structure at smaller sizes, and this advantage did not change with eccentricity. A control experiment showed that the result could not be attributed to differences in visual acuity, leaving attentional resolution as a possible explanation. Overall, we conclude that drawing accuracy is related to faster encoding of object structure and better access to crowded details. |
Effie J. Pereira; Monica S. Castelhano Peripheral guidance in scenes: The interaction of scene context and object content Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 40, no. 5, pp. 2056–2072, 2014. @article{Pereira2014, In the present study, we examined how gaze guidance is affected by immediately available information in the periphery and investigated how search strategies differed across manipulations in the availability of scene context and object content information. Across 3 experiments, participants performed a visual search task in scenes while using a gaze-contingent moving-window paradigm. Extrafoveal information was manipulated across conditions to examine the contributions of object content, scene context, or some combination of the two. Experiment 1 demonstrated a possible interaction between scene context and object content information in improving guidance. Experiments 2 and 3 supported the notion that object content is selected for further scrutiny based on its position within scene context. These results suggest a prioritization of object information based on scene context, such that contextual information acts as a framework in the selection of relevant regions, and object information can then affect which specific locations in those regions are selected for further examination. |
Carolyn J. Perry; Abdullah Tahiri; Mazyar Fallah Feature integration within and across visual streams occurs at different visual processing stages Journal Article In: Journal of Vision, vol. 14, no. 2, pp. 1–8, 2014. @article{Perry2014, Direction repulsion is a perceptual illusion in which the directions of two superimposed surfaces are repulsed away from the real directions of motion. The repulsion is reduced when the surfaces differ in dorsal stream features such as speed. We have previously shown that segmenting the surfaces by color, a ventral stream feature, did not affect repulsion but instead reduced the time needed to process both surfaces. The current study investigated whether segmenting two superimposed surfaces by a feature coprocessed with direction in the dorsal stream (i.e., speed) would also reduce processing time. We found that increasing the speed of one or both surfaces reduced direction repulsion. Since color segmentation does not affect direction repulsion, these results suggest that motion processing integrates speed and direction prior to forming an object representation that includes ventral stream features such as color. Like our previous results for differences in color, differences in speed also decreased processing time. Therefore, the reduction in processing time derives from a later processing stage where both ventral and dorsal features bound into the object representations can reduce the time needed for decision making when those features differentiate the superimposed surfaces from each other. |
Yoni Pertzov; Masud Husain The privileged role of location in visual working memory Journal Article In: Attention, Perception, and Psychophysics, vol. 76, no. 7, pp. 1914–1924, 2014. @article{Pertzov2014, Reports have conflicted about the possible special role of location in visual working memory (WM). One important question is: Do we maintain the locations of objects in WM even when they are irrelevant to the task at hand? Here we used a continuous response scale to study the types of reporting errors that participants make when objects are presented at the same or at different locations in space. When several objects successively shared the same location, participants exhibited a higher tendency to report features of the wrong object in memory; that is, they responded with features that belonged to objects retained in memory but not probed at retrieval. On the other hand, a similar effect was not observed when objects shared a nonspatial feature, such as color. Furthermore, the effect of location on reporting errors was present even when its manipulation was orthogonal to the task at hand. These findings are consistent with the view that binding together different nonspatial features of an object in memory might be mediated through an object's location. Hence, spatial location may have a privileged role in WM. The relevance of these findings to conceptual models, as well as to neural accounts of visual WM, is discussed. |
Matthew F. Peterson; Miguel P. Eckstein Learning optimal eye movements to unusual faces Journal Article In: Vision Research, vol. 99, pp. 57–68, 2014. @article{Peterson2014, Eye movements, which guide the fovea's high resolution and computational power to relevant areas of the visual scene, are integral to efficient, successful completion of many visual tasks. How humans modify their eye movements through experience with their perceptual environments, and its functional role in learning new tasks, has not been fully investigated. Here, we used a face identification task where only the mouth discriminated exemplars to assess if, how, and when eye movement modulation may mediate learning. By interleaving trials of unconstrained eye movements with trials of forced fixation, we attempted to separate the contributions of eye movements and covert mechanisms to performance improvements. Without instruction, a majority of observers substantially increased accuracy and learned to direct their initial eye movements towards the optimal fixation point. The proximity of an observer's default face identification eye movement behavior to the new optimal fixation point and the observer's peripheral processing ability were predictive of performance gains and eye movement learning. After practice in a subsequent condition in which observers were directed to fixate different locations along the face, including the relevant mouth region, all observers learned to make eye movements to the optimal fixation point. In this fully learned state, augmented fixation strategy accounted for 43% of total efficiency improvements while covert mechanisms accounted for the remaining 57%. The findings suggest a critical role for eye movement planning to perceptual learning, and elucidate factors that can predict when and how well an observer can learn a new task with unusual exemplars. |
Jella Pfeiffer; Martin Meißner; Eduard Brandstätter; René Riedl; Reinhold Decker; Franz Rothlauf On the influence of context-based complexity on information search patterns: An individual perspective Journal Article In: Journal of Neuroscience, Psychology, and Economics, vol. 7, no. 2, pp. 103–124, 2014. @article{Pfeiffer2014, Although context-based complexity measured as the similarity and conflict across alternatives is dependent on individual preference structures, existing studies investi- gating the influence of context-based complexity on information search patterns have largely ignored that context-based complexity is user- and preference-dependent. Addressing this research gap, this article elicits the individual preferences of decision makers by using the pairwise-comparison-based preference measurement (PCPM) technique and records individuals' search patterns using eye tracking. Our results show that an increased context-based complexity leads to an increase in information acqui- sition and the use of a more attribute-wise search pattern. Moreover, the information search pattern changes within a choice task as information is processed attribute-wise in earlier stages of the search process and alternative-wise in later ones. The fact that we do not find an interaction effect of context-based complexity and decision stages on the search patterns indicates that the influence of complexity on search patterns stays constant throughout the decision process and suggests that the more complex the choice task is, the later the switch from attribute-wise strategies to alternative-wise strategies will be. |
Ulrich J. Pfeiffer; Leonhard Schilbach; Bert Timmermans; Bojana Kuzmanovic; Alexandra L. Georgescu; Gary Bente; Kai Vogeley Why we interact: On the functional role of the striatum in the subjective experience of social interaction Journal Article In: NeuroImage, vol. 101, pp. 124–137, 2014. @article{Pfeiffer2014a, There is ample evidence that human primates strive for social contact and experience interactions with conspecifics as intrinsically rewarding. Focusing on gaze behavior as a crucial means of human interaction, this study employed a unique combination of neuroimaging, eye-tracking, and computer-animated virtual agents to assess the neural mechanisms underlying this component of behavior. In the interaction task, participants believed that during each interaction the agent's gaze behavior could either be controlled by another participant or by a computer program. Their task was to indicate whether they experienced a given interaction as an interaction with another human participant or the computer program based on the agent's reaction. Unbeknownst to them, the agent was always controlled by a computer to enable a systematic manipulation of gaze reactions by varying the degree to which the agent engaged in joint attention. This allowed creating a tool to distinguish neural activity underlying the subjective experience of being engaged in social and non-social interaction. In contrast to previous research, this allows measuring neural activity while participants experience active engagement in real-time social interactions. Results demonstrate that gaze-based interactions with a perceived human partner are associated with activity in the ventral striatum, a core component of reward-related neurocircuitry. In contrast, interactions with a computer-driven agent activate attention networks. Comparisons of neural activity during interaction with behaviorally naïve and explicitly cooperative partners demonstrate different temporal dynamics of the reward system and indicate that the mere experience of engagement in social interaction is sufficient to recruit this system. |
Andrea Phillipou; Susan Lee Rossell; David Jonathan Castle; Caroline T. Gurvich; Larry Allen Abel Square wave jerks and anxiety as distinctive biomarkers for anorexia nervosa Journal Article In: Investigative Ophthalmology & Visual Science, vol. 55, no. 12, pp. 8366–8370, 2014. @article{Phillipou2014, PURPOSE. The factors contributing to the cause and maintenance of anorexia nervosa (AN) are poorly understood, though increasing interest surrounds the neurobiological underpinnings of the condition. The examination of saccadic eye movements has proven useful in our understanding of the neurobiology of some other psychiatric illnesses, as they utilize identifiable brain circuits. Square wave jerks (SWJs), which describe an involuntary saccade away and back to fixation, have been observed to occur at abnormally high rates in neurodegenerative disorders and some psychiatric illnesses, but have not been examined in AN. Therefore, the aim of this study was to investigate whether individuals with AN and healthy control (HC) individuals differ in SWJ rate during attempted fixation. METHODS. Square wave jerk frequency was compared across 23 female participants with AN and 22 HC participants matched for age, sex, and premorbid intelligence. RESULTS. Anorexia nervosa participants were found to make SWJs at a significantly higher rate than HC participants. The rate of SWJs in AN was also found to negatively correlate with anxiety. Square wave jerk rate and anxiety were found to correctly classify groups, with an accuracy of 87% for AN participants and 95.5% for HCs. CONCLUSIONS. Given our current understanding of saccadic eye movements, the findings suggest a potential role of c-aminobutyric acid (GABA) in the superior colliculus, frontal eye fields, or posterior parietal cortex in the psychopathology of AN. |
Aleksandra Pieczykolan; Lynn Huestegge Oculomotor dominance in multitasking: Mechanisms of conflict resolution in cross-modal action Journal Article In: Journal of Vision, vol. 14, no. 13, pp. 1–17, 2014. @article{Pieczykolan2014, In daily life, eye movement control usually occurs in the context of concurrent action demands in other effector domains. However, little research has focused on understanding how such cross-modal action demands are coordinated, especially when conflicting information needs to be processed conjunctly in different action modalities. In two experiments, we address this issue by studying vocal responses in the context of spatially conflicting eye movements (Experiment 1) and in the context of spatially conflicting manual actions (Experiment 2, under controlled eye fixation conditions). Crucially, a comparison across experiments allows us to assess resource scheduling priorities among the three effector systems by comparing the same (vocal) response demands in the context of eye movements in contrast to manual responses. The results indicate that in situations involving response conflict, eye movements are prioritized over concurrent action demands in another effector system. This oculomotor dominance effect corroborates previous observations in the context of multiple action demands without spatial response conflict. Furthermore, and in line with recent theoretical accounts of parallel multiple action control, resource scheduling patterns appear to be flexibly adjustable based on the temporal proximity of the two actions that need to be performed. |
Joanna Pilarczyk; Michał Kuniecki Emotional content of an image attracts attention more than visually salient features in various signal-to-noise ratio conditions Journal Article In: Journal of Vision, vol. 14, no. 12, pp. 1–19, 2014. @article{Pilarczyk2014, Emotional images are processed in a prioritized manner, attracting attention almost immediately. In the present study we used eye tracking to reveal what type of features within neutral, positive, and negative images attract early visual attention: semantics, visual saliency, or their interaction. Semantic regions of interest were selected by observers, while visual saliency was determined using the Graph-Based Visual Saliency model. Images were transformed by adding pink noise in several proportions to be presented in a sequence of increasing and decreasing clarity. Locations of the first two fixations were analyzed. The results showed dominance of semantic features over visual saliency in attracting attention. This dominance was linearly related to the signal-to-noise ratio. Semantic regions were fixated more often in emotional images than in neutral ones, if signal-to-noise ratio was high enough to allow participants to comprehend the gist of a scene. Visual saliency on its own did not attract attention above chance, even in the case of pure noise images. Regions both visually salient and semantically relevant attracted a similar amount of fixation compared to semantic regions alone, or even more in the case of neutral pictures. Results provide evidence for fast and robust detection of semantically relevant features. |
Elmar H. Pinkhardt; Hazem Issa; Martin Gorges; Reinhart Jürgens; Dorothée Lulé; Johanna Heimrath; Hans Peter Müller; Albert C. Ludolph; Wolfgang Becker; Jan Kassubek In: Journal of Neurology, vol. 261, no. 4, pp. 791–803, 2014. @article{Pinkhardt2014, Small vessel cerebrovascular disease (SVCD) is one of the most frequent vessel disorders in the aged brain. Among the spectrum of neurological disturbances related to SVCD, oculomotor dysfunction is a not well understood symptom- in particular, it remains unclear whether vascular lesion load in specific brain regions affects oculomotor function independent of cognitive decline in SVCD patients or whether the effect of higher brain function deficits prevails. In this study, we examined a cohort of 25 SVCD patients and 19 healthy controls using video-oculographic eye movement recording in a laboratory environment, computer-based MRI assessment of white matter lesion load (WMLL), assessment of extrapyramidal motor deficits, and psychometric testing. In comparison to controls, the mean WMLL of patients was significantly larger than in controls. With respect to eye movement control, patients performed significantly worse than controls in almost all aspects of oculomotion. Likewise, patients showed a significantly worse performance in all but one of the neuropsychological tests. Oculomotor deficits in SVCD correlated with the patients' cognitive dysfunctioning while there was only weak evidence for a direct effect of WMLL on eye movement control. In conclusion, oculomotor impairment in SVCD seems to be mainly contingent upon cognitive deterioration in SVCD while WMLL might have only a minor specific effect upon oculomotor pathways. |
Alessandro Piras; Roberto Lobietti; Salvatore Squatrito Response time, visual search strategy, and anticipatory skills in volleyball players Journal Article In: Journal of Ophthalmology, vol. 2014, pp. 1–10, 2014. @article{Piras2014, This paper aimed at comparing expert and novice volleyball players in a visuomotor task using realistic stimuli. Videos of a volleyball setter performing offensive action were presented to participants, while their eye movements were recorded by a head-mounted video based eye tracker. Participants were asked to foresee the direction (forward or backward) of the setter's toss by pressing one of two keys. Key-press response time, response accuracy, and gaze behaviour were measured from the first frame showing the setter's hand-ball contact to the button pressed by the participants. Experts were faster and more accurate in predicting the direction of the setting than novices, showing accurate predictions when they used a search strategy involving fewer fixations of longer duration, as well as spending less time in fixating all display areas from which they extract critical information for the judgment. These results are consistent with the view that superior performance in experts is due to their ability to efficiently encode domain-specific information that is relevant to the task. |
Alessandro Piras; Emanuela Pierantozzi; Salvatore Squatrito Visual search strategy in judo fighters during the execution of the first grip Journal Article In: International Journal of Sports Science & Coaching, vol. 9, no. 1, pp. 185–198, 2014. @article{Piras2014a, Visual search behaviour is believed to be very relevant for athlete performance, especially for sports requiring refined visuo-motor coordination skills. Modern coaches believe that optimal visuo-motor strategy may be part of advanced training programs. Gaze behaviour of expert and novice judo fighters was investigated while they were doing a real sport-specific task. The athletes were tested while they performed a first grip either in an attack or defence condition. The results showed that expert judo fighters use a search strategy involving fewer fixations of longer duration than their novice counterparts. Experts spent a greater percentage of their time fixating on lapel and face with respect to other areas of the scene. On the contrary, the most frequently fixed cue for novice group was the sleeve area. It can be concluded that experts orient their gaze in the middle of the scene, both in attack and in defence, in order to gather more information at once, perhaps using parafoveal vision. |
Irina Pivneva; Julie Mercier; Debra Titone Executive control modulates cross-language lexical activation during L2 reading: Evidence from eye movements Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 40, no. 3, pp. 787–796, 2014. @article{Pivneva2014, Models of bilingual reading such as Bilingual Interactive Activation Plus (Dijkstra & van Heuven, 2002) do not predict a central role for domain-general executive control during bilingual reading, in contrast with bilingual models from other domains, such as production (e.g., the Inhibitory Control Model; Green, 1998). We thus investigated whether individual differences among bilinguals in domain-general executive control modulate cross-language activation during L2 sentence reading, over and above other factors such as L2 proficiency. Fifty French-English bilinguals read L2-English sentences while their eye movements were recorded, and they subsequently completed a battery of executive control and L2 proficiency tasks. High- and low-constraint sentences contained interlingual homographs (chat = "casual conversation" in English, "a cat" in French), cognates (piano in English and French), or L2-specific control words. The results showed that greater executive control among bilinguals but not L2 proficiency reduced cross-language activation in terms of interlingual homograph interference. In contrast, increased L2 proficiency but not executive control reduced cross-language activation in terms of cognate facilitation. These results suggest that models of bilingual reading must incorporate mechanisms by which domain-general executive control can alter the earliest stages of bilingual lexical activation. |
Frederik Platten; Maximilian Schwalm; Julia Hülsmann; Josef Krems Analysis of compensative behavior in demanding driving situations Journal Article In: Transportation Research Part F: Traffic Psychology and Behaviour, vol. 26, no. A, pp. 38–48, 2014. @article{Platten2014, Drivers usually perform a range of different activities while driving. Following a classical workload approach, additional activities are expected to increase the demand on the driver. Nevertheless, drivers can usually manage even demanding situations successfully. They seem to be able to compensate demands by behavior adaptations, mainly in the following factors: in the driving task itself, in an additional (secondary) task and in their mental workload. It is suggested that by analyzing these three factors in temporal coherence, compensative interactions between them become measurable. Additionally, a reduction of activity in the secondary task is expected to be influenced by the characteristics of this task. To analyze these effects, a driving simulator study with 33 participants was accomplished. It could be shown that if a secondary task can be interrupted without a perceived decline in performance, it is interrupted in demanding driving situations. If an interruption causes a perceived performance loss, efforts are increased, and so the workload is heightened (measured with a high resolution physiological measurement based on pupillometry). Thus, drivers compensate their current demands by behavior adaptations in different factors, depending on the characteristics of a secondary task. |
Patrick Plummer; Manuel Perea; Keith Rayner The influence of contextual diversity on eye movements in reading Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 40, no. 1, pp. 275–283, 2014. @article{Plummer2014, Recent research has shown contextual diversity (i.e., the number of passages in which a given word appears) to be a reliable predictor of word processing difficulty. It has also been demonstrated that word-frequency has little or no effect on word recognition speed when accounting for contextual diversity in isolated word processing tasks. An eye-movement experiment was conducted wherein the effects of word-frePlummer, P., Perea, M., & Rayner, K. (2014). The influence of contextual diversity on eye movements in reading. Journal of Experimental Psychology: Learning Memory and Cognition, 40(1), 275–283. https://doi.org/10.1037/a0034058quency and contextual diversity were directly contrasted in a normal sentence reading scenario. Subjects read sentences with embedded target words that varied in word-frequency and contextual diversity. All 1st-pass and later reading times were significantly longer for words with lower contextual diversity compared to words with higher contextual diversity when controlling for word-frequency and other important lexical properties. Furthermore, there was no difference in reading times for higher frequency and lower frequency words when controlling for contextual diversity. The results confirm prior findings regarding contextual diversity and word-frequency effects and demonstrate that contextual diversity is a more accurate predictor of word processing speed than word-frequency within a normal reading task. |
Katja Poellmann; Hans Rutger Bosker; James M. McQueen; Holger Mitterer Perceptual adaptation to segmental and syllabic reductions in continuous spoken Dutch Journal Article In: Journal of Phonetics, vol. 46, no. 1, pp. 101–127, 2014. @article{Poellmann2014a, This study investigates if and how listeners adapt to reductions in casual continuous speech. In a perceptual-learning variant of the visual-world paradigm, two groups of Dutch participants were exposed to either segmental (/b/ → [v]) or syllabic (ver- → [f:]) reductions in spoken Dutch sentences. In the test phase, both groups heard both kinds of reductions, but now applied to different words. In one of two experiments, the segmental reduction exposure group was better than the syllabic reduction exposure group in recognizing new reduced /b/-words. In both experiments, the syllabic reduction group showed a greater target preference for new reduced ver-words. Learning about reductions was thus applied to previously unheard words. This lexical generalization suggests that mechanisms compensating for segmental and syllabic reductions take place at a prelexical level, and hence that lexical access involves an abstractionist mode of processing. Existing abstractionist models need to be revised, however, as they do not include representations of sequences of segments (corresponding e.g. to ver-) at the prelexical level. |
Katja Poellmann; Holger Mitterer; James M. McQueen Use what you can: Storage, abstraction processes, and perceptual adjustments help listeners recognize reduced forms Journal Article In: Frontiers in Psychology, vol. 5, pp. 437, 2014. @article{Poellmann2014, Three eye-tracking experiments tested whether native listeners recognized reduced Dutch words better after having heard the same reduced words, or different reduced words of the same reduction type and whether familiarization with one reduction type helps listeners to deal with another reduction type. In the exposure phase, a segmental reduction group was exposed to /b/-reductions (e.g., minderij instead of binderij, "book binder") and a syllabic reduction group was exposed to full-vowel deletions (e.g., p'raat instead of paraat, "ready"), while a control group did not hear any reductions. In the test phase, all three groups heard the same speaker producing reduced-/b/ and deleted-vowel words that were either repeated (Experiments 1 and 2) or new (Experiment 3), but that now appeared as targets in semantically neutral sentences. Word-specific learning effects were found for vowel-deletions but not for /b/-reductions. Generalization of learning to new words of the same reduction type occurred only if the exposure words showed a phonologically consistent reduction pattern (/b/-reductions). In contrast, generalization of learning to words of another reduction type occurred only if the exposure words showed a phonologically inconsistent reduction pattern (the vowel deletions; learning about them generalized to recognition of the /b/-reductions). In order to deal with reductions, listeners thus use various means. They store reduced variants (e.g., for the inconsistent vowel-deleted words) and they abstract over incoming information to build up and apply mapping rules (e.g., for the consistent /b/-reductions). Experience with inconsistent pronunciations leads to greater perceptual flexibility in dealing with other forms of reduction uttered by the same speaker than experience with consistent pronunciations. |
Rafael Polanía; Ian Krajbich; Marcus Grueschow; Christian C. Ruff Neural oscillations and synchronization differentially support evidence accumulation in perceptual and value-based decision making Journal Article In: Neuron, vol. 82, no. 3, pp. 709–720, 2014. @article{Polania2014, Organisms make two types of decisions on a regular basis. Perceptual decisions are determined by objective states of the world (e.g., melons are bigger than apples), whereas value-based decisions are determined by subjective preferences (e.g., I prefer apples to melons). Theoretical accounts suggest that both types of choice involve neural computations accumulating evidence for the choice alternatives; however, little is known about the overlap or differences in the processes underlying perceptual versus value-based decisions. We analyzed EEG recordings during a paradigm where perceptual- and value-based choices were based on identical stimuli. For both types of choice, evidence accumulation was evident in parietal gamma-frequency oscillations, whereas a similar frontal signal was unique for value-based decisions. Fronto-parietal synchronization of these signals predicted value-based choice accuracy. These findings uncover how decisions emerge from topographic- and frequency-specificoscillations that accumulate distinct aspects of evidence, with large-scale synchronization as a mechanism integrating these spatially distributed signals. |
Arezoo Pooresmaeili; Thomas H. B. FitzGerald; Dominik R. Bach; Ulf Toelch; Florian Ostendorf; Raymond J. Dolan Cross-modal effects of value on perceptual acuity and stimulus encoding Journal Article In: Proceedings of the National Academy of Sciences, vol. 111, no. 42, pp. 15244–15249, 2014. @article{Pooresmaeili2014, Cross-modal interactions are very common in perception. An important feature of many perceptual stimuli is their reward-predicting properties, the utilization of which is essential for adaptive behavior. What is unknown is whether reward associations in one sensory modality influence perception of stimuli in another modality. Here we show that auditory stimuli with high-reward associations increase the sensitivity of visual perception, even when sounds and reward associations are both irrelevant for the visual task. This increased sensitivity correlates with a change in stimulus representation in the visual cortex, indexed by increased multivariate decoding accuracy in simultaneously acquired functional MRI data. Univariate analysis showed that reward associations modulated responses in regions associated with multisensory processing in which the strength of modulation was a better predictor of the magnitude of the behavioral effect than the modulation in classical reward regions. Our findings demonstrate a value-driven cross-modal interaction that affects perception and stimulus encoding, with a resemblance to well-described modulatory effects of attention. We suggest that multisensory processing areas may mediate the transfer of value signals across senses. |
Ivo D. Popivanov; Jan Jastorff; Wim Vanduffel; Rufin Vogels Heterogeneous single-unit selectivity in an fMRI-defined body-selective patch Journal Article In: Journal of Neuroscience, vol. 34, no. 1, pp. 95–111, 2014. @article{Popivanov2014, Although the visual representation of bodies is essential for reproduction, survival, and social communication, little is known about the mechanisms of body recognition at the single neuron level. Imaging studies showed body-category selective regions in the primate occipitotemporal cortex, but it is difficult to infer the stimulus selectivities of the neurons from the population activity measured in these fMRI studies. To overcome this, we recorded single unit activity and local field potentials (LFPs) in the middle superior temporal sulcus body patch, defined by fMRI in the same rhesus monkeys. Both the spiking activity, averaged across single neurons, and LFP gamma power in this body patch was greater for bodies (including monkey bodies, human bodies, mammals, and birds) compared with other objects, which fits the fMRI activation. Single neurons responded to a small proportion of body images. Thus, the category selectivity at the population level resulted from averaging responses of a heterogeneous population of single units. Despite such strong within-category selectivity at the single unit level, two distinct clusters, bodies and nonbodies, were present when analyzing the responses at the population level, and a classifier that was trained using the responses to a subset of images was able to classify novel images of bodies with high accuracy. The body-patch neurons showed strong selectivity for individual body parts at different orientations. Overall, these data suggest that single units in the fMRI-defined body patch are biased to prefer bodies over nonbody objects, including faces, with a strong selectivity for individual body images. |
Guojie Ma; Xingshan Li; Keith Rayner Word segmentation of overlapping ambiguous strings during Chinese reading Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 40, no. 3, pp. 1046–1059, 2014. @article{Ma2014, In 3 experiments, we tested 3 possible mechanisms for segmenting overlapping ambiguous strings in Chinese reading. The first 2 characters and the last 2 characters in a 3-character ambiguous string could both constitute a word in the reported studies. The left-priority hypothesis assumes that the word on the left has an advantage in the competition and the other word cannot be processed until the word on the left is recognized. The independent processing hypothesis assumes that words in different positions are processed simultaneously and independently, and the word segmentation ambiguity cannot be settled without the help of sentence context. The competition hypothesis assumes that all of the words compete for a single winner. The results support a competition account that the characters in the perceptual span activate all of the words they can constitute, and any word can win the competition if its activation is high enough. |
Christine Macare; Thomas Meindl; Igor Nenadic; Dan Rujescu; Ulrich Ettinger Preliminary findings on the heritability of the neural correlates of response inhibition Journal Article In: Biological Psychology, vol. 103, no. 1, pp. 19–23, 2014. @article{Macare2014, Imaging genetics examines genetic influences on brain structure and function. This preliminary study tested a fundamental assumption of that approach by estimating the heritability of the blood oxygen level dependent (BOLD) signal during antisaccades, a measure of response inhibition impaired in different psychiatric conditions. One hundred thirty-two healthy same-sex reared-together twins (90 monozygotic (MZ; 32 male) and 42 dizygotic (DZ; 24 male)) performed antisaccades in the laboratory. Of these, 96 twins (60 MZ, 28 male; 36 DZ, 22 male) subsequently underwent functional magnetic resonance imaging (fMRI) during antisaccades. Variation in antisaccade direction errors in the laboratory showed significant heritability (47%; 95% confidence interval (CI) 22-65). In fMRI, the contrast of antisaccades with prosaccades yielded BOLD signal in fronto-parietal-subcortical networks. Twin modelling provided tentative evidence of significant heritability (50%, 95% CI: 18-72) of BOLD in the left thalamus only. However, due to the limited power to detect heritability in this study, replications in larger samples are needed. |
Bart Machilsen; Johan Wagemans Both predictability and familiarity facilitate contour integration Journal Article In: Journal of Vision, vol. 14, no. 5, pp. 1–15, 2014. @article{Machilsen2014, Research has shown that contour detection is impaired in the visual periphery for snake-shaped Gabor contours but not for circular and elliptical contours. This discrepancy in findings could be due to differences in intrinsic shape properties, including shape closure and curvature variation, as well as to differences in stimulus predictability and familiarity. In a detection task using only circular contours, the target shape is both more familiar and more predictable to the observer compared with a detection task in which a different snake-shaped contour is presented on each trial. In this study, we investigated the effects of stimulus familiarity and predictability on contour integration by manipulating and disentangling the familiarity and predictability of snake-like stimuli. We manipulated stimulus familiarity by extensively training observers with one particular snake shape. Predictability was varied by alternating trial blocks with only a single target shape and trial blocks with multiple target shapes. Our results show that both predictability and familiarity facilitated contour integration, which constitutes novel behavioral evidence for the adaptivity of the contour integration mechanism in humans. If familiarity or predictability facilitated contour integration in the periphery specifically, this could explain the discrepant findings obtained with snake contours as compared with circles or ellipses. However, we found that their facilitatory effects did not differ between central and peripheral vision and thus cannot explain that particular discrepancy in the literature. |
W. Joseph MacInnes; Amelia R. Hunt Attentional load interferes with target localization across saccades Journal Article In: Experimental Brain Research, vol. 232, no. 12, pp. 3737–3748, 2014. @article{MacInnes2014, The retinal positions of objects in the world change with each eye movement, but we seem to have little trouble keeping track of spatial information from one fixation to the next. We examined the role of attention in trans-saccadic localization by asking participants to localize targets while performing an attentionally demanding secondary task. In the first experiment, attentional load decreased localization precision for a remembered target, but only when a saccade intervened between target presentation and report. We then repeated the experiment and included a salient landmark that shifted on half the trials. The shifting landmark had a larger effect on localization under high load, indicating that observers rely more on landmarks to make localization judgments under high than under low attentional load. The results suggest that attention facilitates trans-saccadic localization judgments based on spatial updating of gaze-centered coordinates when visual landmarks are not available. The availability of reliable landmarks (present in most natural circumstances) can compensate for the effects of scarce attentional resources on trans-saccadic localization. |
W. Joseph MacInnes; Amelia R. Hunt; Matthew D. Hilchey; Raymond M. Klein Driving forces in free visual search: An ethology Journal Article In: Attention, Perception, and Psychophysics, vol. 76, no. 2, pp. 280–295, 2014. @article{MacInnes2014a, Visual search typically involves sequences of eye movements under the constraints of a specific scene and specific goals. Visual search has been used as an experimental paradigm to study the interplay of scene salience and top-down goals, as well as various aspects of vision, attention, and memory, usually by introducing a secondary task or by controlling and manipulating the search environment. An ethology is a study of an animal in its natural environment, and here we examine the fixation patterns of the human animal searching a series of challenging illustrated scenes that are well-known in popular culture. The search was free of secondary tasks, probes, and other distractions. Our goal was to describe saccadic behavior, including patterns of fixation duration, saccade amplitude, and angular direction. In particular, we employed both new and established techniques for identifying top-down strategies, any influences of bottom-up image salience, and the midlevel attentional effects of saccadic momentum and inhibition of return. The visual search dynamics that we observed and quantified demonstrate that saccades are not independently generated and incorporate distinct influences from strategy, salience, and attention. Sequential dependencies consistent with inhibition of return also emerged from our analyses. |
Indra T. Mahayana; Chia-Lun Liu; Chi Fu Chang; Daisy L. Hung; Ovid J. L. Tzeng; Chi-Hung Juan; Neil G. Muggleton Far-space neglect in conjunction but not feature search following transcranial magnetic stimulation over right posterior parietal cortex Journal Article In: Journal of Neurophysiology, vol. 111, no. 4, pp. 705–714, 2014. @article{Mahayana2014, Near- and far-space coding in the human brain is a dynamic process. Areas in dorsal, as well as ventral visual association cortex, including right posterior parietal cortex (rPPC), right frontal eye field (rFEF), and right ventral occipital cortex (rVO), have been shown to be important in visuospatial processing, but the involvement of these areas when the information is in near or far space remains unclear. There is a need for investigations of these representations to help explain the pathophysiology of hemispatial neglect, and the role of near and far space is crucial to this. We used a conjunction visual search task using an elliptical array to investigate the effects of transcranial magnetic stimulation delivered over rFEF, rPPC, and rVO on the processing of targets in near and far space and at a range of horizontal eccentricities. As in previous studies, we found that rVO was involved in far-space search, and rFEF was involved regardless of the distance to the array. It was found that rPPC was involved in search only in far space, with a neglect-like effect when the target was located in the most eccentric locations. No effects were seen for any site for a feature search task. As the search arrays had higher predictability with respect to target location than is often the case, these data may form a basis for clarifying both the role of PPC in visual search and its contribution to neglect, as well as the importance of near and far space in these. |
Michaela Mahlberg; Kathy Conklin; Marie-Josée Bisson Reading Dickens's characters: Employing psycholinguistic methods to investigate the cognitive reality of patterns in texts Journal Article In: Language and Literature, vol. 23, no. 4, pp. 369–388, 2014. @article{Mahlberg2014, This article reports the findings of an empirical study that uses eye-tracking and follow-up interviews as methods to investigate how participants read body language clusters in novels by Charles Dickens. The study builds on previous corpus stylistic work that has identified patterns of body language presentation as techniques of characterisation in Dickens (Mahlberg, 2013). The article focuses on the reading of 'clusters', that is, repeated sequences of words. It is set in a research context that brings together observations from both corpus linguistics and psycholinguistics on the processing of repeated patterns. The results show that the body language clusters are read significantly faster than the overall sample extracts which suggests that the clusters are stored as units in the brain. This finding is complemented by the results of the follow-up questions which indicate that readers do not seem to refer to the clusters when talking about character information, although they are able to refer to clusters when biased prompts are used to elicit information. Beyond the specific results of the study, this article makes a contribution to the development of complementary methods in literary stylistics and it points to directions for further subclassifications of clusters that could not be achieved on the basis of corpus data alone. |
Guido Maiello; Manuela Chessa; Fabio Solari; Peter J. Bex Simulated disparity and peripheral blur interact during binocular fusion Journal Article In: Journal of Vision, vol. 14, no. 8, pp. 1–14, 2014. @article{Maiello2014, We have developed a low-cost, practical gaze-contingent display in which natural images are presented to the observer with dioptric blur and stereoscopic disparity that are dependent on the three-dimensional structure of natural scenes. Our system simulates a distribution of retinal blur and depth similar to that experienced in real-world viewing conditions by emmetropic observers. We implemented the system using light-field photographs taken with a plenoptic camera which supports digital refocusing anywhere in the images. We coupled this capability with an eye-tracking system and stereoscopic rendering. With this display, we examine how the time course of binocular fusion depends on depth cues from blur and stereoscopic disparity in naturalistic images. Our results show that disparity and peripheral blur interact to modify eye-movement behavior and facilitate binocular fusion, and the greatest benefit was gained by observers who struggled most to achieve fusion. Even though plenoptic images do not replicate an individual's aberrations, the results demonstrate that a naturalistic distribution of depth-dependent blur may improve 3-D virtual reality, and that interruptions of this pattern (e.g., with intraocular lenses) which flatten the distribution of retinal blur may adversely affect binocular fusion. |
George L. Malcolm; Antje Nuthmann; Philippe G. Schyns Beyond gist: Strategic and incremental information accumulation for scene categorization Journal Article In: Psychological Science, vol. 25, no. 5, pp. 1087–1097, 2014. @article{Malcolm2014, Research on scene categorization generally concentrates on gist processing, particularly the speed and minimal features with which the "story" of a scene can be extracted. However, this focus has led to a paucity of research into how scenes are categorized at specific hierarchical levels (e.g., a scene could be a road or more specifically a highway); consequently, research has disregarded a potential diagnostically driven feedback process. We presented participants with scenes that were low-pass filtered so only their gist was revealed, while a gaze-contingent window provided the fovea with full-resolution details. By recording where in a scene participants fixated prior to making a basic- or subordinate-level judgment, we identified the scene information accrued when participants made either categorization. We observed a feedback process, dependent on categorization level, that systematically accrues sufficient and detailed diagnostic information from the same scene. Our results demonstrate that during scene processing, a diagnostically driven bidirectional interplay between top-down and bottom-up information facilitates relevant category processing. |
Jonathan T. Mall; Candice C. Morey; Michael J. Wolff; Franziska Lehnert In: Attention, Perception, and Psychophysics, vol. 76, no. 7, pp. 1998–2014, 2014. @article{Mall2014, Selective attention and working memory capacity (WMC) are related constructs, but debate about the manner in which they are related remains active. One elegant explanation of variance in WMC is that the efficiency of filtering irrelevant information is the crucial determining factor, rather than differences in capacity per se. We examined this hypothesis by relating WMC (as measured by complex span tasks) to accuracy and eye movements during visual change detection tasks with different degrees of attentional filtering and allocation requirements. Our results did not indicate strong filtering differences between high- and low-WMC groups, and where differences were observed, they were counter to those predicted by the strongest attentional filtering hypothesis. Bayes factors indicated evidence favoring positive or null relationships between WMC and correct responses to unemphasized information, as well as between WMC and the time spent looking at unemphasized information. These findings are consistent with the hypothesis that individual differences in storage capacity, not only filtering efficiency, underlie individual differences in working memory. |
Ryan T. Maloney; Tamara L. Watson; Colin W. G. Clifford Determinants of motion response anisotropies in human early visual cortex: The role of configuration and eccentricity Journal Article In: NeuroImage, vol. 100, pp. 564–579, 2014. @article{Maloney2014, Anisotropies in the cortical representation of various stimulus parameters can reveal the fundamental mechanisms by which sensory properties are analysed and coded by the brain. One example is the preference for motion radial to the point of fixation (i.e. centripetal or centrifugal) exhibited in mammalian visual cortex. In two experiments, this study used functional magnetic resonance imaging (fMRI) to explore the determinants of these radial biases for motion in functionally-defined areas of human early visual cortex, and in particular their dependence upon eccentricity which has been indicated in recent reports. In one experiment, the cortical response to wide-field random dot kinematograms forming 16 different complex motion patterns (including centrifugal, centripetal, rotational and spiral motion) was measured. The response was analysed according to preferred eccentricity within four different eccentricity ranges. Response anisotropies were characterised by enhanced activity for centripetal or centrifugal patterns that changed systematically with eccentricity in visual areas V1-V3 and hV4 (but not V3A/B or V5/MT. +). Responses evolved from a preference for centrifugal over centripetal patterns close to the fovea, to a preference for centripetal over centrifugal at the most peripheral region stimulated, in agreement with previous work. These effects were strongest in V2 and V3. In a second experiment, the stimuli were restricted to within narrow annuli either close to the fovea (0.75-1.88°) or further in the periphery (4.82-6.28°), in a way that preserved the local motion information available in the first experiment. In this configuration a preference for radial motion (centripetal or centrifugal) persisted but the dependence upon eccentricity disappeared. Again this was clearest in V2 and V3. A novel interpretation of the dependence upon eccentricity of motion anisotropies in early visual cortex is offered that takes into account the spatiotemporal "predictability" of the moving pattern. Such stimulus predictability, and its relationship to models of predictive coding, has found considerable support in recent years in accounting for a number of other perceptual and neural phenomena. |
David Méary; Zhihan Li; Wu Li; Kun Guo; Olivier Pascalis Seeing two faces together: Preference formation in humans and rhesus macaques Journal Article In: Animal Cognition, vol. 17, no. 5, pp. 1107–1119, 2014. @article{Meary2014, Humans, great apes and old world monkeys show selective attention to faces depending on conspecificity, familiarity, and social status supporting the view that primates share similar face processing mechanisms. Although many studies have been done on face scanning strategy in monkeys and humans, the mechanisms influencing viewing preference have received little attention. To determine how face categories influence viewing preference in humans and rhesus macaques (Macaca mulatta), we performed two eye-tracking experiments using a visual preference task whereby pairs of faces from different species were presented simultaneously. The results indicated that viewing time was significantly influenced by the pairing of the face categories. Humans showed a strong bias towards an own-race face in an Asian-Caucasian condition. Rhesus macaques directed more attention towards non-human primate faces when they were paired with human faces, regardless of the species. When rhesus faces were paired with faces from Barbary macaques (Macaca sylvanus) or chimpanzees (Pan troglodytes), the novel species' faces attracted more attention. These results indicate that monkeys' viewing preferences, as assessed by a visual preference task, are modulated by several factors, species and dominance being the most influential. |
Alberto Megías; Leandro Luigi Di Stasi; Antonio Maldonado; Andrés Catena; Antonio Cándido Emotion-laden stimuli influence our reactions to traffic lights Journal Article In: Transportation Research Part F: Traffic Psychology and Behaviour, vol. 22, pp. 96–103, 2014. @article{Megias2014, This study focused on the effects of emotion-laden stimuli (emotional roadside advertisements) on driver decision making. A common dilemma in driving is whether to speed up or brake when the lights turn yellow at an intersection. This study focused on this aspect of driver decision making. We compared the influence of emotion-laden roadside advertisements (positive, negative, and neutral solutions) either on the evaluation of possible risk (i.e., evaluative behavior) or the decision to stop/speed up (i.e., urgent behavior). We showed that drivers brake more often after negative advertisements than after positive and neutral ones; at the same time, the response latency was shorter when they decided to speed up. We also demonstrated that urgent behavior responses were faster than evaluative ones, independent of the emotional content. Thus, we conclude that urgent behavior may be more automatic than evaluative behavior according to the dual system models of risk perception and decision-making. Overall, our results suggest that emotional factors play a decisive role in making driving decisions, particularly in risky driving situations. These findings provide important information for the development of new and advanced driver emotional support systems and, in general, for the specification of future transportation police design guidelines. |