All EyeLink Eye Tracker Publications
All 14,000+ peer-reviewed EyeLink research publications up until 2025 (with some early 2026s) 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!
2016 |
Umesh Patil; Shravan Vasishth; Richard L. Lewis Retrieval interference in syntactic processing: The case of reflexive binding in English Journal Article In: Frontiers in Psychology, vol. 7, pp. 329, 2016. @article{Patil2016,It has been proposed that in online sentence comprehension the dependency between a reflexive pronoun such as himself/herself and its antecedent is resolved using exclusively syntactic constraints. Under this strictly syntactic search account, Principle A of the binding theory-which requires that the antecedent c-command the reflexive within the same clause that the reflexive occurs in-constrains the parser's search for an antecedent. The parser thus ignores candidate antecedents that might match agreement features of the reflexive (e.g., gender) but are ineligible as potential antecedents because they are in structurally illicit positions. An alternative possibility accords no special status to structural constraints: in addition to using Principle A, the parser also uses non-structural cues such as gender to access the antecedent. According to cue-based retrieval theories of memory (e.g., Lewis and Vasishth, 2005), the use of non-structural cues should result in increased retrieval times and occasional errors when candidates partially match the cues, even if the candidates are in structurally illicit positions. In this paper, we first show how the retrieval processes that underlie the reflexive binding are naturally realized in the Lewis and Vasishth (2005) model. We present the predictions of the model under the assumption that both structural and non-structural cues are used during retrieval, and provide a critical analysis of previous empirical studies that failed to find evidence for the use of non-structural cues, suggesting that these failures may be Type II errors. We use this analysis and the results of further modeling to motivate a new empirical design that we use in an eye tracking study. The results of this study confirm the key predictions of the model concerning the use of non-structural cues, and are inconsistent with the strictly syntactic search account. These results present a challenge for theories advocating the infallibility of the human parser in the case of reflexive resolution, and provide support for the inclusion of agreement features such as gender in the set of retrieval cues. |
Sergei L. Shishkin; Yuri O. Nuzhdin; Evgeny P. Svirin; Alexander G. Trofimov; Anastasia A. Fedorova; Bogdan L. Kozyrskiy; Boris M. Velichkovsky EEG negativity in fixations used for gaze-based control: Toward converting intentions into actions with an eye-brain-computer interface Journal Article In: Frontiers in Neuroscience, vol. 10, pp. 528, 2016. @article{snstfkv16,We usually look at an object when we are going to manipulate it. Thus, eye tracking can be used to communicate intended actions. An effective human-machine interface, however, should be able to differentiate intentional and spontaneous eye movements. We report an electroencephalogram (EEG) marker that differentiates gaze fixations used for control from spontaneous fixations involved in visual exploration. Eight healthy participants played a game with their eye movements only. Their gaze-synchronized EEG data (fixation-related potentials, FRPs) were collected during game's control-on and control-off conditions. A slow negative wave with a maximum in the parietooccipital region was present in each participant's averaged FRPs in the control-on conditions and was absent or had much lower amplitude in the control-off condition. This wave was similar but not identical to stimulus-preceding negativity, a slow negative wave that can be observed during feedback expectation. Classification of intentional vs. spontaneous fixations was based on amplitude features from 13 EEG channels using 300 ms length segments free from electrooculogram contamination (200..500 ms relative to the fixation onset). For the first fixations in the fixation triplets required to make moves in the game, classified against control-off data, a committee of greedy classifiers provided 0.90 ± 0.07 specificity and 0.38 ± 0.14 sensitivity. Similar (slightly lower) results were obtained for the shrinkage LDA classifier. The second and third fixations in the triplets were classified at lower rate. We expect that, with improved feature sets and classifiers, a hybrid dwell-based Eye-Brain-Computer Interface (EBCI) can be built using the FRP difference between the intended and spontaneous fixations. If this direction of BCI development will be successful, such a multimodal interface may improve the fluency of interaction and can possibly become the basis for a new input device for paralyzed and healthy users, the EBCI “Wish Mouse”. |
Aidan P. Murphy; David A. Leopold; Glyn W. Humphreys; Andrew E. Welchman Lesions to right posterior parietal cortex impair visual depth perception from disparity but not motion cues Journal Article In: Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 371, pp. 1–17, 2016. @article{Murphy2016,The posterior parietal cortex (PPC) is understood to be active when observers perceive three-dimensional (3D) structure. However, it is not clear how central this activity is in the construction of 3D spatial representations. Here, we examine whether PPC is essential for two aspects of visual depth perception by testing patients with lesions affecting this region. First, we measured subjects' ability to discriminate depth structure in various 3D surfaces and objects using binocular disparity. Patients with lesions to right PPC (N = 3) exhibited marked perceptual deficits on these tasks, whereas those with left hemisphere lesions (N = 2) were able to reliably discriminate depth as accurately as control subjects. Second, we presented an ambiguous 3D stimulus defined by structure from motion to determine whether PPC lesions influence the rate of bistable perceptual alternations. Patients' percept durations for the 3D stimulus were generally within a normal range, although the two patients with bilateral PPC lesions showed the fastest perceptual alternation rates in our sample. Intermittent stimulus presentation reduced the reversal rate similarly across subjects. Together, the results suggest that PPC plays a causal role in both inferring and maintaining the perception of 3D structure with stereopsis supported primarily by the right hemisphere, but do not lend support to the view that PPC is a critical contributor to bistable perceptual alternations. |
Anouk Mariette Loon; Johannes J. Fahrenfort; Bauke Velde; Philipp B. Lirk; Nienke C. C. Vulink; Markus W. Hollmann; H. Steven Scholte; Victor A. F. Lamme NMDA receptor antagonist ketamine distorts object recognition by reducing feedback to early visual cortex Journal Article In: Cerebral Cortex, vol. 26, no. 5, pp. 1986–1996, 2016. @article{Loon2016,It is a well-established fact that top-down processes influence neural representations in lower-level visual areas. Electrophysiological recordings in monkeys as well as theoretical models suggest that these top-down processes depend on NMDA receptor functioning. However, this underlying neural mechanism has not been tested in humans. We used fMRI multivoxel pattern analysis to compare the neural representations of ambiguous Mooney images before and after they were recognized with their unambiguous grayscale version. Additionally, we administered ketamine, an NMDA receptor antagonist, to interfere with this process. Our results demonstrate that after recognition, the pattern of brain activation elicited by a Mooney image is more similar to that of its easily recognizable grayscale version than to the pattern evoked by the identical Mooney image before recognition. Moreover, recognition of Mooney images decreased mean response; however, neural representations of separate images became more dissimilar. So from the neural perspective, unrecognizable Mooney images all “look the same”, whereas recognized Mooneys look different. We observed these effects in posterior fusiform part of lateral occipital cortex and in early visual cortex. Ketamine distorted these effects of recognition, but in early visual cortex only. This suggests that top-down processes from higher- to lower-level visual areas might operate via an NMDA pathway. |
Anthony Shook; Viorica Marian The influence of native-language tones on lexical access in the second language Journal Article In: The Journal of the Acoustical Society of America, vol. 139, no. 6, pp. 3102–3109, 2016. @article{Shook2016,When listening to speech in a second language, bilinguals' perception of acoustic-phonetic properties is often influenced by the features that are important in the native language of the bilingual. Furthermore, changes in the perception of segmental contrasts due to L1 experience can influence L2 lexical access during comprehension. The present study investigates whether the effect of L1 experience on L2 processing seen at the segmental level extends to suprasegmental processing. In an eye-tracking task, Mandarin–English bilinguals heard an auditorily presented English word and selected which of two visually presented Chinese characters represented the correct Mandarin translation. The pitch contour of the spoken word was manipulated to either match or mismatch the lexical tone of the Mandarin translation. Results revealed that bilinguals were significantly faster to correctly identify the target and made earlier eye movements to targets when the suprasegmental information of the word spoken in English matched that of its Mandarin translation. The findings provide compelling evidence for bilinguals' sensitivity to suprasegmental tone information, even when listening to a non-tonal language. These results have important implications for the effect of L1 experience on L2 lexical access and language interaction in bilinguals, and are consistent with a highly interactive account of language processing. |
Eelke Spaak; Yvonne Fonken; Ole Jensen; Floris P. Lange The neural mechanisms of prediction in visual search Journal Article In: Cerebral Cortex, vol. 26, no. 11, pp. 4327–4336, 2016. @article{sfjd16,The speed of visual search depends on bottom-up stimulus features (e.g., we quickly locate a red item among blue distractors), but it is also facilitated by the presence of top-down perceptual predictions about the item. Here, we identify the nature, source, and neuronal substrate of the predictions that speed up resumed visual search. Human subjects were presented with a visual search array that was repeated up to 4 times, while brain activity was recorded using magnetoencephalography (MEG). Behaviorally, we observed a bimodal reaction time distribution for resumed visual search, indicating that subjects were extraordinarily rapid on a proportion of trials. MEG data demonstrated that these rapid-response trials were associated with a prediction of (1) target location, as reflected by alpha-band (8-12 Hz) lateralization; and (2) target identity, as reflected by beta-band (15-30 Hz) lateralization. Moreover, we show that these predictions are likely generated in a network consisting of medial superior frontal cortex and right temporo-parietal junction. These findings underscore the importance and nature of perceptual hypotheses for efficient visual search. |
Nicola Binetti; Charlotte Harrison; Alan Johnston; Isabelle Mareschal Pupil dilation as an index of preferred mutual gaze duration Journal Article In: Royal Society Open Science, vol. 3, no. 16008, pp. 1–11, 2016. @article{Binetti2016,Most animals look at each other to signal threat or interest. In humans, this social interaction is usually punctuated with brief periods of mutual eye contact. Deviations from this pattern of gazing behaviour generally make us feel uncomfortable and are a defining characteristic of clinical conditions such as autism or schizophrenia, yet it is unclear what constitutes normal eye contact.Here, we measured, across a wide range of ages, cultures and personality types, the period of direct gaze that feels comfortable and examined whether autonomic factors linked to arousal were indicative of people's preferred amount of eye contact. Surprisingly, we find that preferred period of gaze duration is not dependent on fundamental characteristics such as gender, personality traits or attractiveness. However, we do find that subtle pupillary changes, indicative of physiological arousal, correlate with the amount of eye contact people find comfortable. Specifically, people preferring longer durations of eye contact display faster increases in pupil size when viewing another person than those preferring shorter durations. These results reveal that a person's preferred duration of eye contact is signalled by physiological indices (pupil dilation) beyond volitional control that may play a modulatory role in gaze behaviour. |
Xin Liu; Tong Chen; Guoqiang Xie; Guangyuan Liu Contact-free cognitive load recognition based on eye movement Journal Article In: Journal of Electrical and Computer Engineering, pp. 1–8, 2016. @article{Liu2016e,The cognitive overload not only affects the physical and mental diseases, but also affects the work efficiency and safety. Hence, the research of measuring cognitive load has been an important part of cognitive load theory. In this paper, we proposed a method to identify the state of cognitive load by using eye movement data in a noncontact manner. We designed a visual experiment to elicit human's cognitive load as high and low state in two light intense environments and recorded the eye movement data in this whole process. Twelve salient features of the eye movement were selected by using statistic test. Algorithms for processing some features are proposed for increasing the recognition rate. Finally we used the support vector machine (SVM) to classify high and low cognitive load. The experimental results show that the method can achieve 90.25% accuracy in light controlled condition. |
Leandro L. Di Stasi; Michael B. McCamy; Susana Martinez-Conde; Ellis Gayles; Chad Hoare; Michael Foster; Andrés Catena; Stephen L. Macknik Effects of long and short simulated flights on the saccadic eye movement velocity of aviators Journal Article In: Physiology and Behavior, vol. 153, pp. 91–96, 2016. @article{DiStasi2016,Aircrew fatigue is a major contributor to operational errors in civil and military aviation. Objective detection of pilot fatigue is thus critical to prevent aviation catastrophes. Previous work has linked fatigue to changes in oculomotor dynamics, but few studies have studied this relationship in critical safety environments. Here we measured the eye movements of US Marine Corps combat helicopter pilots before and after simulated flight missions of different durations. We found a decrease in saccadic velocities after long simulated flights compared to short simulated flights. These results suggest that saccadic velocity could serve as a biomarker of aviator fatigue. |
Peter R. Murphy; Evert Boonstra; Sander Nieuwenhuis Global gain modulation generates time-dependent urgency during perceptual choice in humans Journal Article In: Nature Communications, vol. 7, pp. 13526, 2016. @article{Murphy2016a,Decision-makers must often balance the desire to accumulate information with the costs of protracted deliberation. Optimal, reward-maximizing decision-making can require dynamic adjustment of this speed/accuracy trade-off over the course of a single decision. However, it is unclear whether humans are capable of such time-dependent adjustments. Here, we identify several signatures of time-dependency in human perceptual decision-making and highlight their possible neural source. Behavioural and model-based analyses reveal that subjects respond to deadline-induced speed pressure by lowering their criterion on accumulated perceptual evidence as the deadline approaches. In the brain, this effect is reflected in evidence-independent urgency that pushes decision-related motor preparation signals closer to a fixed threshold. Moreover, we show that global modulation of neural gain, as indexed by task-related fluctuations in pupil diameter, is a plausible biophysical mechanism for the generation of this urgency. These findings establish context-sensitive time-dependency as a critical feature of human decision-making. |
Eyal M. Reingold; Heather Sheridan; Katie L. Meadmore; Denis Drieghe; Simon P. Liversedge Attention and eye-movement control in reading: The selective reading paradigm Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 42, no. 12, pp. 2003–2020, 2016. @article{Reingold2016,We introduced a novel paradigm for investigating covert attention and eye-movement control in reading. In 2 experiments, participants read sentence words (shown in blue color) while ignoring interleaved distractor strings (shown in orange color). Each single-line text display contained a target word and a critical distractor. Critical distractors were located just prior to the target in the text and were either words or symbol strings (e.g., @#%&). Target word availability for parafoveal processing (i.e., preview validity) was also manipulated. The results indicated much shallower processing of distractors than targets, and this pattern was more pronounced for symbol than word distractors. The influences of word frequency and fixation location on first-pass fixation durations on distractors were dramatically different than the well-documented pattern obtained in normal reading. Robust preview benefits were demon- strated both when the critical distractors were fixated and when the critical distractors were skipped. Finally, with the exception of larger preview benefits that were obtained in the condition in which the target and critical distractor were identical, the magnitude of the preview effect was largely unaffected by the nature of the critical distractor. Implications of the present paradigm and findings to the study of eye-movement control in reading are discussed. |
Vanessa Beanland; Rebecca K. Le; Jamie E. M. Byrne Object-scene relationships vary the magnitude of target prevalence effects in visual search Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 42, no. 6, pp. 766–775, 2016. @article{Beanland2016,Efficiency of visual search in real-world tasks is affected by several factors, including scene context and target prevalence. Observers are more efficient at detecting target objects in congruent locations, and less efficient at detecting rare targets. Although target prevalence and placement often covary, previous research has investigated context and prevalence effects independently. We conducted 2 experiments to explore the potential interaction between scene context and target prevalence effects. In Experiment 1, we varied target prevalence (high, low) and context (congruent, incongruent), and, for congruent contexts, target location (typical, atypical). Experiment 2 focused on the interaction between target prevalence (high, low) and location (typical, atypical) for congruent contexts, and recorded observers' eye movements to examine search strategies. Observers were poorer at detecting low versus high prevalence targets; however, prevalence effects were significantly reduced for targets in typical, con-gruent locations compared with atypical or incongruent locations. Eye movement analyses in Experiment 2 revealed this was related to observers dwelling disproportionately on the most typical target locations within a scene. This suggests that a byproduct of contextual guidance within scenes is that placing targets in unexpected or atypical locations will further increase miss rates for uncommon targets, which has implications for real-world situations in which rare targets appear in unexpected locations. Although prevalence effects are robust, our results suggest potential for mitigating the negative consequences of low prevalence through targeted training that teaches observers where to focus their search. |
Masato Inoue; Motoaki Uchimura; Shigeru Kitazawa Error signals in motor cortices drive adaptation in reaching Journal Article In: Neuron, vol. 90, no. 5, pp. 1114–1126, 2016. @article{Inoue2016,Reaching movements are subject to adaptation in response to errors induced by prisms or external perturbations. Motor cortical circuits have been hypothesized to provide execution errors that drive adaptation, but human imaging studies to date have reported that execution errors are encoded in parietal association areas. Thus, little evidence has been uncovered that supports the motor hypothesis. Here, we show that both primary motor and premotor cortices encode information on end-point errors in reaching. We further show that post-movement microstimulation to these regions caused trial-by-trial increases in errors, which subsided exponentially when the stimulation was terminated. The results indicate for the first time that motor cortical circuits provide error signals that drive trial-by-trial adaptation in reaching movements. |
Anna-Maria Kasparbauer; Inga Meyhöfer; Maria Steffens; Bernd Weber; Merve Aydin; Veena Kumari; Rene Hurlemann; Ulrich Ettinger Neural effects of methylphenidate and nicotine during smooth pursuit eye movements Journal Article In: NeuroImage, vol. 141, pp. 52–59, 2016. @article{Kasparbauer2016,Introduction: Nicotine and methylphenidate are putative cognitive enhancers in healthy and patient populations. Although they stimulate different neurotransmitter systems, they have been shown to enhance performance on overlapping measures of attention. So far, there has been no direct comparison of the effects of these two stimulants on behavioural performance or brain function in healthy humans. Here, we directly compare the two compounds using a well-established oculomotor biomarker in order to explore common and distinct behavioural and neural effects. Methods: Eighty-two healthy male non-smokers performed a smooth pursuit eye movement task while lying in an fMRI scanner. In a between-subjects, double-blind design, subjects either received placebo (placebo patch and capsule), nicotine (7 mg nicotine patch and placebo capsule), or methylphenidate (placebo patch and 40 mg methylphenidate capsule). Results: There were no significant drug effects on behavioural measures. At the neural level, methylphenidate elicited higher activation in left frontal eye field compared to nicotine, with an intermediate response under placebo. Discussion: The reduced activation of task-related regions under nicotine could be associated with more efficient neural processing, while increased hemodynamic response under methylphenidate is interpretable as enhanced processing of task-relevant networks. Together, these findings suggest dissociable neural effects of these putative cognitive enhancers. |
Leendert Maanen; Laura Fontanesi; Guy E. Hawkins; Birte U. Forstmann Striatal activation reflects urgency in perceptual decision making Journal Article In: NeuroImage, vol. 139, pp. 294–303, 2016. @article{Maanen2016,Deciding between multiple courses of action often entails an increasing need to do something as time passes - a sense of urgency. This notion of urgency is not incorporated in standard theories of speeded decision making that assume information is accumulated until a critical fixed threshold is reached. Yet, it is hypothesized in novel theoretical models of decision making. In two experiments, we investigated the behavioral and neural evidence for an “urgency signal” in human perceptual decision making. Experiment 1 found that as the duration of the decision making process increased, participants made a choice based on less evidence for the selected option. Experiment 2 replicated this finding, and additionally found that variability in this effect across participants covaried with activation in the striatum. We conclude that individual differences in susceptibility to urgency are reflected by striatal activation. By dynamically updating a response threshold, the striatum is involved in signaling urgency in humans. |
Yan Zhang; Xiaochuan Pan; Rubin Wang; Masamichi Sakagami Functional connectivity between prefrontal cortex and striatum estimated by phase locking value Journal Article In: Cognitive Neurodynamics, vol. 10, no. 3, pp. 245–254, 2016. @article{Zhang2016,The interplay between the prefrontal cortex (PFC) and striatum has an important role in cognitive processes. To investigate interactive functions between the two areas in reward processing, we recorded local field potentials (LFPs) simultaneously from the two areas of two monkeys performing a reward prediction task (large reward vs small reward). The power of the LFPs was calculated in three frequency bands: the beta band (15–29 Hz), the low gamma band (30–49 Hz), and the high gamma band (50–100 Hz). We found that both the PFC and striatum encoded the reward information in the beta band. The reward information was also found in the high gamma band in the PFC, not in the striatum. We further calculated the phase-locking value (PLV) between two LFP signals to measure the phase synchrony between the PFC and striatum. It was found that significant differences occurred between PLVs in different task periods and in different frequency bands. The PLVs in small reward condition were significant higher than that in large reward condition in the beta band. In contrast, the PLVs in the high gamma band were stronger in large reward trials than in small trials. These results suggested that the functional connectivity between the PFC and striatum depended on the task periods and reward conditions. The beta synchrony between the PFC and striatum may regulate behavioral outputs of the monkeys in the small reward condition. |
Meg Fluharty; Ines Jentzsch; Manuel Spitschan; Dhanraj Vishwanath Eye fixation during multiple object attention is based on a representation of discrete spatial foci Journal Article In: Scientific Reports, vol. 6, pp. 31832, 2016. @article{Fluharty2016,We often look at and attend to several objects at once. How the brain determines where to point our eyes when we do this is poorly understood. Here we devised a novel paradigm to discriminate between different models of spatial selection guiding fixation. In contrast to standard static attentional tasks where the eye remains fixed at a predefined location, observers selected their own preferred fixation position while they tracked static targets that were arranged in specific geometric configurations and which changed identity over time. Fixations were best predicted by a representation of discrete spatial foci, not a polygonal grouping, simple 2-foci division of attention or a circular spotlight. Moreover, attentional performance was incompatible with serial selection. Together with previous studies, our findings are compatible with a view that attentional selection and fixation rely on shared spatial representations and suggest a more nuanced definition of overt vs. covert attention. |
Lesya Y. Ganushchak; Yiya Chen Incrementality in planning of speech during speaking and reading aloud: Evidence from eye-tracking Journal Article In: Frontiers in Psychology, vol. 7, pp. 33, 2016. @article{Ganushchak2016,Speaking is an incremental process where planning and articulation interleave. While incrementality has been studied in reading and online speech production separately, it has not been directly compared within one investigation. This study set out to compare the extent of planning incrementality in online sentence formulation versus reading aloud and how discourse context may constrain the planning scope of utterance preparation differently in these two modes of speech planning. Two eye-tracking experiments are reported: participants either described pictures of transitive events (Experiment 1) or read aloud the written descriptions of those events (Experiment 2). In both experiments, the information status of an object character was manipulated in the discourse preceding each picture or sentence. In the Literal condition, participants heard a story where object character was literally mentioned (e.g., fly). In the No Mention condition, stories did not literally mention nor prime the object character depicted on the picture or written in the sentence. The target response was expected to have the same structure and content in all conditions (The frog catches the fly). During naming, the results showed shorter speech onset latencies in the Literal condition than in the No Mention condition. However, no significant differences in gaze durations were found. In contrast, during reading, there were no significant differences in speech onset latencies but there were significantly longer gaze durations to the target picture/word in the Literal than in the No Mention condition. Our results shot that planning is more incremental during reading than during naming and that discourse context can be helpful during speaker but may hinder during reading aloud. Taken together our results suggest that on-line planning of response is affected by both linguistic and non-linguistic factors. |
Alexander Niklas Hausler; Sergio Oroz Artigas; Peter Trautner; Bernd Weber Gain- and loss-related brain activation are associated with information search differences in risky gambles: An fMRI and eye-tracking study Journal Article In: eNeuro, vol. 3, no. 5, pp. 1–13, 2016. @article{Hausler2016,People differ in the way they approach and handle choices with unsure outcomes. In this study, we demonstrate that individual differences in the neural processing of gains and losses relates to attentional differences in the way individuals search for information in gambles. Fifty subjects participated in two independent experiments. Participants first completed an fMRI experiment involving financial gains and losses. Subsequently, they performed an eye-tracking experiment on binary choices between risky gambles, each displaying monetary outcomes and their respective probabilities. We find that individual differences in gain and loss processing relate to attention distribution. Individuals with a stronger reaction to gains in the ventromedial prefrontal cortex paid more attention to monetary amounts, while a stronger reaction in the ventral striatum to losses was correlated with an increased attention to probabilities. Reaction in the posterior cingulate cortex to losses was also found to correlate with an increased attention to probabilities. Our data show that individual differences in brain activity and differences in information search processes are closely linked. |
Monika Intaitė; João Valente Duarte; Miguel Castelo-Branco Working memory load influences perceptual ambiguity by competing for fronto-parietal attentional resources Journal Article In: Brain Research, vol. 1650, pp. 142–151, 2016. @article{Intaite2016,A visual stimulus is defined as ambiguous when observers perceive it as having at least two distinct and spontaneously alternating interpretations. Neuroimaging studies suggest an involvement of a right fronto-parietal network regulating the balance between stable percepts and the triggering of alternative interpretations. As spontaneous perceptual reversals may occur even in the absence of attention to these stimuli, we investigated neural activity patterns in response to perceptual changes of ambiguous Necker cube under different amounts of working memory load using a dual-task design. We hypothesized that the same regions that process working memory load are involved in perceptual switching and confirmed the prediction that perceptual reversals led to fMRI responses that linearly depended on load. Accordingly, posterior Superior Parietal Lobule, anterior Prefrontal and Dorsolateral Prefrontal cortices exhibited differential BOLD signal changes in response to perceptual reversals under working memory load. Our results also suggest that the posterior Superior Parietal Lobule may be directly involved in the emergence of perceptual reversals, given that it specifically reflects both perceptual versus real changes and load levels. The anterior Prefrontal and Dorsolateral Prefrontal cortices, showing a significant interaction between reversal levels and load, might subserve a modulatory role in such reversals, in a mirror symmetric way: in the former activation is suppressed by the highest loads, and in the latter deactivation is reduced by highest loads, suggesting a more direct role of the aPFC in reversal generation. |
Dimitris Voudouris; Alexander Goettker; Stefanie Mueller; Katja Fiehler Kinesthetic information facilitates saccades towards proprioceptive-tactile targets Journal Article In: Vision Research, vol. 122, pp. 73–80, 2016. @article{Voudouris2016,Saccades to somatosensory targets have longer latencies and are less accurate and precise than saccades to visual targets. Here we examined how different somatosensory information influences the planning and control of saccadic eye movements. Participants fixated a central cross and initiated a saccade as fast as possible in response to a tactile stimulus that was presented to either the index or the middle fingertip of their unseen left hand. In a static condition, the hand remained at a target location for the entire block of trials and the stimulus was presented at a fixed time after an auditory tone. Therefore, the target location was derived only from proprioceptive and tactile information. In a moving condition, the hand was first actively moved to the same target location and the stimulus was then presented immediately. Thus, in the moving condition additional kinesthetic information about the target location was available. We found shorter saccade latencies in the moving compared to the static condition, but no differences in accuracy or precision of saccadic endpoints. In a second experiment, we introduced variable delays after the auditory tone (static condition) or after the end of the hand movement (moving condition) in order to reduce the predictability of the moment of the stimulation and to allow more time to process the kinesthetic information. Again, we found shorter latencies in the moving compared to the static condition but no improvement in saccade accuracy or precision. In a third experiment, we showed that the shorter saccade latencies in the moving condition cannot be explained by the temporal proximity between the relevant event (auditory tone or end of hand movement) and the moment of the stimulation. Our findings suggest that kinesthetic information facilitates planning, but not control, of saccadic eye movements to proprioceptive-tactile targets. |
Thomas D. W. Wilcockson; N. E. M. Sanal Heavy cannabis use and attentional avoidance of anxiety-related stimuli Journal Article In: Addictive Behaviors Reports, vol. 3, pp. 38–42, 2016. @article{Wilcockson2016,Objectives: Cannabis is now the most widely used illicit substance in the world. Previous research demonstrates that cannabis use is associated with dysfunctional affect regulation and anxiety. Anxiety is characterised by attentional biases in the presence of emotional information. This novel study therefore examined the attentional bias of cannabis users when presented with anxiety-related stimuli. The aim was to establish whether cannabis users respond to anxiety-related stimuli differently to control participants. Methods: A dot-probe paradigm was utilised using undergraduate students. Trials contained anxiety-related stimuli and neutral control stimuli. Eye-tracking was used to measure attention for the stimuli. Results: Results indicated that cannabis users demonstrated attentional-avoidance behaviour when presented with anxiety-related stimuli. Conclusions: The findings suggest a difference in processing of emotional information in relation to neutral information between groups. It would appear that cannabis users avoid anxiety provoking stimuli. Such behaviour could potentially have motivational properties that could lead to exacerbating anxiety disorder-type behaviour. |
Jessie S. Nixon; Jacolien Rij; Peggy Mok; R. Harald Baayen; Yiya Chen The temporal dynamics of perceptual uncertainty: Eye movement evidence from Cantonese segment and tone perception Journal Article In: Journal of Memory and Language, vol. 90, pp. 103–125, 2016. @article{Nixon2016,Two visual world eyetracking experiments investigated how acoustic cue value and statistical variance affect perceptual uncertainty during Cantonese consonant (Experiment 1) and tone perception (Experiment 2). Participants heard low- or high-variance acoustic stimuli. Euclidean distance of fixations from target and competitor pictures over time was analysed using Generalised Additive Mixed Modelling. Distance of fixations from target and competitor pictures varied as a function of acoustic cue, providing evidence for gradient, nonlinear sensitivity to cue values. Moreover, cue value effects significantly interacted with statistical variance, indicating that the cue distribution directly affects perceptual uncertainty. Interestingly, the time course of effects differed between target distance and competitor distance models. The pattern of effects over time suggests a global strategy in response to the level of uncertainty: as uncertainty increases, verification looks increase accordingly. Low variance generally creates less uncertainty, but can lead to greater uncertainty in the face of unexpected speech tokens. |
Caspar M. Schwiedrzik; Benjamin Bernstein; Lucia Melloni Motion along the mental number line reveals shared representations for numerosity and space Journal Article In: eLife, vol. 5, pp. 1–18, 2016. @article{sbm16,Perception of number and space are tightly intertwined. It has been proposed that this is due to ‘cortical recycling', where numerosity processing takes over circuits originally processing space. Do such ‘recycled' circuits retain their original functionality? Here, we investigate interactions between numerosity and motion direction, two functions that both localize to parietal cortex. We describe a new phenomenon in which visual motion direction adapts nonsymbolic numerosity perception, giving rise to a repulsive aftereffect: motion to the left adapts small numbers, leading to overestimation of numerosity, while motion to the right adapts large numbers, resulting in underestimation. The reference frame of this effect is spatiotopic. Together with the tuning properties of the effect this suggests that motion direction-numerosity cross-adaptation may occur in a homolog of area LIP. ‘Cortical recycling' thus expands but does not obliterate the functions originally performed by the recycled circuit, allowing for shared computations across domains. |
Zheng Zhiwei Wang; Kristina Zeljic; Qinying Jiang; Yong Gu; Wei Wang; Zheng Wang Dynamic network communication in the human functional connectome predicts perceptual variability in visual illusion Journal Article In: Cerebral Cortex, vol. 28, no. 1, pp. 1–15, 2016. @article{Wang2016h,The eukaryotic RNA exosome is an essential, multi-subunit complex that catalyzes RNA turnover, maturation, and quality control processes. Its non-catalytic donut-shaped core includes 9 subunits that associate with the 3' to 5' exoribonucleases Rrp6, and Rrp44/Dis3, a subunit that also catalyzes endoribonuclease activity. Although recent structures and biochemical studies of RNA bound exosomes from S. cerevisiae revealed that the Exo9 central channel guides RNA to either Rrp6 or Rrp44 using partially overlapping and mutually exclusive paths, several issues related to RNA recruitment remain. Here, we identify activities for the highly basic Rrp6 C-terminal tail that we term the 'lasso' because it binds RNA and stimulates ribonuclease activities associated with Rrp44 and Rrp6 within the 11-subunit nuclear exosome. Stimulation is dependent on the Exo9 central channel, and the lasso contributes to degradation and processing activities of exosome substrates in vitro and in vivo. Finally, we present evidence that the Rrp6 lasso may be a conserved feature of the eukaryotic RNA exosome. |
Alyssa S. Hess; Andrew J. Wismer; Corey J. Bohil; Mark B. Neider On the hunt: Searching for poorly defined camouflaged targets Journal Article In: PLoS ONE, vol. 11, no. 3, pp. e0152502, 2016. @article{Hess2016,As camouflaged targets share visual characteristics with the environment within which they are embedded, searchers rarely have access to a perfect visual template of such targets. Instead, they must rely on less specific representations to guide search. Although search for camouflaged and non-specified targets have both received attention in the literature, to date they have not been explored in a combined context. Here we introduce a new paradigm for characterizing behavior during search for camouflaged targets in natural scenes, while also exploring how the fidelity of the target template affects search processes. Search scenes were created from forest images, with targets a distortion (varied size) of that image at a random location. In Experiment 1 a preview of the target was provided; in Experiment 2 there was no preview. No differences were found between experiments on nearly all measures. Generally, reaction times and accuracy improved with familiarity on the task (more so for small targets). Analysis of eye movements indicated that performance benefits were related to improvements in both Search and Target Verification time. Combined, our data suggest that search for camouflaged targets can be improved over a short time-scale, even when targets are poorly defined. |
Anna Klapetek; Donatas Jonikaitis; Heiner Deubel Attention allocation before antisaccades Journal Article In: Journal of Vision, vol. 16, no. 1, pp. 1–16, 2016. @article{Klapetek2016,In the present study, we investigated the distribution of attention before antisaccades. We used a dual task paradigm, in which participants made prosaccades or antisaccades and discriminated the orientation of a visual probe shown at the saccade goal, the visual cue location (antisaccade condition), or a neutral location. Moreover, participants indicated whether they had made a correct antisaccade or an erroneous prosaccade. We observed that, while spatial attention in the prosaccade task was allocated only to the saccade goal, attention in the antisaccade task was allocated both to the cued location and to the antisaccade goal. This suggests parallel attentional selection of the cued and antisaccade locations. We further observed that in error trials—in which participants made an incorrect prosaccade instead of an antisaccade—spatial attention was biased towards the prosaccade goal. These erroneous prosaccades were mostly unnoticed and were often followed by corrective antisaccades with very short latencies (<100 ms). Data from error trials therefore provide further evidence for the parallel programming of the reflexive prosaccade to the cue and the antisaccade to the intended location. Taken together, our results suggest that attention allocation and saccade goal selection in the antisaccade task are mediated by a common competitive process. |
Dimitris Voudouris; Jeroen B. J. Smeets; Eli Brenner Fixation biases towards the index finger in almost-natural grasping Journal Article In: PLoS ONE, vol. 11, no. 1, pp. e0146864, 2016. @article{Voudouris2016a,We use visual information to guide our grasping movements. When grasping an object with a precision grip, the two digits need to reach two different positions more or less simulta- neously, but the eyes can only be directed to one position at a time. Several studies that have examined eye movements in grasping have found that people tend to direct their gaze near where their index finger will contact the object. Here we aimed at better understanding why people do so by asking participants to lift an object off a horizontal surface. They were to grasp the object with a precision grip while movements of their hand, eye and head were recorded. We confirmed that people tend to look closer to positions that a digit needs to reach more accurately. Moreover, we show that where they look as they reach for the object depends on where they were looking before, presumably because they try to minimize the time during which the eyes are moving so fast that no new visual information is acquired. Most importantly, we confirmed that people have a bias to direct gaze towards the index fin- ger's contact point rather than towards that of the thumb. In our study, this cannot be explained by the index finger contacting the object before the thumb. Instead, it appears to be because the index finger moves to a position that is hidden behind the object that is grasped, probably making this the place at which one is most likely to encounter unex- pected problems that would benefit from visual guidance. However, this cannot explain the bias that was found in previous studies, where neither contact point was hidden, so it cannot be the only explanation for the bias. |
Hosam Al-Samarraie; Samer Muthana Sarsam; Hans Guesgen Predicting user preferences of environment design: A perceptual mechanism of user interface customisation Journal Article In: Behaviour & Information Technology, vol. 35, no. 8, pp. 644–653, 2016. @article{AlSamarraie2016,It is a well-known fact that users vary in their preferences and needs. Therefore, it is very crucial to provide the customisation or personalisation for users in certain usage conditions that are more associated with their preferences. With the current limitation in adopting perceptual processing into user interface personalisation, we introduced the possibility of inferring interface design preferences from the user?s eye-movement behaviour. We firstly captured the user?s preferences of graphic design elements using an eye-tracker. Then we diagnosed these preferences towards the region of interests to build a prediction model for interface customisation. The prediction models from eye-movement behaviour showed a high potential for predicting users? preferences of interface design based on the paralleled relation between their fixation and saccadic movement. This mechanism provides a novel way of user interface design customisation and opens the door for new research in the areas of human?computer interaction and decision-making. |
Rebecca M. Foerster In: Frontiers in Psychology, vol. 7, pp. 1845, 2016. @article{Foerster2016,When performing sequential manual actions (e.g., cooking), visual information is prioritized according to the task determining where and when to attend, look, and act. In well-practiced sequential actions, long-term memory (LTM)-based expectations specify which action targets might be found where and when.We have previously demonstrated (Foerster and Schneider, 2015b) that violations of such expectations that are task- relevant (e.g., target location change) cause a regression from a memory-based mode of attentional selection to visual search. How might task-irrelevant expectation violations in such well-practiced sequential manual actions modify attentional selection? This question was investigated by a computerized version of the number-connection test. Participants clicked on nine spatially distributed numbered target circles in ascending order while eye movements were recorded as proxy for covert attention. Target's visual features and locations stayed constant for 65 prechange-trials, allowing practicing the manual action sequence. Consecutively, a task-irrelevant expectation violation occurred and stayed for 20 change-trials. Specifically, action target number 4 appeared in a different font. In 15 reversion-trials, number 4 returned to the original font. During the first task-irrelevant change trial, manual clicking was slower and eye scanpaths were larger and contained more fixations. The additional fixations were mainly checking fixations on the changed target while acting on later targets. Whereas the eyes repeatedly revisited the task-irrelevant change, cursor-paths remained completely unaffected. Effects lasted for 2–3 change trials and did not reappear during reversion. In conclusion, an unexpected task-irrelevant change on a task-defining feature of a well-practiced manual sequence leads to eye-hand decoupling and a “check-after-surprise” mode of attentional selection. |
Jarkko Hautala; Otto Loberg; Piia Astikainen; Lauri Nummenmaa; Jari K. Hietanen Effects of conversation content on viewing dyadic conversations Journal Article In: Journal of Eye Movement Research, vol. 9, no. 7, pp. 1–12, 2016. @article{Hautala2016,People typically follow conversations closely with their gaze. We asked whether this viewing is influenced by what is actually said in the conversation and by the viewer's psychological condition. We recorded the eye movements of healthy (N = 16) and de- pressed (N = 25) participants while they were viewing video clips. Each video showed two people, each speaking one line of dialogue about socio-emotionally important (i.e., per- sonal) or unimportant topics (matter-of-fact). Between the spoken lines, the viewers made more saccadic shifts between the discussants, and looked more at the second speaker, in personal vs. matter-of-fact conversations. Higher depression scores were correlated with less looking at the currently speaking discussant. We conclude that subtle social attention dynamics can be detected from eye movements and that these dynamics are sensitive to the observer's psychological condition, such as depression. |
Qian Guo; Young-Suk Grace Kim; Li Yang; Lihui Liu Does previewing answer choice options improve performance on reading tests? Journal Article In: Reading and Writing, vol. 29, no. 4, pp. 745–760, 2016. @article{Guo2016,Previewing answer-choice options before finishing reading the text is a widely employed test-taking behavior. In the present study we examined whether previewing is related to item response accuracy and response time, using data from Chinese learners of varying English proficiency levels and English native speakers. We examined eye movement patterns of participants who completed online multiple-choice sentence completion tasks, and how previewing was related to reading performance and whether the relation varied as a function of English proficiency level. The results showed that, relative to no previewing, previewing was associated with a significantly lower probability of answering an item correctly but not with significantly longer response time. Importantly, these relations varied across English proficiency levels such that participants with higher proficiency performed better without previewing, but there was no difference for lower-intermediate learners of English. These findings suggest that previewing does not facilitate performance on a sentence comprehension task, but instead interferes with the comprehension process, particularly for individuals with relatively high language proficiency. |
Mitchell R. P. LaPointe; Bruce Milliken Semantically incongruent objects attract eye gaze when viewing scenes for change Journal Article In: Visual Cognition, vol. 24, no. 1, pp. 63–77, 2016. @article{LaPointe2016,Past research has shown that change detection performance is often more efficient for target objects that are semantically incongruent with a surrounding scene context than for target objects that are semantically congruent with the scene context. One account of these findings is that attention is attracted to objects for which the identity of the object conflicts with the meaning of the scene, perhaps as a violation of expectancies created by earlier recruitment of scene gist information. An alternative account of the performance benefit for incongruent objects is that attention is more apt to linger on incongruent objects, as perhaps identifying these objects is more difficult due to conflicting information from the scene context. In the current experiment, we present natural scenes in a change detection task while monitoring eye movements. We find that eye gaze is attracted to these objects relatively early during scene processing. |
Agnès Alsius; Rachel V. Wayne; Martin Paré; Kevin G. Munhall High visual resolution matters in audiovisual speech perception, but only for some Journal Article In: Attention, Perception, & Psychophysics, vol. 78, no. 5, pp. 1472–1487, 2016. @article{Alsius2016,The basis for individual differences in the degree to which visual speech input enhances comprehension of acoustically degraded speech is largely unknown. Previous research indicates that fine facial detail is not critical for visual enhancement when auditory information is available; however, these studies did not examine individual differences in ability to make use of fine facial detail in relation to audiovisual speech perception ability. Here, we compare participants based on their ability to benefit from visual speech information in the presence of an auditory signal degraded with noise, modulating the resolution of the visual signal through low-pass spatial frequency filtering and monitoring gaze behavior. Participants who benefited most from the addition of visual information (high visual gain) were more adversely affected by the removal of high spatial frequency information, compared to participants with low visual gain, for materials with both poor and rich contextual cues (i.e., words and sentences, respectively). Differences as a function of gaze behavior between participants with the highest and lowest visual gains were observed only for words, with participants with the highest visual gain fixating longer on the mouth region. Our results indicate that the individual variance in audiovisual speech in noise performance can be accounted for, in part, by better use of fine facial detail information extracted from the visual signal and increased fixation on mouth regions for short stimuli. Thus, for some, audiovisual speech perception may suffer when the visual input (in addition to the auditory signal) is less than perfect. |
Theresa Wildegger; Glyn W. Humphreys; Anna C. Nobre Retrospective attention interacts with stimulus strength to shape working memory performance Journal Article In: PLoS ONE, vol. 11, no. 10, pp. e0164174, 2016. @article{Wildegger2016,Orienting attention retrospectively to selective contents in working$backslash$nmemory (WM) influences performance. A separate line of research has$backslash$nshown that stimulus strength shapes perceptual representations. There is$backslash$nlittle research on how stimulus strength during encoding shapes WM$backslash$nperformance, and how effects of retrospective orienting might vary with$backslash$nchanges in stimulus strength. We explore these questions in three$backslash$nexperiments using a continuous-recall WM task. In Experiment 1 we show$backslash$nthat benefits of cueing spatial attention retrospectively during WM$backslash$nmaintenance (retrocueing) varies according to stimulus contrast during$backslash$nencoding. Retrocueing effects emerge for supraliminal but not$backslash$nsub-threshold stimuli. However, once stimuli are supraliminal,$backslash$nperformance is no longer influenced by stimulus contrast. In Experiments$backslash$n2 and 3 we used a mixture-model approach to examine how different$backslash$nsources of error in WM are affected by contrast and retrocueing. For$backslash$nhigh-contrast stimuli (Experiment 2), retrocues increased the precision$backslash$nof successfully remembered items. For low-contrast stimuli (Experiment$backslash$n3), retrocues decreased the probability of mistaking a target with$backslash$ndistracters. These results suggest that the processes by which$backslash$nretrospective attentional orienting shape WM performance are dependent$backslash$non the quality of WM representations, which in turn depends on stimulus$backslash$nstrength during encoding. |
Graham G. Scott; Christopher J. Hand Motivation determines Facebook viewing strategy: An eye movement analysis Journal Article In: Computers in Human Behavior, vol. 56, pp. 267–280, 2016. @article{sh16,Individuals' Social Networking Site (SNS) profiles are central to online impression formation. Distinct profile elements (e.g., Profile Picture) experimentally manipulated in isolation can alter perception of profile owners, but it is not known which elements are focused on and attributed most importance when profiles are viewed naturally. The current study recorded the eye movement behaviour of 70 participants who viewed experimenter-generated Facebook timelines of male and female targets carefully controlled for content. Participants were instructed to process the targets either as potential friends or as potential employees. Target timelines were delineated into Regions of Interest (RoIs) prior to data collection. We found pronounced effects of target gender, viewer motivation and interactions between these factors on processing. Global processing patterns differed based on whether a 'social' or a 'professional' viewing motivation was used. Both patterns were distinct to the 'F'-shaped patterns observed in previous research. When viewing potential employees viewers focused on the text content of timelines and when viewing potential friends image content was more important. Viewing patterns provide insight into the characteristics and abilities of targets most valued by viewers with distinct motivations. These results can inform future research, and allow new perspectives on previous findings. |
Philipp N. Hesse; Katja Fiehler; Frank Bremmer SNARC effect in different effectors Journal Article In: Perception, vol. 45, no. 1-2, pp. 180–195, 2016. @article{Hesse2016,The SNARC (spatial numerical association of response codes) effect, indicating that subjects react faster to the left for small numbers and to the right for large numbers, is used as evidence for the idea that humans use space to organize number representations. Previous studies compared the SNARC effect across sensory modalities within participants and concluded modality independence. So far, it is unknown what sensory-to-motor mappings are involved in generating the SNARC effect and whether these mappings are identical for different effectors within subjects. Hence, we tested whether the SNARC effect is effector specific. Participants performed an auditory parity judgment task and responded with three different effectors: finger (button release), eyes (saccades), and arm (pointing). The SNARC effect occurred in each effector but varied in strength across the effectors. Across subjects, we found a significant correlation of SNARC strength for finger and arm responses suggesting the use of a shared sensory-to-motor mapping. SNARC strength did not correlate, however, between finger and eyes or arm and eyes. An additional statistical analysis based on conditional probabilities provided further evidence for SNARC-effector specificity. Taken together, our results suggest that the sensory-to-motor mapping is not as tight as it would be expected if the SNARC effect was effector independent. |
Meytal Wilf; Michal Ramot; Edna Furman-Haran; Anat Arzi; Yechiel Levkovitz; Rafael Malach Diminished auditory responses during NREM sleep correlate with the hierarchy of language processing Journal Article In: PLoS ONE, vol. 11, no. 6, pp. e0157143, 2016. @article{Wilf2016,Natural sleep provides a powerful model system for studying the neuronal correlates of awareness and state changes in the human brain. To quantitatively map the nature of sleep-induced modulations in sensory responses we presented participants with auditory stimuli possessing different levels of linguistic complexity. Ten participants were scanned using functional magnetic resonance imaging (fMRI) during the waking state and after falling asleep. Sleep staging was based on heart rate measures validated independently on 20 participants using concurrent EEG and heart rate measurements and the results were confirmed using permutation analysis. Participants were exposed to three types of auditory stimuli: scrambled sounds, meaningless word sentences and comprehensible sentences. During non-rapid eye movement (NREM) sleep, we found diminishing brain activation along the hierarchy of language processing, more pronounced in higher processing regions. Specifically, the auditory thalamus showed similar activation levels during sleep and waking states, primary auditory cortex remained activated but showed a significant reduction in auditory responses during sleep, and the high order language-related representation in inferior frontal gyrus (IFG) cortex showed a complete abolishment of responses during NREM sleep. In addition to an overall activation decrease in language processing regions in superior temporal gyrus and IFG, those areas manifested a loss of semantic selectivity during NREM sleep. Our results suggest that the decreased awareness to linguistic auditory stimuli during NREM sleep is linked to diminished activity in high order processing stations. |
Ioanna Katidioti; Jelmer P. Borst; Douwe J. Bierens de Haan; Tamara Pepping; Marieke K. Vugt; Niels A. Taatgen Interrupted by your pupil: An interruption management system based on pupil dilation Journal Article In: International Journal of Human-Computer Interaction, vol. 32, no. 10, pp. 791–801, 2016. @article{Katidioti2016a,Interruptions are prevalent in everyday life and can be very disruptive. An important factor that affects the level of disruptiveness is the timing of the interruption: Interruptions at low-workload moments are known to be less disruptive than interruptions at high-workload moments. In this study, we developed a task-independent interruption management system (IMS) that interrupts users at low-workload moments in order to minimize the disruptiveness of interruptions. The IMS identifies low-workload moments in real time by measuring users' pupil dilation, which is a well-known indicator of workload. Using an experimental setup we showed that the IMS succeeded in finding the optimal moments for interruptions and marginally improved performance. Because our IMS is task-independent—it does not require a task analysis—it can be broadly applied. |
Yanping Liu; Erik D. Reichle; Xingshan Li The effect of word frequency and parafoveal preview on saccade length during the reading of Chinese Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 42, no. 7, pp. 1008–1025, 2016. @article{Liu2016,There are currently 2 theoretical accounts of how readers of Chinese select their saccade targets: (a) by moving their eyes to specific saccade targets (i.e., the default-targeting hypothesis) and (b) by adjusting their saccade lengths to accommodate lexical processing (i.e., the dynamic-adjustment hypothesis). In this article, we first report the results of an eye-movement experiment using a gaze-contingent boundary paradigm. This experiment demonstrates that both target-word frequency and its preview validity modulate the lengths of the saccades entering and exiting the target words, with longer saccades to/from high-frequency words when their preview was available. We then report the results of 2 simulations using computational models that instantiate the core theoretical assumptions of the default-targeting and dynamic-adjustment hypotheses. Comparisons of these simulations indicate that the dynamic-adjustment hypothesis provides a better quantitative account of the data from our experiment using fewer free parameters. We conclude by discussing evidence for dynamic saccade adjustment during the reading of alphabetic languages, and why such a heuristic may be necessary to fully explain eye-movement control during the reading of both alphabetic and nonalphabetic languages. |
Alessandro Piras; Ivan M. Lanzoni; Milena Raffi; Michela Persiani; Salvatore Squatrito The within-task criterion to determine successful and unsuccessful table tennis players Journal Article In: International Journal of Sports Science & Coaching, vol. 11, no. 4, pp. 523–531, 2016. @article{Piras2016,The aim of this study was to examine the differences in visual search behaviour between a group of expert-level and one of novice table tennis players, to determine the temporal and spatial aspects of gaze orientation associated with correct responses. Expert players were classified as successful or unsuccessful depending on their performance in a video-based test of anticipation skill involving two kinds of stroke techniques: forehand top spin and backhand drive. Eye movements were recorded binocularly with a video-based eye tracking system. Successful experts were more effective than novices and unsuccessful experts in accurately anticipating both type and direction of stroke, showing fewer fixations of longer duration. Participants fixated mainly on arm area during forehand top spin, and on hand–racket and trunk areas during backhand drive. This study can help to develop interventions that facilitate the acquisition of anticipatory skills by improving visual search strategies. |
M. Gabriela Costello; Dantong Zhu; Paul J. May; Emilio Salinas; Terrence R. Stanford Task dependence of decision- and choice-related activity in monkey oculomotor thalamus Journal Article In: Journal of Neurophysiology, vol. 115, no. 1, pp. 581–601, 2016. @article{Costello2016,Oculomotor signals circulate within putative recurrent feedback loops that include the frontal eye field (FEF) and the oculomotor thalamus (OcTh). To examine how OcTh contributes to visuomotor control, and perceptually informed saccadic choices in particular, neural correlates of perceptual judgment and motor selection in OcTh were evaluated and compared with those previously reported for FEF in the same subjects. Monkeys performed three tasks: a choice task in which perceptual decisions are urgent, a choice task in which identical decisions are made without time pressure, and a single-target, delayed saccade task. The OcTh yielded far fewer task-responsive neurons than the FEF, but across responsive pools, similar neuron types were found, ranging from purely visual to purely saccade related. Across such types, the impact of the perceptual information relevant to saccadic choices was qualitatively the same in FEF and OcTh. However, distinct from that in FEF, activity in OcTh was strongly task dependent, typically being most vigorous in the urgent task, less so in the easier choice task, and least in the single-target task. This was true for responsive and nonresponsive cells alike. Neurons with exclusively motor-related activity showed strong task dependence, fired less, and differed most patently from their FEF counterparts, whereas those that combined visual and motor activity fired most similarly to their FEF counterparts. The results suggest that OcTh activity is more distantly related to saccade production per se, because its degree of commitment to a motor choice varies markedly as a function of ongoing cognitive or behavioral demands. |
Ioanna Katidioti; Jelmer P. Borst; Marieke K. Vugt; Niels A. Taatgen Interrupt me: External interruptions are less disruptive than self-interruptions Journal Article In: Computers in Human Behavior, vol. 63, pp. 906–915, 2016. @article{Katidioti2016,Interruptions are part of everyday life and are known to be disruptive. With the current study we investigated which kind of interruption is more disruptive: external interruptions or self-interruptions. We conducted two experiments, one behavioral experiment (28 participants) and one in which pupil dilation was measured (21 participants). In both experiments, self-interruptions made participants complete the main task slower than external interruptions (occurring at similar moments in the task as the self-interruptions). However, there was no difference between the two kinds of interruptions in the time needed to resume the main task (resumption lag). Instead, the pupil dilation data revealed that the decision to self-interrupt takes about 1 s, resulting in slower performance overall. |
2015 |
Gareth Carrol; Kathy Conklin; Josephine Guy; Rebekah Scott Processing punctuation and word changes in different editions of prose fiction Journal Article In: Scientific Study of Literature, vol. 5, no. 2, pp. 200–228, 2015. @article{Carrol2015,The digital era has brought with it a shift in the field of literary editing in terms of the amount and kind of textual variation that can reasonably be annotated by editors. However, questions remain about how far readers engage with textual variants, especially minor ones such as small-scale changes to punctuation. In this study we present an eye-tracking experiment investigating reader sensitivity to variations in surface textual features of prose fiction. We monitored eye movements while participants read textual variants from Dickens and James, hypothesising that readers may pay more attention to lexical rather than punctuation changes. We found longer reading times for both types, but only lexical changes also increased reading times for the rest of the sentence. In addition, eye-movement behaviour and conscious ability to report changes were highly correlated. We discuss the implications for how such methods might be applied to questions of “literary” significance and textual processing. |
Matthew J. Abbott; Bernhard Angele; Y. Danbi Ahn; Keith Rayner Skipping syntactically illegal the previews: The role of predictability. Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 6, pp. 1703–1714, 2015. @article{Abbott2015a,Readers tend to skip words, particularly when they are short, frequent, or predictable. Angele and Rayner (2013) recently reported that readers are often unable to detect syntactic anomalies in parafoveal vision. In the present study, we manipulated target word predictability to assess whether contextual constraint modulates the-skipping behavior. The results provide further evidence that readers frequently skip the article the when infelicitous in context. Readers skipped predictable words more often than unpredictable words, even when the, which was syntactically illegal and unpredictable from the prior context, was presented as a parafoveal preview. The results of the experiment were simulated using E-Z Reader 10 by assuming that cloze probability can be dissociated from parafoveal visual input. It appears that when a short word is predictable in context, a decision to skip it can be made even if the information available parafoveally conflicts both visually and syntactically with those predictions. |
Giles M. Anderson; Glyn W. Humphreys Top-down expectancy versus bottom-up guidance in search for known color-form conjunctions Journal Article In: Attention, Perception, & Psychophysics, vol. 77, no. 8, pp. 2622–2639, 2015. @article{Anderson2015,We assessed the effects of pairing a target object with its familiar color on eye movements in visual search, under conditions where the familiar color could or could not be predicted. In Experiment 1 participants searched for a yellow- or purple-colored corn target amongst aubergine distractors, half of which were yellow and half purple. Search was more efficient when the color of the target was familiar and early eye movements more likely to be directed to targets carrying a familiar color than an unfamiliar color. Ex- periment 2 introduced cues which predicted the target color at 80 % validity. Cue validity did not affect whether early fixations were to the target. Invalid cues, however, disrupted search efficiency for targets in an unfamiliar color whilst there was little cost to search efficiency for targets in their familiar color. These re- sults generalized across items with different colors (Experiment 3). The data are consistent with early pro- cesses in selection being automatically modulated in a bottom-up manner to targets in their familiar color, even when expectancies are set for other colors. |
Craig Hedge; Klaus Oberauer; Ute Leonards Selection in spatial working memory is independent of perceptual selective attention, but they interact in a shared spatial priority map Journal Article In: Attention, Perception, & Psychophysics, vol. 77, no. 8, pp. 2653–2668, 2015. @article{Hedge2015,We examined the relationship between the attentional selection of perceptual information and of information in working memory (WM) through four experiments, using a spatial WM-updating task. Participants remembered the locations of two objects in a matrix and worked through a sequence of updating operations, each mentally shifting one dot to a new location according to an arrow cue. Repeatedly updating the same object in two successive steps is typically faster than switching to the other object; this object switch cost reflects the shifting of attention in WM. In Experiment 1,the arrows were presented in random peripheral locations, drawing perceptual attention away from the selected object in WM. This manipulation did not eliminate the object switch cost, indicating that the mechanisms of perceptual selection do not underlie selection in WM. Experiments 2a and 2b corroborated the independence of selection observed in Experiment 1, but showed a benefit to reaction times when the placement of the arrow cue was aligned with the locations of relevant objects in WM. Experiment 2c showed that the same benefit also occurs when participants are not able to mark an updating location through eye fixations. Together, these data can be accounted for by a framework in which perceptual selection and selection in WM are separate mechanisms that interact through a shared spatial priority map. |
Joanna E. Lewis; Mark B. Neider Fixation not required: Characterizing oculomotor attention capture for looming stimuli Journal Article In: Attention, Perception, & Psychophysics, vol. 77, no. 7, pp. 2247–2259, 2015. @article{Lewis2015,A stimulus moving toward us, such as a ball being thrown in our direction or a vehicle braking suddenly in front of ours, often represents a stimulus that requires a rapid response. Using a visual search task in which target and distractor items were systematically associated with a looming object, we explored whether this sort of looming motion captures attention, the nature of such capture using eye movement measures (overt/covert), and the extent to which such capture effects are more closely tied to motion onset or the motion itself. We replicated previous findings indicating that looming motion induces response time benefits and costs during visual search Lin, Franconeri, & Enns(Psychological Science 19(7): 686-693, 2008). These differences in response times were independent of fixation, indicating that these capture effects did not necessitate overt attentional shifts to a looming object for search benefits or costs to occur. Interestingly, we found no differences in capture benefits and costs associated with differences in looming motion type. Combined, our results suggest that capture effects associated with looming motion are more likely subserved by covert attentional mechanisms rather than overt mechanisms, and attention capture for looming motion is likely related to motion itself rather than the onset of motion. |
Charles C. -F. Or; Matthew F. Peterson; Miguel P. Eckstein Initial eye movements during face identification are optimal and similar across cultures Journal Article In: Journal of Vision, vol. 15, no. 13, pp. 1–25, 2015. @article{Or2015,Culture influences not only human high-level cognitive processes but also low-level perceptual operations. Some perceptual operations, such as initial eye movements to faces, are critical for extraction of information supporting evolutionarily important tasks such as face identification. The extent of cultural effects on these crucial perceptual processes is unknown. Here, we report that the first gaze location for face identification was similar across East Asian and Western Caucasian cultural groups: Both fixated a featureless point between the eyes and the nose, with smaller between-group than within-group differences and with a small horizontal difference across cultures (8% of the interocular distance). We also show that individuals of both cultural groups initially fixated at a slightly higher point on Asian faces than on Caucasian faces. The initial fixations were found to be both fundamental in acquiring the majority of information for face identification and optimal, as accuracy deteriorated when observers held their gaze away from their preferred fixations. An ideal observer that integrated facial information with the human visual system's varying spatial resolution across the visual field showed a similar information distribution across faces of both races and predicted initial human fixations. The model consistently replicated the small vertical difference between human fixations to Asian and Caucasian faces but did not predict the small horizontal leftward bias of Caucasian observers. Together, the results suggest that initial eye movements during face identification may be driven by brain mechanisms aimed at maximizing accuracy, and less influenced by culture. The findings increase our understanding of the interplay between the brain's aims to optimally accomplish basic perceptual functions and to respond to sociocultural influences. |
Hélène Devillez; Nathalie Guyader; Anne Guérin-Dugué An eye fixation–related potentials analysis of the P300 potential for fixations onto a target object when exploring natural scenes Journal Article In: Journal of Vision, vol. 15, no. 13, pp. 20, 2015. @article{Devillez2015,The P300 event-related potential has been extensively studied in electroencephalography with classical paradigms that force observers to not move their eyes. This potential is classically used to infer whether a target or a task-relevant stimulus was presented. Few researches have studied this potential through more ecological paradigms where observers were able to move their eyes. In this study, we examined with an ecological paradigm and an adapted methodology the P300 potential using a visual search task that involves eye movements to actively explore natural scenes and during which eye movements and electroencephalographic activity were coregistered. Averaging the electroencephalography signal time-locked to fixation onsets, a P300 potential was observed for fixations onto the target object but not for other fixations recorded for the same visual search or for fixations recorded during the free viewing without any task. Our approach consists of using control experimental conditions with similar eye movements to ensure that the P300 potential was attributable to the fact that the observer gazed at the target rather than to other factors such as eye movement pattern (the size of the previous saccade) or the ‘‘overlap issue'' between the potentials elicited by two successive fixations. We also proposed to model the time overlap issue of the potentials elicited by consecutive fixations with various durations. Our results show that the P300 potential can be studied in ecological situations without any constraint on the type of visual exploration, with some precautions in the interpretation of results due to the overlap issue. |
Zvi N. Roth; Ehud Zohary Position and identity information available in fMRI patterns of activity in human visual cortex Journal Article In: Journal of Neuroscience, vol. 35, no. 33, pp. 11559–11571, 2015. @article{Roth2015,Parietal cortex is often implicated in visual processing of actions. Action understanding is essentially abstract, specific to the type or goal of action, but greatly independent of variations in the perceived position of the action. If certain parietal regions are involved in action understanding, then we expect them to show these generalization and selectivity properties. However, additional functions of parietal cortex, such as self-action control, may impose other demands by requiring an accurate representation of the location of graspable objects. Therefore, the dimensions along which responses are modulated may indicate the functional role of specific parietal regions. Here, we studied the degree of position invariance and hand/object specificity during viewing of tool-grasping actions. To that end, we characterize the information available about location, hand, and tool identity in the patterns of fMRI activation in various cortical areas: early visual cortex, posterior intraparietal sulcus, anterior superior parietal lobule, and the ventral object-specific lateral occipital complex. Our results suggest a gradient within the human dorsal stream: along the posterior-anterior axis, position information is gradually lost, whereas hand and tool identity information is enhanced. This may reflect a gradual transformation of visual input from an initial retinotopic representation in early visual areas to an abstract, position-invariant representation of viewed action in anterior parietal cortex. |
Bram-Ernst Verhoef; Rufin Vogels; Peter Janssen; Leonardo Chelazzi Effects of microstimulation in the anterior intraparietal area during three-dimensional shape categorization Journal Article In: PLoS ONE, vol. 10, no. 8, pp. e0136543, 2015. @article{Verhoef2015,The anterior intraparietal area (AIP) of rhesus monkeys is part of the dorsal visual stream and contains neurons whose visual response properties are commensurate with a role in three-dimensional (3D) shape perception. Neuronal responses in AIP signal the depth structure of disparity-defined 3D shapes, reflect the choices of monkeys while they categorize 3D shapes, and mirror the behavioral variability across different stimulus conditions during 3D-shape categorization. However, direct evidence for a role of AIP in 3D-shape perception has been lacking. We trained rhesus monkeys to categorize disparity-defined 3D shapes and examined AIP's contribution to 3D-shape categorization by microstimulating in clusters of 3D-shape selective AIP neurons during task performance. We find that microstimulation effects on choices (monkey M1) and reaction times (monkey M1 and M2) depend on the 3D-shape preference of the stimulated site. Moreover, electrical stimulation of the same cells, during either the 3D-shape-categorization task or a saccade task, could affect behavior differently. Interestingly, in one monkey we observed a strong correlation between the strength of choice-related AIP activity (choice probabilities) and the influence of microstimulation on 3D-shape-categorization behavior (choices and reaction time). These findings propose AIP as part of the network responsible for 3D-shape perception. The results also show that the anterior intraparietal cortex contains cells with different tuning properties, i.e. 3D-shape- or saccade-related, that can be dynamically read out depending on the requirements of the task at hand. |
Hayley Crawford; Joanna Moss; Giles M. Anderson; Chris Oliver; Joseph P. McCleery Implicit discrimination of basic facial expressions of positive/negative emotion in Fragile X syndrome and autism spectrum disorder Journal Article In: American Journal on Intellectual and Developmental Disabilities, vol. 120, no. 4, pp. 328–345, 2015. @article{Crawford2015,Fragile X syndrome (FXS) and autism spectrum disorders (ASD) are characterized by impaired social functioning. We examined the spontaneous discrimination of happy and disgusted facial expressions, from neutral faces, in individuals with FXS (n = 13 |
Yaoguang Jiang; Dmitry Yampolsky; Gopathy Purushothaman; Vivien A. Casagrande Perceptual decision related activity in the lateral geniculate nucleus Journal Article In: Journal of Neurophysiology, vol. 114, no. 1, pp. 717–735, 2015. @article{Jiang2015,Fundamental to neuroscience is the understanding of how the language of neurons relates to behavior. In the lateral geniculate nucleus (LGN), cells show distinct properties such as selectivity for particular wavelengths, increments or decrements in contrast, or preference for fine detail versus rapid motion. No studies, however, have measured how LGN cells respond when an animal is challenged to make a perceptual decision using information within the receptive fields of those LGN cells. In this study we measured neural activity in the macaque LGN during a two alternative forced choice (2AFC) contrast detection task or during a passive fixation task, and found that a small proportion (13.5%) of single LGN parvocellular (P) and magnocellular (M) neurons matched the psychophysical performance of the monkey. The majority of LGN neurons measured in both tasks were not as sensitive as the monkey. The covariation between neural response and behavior (quantified as choice probability) was significantly above chance during active detection, even when there was no external stimulus. Interneuronal correlations and task-related gain modulations were negligible under the same condition. A bottom-up pooling model that compared sensory neural responses to make perceptual choices in the absence of interneuronal correlations could fully explain these results at the level of the LGN, supporting the hypothesis that the perceptual decision pool consists of multiple sensory neurons, and that response fluctuations in these neurons can influence perception. |
Barbara Nordhjem; Constanza I. Kurman Petrozzelli; Nicolás Gravel; Remco J. Renken; Frans W. Cornelissen Eyes on emergence: Fast detection yet slow recognition of emerging images Journal Article In: Journal of Vision, vol. 15, no. 9, pp. 1–16, 2015. @article{Nordhjem2015,Visual object recognition occurs at the intersection of visual perception and visual cognition. It typically occurs very fast and it has therefore been difficult to disentangle its constituent processes. Recognition time can be extended when using images with emergent properties, suggesting they may help examining how visual recognition unfolds over time. Until now, their use has been constrained by limited availability. We used a set of stimuli with emergent properties—akin to the famous Gestalt image of a Dalmatian—in combination with eye tracking to examine the processes underlying object recognition. To test whether cognitive processes influenced eye movement behavior during recognition, an unprimed and three primed groups were included. Recognition times were relatively long (median ; 5s for the unprimed group), confirming the object's emergent properties. Surprisingly, within the first 500 ms, the majority of fixations were already aimed at the object. Computational models of saliency could not explain these initial fixations. This suggests that observers relied on image statistics not captured by saliency models. For the primed groups, recognition times were reduced. However, threshold-free cluster enhancement-based analysis of the time courses indicated that viewing behavior did not differ between the groups, neither during the initial viewing nor around the moment of recognition. This implies that eye movements are mainly driven by perceptual processes and not affected by cognition. It further suggests that priming mainly boosts the observer's confidence in the decision reached. We conclude that emerging images can be a useful tool to dissociate the perceptual and cognitive contributions to visual object recognition. |
Ana Radonjić; Nicolas P. Cottaris; David H. Brainard Color constancy supports cross-illumination color selection Journal Article In: Journal of Vision, vol. 15, no. 6, pp. 1–19, 2015. @article{Radonjic2015,We rely on color to select objects as the targets of our actions (e.g., the freshest fish, the ripest fruit). To be useful for selection, color must provide accurate guidance about object identity across changes in illumination. Although the visual system partially stabilizes object color appearance across illumination changes, how such color constancy supports object selection is not understood. To study how constancy operates in real-life tasks, we developed a novel paradigm in which subjects selected which of two test objects presented under a test illumination appeared closer in color to a target object presented under a standard illumination. From subjects' choices, we inferred a selection-based match for the target via a variant of maximum likelihood difference scaling, and used it to quantify constancy. Selection-based constancy was good when measured using naturalistic stimuli, but was dramatically reduced when the stimuli were simplified, indicating that a naturalistic stimulus context is critical for good constancy. Overall, our results suggest that color supports accurate object selection across illumination changes when both stimuli and task match how color is used in real life. We compared our selection-based constancy results with data obtained using a classic asymmetric matching task and found that the adjustment-based matches predicted selection well for our stimuli and instructions, indicating that the appearance literature provides useful guidance for the emerging study of constancy in natural tasks. |
Yuka Matsuo; Masayuki Watanabe; Masako Taniike; Ikuko Mohri; Syoji Kobashi; Masaya Tachibana; Yasushi Kobayashi; Yuri Kitamura Kitamura Gap effect abnormalities during a visually guided pro-saccade task in children with attention deficit hyperactivity disorder Journal Article In: PLoS ONE, vol. 10, no. 5, pp. e0125573, 2015. @article{Matsuo2015,Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that starts in early childhood and has a comprehensive impact on psychosocial activity and education as well as general health across the lifespan. Despite its prevalence, the current diagnostic criteria for ADHD are debated. Saccadic eye movements are easy to quantify and may be a quantitative biomarker for a wide variety of neurological and psychiatric disorders, including ADHD. The goal of this study was to examine whether children with ADHD exhibit abnormalities during a visually guided pro-saccadic eye-movement and to clarify the neurophysiological mechanisms associated with their behavioral impairments. Thirty-seven children with ADHD (aged 5–11 years) and 88 typically developing (TD) children (aged 5–11 years) were asked to perform a simple saccadic eye-movement task in which step and gap conditions were randomly interleaved. We evaluated the gap effect, which is the difference in the reaction time between the two conditions. Children with ADHD had a significantly longer reaction time than TD children (p < 0.01) and the gap effect was markedly attenuated (p < 0.01). These results suggest that the measurement of saccadic eye movements may provide a novel method for evaluating the behavioral symptoms and clinical features of ADHD, and that the gap effect is a potential biomarker for the diagnosis of ADHD in early childhood. |
Paul Dassonville; Scott A. Reed The Two-Wrongs model explains perception-action dissociations for illusions driven by distortions of the egocentric reference frame Journal Article In: Frontiers in Human Neuroscience, vol. 9, pp. 140, 2015. @article{Dassonville2015,Several studies have demonstrated a dissociation of the effects of illusion on perception and action, with perception generally reported to be susceptible to illusions, while actions are seemingly immune. These findings have been interpreted to support Milner and Goodale's Two Visual Systems model, which proposes the existence of separate visual processing streams for perception and action. However, an alternative interpretation suggests that this type of behavioral dissociation will occur for any illusion that is caused by a distortion of the observer's egocentric reference frame, without requiring the existence of separate perception and action systems that are differently affected by the illusion. In this scenario, movements aimed at illusory targets will be accurate if they are guided within the same distorted reference frame used for target encoding, since the error of motor guidance will cancel with the error of encoding (hence, for actions, two wrongs do make a right). We further test this Two-Wrongs model by examining two illusions for which the hypothesis makes very different predictions: the rod-and-frame illusion (which affects perception but not actions) and the simultaneous-tilt illusion (which affects perception and actions equally). We demonstrate that the rod-and-frame illusion is caused by a distortion of the observer's egocentric reference frame suitable for the cancellation of errors predicted by the Two-Wrongs model. In contrast, the simultaneous-tilt illusion is caused by local interactions between stimulus elements within an undistorted reference frame, precluding the cancellation of errors associated with the Two-Wrongs model such that the illusion is reflected in both perception and actions. These results provide evidence for a class of illusions that lead to dissociations of perception and action through distortions of the observer's spatial reference frame, rather than through the actions of functionally separate visual processing streams. |
Christopher A. Sanchez; Allison J. Jaeger If it's hard to read, it changes how long you do it: Reading time as an explanation for perceptual fluency effects on judgment Journal Article In: Psychonomic Bulletin & Review, vol. 22, no. 1, pp. 206–211, 2015. @article{sj15,Perceptual manipulations, such as changes in font type or figure-ground contrast, have been shown to increase judgments of difficulty or effort related to the presented material. Previous theory has suggested that this is the result of changes in online processing or perhaps the post-hoc influence of perceived difficulty recalled at the time of judgment. These two experiments seek to examine by which mechanism (or both) the fluency effect is pro-duced. Results indicate that disfluency does in fact change in situ reading behavior, and this change significantly me-diates judgments. Eye movement analyses corroborate this suggestion and observe a difference in how people read a disfluent presentation. These findings support the notion that readers are using perceptual cues in their reading ex-periences to change how they interact with the material, which in turn produces the observed biases. |
Alessandro Piras; Milena Raffi; Ivan M. Lanzoni; Michela Persiani; Salvatore Squatrito Microsaccades and prediction of a motor act outcome in a dynamic sport situation Journal Article In: Investigative Ophthalmology & Visual Science, vol. 56, no. 8, pp. 4520–4530, 2015. @article{Piras2015,PURPOSE Microsaccades could indicate the place where our mind is unconsciously focusing, although our gaze is directed elsewhere. Many studies report the importance of microsaccades in visual scene perception, but none of them has addressed their relationship with the perception of a dynamic action and the prediction of its outcome. METHODS Expert and novice table tennis players were asked to fixate their gaze on a precise spot while viewing the launch of a ball whose final landing had to be predicted. Four separate epochs of the action were considered for their information content. The correctness of the prediction and microsaccade statistics were measured in order to estimate the relationship between covert attention and predictions. RESULTS Microsaccades rate showed a time course modulated by the different epochs, with a significant enhancement during the post-bounce. In this epoch, novices showed a significantly higher rate than experts when the responses were correct. Duration and amplitude were highest in the pre- and post-bounce periods and lowest in the other two. Mean microsaccades direction was toward the stimuli that most probably attracted the visual attention (ball or racket), whereas there was no relationship with the predicted side of the final bounce. CONCLUSIONS Distribution of microsaccades can be influenced by attentional cues in a task-specific situation, revealing links between visuomotor performance and covert attention shifts in fast visuomotor perception. Microsaccade orientation is conditioned by objects that attract visual attention and not by the direction in which action is expected to be performed. |
Alisha Siebold; Matthew David Weaver; Mieke Donk; Wieske Zoest Social salience does not transfer to oculomotor visual search Journal Article In: Visual Cognition, vol. 23, no. 8, pp. 989–1019, 2015. @article{Siebold2015,Evidence suggests that socially relevant information, such as self-referential information, leads to perceptual prioritization that is considered to be similar to prioritization based on physical stimulus salience. The current study used an oculomotor visual search paradigm to investigate whether self-prioritization affects visual selection early in time, akin to physical salience, or later in time, where it would relate to processing of top-down strategies. We report three experiments. Prior to each experiment, observers first performed a manual line-label matching task where they were asked to form associations between two orientation lines (right-tilted and left-tilted) and two labels (you and stranger). Participants then had to make a speeded eye-movement to one of the two lines without any task instructions (Experiment 1), to a dot probe target located on one of the two lines (Experiment 2), or to the line that was validly cued by its associated label (Experiment 3). We replicate previous findings with the manual stimulus-matching task. However, we did not find any evidence for increased salience of the self-relevant you stimulus during visual search, nor did we observe any self-prioritization due to later goal-driven or strategic processing. We argue that self-prioritization does not affect overt visual selection. The results suggest that the effects found in the manual matching task are unlikely to reflect self-prioritization during perceptual processing but might rather act on higher-level processing related to recognition or decision-making. |
Antonios I. Christou; Yvonne Wallis; Hayley Bair; Hayley Crawford; Steven Frisson; Maurice P. Zeegers; Joseph P. McCleery BDNF Val66Met and 5-HTTLPR Genotype are each associated with visual scanning patterns of faces in young children Journal Article In: Frontiers in Behavioral Neuroscience, vol. 9, pp. 175, 2015. @article{Christou2015,Previous studies have documented both neuroplasticity-related BDNF VaI(66)Met and emotion regulation-related 5-HTTLPR polymorphisms as genetic variants that contribute to the processing of emotions from faces. More specifically, research has shown the BDNF Met allele and the 5-HTTLPR Short allele to be associated with mechanisms of negative affectivity that relate to susceptibility for psychopathology. We examined visual scanning pathways in response to angry, happy, and neutral faces in relation to BDNF VaI(66)Met and 5-HTTLPR genotyping in 49 children aged 4-7 years. Analyses revealed that variations in the visual processing of facial expressions of anger interacted with BDNF VaI(66)Met genotype, such that children who carried at least one low neuroplasticity Met allele exhibited a vigilance avoidance pattern of visual scanning compared to homozygotes for the high neuroplasticity Val allele. In a separate investigation of eye gaze towards the eye versus mouth regions of neutral faces, we observed that short allele 5-HTTLPR carriers exhibited reduced looking at the eye region compared with those with the higher serotonin uptake Long allele. Together, these findings suggest that genetic mechanisms early in life may influence the establishment of patterns of visual scanning of environmental stressors, which in conjunction with other factors such as negative life events, may lead to psychological difficulties and disorders in the later adolescent and adult years. |
Demet Gurler; Nathan Doyle; Edgar Walker; John Magnotti; Michael S. Beauchamp A link between individual differences in multisensory speech perception and eye movements Journal Article In: Attention, Perception, & Psychophysics, vol. 77, no. 4, pp. 1333–1341, 2015. @article{Gurler2015,The McGurk effect is an illusion in which visual speech information dramatically alters the perception of auditory speech. However, there is a high degree of individual variability in how frequently the illusion is perceived: some individuals almost always perceive the McGurk effect, while others rarely do. Another axis of individual variability is the pattern of eye movements make while viewing a talking face: some individuals often fixate the mouth of the talker, while others rarely do. Since the talker's mouth carries the visual speech necessary information to induce the McGurk effect, we hypothesized that individuals who frequently perceive the McGurk effect should spend more time fixating the talker's mouth. We used infrared eye tracking to study eye movements as 40 participants viewed audiovisual speech. Frequent perceivers of the McGurk effect were more likely to fixate the mouth of the talker, and there was a significant correlation between McGurk frequency and mouth looking time. The noisy encoding of disparity model of McGurk perception showed that individuals who frequently fixated the mouth had lower sensory noise and higher disparity thresholds than those who rarely fixated the mouth. Differences in eye movements when viewing the talker's face may be an important contributor to interindividual differences in multisensory speech perception. |
Rebecca L. Johnson; Ann Marie Raphail Untangling letter confusability and word length effects in pure alexia Journal Article In: Cognitive Neuropsychology, vol. 32, no. 7-8, pp. 442–456, 2015. @article{Johnson2015,Pure alexia is an acquired neuropsychological disorder that follows damage to the occipito-temporal lobe. This brain damage results in a severe reading impairment in which previously literate individuals are no longer able to efficiently read words, but are still able to perform other language tasks. The present study sought to identify factors of words that make it more difficult for pure alexic individuals to read, such as letter confusability and word length. Eye-tracking methodology was paired with a naming task to examine whether word length or letter confusability is a better predictor of processing difficulty. It was found that word length was a significant predictor of reading time, while summed letter confusability was not significant. This study contradicts some previous research and shows that when an orthogonal set of stimuli is used, letter confusability is not a significant factor driving this reading impairment in all individuals with pure alexia. |
Vivian C. Paulun; Alexander C. Schütz; Melchi M. Michel; Wilson S. Geisler; Karl R. Gegenfurtner Visual search under scotopic lighting conditions Journal Article In: Vision Research, vol. 113, pp. 155–168, 2015. @article{Paulun2015,When we search for visual targets in a cluttered background we systematically move our eyes around to bring different regions of the scene into foveal view. We explored how visual search behavior changes when the fovea is not functional, as is the case in scotopic vision. Scotopic contrast sensitivity is significantly lower overall, with a functional scotoma in the fovea. We found that in scotopic search, for a medium- and a low-spatial-frequency target, individuals made longer lasting fixations that were not broadly distributed across the entire search display but tended to peak in the upper center, especially for the medium-frequency target. The distributions of fixation locations are qualitatively similar to those of an ideal searcher that has human scotopic detectability across the visual field, and interestingly, these predicted distributions are different from those predicted by an ideal searcher with human photopic detectability. We conclude that although there are some qualitative differences between human and ideal search behavior, humans make principled adjustments in their search behavior as ambient light level decreases. |
Ying-Zi Xiong; Cong Yu; Jun-Yun Zhang Perceptual learning eases crowding by reducing recognition errors but not position errors Journal Article In: Journal of Vision, vol. 15, no. 11, pp. 16, 2015. @article{Xiong2015,When an observer reports a letter flanked by additional letters in the visual periphery, the response errors (the crowding effect) may result from failure to recognize the target letter (recognition errors), from mislocating a correctly recognized target letter at a flanker location (target misplacement errors), or from reporting a flanker as the target letter (flanker substitution errors). Crowding can be reduced through perceptual learning. However, it is not known how perceptual learning operates to reduce crowding. In this study we trained observers with a partial-report task (Experiment 1), in which they reported the central target letter of a three- letter string presented in the visual periphery, or a whole-report task (Experiment 2), in which they reported all three letters in order.We then assessed the impact of training on recognition of both unflanked and flanked targets, with particular attention to how perceptual learning affected the types of errors. Our results show that training improved target recognition but not single-letter recognition, indicating that training indeed affected crowding. However, training did not reduce target misplacement errors or flanker substitution errors. This dissociation between target recognition and flanker substitution errors supports the view that flanker substitution may be more likely a by- product (due to response bias), rather than a cause, of crowding. Moreover, the dissociation is not consistent with hypothesized mechanisms of crowding that would predict reduced positional errors. |
Pablo Gomez; Roger Ratcliff; Russ Childers Pointing, looking at, and pressing keys: A diffusion model account of response modality Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 41, no. 6, pp. 1515–1523, 2015. @article{Gomez2015,Accumulation of evidence models of perceptual decision making have been able to account for data from a wide range of domains at an impressive level of precision. In particular, Ratcliff's (1978) diffusion model has been used across many different 2-choice tasks in which the response is executed via a key-press. In this article, we present 2 experiments in which we used a letter-discrimination task exploring 3 central aspects of a 2-choice task: the discriminability of the stimulus, the modality of the response execution (eye movement, key pressing, and pointing on a touchscreen), and the mapping of the response areas for the eye movement and the touchscreen conditions (consistent vs. inconsistent). We fitted the diffusion model to the data from these experiments and examined the behavior of the model's parameters. Fits of the model were consistent with the hypothesis that the same decision mechanism is used in the task with 3 different response methods. Drift rates are affected by the duration of the presentation of the stimulus while the response execution time changed as a function of the response modality. |
Rebecca Haworth; Stephanie Sobey; Jill M. Chorney; Michael Bezuhly; Paul Hong Measuring attentional bias in children with prominent ears: A prospective eye-tracking study Journal Article In: Journal of Plastic, Reconstructive & Aesthetic Surgery, vol. 68, no. 12, pp. 1662–1666, 2015. @article{Haworth2015,Background and aim: When observing new faces, most people focus their attention on the central triangle of the face containing the eyes, nose and mouth. When viewing faces with prominent ears, observers may divert their attention from the central triangle. The objective of this study was to determine whether there was an objective attentional bias to prominent ears in comparison to non-prominent ears. Methods: A total of 24 naïve participants (13 female; mean age 22.88 years) viewed 15 photographs of children with bilateral prominent ears, unilateral prominent ears and non-prominent ears. Both pre- and post-otoplasty photographs of two patients were included. The eye movements of participants were recorded using the EyeLink 1000, a table-mounted eye-tracking device. Results: Overall, the participants spent more time looking at the ear regions for faces with prominent ears in comparison to faces without prominent ears (p = 0.007 |
Frieder M. Paulus; Sören Krach; Marius Blanke; Christine Roth; Marcus Belke; Jens Sommer; Laura Müller-Pinzler; Katja Menzler; Andreas Jansen; Felix Rosenow; Frank Bremmer; Wolfgang Einhäuser; Susanne Knake Fronto-insula network activity explains emotional dysfunctions in juvenile myoclonic epilepsy: Combined evidence from pupillometry and fMRI Journal Article In: Cortex, vol. 65, pp. 219–231, 2015. @article{Paulus2015,Emotional instability, difficulties in social adjustment, and disinhibited behavior are the most common symptoms of the psychiatric comorbidities in juvenile myoclonic epilepsy (JME). This psychopathology has been associated with dysfunctions of mesial-frontal brain circuits. The present work is a first direct test of this link and adapted a paradigm for probing frontal circuits during empathy for pain. Neural and psychophysiological parameters of pain empathy were assessed by combining functional magnetic resonance imaging (fMRI) with simultaneous pupillometry in 15 JME patients and 15 matched healthy controls. In JME patients, we observed reduced neural activation of the anterior cingulate cortex (ACC), the anterior insula (AI), and the ventrolateral prefrontal cortex (VLPFC). This modulation was paralleled by reduced pupil dilation during empathy for pain in patients. At the same time, pupil dilation was positively related to neural activity of the ACC, AI, and VLPFC. In JME patients, the ACC additionally showed reduced functional connectivity with the primary and secondary somatosensory cortex, areas fundamentally implicated in processing the somatic cause of another's pain. Our results provide first evidence that alterations of mesial-frontal circuits directly affect psychosocial functioning in JME patients and draw a link of pupil dynamics with brain activity during emotional processing. The findings of reduced pain empathy related activation of the ACC and AI and aberrant functional integration of the ACC with somatosensory cortex areas provide further evidence for this network's role in social behavior and helps explaining the JME psychopathology and patients' difficulties in social adjustment. |
Anja Sperlich; Daniel J. Schad; Jochen Laubrock When preview information starts to matter: Development of the perceptual span in German beginning readers Journal Article In: Journal of Cognitive Psychology, vol. 27, no. 5, pp. 511–530, 2015. @article{Sperlich2015,How is reading development reflected in eye-movement measures? How does the perceptual span change during the initial years of reading instruction? Does parafoveal processing require competence in basic word-decoding processes? We report data from the first cross-sectional measurement of the perceptual span of German beginning readers (n = 139), collected in the context of the large longitudinal PIER (Potsdamer Intrapersonale Entwicklungsrisiken/Potsdam study of intra-personal developmental risk factors) study of intrapersonal developmental risk factors. Using the moving-window paradigm, eye movements of three groups of students (Grades 1–3) were measured with gaze-contingent presentation of a variable amount of text around fixation. Reading rate increased from Grades 1–3, with smaller increases for higher grades. Perceptual-span results showed the expected main effects of grade and window size: fixation durations and refixation probability decreased with grade and window size, whereas reading rate and saccade length increased. Critically, for reading rate, first-fixation duration, saccade length and refixation probability, there were significant interactions of grade and window size that were mainly based on the contrast between Grades 3 and 2 rather than Grades 2 and 1. Taken together, development of the perceptual span only really takes off between Grades 2 and 3, suggesting that efficient parafoveal processing presupposes that basic processes of reading have been mastered. |
Charlotte Willems; Atser Damsma; Stefan M. Wierda; Niels A. Taatgen; Sander Martens Training-induced changes in the dynamics of attention as reflected in pupil dilation Journal Article In: Journal of Cognitive Neuroscience, vol. 27, no. 6, pp. 1161–1171, 2015. @article{Willems2015,One of the major topics in attention literature is the atten- tional blink (AB), which demonstrates a limited ability to iden- tify the second of two targets (T1 and T2) when presented in close temporal succession (200–500 msec). Given that the effect has been thought of as robust and resistant to training for over 2 decades, one of the most remarkable findings in recent years is that the AB can be eliminated after a 1-hr training with a color-salient T2. However, the underlying mechanism of the training effect as well as the AB itself is as of yet still poorly understood. To elucidate this training effect, we employed a refined version of our recently developed pupil dilation deconvolution method to track any training-induced changes in the amount and onset of attentional processing in response to target stimuli. Behaviorally, we replicated the orig- inal training effect with a color-salient T2. However, we showed that training without a salient target, but with a consistent short target interval, is already sufficient to attenuate the AB. Pupil deconvolution did not reveal any posttraining changes in T2- related dilation but instead an earlier onset of dilation around T1. Moreover, normalized pupil dilation was enhanced post- training compared with pretraining. We conclude that the AB can be eliminated by training without a salient cue. Further- more, our data point to the existence of temporal expectations at the time points of the trained targets posttraining. Therefore, we tentatively conclude that temporal expectations arise as a result of training. |
Youming Zhang; Jorma Laurikkala; Martti Juhola; Youming Zhang; Jorma Laurikkala; Martti Juhola Biometric verification with eye movements: Results from a long-term recording series Journal Article In: IET Biometrics, vol. 4, no. 3, pp. 162–168, 2015. @article{Zhang2015c,The authors present the author's results of using saccadic eye movements for biometric user verification. The method can be applied to computers or other devices, in which it is possible to include an eye movement camera system. Thus far, this idea has been little researched. As they have extensively studied eye movement signals for medical applications, they saw an opportunity for the biometric use of saccades. Saccades are the fastest of all eye movements, and are easy to stimulate and detect from signals. As signals measured from a physiological origin, the properties of eye movements (e.g. latency and maximum angular velocity) may contain considerable variability between different times of day, between days or weeks and so on. Since such variability might impair biometric verification based on saccades, they attempted to tackle this issue. In contrast to their earlier results, where they did not include such long intervals between sessions of eye movement recordings as in the present research, their results showed that – notwithstanding some variability present in saccadic variables – this variability was not considerable enough to essentially disturb or impair verification results. The only exception was a test series of very long intervals ∼16 or 32 months in length. For the best results obtained with various classification methods, false rejection and false acceptance rates were <5%. Thus, they conclude that saccadic eye movements can provide a realistic basis for biometric user verification. |
Andriy Myachykov; Angelo Cangelosi; Rob Ellis; Martin H. Fischer The oculomotor resonance effect in spatial-numerical mapping Journal Article In: Acta Psychologica, vol. 161, pp. 162–169, 2015. @article{Myachykov2015,We investigated automatic Spatial-Numerical Association of Response Codes (SNARC) effect in auditory number processing. Two experiments continually measured spatial characteristics of ocular drift at central fixation during and after auditory number presentation. Consistent with the notion of a spatially oriented mental number line, we found spontaneous magnitude-dependent gaze adjustments, both with and without a concurrent saccadic task. This fixation adjustment (1) had a small-number/left-lateralized bias and (2) it was biphasic as it emerged for a short time around the point of lexical access and it received later robust representation around following number onset. This pattern suggests a two-step mechanism of sensorimotor mapping between numbers and space - a first-pass bottom-up activation followed by a top-down and more robust horizontal SNARC. Our results inform theories of number processing as well as simulation-based approaches to cognition by identifying the characteristics of an oculomotor resonance phenomenon. |
Charlotte Willems; Johannes Herdzin; Sander Martens Individual differences in temporal selective attention as reflected in pupil dilation Journal Article In: PLoS ONE, vol. 10, no. 12, pp. e0145056, 2015. @article{Willems2015a,Background Attention is restricted for the second of two targets when it is presented within 200–500 ms of the first target. This attentional blink (AB) phenomenon allows one to study the dynamics of temporal selective attention by varying the interval between the two targets (T1 and T2). Whereas the AB has long been considered as a robust and universal cognitive limitation, several studies have demonstrated that AB task performance greatly differs between individuals, with some individuals showing no AB whatsoever. Methodology/Principal Findings Here, we studied these individual differences in AB task performance in relation to differences in attentional timing. Furthermore, we investigated whether AB magnitude is predictive for the amount of attention allocated to T1. For both these purposes pupil dilation was measured, and analyzed with our recently developed deconvolution method. We found that the dynamics of temporal attention in small versus large blinkers differ in a number of ways. Individuals with a relatively small AB magnitude seem better able to preserve temporal order information. In addition, they are quicker to allocate attention to both T1 and T2 than large blinkers. Although a popular explanation of the AB is that it is caused by an unnecessary overinvestment of attention allocated to T1, a more complex picture emerged from our data, suggesting that this may depend on whether one is a small or a large blinker. Conclusion The use of pupil dilation deconvolution seems to be a powerful approach to study the temporal dynamics of attention, bringing us a step closer to understanding the elusive nature of the AB. We conclude that the timing of attention to targets may be more important than the amount of allocated attention in accounting for individual differences. |
Min-Yuan Ma; Hsien-Chih Chuang How form and structure of Chinese characters affect eye movement control Min-Yuan Journal Article In: Journal of Eye Movement Research, vol. 8, no. 3, pp. 1–12, 2015. @article{Ma2015,This study investigated the correlations between the form features and legibility of Chinese characters by employing the eye tracking method in two experiments: Experiment 1 examined factors affecting Chinese character legibility with character modules and identified the correlations between character form and legibility of crossing strokes; and Experiment 2 examined the effect of crossing strokes on subjective complicacy perception in both Chinese characters and English letters. This study determined that enclosed Chinese characters affect subjective complicacy perception and reduce saccadic amplitude. In addition, greater number of stroke crossings produced higher subjective complicacy perceived for both Chinese characters and English letters. The results of this study serve as a reference for predicting Chinese character legibility and assessing type design superiority. |
Marie-Josée Bisson; Walter J. B. Heuven; Kathy Conklin; Richard J. Tunney The role of verbal and pictorial information in multimodal incidental acquisition of foreign language vocabulary Journal Article In: Quarterly Journal of Experimental Psychology, vol. 68, no. 7, pp. 1306–1326, 2015. @article{Bisson2015,This study used eye tracking to investigate the allocation of attention to multimodal stimuli during an incidental learning situation, as well as its impact on subsequent explicit learning. Participants were exposed to foreign language (FL) auditory words on their own, in conjunction with written native language (NL) translations, or with both written NL translations and pictures. Incidental acquisition of FL words was assessed the following day through an explicit learning task where participants learned to recognize translation equivalents, as well as one week later through recall and translation recognition tests. Results showed higher accuracy scores in the explicit learning task for FL words presented with meaning during incidental learning, whether written meaning or both written meaning and picture, than for FL words presented auditorily only. However, participants recalled significantly more FL words after a week delay if they had been presented with a picture during incidental learning. In addition, the time spent looking at the pictures during incidental learning significantly predicted recognition and recall scores one week later. Overall, results demonstrated the impact of exposure to multimodal stimuli on subsequent explicit learning, as well as the important role that pictorial information can play in incidental vocabulary acquisition. |
Linnéa Larsson; Marcus Nyström; Richard Andersson; Martin Stridh Detection of fixations and smooth pursuit movements in high-speed eye-tracking data Journal Article In: Biomedical Signal Processing and Control, vol. 18, pp. 145–152, 2015. @article{Larsson2015,A novel algorithm for the detection of fixations and smooth pursuit movements in high-speed eye-tracking data is proposed, which uses a three-stage procedure to divide the intersaccadic intervals into a sequence of fixation and smooth pursuit events. The first stage performs a preliminary segmentation while the latter two stages evaluate the characteristics of each such segment and reorganize the preliminary segments into fixations and smooth pursuit events. Five different performance measures are calculated to investigate different aspects of the algorithm's behavior. The algorithm is compared to the current state-of-the-art (I-VDT and the algorithm in [11]), as well as to annotations by two experts. The proposed algorithm performs considerably better (average Cohen's kappa 0.42) than the I-VDT algorithm (average Cohen's kappa 0.20) and the algorithm in [11] (average Cohen's kappa 0.16), when compared to the experts' annotations. |
Min-Yuan Ma; Hsien-Chih Chuang A legibility study of Chinese character complicacy and eye movement data Journal Article In: Perceptual and Motor Skills, vol. 120, no. 1, pp. 232–246, 2015. @article{Ma2015a,This study investigated the correlations between the complicacy and legibility of Chinese characters by using eye tracking analyzed with structural equation modeling. 13 university students, 6 men and 7 women, with a mean age of 21 yr. (SD = 1.7) participated. The results indicated that block types affected legibility and that saccade amplitude, number of fixations, and complicacy differed due to diverse character structures. Structural Equation Modeling showed that the number of strokes, number of nodes, and image density in stroke complicacy affected the number of fixations and saccade amplitude in eye movement data. Constructing a character complicacy and eye tracking information model to investigate the correlations between Chinese character features and human viewing behavior can provide guidance for Chinese character recognizability and type design. |
Amandine Lassalle; Roxane J. Itier Autistic traits influence gaze-oriented attention to happy but not fearful faces Journal Article In: Social Neuroscience, vol. 10, no. 1, pp. 70–88, 2015. @article{Lassalle2015,The relationship between autistic traits and gaze-oriented attention to fearful and happy faces was investigated at the behavioral and neuronal levels. Upright and inverted dynamic face stimuli were used in a gaze-cueing paradigm while event related potentials (ERPs) were recorded. Participants responded faster to gazed-at than to non-gazed-at targets, and this gaze orienting effect (GOE) diminished with inversion, suggesting it relies on facial configuration. It was also larger for fearful than happy faces but only in participants with high autism-spectrum quotient (AQ) scores. While the GOE to fearful faces was of similar magnitude regardless of AQ scores, a diminished GOE to happy faces was found in participants with high AQ scores. At the ERP level, a congruency effect on target-elicited P1 component reflected enhanced visual processing of gazed-at targets. In addition, cue-triggered early directing attention negativity and anterior directing attention negativity reflected, respectively, attention orienting and attention holding at gazed-at locations. These neural markers of spatial attention orienting were not modulated by emotion and were not found in participants with high AQ scores. Together, these findings suggest that autistic traits influence attention orienting to gaze and its modulation by social emotions such as happiness. |
Heida M. Sigurdardottir; David L. Sheinberg The effects of short-term and long-term learning on the responses of lateral intraparietal neurons to visually presented objects Journal Article In: Journal of Cognitive Neuroscience, vol. 27, no. 7, pp. 1360–1375, 2015. @article{ss15b,The lateral intraparietal area (LIP) is thought to play an important role in the guidance of where to look and pay attention. LIP can also respond selectively to differently shaped objects. We sought to understand to what extent short-term and long-term experience with visual orienting determines the responses of LIP to objects of different shapes. We taught monkeys to arbitrarily associate centrally presented objects of various shapes with orienting either toward or away from a preferred spatial location of a neuron. The training could last for less than a single day or for several months. We found that neural responses to objects are affected by such experience, but that the length of the learning period determines how this neural plasticity manifests. Short-term learning affects neural responses to objects, but these effects are only seen relatively late after visual onset; at this time, the responses to newly learned objects resemble those of familiar objects that share their meaning or arbitrary association. Long-term learning affects the earliest bottom–up responses to visual objects. These responses tend to be greater for objects that have been associated with looking toward, rather than away from, LIP neurons' preferred spatial locations. Responses to objects can nonetheless be distinct, although they have been similarly acted on in the past and will lead to the same orienting behavior in the future. Our results therefore indicate that a complete experience-driven override of LIP object responses may be difficult or impossible. We relate these results to behavioral work on visual attention. |
Joanna R. Wares; David X. Cifu; Kathy W. Hoke; Paul A. Wetzel; George T. Gitchel; William Carne Differential eye movements in mild traumatic brain injury versus normal controls Journal Article In: Journal of Head Trauma Rehabilitation, vol. 30, no. 1, pp. 21–28, 2015. @article{Wares2015,Objectives: Objective measures to diagnose and to monitor improvement of symptoms following mild traumatic brain injury (mTBI) are lacking. Computerized eye tracking has been advocated as a rapid, user friendly, and field-ready technique to meet this need. Design: Eye-tracking data collected via a head-mounted, video-based binocular eye tracker was used to examine saccades, fixations, and smooth pursuit movement in military Service Members with postconcussive syndrome (PCS) and asymptomatic control subjects in an effort to determine if eye movement differences could be found and quantified. Participants: Sixty Military Service Members with PCS and 26 asymptomatic controls. Outcome measures: The diagnosis of mTBI was confirmed by the study physiatrist's history, physical examination, and a review of any medical records. Various features of saccades, fixation and smooth pursuit eye movements were analyzed. Results: Subjects with symptomatic mTBI had statistically larger position errors, smaller saccadic amplitudes, smaller predicted peak velocities, smaller peak accelerations, and longer durations. Subjects with symptomatic mTBI were also less likely to follow a target movement (less primary saccades). In general, symptomatic mTBI tracked the stepwise moving targets less accurately, revealing possible brain dysfunction. Conclusions: A reliable, standardized protocol that appears to differentiate mTBI from normals was developed for use in future research. This investigation represents a step toward objective identification of those with PCS. Future studies focused on increasing the specificity of eye movement differences in those with PCS are needed. |
Isabelle Dautriche; Daniel Swingley; Anne Christophe Learning novel phonological neighbors: Syntactic category matters Journal Article In: Cognition, vol. 143, pp. 77–86, 2015. @article{Dautriche2015,Novel words (like tog) that sound like well-known words (dog) are hard for toddlers to learn, even though children can hear the difference between them (Swingley & Aslin, 2002, 2007). One possibility is that phonological competition alone is the problem. Another is that a broader set of probabilistic considerations is responsible: toddlers may resist considering tog as a novel object label because its neighbor dog is also an object. In three experiments, French 18-month-olds were taught novel words whose word forms were phonologically similar to familiar nouns (noun-neighbors), to familiar verbs (verb-neighbors) or to nothing (no-neighbors). Toddlers successfully learned the no-neighbors and verb-neighbors but failed to learn the noun-neighbors, although both novel neighbors had a familiar phonological neighbor in the toddlers' lexicon. We conclude that when creating a novel lexical entry, toddlers' evaluation of similarity in the lexicon is multidimensional, incorporating both phonological and semantic or syntactic features. |
Ivan Diaz; Sabine Schmidt; Francis R. Verdun; François O. Bochud Eye‐tracking of nodule detection in lung CT volumetric data Journal Article In: Medical Physics, vol. 42, no. 6, pp. 2925–2932, 2015. @article{Diaz2015,PURPOSE: Signal detection on 3D medical images depends on many factors, such as foveal and peripheral vision, the type of signal, and background complexity, and the speed at which the frames are displayed. In this paper, the authors focus on the speed with which radiologists and naïve observers search through medical images. Prior to the study, the authors asked the radiologists to estimate the speed at which they scrolled through CT sets. They gave a subjective estimate of 5 frames per second (fps). The aim of this paper is to measure and analyze the speed with which humans scroll through image stacks, showing a method to visually display the behavior of observers as the search is made as well as measuring the accuracy of the decisions. This information will be useful in the development of model observers, mathematical algorithms that can be used to evaluate diagnostic imaging systems.$backslash$n$backslash$nMETHODS: The authors performed a series of 3D 4-alternative forced-choice lung nodule detection tasks on volumetric stacks of chest CT images iteratively reconstructed in lung algorithm. The strategy used by three radiologists and three naïve observers was assessed using an eye-tracker in order to establish where their gaze was fixed during the experiment and to verify that when a decision was made, a correct answer was not due only to chance. In a first set of experiments, the observers were restricted to read the images at three fixed speeds of image scrolling and were allowed to see each alternative once. In the second set of experiments, the subjects were allowed to scroll through the image stacks at will with no time or gaze limits. In both static-speed and free-scrolling conditions, the four image stacks were displayed simultaneously. All trials were shown at two different image contrasts.$backslash$n$backslash$nRESULTS: The authors were able to determine a histogram of scrolling speeds in frames per second. The scrolling speed of the naïve observers and the radiologists at the moment the signal was detected was measured at 25-30 fps. For the task chosen, the performance of the observers was not affected by the contrast or experience of the observer. However, the naïve observers exhibited a different pattern of scrolling than the radiologists, which included a tendency toward higher number of direction changes and number of slices viewed.$backslash$n$backslash$nCONCLUSIONS: The authors have determined a distribution of speeds for volumetric detection tasks. The speed at detection was higher than that subjectively estimated by the radiologists before the experiment. The speed information that was measured will be useful in the development of 3D model observers, especially anthropomorphic model observers which try to mimic human behavior. |
Christina Marx; Stefan Hawelka; Sarah Schuster; Florian Hutzler An incremental boundary study on parafoveal preprocessing in children reading aloud: Parafoveal masks overestimate the preview benefit Journal Article In: Journal of Cognitive Psychology, vol. 27, no. 5, pp. 549–561, 2015. @article{Marx2015a,Parafoveal preprocessing is an important factor for efficient reading and, in eye-movement studies, is typically investigated by means of parafoveal masking: Valid previews are compared to instances in which masks prevent preprocessing. A long-held assumption was that parafoveal preprocessing, as assessed by this technique, only reflects facilitation (i.e., a preview benefit). Recent studies, however, suggested that the benefit estimate is inflated due to interference of the parafoveal masks, i.e., the masks inflict processing costs. With children from Grades 4 and 6, we administered the novel incremental priming technique. The technique manipulates the salience of the previews by systematically varying its perceptibility (i.e., by visually degrading the previews). This technique does not require a baseline condition, but makes it possible to determine whether a preview induces facilitation or interference. Our salience manipulation of valid previews revealed a preview benefit in the children of both Grades. For two commonly used parafoveal masks, we observed interference corroborating the notion that masks are not a proper baseline. With the novel incremental boundary technique, in contrast, one can achieve an accurate estimate of the preview benefit. |
Haoyue Qian; Xiangping Gao; Zhiguo Wang Faces distort eye movement trajectories, but the distortion is not stronger for your own face Journal Article In: Experimental Brain Research, vol. 233, no. 7, pp. 2155–2166, 2015. @article{Qian2015,It is currently unclear whether a person's own face has greater capacity in absorbing his/her attention than faces of others. With two visual distractor tasks, the present study assessed the extent to which a person's own face attracts his/her attention, by measuring face distractor elicited distortion of saccade trajectories. Experiment 1 showed that upright faces induced stronger distortion of saccade trajectories than inverted ones. This face inversion effect, however, was not stronger for the participant's own face than for unfamiliar other's faces. By manipulating fixation stimulus offset and using peripheral onset target, Experiment 2 further demonstrated that these observations were not contingent on saccade latency. Together, these findings suggest that a person's own face is not more salient or attention-absorbing than unfamiliar other's faces. |
Thomas R. Reppert; Karolina M. Lempert; Paul W. Glimcher; Reza Shadmehr Modulation of saccade vigor during value-based decision making Journal Article In: Journal of Neuroscience, vol. 35, no. 46, pp. 15369–15378, 2015. @article{rlgs15,During value-based decision-making, individuals consider the various options and select the one that provides the maximum subjective value. Although the brain integrates abstract information to compute and compare these values, the only behavioral outcome is often the decision itself. However, if the options are visual stimuli, during deliberation the brain moves the eyes from one stimulus to the other. Previous work suggests that saccade vigor, i.e., peak velocity as a function of amplitude, is greater if reward is associated with the visual stimulus. This raises the possibility that vigor during the free viewing of options may be influenced by the valuation of each option. Here, humans chose between a small, immediate monetary reward and a larger but delayed reward. As the deliberation began, vigor was similar for the saccades made to the two options but diverged 0.5 s before decision time, becoming greater for the preferred option. This difference in vigor increased as a function of the difference in the subjective values that the participant assigned to the delayed and immediate options. After the decision was made, participants continued to gaze at the options, but with reduced vigor, making it possible to infer timing of the decision from the sudden drop in vigor. Therefore, the subjective value that the brain assigned to a stimulus during decision-making affected the motor system via the vigor with which the eyes moved toward that stimulus. |
Tobias Moehler; Katja Fiehler The influence of spatial congruency and movement preparation time on saccade curvature in simultaneous and sequential dual-tasks Journal Article In: Vision Research, vol. 116, pp. 25–35, 2015. @article{Moehler2015,Saccade curvature represents a sensitive measure of oculomotor inhibition with saccades curving away from covertly attended locations. Here we investigated whether and how saccade curvature depends on movement preparation time when a perceptual task is performed during or before saccade preparation. Participants performed a dual-task including a visual discrimination task at a cued location and a saccade task to the same location (congruent) or to a different location (incongruent). Additionally, we varied saccade preparation time (time between saccade cue and Go-signal) and the occurrence of the discrimination task (during saccade preparation = simultaneous vs. before saccade preparation = sequential). We found deteriorated perceptual performance in incongruent trials during simultaneous task performance while perceptual performance was unaffected during sequential task performance. Saccade accuracy and precision were deteriorated in incongruent trials during simultaneous and, to a lesser extent, also during sequential task performance. Saccades consistently curved away from covertly attended non-saccade locations. Saccade curvature was unaffected by movement preparation time during simultaneous task performance but decreased and finally vanished with increasing movement preparation time during sequential task performance. Our results indicate that the competing saccade plan to the covertly attended non-saccade location is maintained during simultaneous task performance until the perceptual task is solved while in the sequential condition, in which the discrimination task is solved prior to the saccade task, oculomotor inhibition decays gradually with movement preparation time. |
Ken-ichi Amemori; Satoko Amemori; Ann M. Graybiel Motivation and affective judgments differentially recruit neurons in the primate dorsolateral prefrontal and anterior cingulate cortex Journal Article In: Journal of Neuroscience, vol. 35, no. 5, pp. 1939–1953, 2015. @article{Amemori2015a,The judgment of whether to accept or to reject an offer is determined by positive and negative affect related to the offer, but affect also induces motivational responses. Rewarding and aversive cues influence the firing rates of many neurons in primate prefrontal and cingulate neocortical regions, but it still is unclear whether neurons in these regions are related to affective judgment or to motivation.To address this issue, we recorded simultaneously the neuronal spike activities of single units in the dorsolateral prefrontal cortex (dlPFC) and the anterior cingulate cortex (ACC) of macaque monkeys as they performed approach–avoidance (Ap–Av) and approach–approach (Ap–Ap) decision-making tasks that can behaviorally dissociate affective judgment and motivation. Notably, neurons having activity correlated with motivational condition could be distinguished from neurons having activity related to affective judgment, especially in the Ap–Av task. Although many neurons in both regions exhibited similar, selective patterns of task-related activity, we found a larger proportion of neurons activated in low motivational conditions in the dlPFC than in the ACC, and the onset of this activity was signifi- cantly earlier in the dlPFC than in the ACC. Furthermore, the temporal onsets of affective judgment represented by neuronal activities were significantly slower in the low motivational conditions than in the other conditions. These findings suggest that motivation and affective judgment both recruit dlPFC and ACC neurons but with differential degrees of involvement and timing. |
Muriel Dysli; Fabian Keller; Mathias Abegg Acute onset incomitant image disparity modifies saccadic and vergence eye movements Journal Article In: Journal of Vision, vol. 15, no. 3, pp. 1–15, 2015. @article{Dysli2015,New-onset impairment of ocular motility will cause incomitant strabismus, i.e., a gaze-dependent ocular misalignment. This ocular misalignment will cause retinal disparity, that is, a deviation of the spatial position of an image on the retina of both eyes, which is a trigger for a vergence eye movement that results in ocular realignment. If the vergence movement fails, the eyes remain misaligned, resulting in double vision. Adaptive processes to such incomitant vergence stimuli are poorly understood. In this study, we have investigated the physiological oculomotor response of saccadic and vergence eye movements in healthy individuals after shifting gaze from a viewing position without image disparity into a field of view with increased image disparity, thus in conditions mimicking incomitance. Repetitive saccadic eye movements into a visual field with increased stimulus disparity lead to a rapid modification of the oculomotor response: (a) Saccades showed immediate disconjugacy (p < 0.001) resulting in decreased retinal image disparity at the end of a saccade. (b) Vergence kinetics improved over time (p < 0.001). This modified oculomotor response enables a more prompt restoration of ocular alignment in new-onset incomitance. |
Svenja Marx; Wolfgang Einhäuser Reward modulates perception in binocular rivalry Journal Article In: Journal of Vision, vol. 15, no. 1, pp. 1–13, 2015. @article{Marx2015,Our perception does not provide us with an exact imprint of the outside world, but is continuously adapted to our internal expectations, task sets, and behavioral goals. Although effects of reward—or value in general—on perception therefore seem likely, how valuation modulates perception and how such modulation relates to attention is largely unknown. We probed effects of reward on perception by using a binocular-rivalry paradigm. Distinct gratings drifting in opposite directions were presented to each observer's eyes. To objectify their subjective perceptual experience, the optokinetic nystagmus was used as measure of current perceptual dominance. In a first experiment, one of the percepts was either rewarded or attended. We found that reward and attention similarly biased perception. In a second experiment, observers performed an attentionally demanding task either on the rewarded stimulus, the other stimulus, or both. We found that—on top of an attentional effect on perception—at each level of attentional load, reward still modulated perception by increasing the dominance of the rewarded percept. Similarly, penalizing one percept increased dominance of the other at each level of attentional load. In turn, rewarding—and similarly nonpunishing—a percept yielded performance benefits that are typically associated with selective attention. In conclusion, our data show that value modulates perception in a similar way as the volitional deployment of attention, even though the relative effect of value is largely unaffected by an attention task. |
David E. Irwin; Maria M. Robinson Detection of stimulus displacements across saccades is capacity-limited and biased in favor of the saccade target Journal Article In: Frontiers in Systems Neuroscience, vol. 9, pp. 161, 2015. @article{Irwin2015,Retinal image displacements caused by saccadic eye movements are generally unnoticed. Recent theories have proposed that perceptual stability across saccades depends on a local evaluation process centered on the saccade target object rather than on remapping and evaluating the positions of all objects in a display. In three experiments, we examined whether objects other than the saccade target also influence perceptual stability by measuring displacement detection thresholds across saccades for saccade targets and a variable number of non-saccade objects. We found that the positions of multiple objects are maintained across saccades, but with variable precision, with the saccade target object having priority in the perception of displacement, most likely because it is the focus of attention before the saccade and resides near the fovea after the saccade. The perception of displacement of objects that are not the saccade target is affected by acuity limitations, attentional limitations, and limitations on memory capacity. Unlike previous studies that have found that a postsaccadic blank improves the detection of displacement direction across saccades, we found that postsaccadic blanking hurt the detection of displacement per se by increasing false alarms. Overall, our results are consistent with the hypothesis that visual working memory underlies the perception of stability across saccades. |
Svenja Marx; Gina Gruenhage; Daniel Walper; Ueli Rutishauser; Wolfgang Einhäuser Competition with and without priority control: Linking rivalry to attention through winner-take-all networks with memory Journal Article In: Annals of the New York Academy of Sciences, vol. 1339, no. 1, pp. 138–153, 2015. @article{Marx2015b,Competition is ubiquitous in perception. For example, items in the visual field compete for processing resources, and attention controls their priority (biased competition). The inevitable ambiguity in the interpretation of sensory signals yields another form of competition: distinct perceptual interpretations compete for access to awareness. Rivalry, where two equally likely percepts compete for dominance, explicates the latter form of competition. Building upon the similarity between attention and rivalry, we propose to model rivalry by a generic competitive circuit that is widely used in the attention literature-a winner-take-all (WTA) network. Specifically, we show that a network of two coupled WTA circuits replicates three common hallmarks of rivalry: the distribution of dominance durations, their dependence on input strength ("Levelt's propositions"), and the effects of stimulus removal (blanking). This model introduces a form of memory by forming discrete states and explains experimental data better than competitive models of rivalry without memory. This result supports the crucial role of memory in rivalry specifically and in competitive processes in general. Our approach unifies the seemingly distinct phenomena of rivalry, memory, and attention in a single model with competition as the common underlying principle. |
Nicholas E. Myers; Gustavo Rohenkohl; Valentin Wyart; Mark W. Woolrich; Anna C. Nobre; Mark G. Stokes Testing sensory evidence against mnemonic templates Journal Article In: eLife, vol. 4, pp. 1–25, 2015. @article{Myers2015,Most perceptual decisions require comparisons between current input and an internal template. Classic studies propose that templates are encoded in sustained activity of sensory neurons. However, stimulus encoding is itself dynamic, tracing a complex trajectory through activity space. Which part of this trajectory is pre-activated to reflect the template? Here we recorded magneto- and electroencephalography during a visual target-detection task, and used pattern analyses to decode template, stimulus, and decision-variable representation. Our findings ran counter to the dominant model of sustained pre-activation. Instead, template information emerged transiently around stimulus onset and quickly subsided. Cross-generalization between stimulus and template coding, indicating a shared neural representation, occurred only briefly. Our results are compatible with the proposal that template representation relies on a matched filter, transforming input into task-appropriate output. This proposal was consistent with a signed difference response at the perceptual decision stage, which can be explained by a simple neural model. |
Virginie Wassenhove; Lukasz Grzeczkowski Visual-induced expectations modulate auditory cortical responses Journal Article In: Frontiers in Neuroscience, vol. 9, pp. 11, 2015. @article{Wassenhove2015,Active sensing has important consequences on multisensory processing (Schroeder et al., 2010). Here, we asked whether in the absence of saccades, the position of the eyes and the timing of transient color changes of visual stimuli could selectively affect the excitability of auditory cortex by predicting the "where" and the "when" of a sound, respectively. Human participants were recorded with magnetoencephalography (MEG) while maintaining the position of their eyes on the left, right, or center of the screen. Participants counted color changes of the fixation cross while neglecting sounds which could be presented to the left, right, or both ears. First, clear alpha power increases were observed in auditory cortices, consistent with participants' attention directed to visual inputs. Second, color changes elicited robust modulations of auditory cortex responses ("when" prediction) seen as ramping activity, early alpha phase-locked responses, and enhanced high-gamma band responses in the contralateral side of sound presentation. Third, no modulations of auditory evoked or oscillatory activity were found to be specific to eye position. Altogether, our results suggest that visual transience can automatically elicit a prediction of "when" a sound will occur by changing the excitability of auditory cortices irrespective of the attended modality, eye position or spatial congruency of auditory and visual events. To the contrary, auditory cortical responses were not significantly affected by eye position suggesting that "where" predictions may require active sensing or saccadic reset to modulate auditory cortex responses, notably in the absence of spatial orientation to sounds. |
Satoko Amemori; Ken-ichi Amemori; Margaret L. Cantor; Ann M. Graybiel A non-invasive head-holding device for chronic neural recordings in awake behaving monkeys Journal Article In: Journal of Neuroscience Methods, vol. 240, pp. 154–160, 2015. @article{Amemori2015,Background: We have developed a novel head-holding device for behaving non-human primates that affords stability suitable for reliable chronic electrophysiological recording experiments. The device is completely non-invasive, and thus avoids the risk of infection and other complications that can occur with the use of conventional, surgically implanted head-fixation devices. New method: The device consists of a novel non-invasive head mold and bar clamp holder, and is customized to the shape of each monkey's head. The head-holding device that we introduce, combined with our recording system and reflection-based eye-tracking system, allows for chronic behavioral experiments and single-electrode or multi-electrode recording, as well as manipulation of brain activity. Results and comparison with existing methods: With electrodes implanted chronically in multiple brain regions, we could record neural activity from cortical and subcortical structures with stability equal to that recorded with conventional head-post fixation. Consistent with the non-invasive nature of the device, we could record neural signals for more than two years with a single implant. Importantly, the monkeys were able to hold stable eye fixation positions while held by this device, demonstrating the possibility of analyzing eye movement data with only the gentle restraint imposed by the non-invasive head-holding device. Conclusions: We show that the head-holding device introduced here can be extended to the head holding of smaller animals, and note that it could readily be adapted for magnetic resonance brain imaging over extended periods of time. |
Francesca Foppolo; Marco Marelli; Luisa Meroni; Andrea Gualmini Hey little sister, who's the only one? Modulating informativeness in the resolution of privative ambiguity Journal Article In: Cognitive science, vol. 39, no. 7, pp. 1646–1674, 2015. @article{Foppolo2015,We present two eye-tracking experiments on the interpretation of sentences like "The tall girl is (not) the only one that …," which are ambiguous between the anaphoric (the only girl that …) and the exophoric interpretation (the only individual that …). These interpretations differ in informativeness: in a positive context, the exophoric (strong) reading entails the anaphoric (weak), while in a negative context the entailment pattern is reversed and the anaphoric reading is the strongest one. We tested whether adults rely on considerations about informativeness in solving the ambiguity. The results show that participants interpreted one exophorically in both positive and negative contexts. Given these findings, we cast doubts on the idea that Informativeness plays a role in ambiguity resolution and proposes a Principle of Maximal Exploitation: When a context is provided, adults extend their domain of evaluation to include the whole scenario, independently from truth-conditional considerations about informativity and strength. |
Jochen Laubrock; Reinhold Kliegl The eye-voice span during reading aloud Journal Article In: Frontiers in Psychology, vol. 6, pp. 1432, 2015. @article{Laubrock2015,Although eye movements during reading are modulated by cognitive processing demands, they also reflect visual sampling of the input, and possibly preparation of output for speech or the inner voice. By simultaneously recording eye movements and the voice during reading aloud, we obtained an output measure that constrains the length of time spent on cognitive processing. Here we investigate the dynamics of the eye-voice span (EVS), the distance between eye and voice. We show that the EVS is regulated immediately during fixation of a word by either increasing fixation duration or programming a regressive eye movement against the reading direction. EVS size at the beginning of a fixation was positively correlated with the likelihood of regressions and refixations. Regression probability was further increased if the EVS was still large at the end of a fixation: if adjustment of fixation duration did not sufficiently reduce the EVS during a fixation, then a regression rather than a refixation followed with high probability. We further show that the EVS can help understand cognitive influences on fixation duration during reading: in mixed model analyses, the EVS was a stronger predictor of fixation durations than either word frequency or word length. The EVS modulated the influence of several other predictors on single fixation durations (SFDs). For example, word-N frequency effects were larger with a large EVS, especially when word N−1 frequency was low. Finally, a comparison of SFDs during oral and silent reading showed that reading is governed by similar principles in both reading modes, although EVS maintenance and articulatory processing also cause some differences. In summary, the EVS is regulated by adjusting fixation duration and/or by programming a regressive eye movement when the EVS gets too large. Overall, the EVS appears to be directly related to updating of the working memory buffer during reading. |
Nicholas E. Myers; Lena Walther; George Wallis; Mark G. Stokes; Anna C. Nobre In: Journal of Cognitive Neuroscience, vol. 27, no. 3, pp. 492–508, 2015. @article{Myers2015a,Working memory (WM) is strongly influenced by attention. In visual WM tasks, recall performance can be improved by an attention-guiding cue presented before encoding (precue) or during maintenance (retrocue). Although precues and retro- cues recruit a similar frontoparietal control network, the two are likely to exhibit some processing differences, because pre- cues invite anticipation of upcoming information whereas retro- cues may guide prioritization, protection, and selection of information already in mind. Here we explored the behavioral and electrophysiological differences between precueing and retrocueing in a new visual WM task designed to permit a direct comparison between cueing conditions. We found marked differences in ERP profiles between the precue and retrocue conditions. In line with precues primarily generating an anti- cipatory shift of attention toward the location of an upcoming item, we found a robust lateralization in late cue-evoked po- tentials associated with target anticipation. Retrocues elicited a different pattern of ERPs that was compatible with an early selec- tion mechanism, but not with stimulus anticipation. In contrast to the distinct ERP patterns, alpha-band (8–14 Hz) lateralization was indistinguishable between cue types (reflecting, in both conditions, the location of the cued item). We speculate that, whereas alpha-band lateralization after a precue is likely to enable anticipatory attention, lateralization after a retrocue may instead enable the controlled spatiotopic access to recently encoded visual information |
Tjerk P. Gutteling; Luc P. J. Selen; W. Pieter Medendorp Parallax-sensitive remapping of visual space in occipito-parietal alpha-band activity during whole-body motion Journal Article In: Journal of Neurophysiology, vol. 113, pp. 1574–1584, 2015. @article{Gutteling2015,Despite the constantly changing retinal image due to eye, head, and body movements, we are able to maintain a stable representation of the visual environment. Various studies on retinal image shifts caused by saccades have suggested that occipital and parietal areas correct for these perturbations by a gaze-centered remapping of the neural image. However, such a uniform, rotational, remapping mechanism cannot work during translations when objects shift on the retina in a more complex, depth-dependent fashion due to motion parallax. Here we tested whether the brain's activity patterns show parallax-sensitive remapping of remembered visual space during whole-body motion. Under continuous recording of electroencephalography (EEG), we passively translated human subjects while they had to remember the location of a world-fixed visual target, briefly presented in front of or behind the eyes' fixation point prior to the motion. Using a psychometric approach we assessed the quality of the memory update, which had to be made based on vestibular feedback and other extraretinal motion cues. All subjects showed a variable amount of parallax-sensitive updating errors, i.e., the direction of the errors depended on the depth of the target relative to fixation. The EEG recordings show a neural correlate of this parallax-sensitive remapping in the alpha-band power at occipito-parietal electrodes. At parietal electrodes, the strength of these alpha-band modulations correlated significantly with updating performance. These results suggest that alpha-band oscillatory activity reflects the time-varying updating of gaze-centered spatial information during parallax-sensitive remapping during whole-body motion. |
Jukka Pekka Kauppi; Melih Kandemir; Veli Matti Saarinen; Lotta Hirvenkari; Lauri Parkkonen; Arto Klami; Riitta Hari; Samuel Kaski Towards brain-activity-controlled information retrieval: Decoding image relevance from MEG signals Journal Article In: NeuroImage, vol. 112, pp. 288–298, 2015. @article{Kauppi2015,We hypothesize that brain activity can be used to control future information retrieval systems. To this end, we conducted a feasibility study on predicting the relevance of visual objects from brain activity. We analyze both magnetoencephalographic (MEG) and gaze signals from nine subjects who were viewing image collages, a subset of which was relevant to a predetermined task. We report three findings: i) the relevance of an image a subject looks at can be decoded from MEG signals with performance significantly better than chance, ii) fusion of gaze-based and MEG-based classifiers significantly improves the prediction performance compared to using either signal alone, and iii) non-linear classification of the MEG signals using Gaussian process classifiers outperforms linear classification. These findings break new ground for building brain-activity-based interactive image retrieval systems, as well as for systems utilizing feedback both from brain activity and eye movements. |