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2015 |
Michael R. Richards; Henry W. Fields; F. Michael Beck; Allen R. Firestone; Dirk B. Walther; Stephen F. Rosenstiel; James M. Sacksteder Contribution of malocclusion and female facial attractiveness to smile esthetics evaluated by eye tracking Journal Article In: American Journal of Orthodontics and Dentofacial Orthopedics, vol. 147, no. 4, pp. 472–482, 2015. @article{rfbfwrs15,There is disagreement in the literature concerning the importance of the mouth in overall facial attractiveness. Eye tracking provides an objective method to evaluate what people see. The objective of this study was to determine whether dental and facial attractiveness alters viewers' visual attention in terms of which area of the face (eyes, nose, mouth, chin, ears, or other) is viewed first, viewed the greatest number of times, and viewed for the greatest total time (duration) using eye tracking. Methods Seventy-six viewers underwent 1 eye tracking session. Of these, 53 were white (49% female, 51% male). Their ages ranged from 18 to 29 years, with a mean of 19.8 years, and none were dental professionals. After being positioned and calibrated, they were shown 24 unique female composite images, each image shown twice for reliability. These images reflected a repaired unilateral cleft lip or 3 grades of dental attractiveness similar to those of grades 1 (near ideal), 7 (borderline treatment need), and 10 (definite treatment need) as assessed in the aesthetic component of the Index of Orthodontic Treatment Need (AC-IOTN). The images were then embedded in faces of 3 levels of attractiveness: attractive, average, and unattractive. During viewing, data were collected for the first location, frequency, and duration of each viewer's gaze. Results Observer reliability ranged from 0.58 to 0.92 (intraclass correlation coefficients) but was less than 0.07 (interrater) for the chin, which was eliminated from the study. Likewise, reliability for the area of first fixation was kappa less than 0.10 for both intrarater and interrater reliabilities; the area of first fixation was also removed from the data analysis. Repeated-measures analysis of variance showed a significant effect (P <0.001) for level of attractiveness by malocclusion by area of the face. For both number of fixations and duration of fixations, the eyes overwhelmingly were most salient, with the mouth receiving the second most visual attention. At times, the mouth and the eyes were statistically indistinguishable in viewers' gazes of fixation and duration. As the dental attractiveness decreased, the visual attention increased on the mouth, approaching that of the eyes. AC-IOTN grade 10 gained the most attention, followed by both AC-IOTN grade 7 and the cleft. AC-IOTN grade 1 received the least amount of visual attention. Also, lower dental attractiveness (AC-IOTN 7 and AC-IOTN 10) received more visual attention as facial attractiveness increased. Conclusions Eye tracking indicates that dental attractiveness can alter the level of visual attention depending on the female models' facial attractiveness when viewed by laypersons. |
George Wallis; Mark Stokes; Helena Cousijn; Mark W. Woolrich; Anna C. Nobre Frontoparietal and cingulo-opercular networks play dissociable roles in control of working memory Journal Article In: Journal of Cognitive Neuroscience, vol. 27, pp. 2019–2034, 2015. @article{Wallis2015a,We used magnetoencephalography to characterize the spatiotemporal dynamics of cortical activity during top–down control of working memory (WM). fMRI studies have previously implicated both the frontoparietal and cingulo-opercular networks in control over WM, but their respective contributions are unclear. In our task, spatial cues indicating the relevant item in a WM array occurred either before the memory array or during the maintenance period, providing a direct comparison between prospective and retrospective control of WM. We found that in both cases a frontoparietal network activated following the cue, but following retrocues this activation was transient and was succeeded by a cinguloopercular network activation. We also characterized the time course of top–down modulation of alpha activity in visual/parietal cortex. This modulation was transient following retrocues, occurring in parallel with the frontoparietal network activation. We suggest that the frontoparietal network is responsible for top–down modulation of activity in sensory cortex during both preparatory attention and orienting within memory. In contrast, the cinguloopercular network plays a more downstream role in cognitive control, perhaps associated with output gating of memory |
Cheng Chen; Xianghui Chen; Min Gao; Qiong Yang; Hongmei Yan Contextual influence on the tilt after-effect in foveal and para-foveal vision Journal Article In: Neuroscience Bulletin, vol. 31, no. 3, pp. 307–316, 2015. @article{Chen2015c,A sensory stimulus can only be properly interpreted in light of the stimuli that surround it in space and time. The tilt illusion (TI) and tilt after-effect (TAE) provide good evidence that the perception of a target depends strongly on both its spatial and temporal context. In previous studies, the TI and TAE have typically been investigated separately, so little is known about their co-effects on visual perception and information processing mechanisms. Here, we considered the influence of the spatial context and the temporal effect together and asked how center- surround context affects the TAE in foveal and para- foveal vision. Our results showed that different center-surround spatial patterns signifi cantly affected the TAE for both foveal and para-foveal vision. In the fovea, the TAE was mainly produced by central adaptive gratings. Cross-oriented surroundings significantly inhibited the TAE, and iso-oriented surroundings slightly facilitated it; surround inhibition was much stronger than surround facilitation. In the para-fovea, the TAE was mainly decided by the surrounding patches. Likewise, a cross-oriented central patch inhibited the TAE, and an iso-oriented one facilitated it, but there was no significant difference between inhibition and facilitation. Our findings demonstrated, at the perceptual level, that our visual system adopts different mechanisms to process consistent or inconsistent central-surround orientation information and that the unequal magnitude magnitude of surround inhibition and facilitation is vitally important for the visual system to improve the detectability or discriminability of novel or incongruent stimuli. |
S. Clavagnier; Serge O. Dumoulin; R. F. Hess Is the cortical deficit in amblyopia due to reduced cortical magnification, loss of neural resolution, or neural disorganization? Journal Article In: Journal of Neuroscience, vol. 35, no. 44, pp. 14740–14755, 2015. @article{Clavagnier2015,The neural basis of amblyopia is a matter of debate. The following possibilities have been suggested: loss of foveal cells, reduced cortical magnification, loss of spatial resolution of foveal cells, and topographical disarray in the cellular map. To resolve this we undertook a population receptive field (pRF) functional magnetic resonance imaging analysis in the central field in humans with moderate-to-severe amblyopia. We measured the relationship between averaged pRF size and retinal eccentricity in retinotopic visual areas. Results showed that cortical magnification is normal in the foveal field of strabismic amblyopes. However, the pRF sizes are enlarged for the amblyopic eye. We speculate that the pRF enlargement reflects loss of cellular resolution or an increased cellular positional disarray within the representation of the amblyopic eye. |
Tom Foulsham; Maria Lock How the eyes tell lies: Social gaze during a preference task Journal Article In: Cognitive Science, vol. 39, no. 7, pp. 1704–1726, 2015. @article{Foulsham2015,Social attention is thought to require detecting the eyes of others and following their gaze. To be effective, observers must also be able to infer the person's thoughts and feelings about what he or she is looking at, but this has only rarely been investigated in laboratory studies. In this study, participants' eye movements were recorded while they chose which of four patterns they preferred. New observers were subsequently able to reliably guess the preference response by watching a replay of the fixations. Moreover, when asked to mislead the person guessing, participants changed their looking behavior and guessing success was reduced. In a second experiment, naïve participants could also guess the preference of the original observers but were unable to identify trials which were lies. These results confirm that people can spontaneously use the gaze of others to infer their judgments, but also that these inferences are open to deception. |
Sebastiaan Mathôt; Alisha Siebold; Mieke Donk; Françoise Vitu Large pupils predict goal-driven eye movements Journal Article In: Journal of Experimental Psychology: General, vol. 144, no. 3, pp. 513–521, 2015. @article{Mathot2015a,Here we report that large pupils predict fixations of the eye on low-salient, inconspicuous parts of a visual scene. We interpret this as showing that mental effort, reflected by a dilation of the pupil, is required to guide gaze toward objects that are relevant to current goals, but that may not be very salient. When mental effort is low, reflected by a constriction of the pupil, the eyes tend to be captured by high-salient parts of the image, irrespective of top-down goals. The relationship between pupil size and visual saliency was not driven by luminance or a range of other factors that we considered. Crucially, the relationship was strongest when mental effort was invested exclusively in eye-movement control (i.e., reduced in a dual-task setting), which suggests that it is not due to general effort or arousal. Our finding illustrates that goal-driven control during scene viewing requires mental effort, and that pupil size can be used as an online measure to track the goal-drivenness of behavior. |
Anouk J. Brouwer; Jeroen B. J. Smeets; Tjerk P. Gutteling; I. Toni; W. Pieter Medendorp The Müller-Lyer illusion affects visuomotor updating in the dorsal visual stream Journal Article In: Neuropsychologia, vol. 77, pp. 119–127, 2015. @article{Brouwer2015,To guide our actions, the brain has developed mechanisms to code target locations in egocentric coordinates (i.e., with respect to the observer), and to update these when the observer moves. The latter mechanism, called visuomotor updating, is implemented in the dorsal visual stream of the brain. In contrast, the ventral visual stream is assumed to transform target locations into an allocentric reference frame that is highly sensitive to visual contextual illusions. Here, we tested the effect of the Müller-Lyer illusion on visuomotor updating in a double-step saccade task. Using the same paradigm in a 3T fMRI scanner, we investigated the effect of the illusion on the neural correlate of the updating process. Participants briefly viewed the Brentano version of the Müller-Lyer illusion with a target at its middle vertex, while fixating at one of the two endpoints of the illusion. Shortly after the disappearance of the stimulus, the eyes' fixation point moved to a position outside the illusion. After a delay, participants made a saccade to the remembered position of the target. The landing position of this saccade was systematically displaced in a manner congruent with the perceptual illusion, showing that visuomotor updating is affected by the illusion. fMRI results showed that the BOLD response in the occipito-parietal cortex (area V7) and the intraparietal sulcus related to planning of the saccade to the updated target was also modulated by the configuration of the illusion. This suggests that the dorsal visual stream represents perceived rather than physical locations of remembered saccade targets. |
Holly S. S. L. Joseph; Georgina Bremner; Simon P. Liversedge; Kate Nation Working memory, reading ability and the effects of distance and typicality on anaphor resolution in children Journal Article In: Journal of Cognitive Psychology, vol. 27, no. 5, pp. 622–639, 2015. @article{Joseph2015,We investigated the time course of anaphor resolution in children and whether this is modulated by individual differences in working memory and reading skill. The eye movements of 30 children (10–11 years) were monitored as they read short paragraphs in which (1) the semantic typicality of an antecedent and (2) its distance in relation to an anaphor were orthogonally manipulated. Children showed effects of distance and typicality on the anaphor itself and also on the word to the right of the anaphor, suggesting that anaphoric processing begins immediately but continues after the eyes have left the anaphor. Furthermore, children showed no evidence of resolving anaphors in the most difficult condition (distant atypical antecedent), suggesting that anaphoric processing that is demanding may not occur online in children of this age. Finally, working memory capacity and reading comprehension skill affect the magnitude and time course of typicality and distance effects during anaphoric processing. |
Martin Szinte; Marisa Carrasco; Patrick Cavanagh; Martin Rolfs Attentional trade-offs maintain the tracking of moving objects across saccades Journal Article In: Journal of Neurophysiology, vol. 113, no. 7, pp. 2220–2231, 2015. @article{Szinte2015,In many situations like playing sports or driving a car, we keep track of moving objects, despite the frequent eye movements that drastically interrupt their retinal motion trajectory. Here we report evidence that transsaccadic tracking relies on trade-offs of attentional resources from a tracked object's motion path to its remapped location. While participants covertly tracked a moving object, we presented pulses of coherent motion at different locations to probe the allocation of spatial attention along the object's entire motion path. Changes in the sensitivity for these pulses showed that during fixation attention shifted smoothly in anticipation of the tracked object's displacement. However, just before a saccade, atten- tional resources were withdrawn from the object's current motion path and reflexively drawn to the retinal location the object would have after saccade. This finding demonstrates the predictive choice the visual system makes to maintain the tracking of moving objects across saccades. |
Meghan Clayards; Oliver Niebuhr; M. Gareth Gaskell The time course of auditory and language-specific mechanisms in compensation for sibilant assimilation Journal Article In: Attention, Perception, & Psychophysics, vol. 77, no. 1, pp. 311–328, 2015. @article{Clayards2015,Models of spoken-word recognition differ onwheth- er compensation for assimilation is language-specific or depends on general auditory processing. English and French participants were taught words that began or ended with the sibilants /s/ and /∫/. Both languages exhibit some assimilation in sibilant sequences (e.g., /s/ becomes like [∫]in dress shop and classe chargée), but they differ in the strength and predomi- nance of anticipatory versus carryover assimilation. After train- ing, participants were presentedwith novelwords embedded in sentences, some of which contained an assimilatory context either preceding or following. A continuum of target sounds ranging from [s] to [∫] was spliced into the novel words, representing a range of possible assimilation strengths. Listeners' perceptions were examined using a visual-world eyetracking paradigm in which the listener clicked on pictures matching the novel words. We found two distinct language- general context effects: a contrastive effect when the assimilat- ing context preceded the target, and flattening of the sibilant categorization function (increased ambiguity) when the assim- ilating context followed. Furthermore, we found that English but not French listeners were able to resolve the ambiguity created by the following assimilatory context, consistent with their greater experience with assimilation in this context. The combination of these mechanisms allows listeners to deal flexibly with variability in speech forms. |
Antje Nuthmann; Wolfgang Einhäuser A new approach to modeling the influence of image features on fixation selection in scenes Journal Article In: Annals of the New York Academy of Sciences, vol. 1339, no. 1, pp. 82–96, 2015. @article{Nuthmann2015,Which image characteristics predict where people fixate when memorizing natural images? To answer this question, we introduce a new analysis approach that combines a novel scene-patch analysis with generalized linear mixed models (GLMMs). Our method allows for (1) directly describing the relationship between continuous feature value and fixation probability, and (2) assessing each feature's unique contribution to fixation selection. To demonstrate this method, we estimated the relative contribution of various image features to fixation selection: luminance and luminance contrast (low-level features); edge density (a mid-level feature); visual clutter and image segmentation to approximate local object density in the scene (higher-level features). An additional predictor captured the central bias of fixation. The GLMM results revealed that edge density, clutter, and the number of homogenous segments in a patch can independently predict whether image patches are fixated or not. Importantly, neither luminance nor contrast had an independent effect above and beyond what could be accounted for by the other predictors. Since the parcellation of the scene and the selection of features can be tailored to the specific research question, our approach allows for assessing the interplay of various factors relevant for fixation selection in scenes in a powerful and flexible manner. |
Alison W. Heard; Michael E. J. Masson; Daniel N. Bub Time course of action representations evoked during sentence comprehension Journal Article In: Acta Psychologica, vol. 156, pp. 98–103, 2015. @article{Heard2015,The nature of hand-action representations evoked during language comprehension was investigated using a variant of the visual-world paradigm in which eye fixations were monitored while subjects viewed a screen displaying four hand postures and listened to sentences describing an actor using or lifting a manipulable object. Displayed postures were related to either a functional (using) or volumetric (lifting) interaction with an object that matched or did not match the object mentioned in the sentence. Subjects were instructed to select the hand posture that matched the action described in the sentence. Even before the manipulable object was mentioned in the sentence, some sentence contexts allowed subjects to infer the object's identity and the type of action performed with it and eye fixations immediately favored the corresponding hand posture. This effect was assumed to be the result of ongoing motor or perceptual imagery in which the action described in the sentence was mentally simulated. In addition, the hand posture related to the manipulable object mentioned in a sentence, but not related to the described action (e.g., a writing posture in the context of a sentence that describes lifting, but not using, a pencil), was favored over other hand postures not related to the object. This effect was attributed to motor resonance arising from conceptual processing of the manipulable object, without regard to the remainder of the sentence context. |
Claire L. Kelly; Sandra I. Sünram-Lea; Trevor J. Crawford The role of motivation, glucose and self-control in the antisaccade task Journal Article In: PLoS ONE, vol. 10, no. 3, pp. e0122218, 2015. @article{Kelly2015,Research shows that self-control is resource limited and there is a gradual weakening in consecutive self-control task performance akin to muscle fatigue. A body of evidence suggests that the resource is glucose and consuming glucose reduces this effect. This study examined the effect of glucose on performance in the antisaccade task - which requires self-control through generating a voluntary eye movement away from a target - following self-control exertion in the Stroop task. The effects of motivation and individual differences in self-control were also explored. In a double-blind design, 67 young healthy adults received a 25g glucose or inert placebo drink. Glucose did not enhance antisaccade performance following self-control exertion in the Stroop task. Motivation however, predicted performance on the antisaccade task; more specifically high motivation ameliorated performance decrements observed after initial self-control exertion. In addition, individuals with high levels of self-control performed better on certain aspects of the antisaccade task after administration of a glucose drink. The results of this study suggest that the antisaccade task might be a powerful paradigm, which could be used as a more objective measure of self-control. Moreover, the results indicate that level of motivation and individual differences in self-control should be taken into account when investigating deficiencies in self-control following prior exertion. |
Thomas S. A. Wallis; Michael Dorr; Peter J. Bex Sensitivity to gaze-contingent contrast increments in naturalistic movies: An exploratory report and model comparison Journal Article In: Journal of Vision, vol. 15, no. 8, pp. 1–33, 2015. @article{Wallis2015b,Sensitivity to luminance contrast is a prerequisite for all but the simplest visual systems. To examine contrast increment detection performance in a way that approximates the natural environmental input of the human visual system, we presented contrast increments gaze-contingently within naturalistic video freely viewed by observers. A band-limited contrast increment was applied to a local region of the video relative to the observer's current gaze point, and the observer made a forced-choice response to the location of the target (≈25,000 trials across five observers). We present exploratory analyses showing that performance improved as a function of the magnitude of the increment and depended on the direction of eye movements relative to the target location, the timing of eye movements relative to target presentation, and the spatiotemporal image structure at the target location. Contrast discrimination performance can be modeled by assuming that the underlying contrast response is an accelerating nonlinearity (arising from a nonlinear transducer or gain control). We implemented one such model and examined the posterior over model parameters, estimated using Markov-chain Monte Carlo methods. The parameters were poorly constrained by our data; parameters constrained using strong priors taken from previous research showed poor cross-validated prediction performance. Atheoretical logistic regression models were better constrained and provided similar prediction performance to the nonlinear transducer model. Finally, we explored the properties of an extended logistic regression that incorporates both eye movement and image content features. Models of contrast transduction may be better constrained by incorporating data from both artificial and natural contrast perception settings. |
Gregory H. MacLean; Raymond M. Klein; Matthew D. Hilchey Does oculomotor readiness mediate exogenous capture of visual attention? Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 41, no. 5, pp. 1260–1270, 2015. @article{MacLean2015,The oculomotor readiness hypothesis makes 2 predictions: Shifts in covert attention are accompanied by preparedness to move one's eyes to the attended region, and preparedness to move one's eyes to a region in space is accompanied by a shift in covert attention to the prepared location. Both predictions have been disconfirmed using an endogenous attention task. In the 2 experiments presented here, the same 2 predictions were tested using an exogenous attention task. It was found that participants experienced covert capture without accompanying oculomotor activation and experienced oculomotor activation without accompanying covert capture. While under everyday conditions the overt and covert orienting systems may be strongly linked, apparently they can nonetheless operate with a high degree of independence from one another. |
Sebastiaan Mathôt; Lotje Linden; Jonathan Grainger; Françoise Vitu The pupillary light response reflects eye-movement preparation Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 41, no. 1, pp. 28–35, 2015. @article{Mathot2015b,When the eyes are exposed to an increased influx of light, the pupils constrict. The pupillary light response (PLR) is traditionally believed to be purely reflexive and not susceptible to cognitive influences. In contrast to this traditional view, we report that preparation of a PLR occurs in parallel with preparation of a saccadic eye movement toward a bright (or dark) stimulus, even before the eyes set in motion. Participants fixated a central gray area and made a saccade toward a peripheral target. Using gaze-contingent display changes, we manipulated whether or not the brightness of the target background was the same during and after saccade preparation. More specifically, on some trials we changed the brightness of the target background during the saccade, thus dissociating the preparatory PLR (i.e., to the brightness of the target background before the saccade) from the regular PLR (i.e., to the brightness after the saccade). We show that preparation triggers a pupillary response to the brightness of a to-be-fixated target background already before the eyes have landed on it. We link our findings to the presaccadic shift of attention: The pupil prepares to adjust its size to the brightness of a to-be-fixated stimulus as soon as attention covertly shifts toward that stimulus. Our findings illustrate that the PLR is a dynamic movement that is tightly linked to visual attention and eye-movement preparation. |
Nicola C. Anderson; Fraser Anderson; Alan Kingstone; Walter F. Bischof A comparison of scanpath comparison methods Journal Article In: Behavior Research Methods, vol. 47, no. 4, pp. 1377–1392, 2015. @article{Anderson2015a,Interest has flourished in studying both the spatial and temporal aspects of eye movement behavior. This has sparked the development of a large number of new methods to compare scanpaths. In the present work, we present a detailed overview of common scanpath comparison measures. Each of these measures was developed to solve a specific problem, but quantifies different aspects of scanpath behavior and requires different data-processing techniques. To understand these differences, we applied each scanpath comparison method to data from an encoding and recognition experiment and compared their ability to reveal scanpath similarities within and between individuals looking at natural scenes. Results are discussed in terms of the unique aspects of scanpath behavior that the different methods quantify. We conclude by making recommendations for choosing an appropriate scanpath comparison measure. |
Xiaofan Peng; Maoyang Zhang; Dajun Zhang; Deguang Xie; Yusheng Guan From anger to attribution: Could attention be a bridge? Journal Article In: Social Behavior and Personality, vol. 43, no. 3, pp. 505–518, 2015. @article{Peng2015,We explored whether or not anger increases attribution bias toward salient information by narrowing attention scope. In Experiment 1, participants made attributions about 6 daily events while experiencing anger or in a neutral state. The anger group was more biased toward the salient factor compared to the neutral group. Using eye-tracking methodology, in Experiment 2 we further demonstrated that attention scope that is narrowed due to anger is related to a polarized distribution of attention resources, particularly decreased eye fixation on the phrase containing nonsalient factors. Finally, in Experiment 3 we separated attention process from information salience and further confirmed that narrowing attention scope (polarizing attention resource) could bias the attribution. In sum, our results indicate that attention scope is the bridge by which anger increases attribution bias. |
Ming Yan Visually complex foveal words increase the amount of parafoveal information acquired Journal Article In: Vision Research, vol. 111, no. Part A, pp. 91–96, 2015. @article{Yan2015,This study investigates the effect of foveal load (i.e., processing difficulty of currently fixated words) on parafoveal information processing. Contrary to the commonly accepted view that high foveal load leads to reduced parafoveal processing efficiency, results of the present study showed that increasing foveal visual (but not linguistic) processing load actually increased the amount of parafoveal information acquired, presumably due to the fact that longer fixation duration on the pretarget word provided more time for parafoveal processing of the target word. It is therefore proposed in the present study that foveal linguistic processing load is not the only factor that determines parafoveal processing; preview time (afforded by foveal word visual processing load) may jointly influence parafoveal processing. |
Evy Cleeren; Cindy Casteels; Karolien Goffin; Peter Janssen; Wim Van Paesschen Ictal perfusion changes associated with seizure progression in the amygdala kindling model in the rhesus monkey Journal Article In: Epilepsia, vol. 56, no. 9, pp. 1366–1375, 2015. @article{Cleeren2015,OBJECTIVE: Amygdala kindling is a widely used animal model for studying mesial temporal lobe epileptogenesis. In the macaque monkey, electrical amygdala kindling develops slowly and provides an opportunity for investigating ictal perfusion changes during epileptogenesis. METHODS: Two rhesus monkeys were electrically kindled through chronically implanted electrodes in the right amygdala over a period of 16 and 17 months. Ictal perfusion single photon emission computed tomography (SPECT) imaging was performed during each of the four predefined clinical stages. RESULTS: Afterdischarge duration increased slowly over 477 days for monkey K and 515 days for monkey S (18 ± 8 s in stage I; 52 ± 13 s in stage IV). During this time, the animals progressed through four clinical stages ranging from interrupting ongoing behavior to bilateral convulsions. Ictal SPECT perfusion imaging showed well-localized but widely distributed regions of hyperperfusion and hypoperfusion, in both cortical and subcortical structures, at every seizure stage. A large portion of the ictal network was involved in the early stages of epileptogenesis and subsequently expanded over time as seizure severity evolved. SIGNIFICANCE: Our data indicate that the different mesial temporal lobe seizure types occur within a common network affecting several parts of the brain, and that seizure severity may be determined by seizure-induced epileptogenesis within a bihemispheric network that is implicated from the start of the process. |
Matthew Haigh; Jean François Bonnefon Conditional sentences create a blind spot in theory of mind during narrative comprehension Journal Article In: Acta Psychologica, vol. 160, pp. 194–201, 2015. @article{Haigh2015a,We identify a blind spot in the early Theory of Mind processing of conditional sentences that describe a protagonist's potential action, and its predictable consequences. We propose that such sentences create expectations through two independent channels. A decision theoretic channel creates an expectation that the action will be taken (viz., not taken) if it has desirable (viz., undesirable) consequences, but a structural channel acts in parallel to create an expectation that the action will be taken, irrespective of desirability. Accordingly, reading should be disrupted when a protagonist avoids an action with desirable consequences, but reading should not be disrupted when a protagonist takes an action with undesirable consequences. This prediction was supported by the eye movements of participants reading systematically varied vignettes. Reading was always disrupted when the protagonist avoided an action with desirable consequences, but disruptions were either delayed (Experiment 1) or recovered from faster (Experiment 2) when the protagonist took an action with undesirable consequences. |
Hugh Knickerbocker; Rebecca L. Johnson; Jeanette Altarriba Emotion effects during reading: Influence of an emotion target word on eye movements and processing Journal Article In: Cognition and Emotion, vol. 29, no. 5, pp. 784–806, 2015. @article{Knickerbocker2015,Recently, Scott, O'Donnell and Sereno reported that words of high valence and arousal are processed with greater ease than neutral words during sentence reading. However, this study unsystematically intermixed emotion (label a state of mind, e.g., terrified or happy) and emotion-laden words (refer to a concept that is associated with an emotional state, e.g., debt or marriage). We compared the eye-movement record while participants read sentences that contained a neutral target word (e.g., chair) or an emotion word (no emotion-laden words were included). Readers were able to process both positive (e.g., happy) and negative emotion words (e.g., distressed) faster than neutral words. This was true across a wide range of early (e.g., first fixation durations) and late (e.g., total times on the post-target region) measures. Additional analyses revealed that State Trait Anxiety Inventory scores interacted with the emotion effect and that the emotion effect was not due to arousal alone. |
Mary H. Maclean; Barry Giesbrecht Neural evidence reveals the rapid effects of reward history on selective attention Journal Article In: Brain Research, vol. 1606, pp. 86–94, 2015. @article{Maclean2015b,Selective attention is often framed as being primarily driven by two factors: task-relevance and physical salience. However, factors like selection and reward history, which are neither currently task-relevant nor physically salient, can reliably and persistently influence visual selective attention. The current study investigated the nature of the persistent effects of irrelevant, physically non-salient, reward-associated features. These features affected one of the earliest reliable neural indicators of visual selective attention in humans, the P1 event-related potential, measured one week after the reward associations were learned. However, the effects of reward history were moderated by current task demands. The modulation of visually evoked activity supports the hypothesis that reward history influences the innate salience of reward associated features, such that even when no longer relevant, nor physically salient, these features have a rapid, persistent, and robust effect on early visual selective attention. |
Annett Schirmer; Christy Reece; Claris Zhao; Erik Ng; Esther Wu; Shih-Cheng Yen Reach out to one and you reach out to many: Social touch affects third-party observers Journal Article In: British Journal of Psychology, vol. 106, no. 1, pp. 107–132, 2015. @article{srznwy15,Casual social touch influences emotional perceptions, attitudes, and behaviours of interaction partners. We asked whether these influences extend to third-party observers. To this end, we developed the Social Touch Picture Set comprising line drawings of dyadic interactions, half of which entailed publicly acceptable casual touch and half of which served as no-touch controls. In Experiment 1, participants provided basic image norms by rating how frequently they observed a displayed touch gesture in everyday life and how comfortable they were observing it. Results implied that some touch gestures were observed more frequently and with greater comfort than others (e.g., handshake vs. hug). All gestures, however, obtained rating scores suitable for inclusion in Experiments 2 and 3. In Experiment 2, participants rated perceived valence, arousal, and likeability of randomly presented touch and no-touch images without being explicitly informed about touch. Image characters seemed more positive, aroused, and likeable when they touched as compared to when they did not touch. Image characters seemed more negative and aroused, but were equally likeable, when they received touch as compared to when there was no physical contact. In Experiment 3, participants passively viewed touch and no-touch images while their eye movements were recorded. Differential gazing at touch as compared to no-touch images emerged within the first 500 ms following image exposure and was largely restricted to the characters' upper body. Gazing at the touching body parts (e.g., hands) was minimal and largely unaffected by touch, suggesting that touch processing occurred outside the focus of visual attention. Together, these findings establish touch as an important visual cue and provide novel insights into how this cue modulates socio-emotional processing in third-party observers. |
Joy J. Geng; Zachary Blumenfeld; Terence L. Tyson; Michael J. Minzenberg Pupil diameter reflects uncertainty in attentional selection during visual search Journal Article In: Frontiers in Human Neuroscience, vol. 9, pp. 453, 2015. @article{Geng2015,Pupil diameter has long been used as a metric of cognitive processing. However, recent advances suggest that the cognitive sources of change in pupil size may reflect LC-NE function and the calculation of unexpected uncertainty in decision processes (Aston-Jones & Cohen, 2005b; Yu & Dayan, 2005). In the current experiments, we explored the role of uncertainty in attentional selection on task-evoked changes in pupil diameter during visual search. We found that task-evoked changes in pupil diameter were related to uncertainty during attentional selection as measured by reaction time and performance accuracy (Experiments 1-2). Control analyses demonstrated that the results are unlikely to be due to error monitoring or response uncertainty. Our results suggest that pupil diameter can be used as an implicit metric of uncertainty in ongoing attentional selection requiring effortful control processes. |
Matthew Haigh; Jean François Bonnefon Eye movements reveal how readers infer intentions from the beliefs and desires of others Journal Article In: Experimental Psychology, vol. 62, no. 3, pp. 206–213, 2015. @article{Haigh2015,We examine how the beliefs and desires of a protagonist are used by readers to predict their intentions as a narrative vignette unfolds. Eye movement measures revealed that readers rapidly inferred an intention when the protagonist desired an outcome, even when this inference was not licensed by the protagonist's belief state. Reading was immediately disrupted when participants encountered a described action that contradicted this inference. During intermediate processing, desire inferences were moderated by the protagonist's belief state. Effects that emerged later in the text were again driven solely by the protagonist's desires. These data suggest that desire-based inferences are initially drawn irrespective of belief state, but are then quickly inhibited if not licensed by relevant beliefs. This inhibition of desire-based inferences may be an effortful process as it was not systematically sustained in later steps of processing. |
Feifei Liang; Hazel I. Blythe; Chuanli Zang; Xuejun Bai; Guoli Yan; Simon P. Liversedge Positional character frequency and word spacing facilitate the acquisition of novel words during Chinese children's reading Journal Article In: Journal of Cognitive Psychology, vol. 27, no. 5, pp. 594–608, 2015. @article{Liang2015,Children's eye movements were recorded to examine the role of word spacing and positional character frequency on the process of Chinese lexical acquisition during reading. Three types of two-character novel pseudowords were constructed: words containing characters in positions in which they frequently occurred (congruent), words containing characters in positions they do not frequently occur in (incongruent) and words containing characters that do not have a strong position bias (balanced). There were two phases within the experiment, a learning phase and a test phase. There were also two learning groups: half the children read sentences in a word-spaced format and the other half read the sentences in an unspaced format during the learning phase. All the participants read normal, unspaced text at test. A benefit of word spacing was observed in the learning phase, but not at test. Also, facilitatory effects of positional character congruency were found both in the learning and test phase; however, this benefit was greatly reduced at test. Furthermore, we did not find any interaction between word spacing and positional character frequencies, indicating that these two types of cues affect lexical acquisition independently. With respect to theoretical accounts of lexical acquisition, we argue that word spacing might facilitate the very earliest stages of word learning by clearly demarking word boundary locations. In contrast, we argue that characters' positional frequencies might affect relatively later stages of word learning. |
Ming Yan; Reinhold Kliegl Perceptual Span Depends on Font Size During the Reading of Chinese Sentences Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 1, pp. 209–219, 2015. @article{Yan2015a,The present study explored the perceptual span (i.e., the physical extent of an area from which useful visual information is extracted during a single fixation) during the reading of Chinese sentences in 2 experiments. In Experiment 1, we tested whether the rightward span can go beyond 3 characters when visually similar masks were used. Results showed that Chinese readers needed at least 4 characters to the right of fixation to maintain a normal reading behavior when visually similar masks were used and when characters were displayed in small fonts, indicating that the span is dynamically influenced by masking materials. In Experiments 2 and 3, we asked whether the perceptual span varies as a function of font size in spaced (German) and unspaced (Chinese) scripts. Results clearly suggest perceptual span depends on font size in Chinese, but we failed to find such evidence for German. We propose that the perceptual span in Chinese is flexible; it is strongly constrained by its language-specific properties such as high information density and lack of word spacing. Implications for saccade-target selection during the reading of Chinese sentences are discussed. |
John F. Ackermann; Michael S. Landy Suboptimal decision criteria are predicted by subjectively weighted probabilities and rewards Journal Article In: Attention, Perception, & Psychophysics, vol. 77, no. 2, pp. 638–658, 2015. @article{Ackermann2015,Subjects performed a visual detection task in which the probability of target occurrence at each of the two possible locations, and the rewards for correct responses for each, were varied across conditions. To maximize monetary gain, observers should bias their responses, choosing one location more often than the other in line with the varied probabilities and rewards. Typically, and in our task, observers do not bias their responses to the extent they should, and instead distribute their responses more evenly across locations, a phenomenon referred to as 'conservatism.' We investigated several hypotheses regarding the source of the conservatism. We measured utility and probability weighting functions under Prospect Theory for each subject in an independent economic choice task and used the weighting-function parameters to calculate each subject's subjective utility (SU(c)) as a function of the criterion c, and the corresponding weighted optimal criteria (wc opt ). Subjects' criteria were not close to optimal relative to wc opt . The slope of SU(c) and of expected gain EG(c) at the neutral criterion corresponding to β = 1 were both predictive of the subjects' criteria. The slope of SU(c) was a better predictor of observers' decision criteria overall. Thus, rather than behaving optimally, subjects move their criterion away from the neutral criterion by estimating how much they stand to gain by such a change based on the slope of subjective gain as a function of criterion, using inherently distorted probabilities and values. |
Scott L. Brincat; Earl K. Miller Frequency-specific hippocampal-prefrontal interactions during associative learning Journal Article In: Nature Neuroscience, vol. 18, no. 4, pp. 576–581, 2015. @article{Brincat2015,Much of our knowledge of the world depends on learning associations (for example, face-name), for which the hippocampus (HPC) and prefrontal cortex (PFC) are critical. HPC-PFC interactions have rarely been studied in monkeys, whose cognitive and mnemonic abilities are akin to those of humans. We found functional differences and frequency-specific interactions between HPC and PFC of monkeys learning object pair associations, an animal model of human explicit memory. PFC spiking activity reflected learning in parallel with behavioral performance, whereas HPC neurons reflected feedback about whether trial-and-error guesses were correct or incorrect. Theta-band HPC-PFC synchrony was stronger after errors, was driven primarily by PFC to HPC directional influences and decreased with learning. In contrast, alpha/beta-band synchrony was stronger after correct trials, was driven more by HPC and increased with learning. Rapid object associative learning may occur in PFC, whereas HPC may guide neocortical plasticity by signaling success or failure via oscillatory synchrony in different frequency bands. |
Caroline Ego; Jean-Jacques Orban de Xivry; Marie-Cécile Nassogne; Demet Yüksel; Philippe Lefèvre; Philippe Lefe Spontaneous improvement in oculomotor function of children with cerebral palsy Journal Article In: Research in Developmental Disabilities, vol. 36, pp. 630–644, 2015. @article{Ego2015,Eye movements are essential to get a clear vision of moving objects. In the present study, we assessed quantitatively the oculomotor deficits of children with cerebral palsy (CP). We recorded eye movements of 51 children with cerebral palsy (aged 5-16 years) with relatively mild motor impairment and compared their performance with age-matched control and premature children. Overall eye movements of children with CP are unexpectedly close to those of controls even though some oculomotor parameters are biased by the side of hemiplegia. Importantly, the difference in performance between children with CP and controls decreases with age, demonstrating that the oculomotor function of children with CP develops as fast as or even faster than controls for some visual tracking parameters. That is, oculomotor function spontaneously improves over the course of childhood. This evolution highlights the ability of lesioned brain of children with CP to compensate for impaired motor function beyond what would be achieved by normal development on its own. |
Jessica Knilans; Gayle DeDe Online sentence reading in people with aphasia: Evidence from eye tracking Journal Article In: American Journal of Speech-Language Pathology, vol. 24, no. 4, pp. S961–S973, 2015. @article{Knilans2015,PURPOSE: There is a lot of evidence that people with aphasia have more difficulty understanding structurally complex sentences (e.g., object clefts) than simpler sentences (subject clefts). However, subject clefts also occur more frequently in English than object clefts. Thus, it is possible that both structural complexity and frequency affect how people with aphasia understand these structures. METHOD: Nine people with aphasia and 8 age-matched controls participated in the study. The stimuli consisted of 24 object cleft and 24 subject cleft sentences. The task was eye tracking during reading, which permits a more fine-grained analysis of reading performance than measures such as self-paced reading. RESULTS: As expected, controls had longer reading times for critical regions in object cleft sentences compared with subject cleft sentences. People with aphasia showed the predicted effects of structural frequency. Effects of structural complexity in people with aphasia did not emerge on their first pass through the sentence but were observed when they were rereading critical regions of complex sentences. CONCLUSIONS: People with aphasia are sensitive to both structural complexity and structural frequency when reading. However, people with aphasia may use different reading strategies than controls when confronted with relatively infrequent and complex sentence structures. |
Shunichi Matsuda; Hideyuki Matsumoto; Toshiaki Furubayashi; Hideki Fukuda; Ritsuko Hanajima; Shoji Tsuji; Yoshikazu Ugawa; Yasuo Terao Visual scanning area is abnormally enlarged in hereditary pure Cerebellar ataxia Journal Article In: Cerebellum, vol. 14, no. 2, pp. 63–71, 2015. @article{Matsuda2015,The aim of paper was to investigate abnormalities in visual scanning using an eye-tracking device with patients with spinocerebellar ataxia type 6 (SCA6) and SCA31, pure cerebellar types of spinocerebellar degeneration. Nineteen SCA patients (12 patients with SCA6 and 7 patients with SCA31) and 19 normal subjects in total participated in the study. While the subjects viewed images of varying complexity for later recall, we compared the visual scanning parameters between SCA patients and normal subjects. SCA patients had lower image recall scores. The scanned area in SCA patients was consistently larger than that in normal subjects. The amplitude of saccades was slightly larger in SCA patients than that in normal subjects, although it did not statistically differ between the two groups and correlated significantly with the scanned area in most images in SCA patients. The instability ratio of fixation, reflecting gaze-evoked nystagmus and downbeat nystagmus, was higher in SCA patients than that in normal subjects. Since SCA patients showed low scores despite wide visual scanning, the scanned area is considered to be abnormally enlarged. The larger scanned area in SCA patients was supposed mainly to result from the slightly larger saccade amplitude. Additionally, SCA patients showed prominent fixation disturbances probably due to gaze-evoked nystagmus and downbeat nystagmus. Consequently, SCA patients suffer from recognizing various objects in daily life, probably due to the impaired saccade control and impaired fixation. |
Nicola C. Anderson; Eduard Ort; Wouter Kruijne; Martijn Meeter; Mieke Donk It depends on when you look at it: Salience influences eye movements in natural scene viewing and search early in time Journal Article In: Journal of Vision, vol. 15, no. 5, pp. 1–22, 2015. @article{Anderson2015b,It is generally accepted that salience affects eye movements in simple artificially created search displays. However, no such consensus exists for eye movements in natural scenes, with several reports arguing that it is mostly high-level cognitive factors that control oculomotor behavior in natural scenes. Here, we manipulate the salience distribution across images by decreasing or increasing the contrast in a gradient across the image. We recorded eye movements in an encoding task (Experiment 1) and a visual search task (Experiment 2) and analyzed the relationship between the latency of fixations and subsequent saccade targeting throughout scene viewing. We find that short-latency first saccades are more likely to land on a region of the image with high salience than long-latency and subsequent saccades in both the encoding and visual search tasks. This implies that salience indeed influences oculomotor behavior in natural scenes, albeit on a different timescale than previously reported. We discuss our findings in relation to current theories of saccade control in natural scenes. |
John J. Foxe; Sophie Molholm; Victor A. Del Bene; Hans Peter Frey; Natalie N. Russo; Daniella Blanco; Dave Saint-Amour; Lars A. Ross In: Cerebral Cortex, vol. 25, no. 2, pp. 298–312, 2015. @article{Foxe2015,Under noisy listening conditions, visualizing a speaker's articulations substantially improves speech intelligibility. This multisensory speech integration ability is crucial to effective communication, and the appropriate development of this capacity greatly impacts a child's ability to successfully navigate educational and social settings. Research shows that multisensory integration abilities continue developing late into childhood. The primary aim here was to track the development of these abilities in children with autism, since multisensory deficits are increasingly recognized as a component of the autism spectrum disorder (ASD) phenotype. The abilities of high-functioning ASD children (n = 84) to integrate seen and heard speech were assessed cross-sectionally, while environmental noise levels were systematically manipulated, comparing them with age-matched neurotypical children (n = 142). Severe integration deficits were uncovered in ASD, which were increasingly pronounced as background noise increased. These deficits were evident in school-aged ASD children (5–12 year olds), but were fully ameliorated in ASD children entering adolescence (13–15 year olds). The severity of multisensory deficits uncovered has important implications for educators and clinicians working in ASD. We consider the observation that the multisensory speech system recovers substantially in adolescence as an indication that it is likely amenable to intervention during earlier childhood, with potentially profound implications for the development of social communication abilities in ASD children. |
Matthias J. Sjerps; Antje S. Meyer Variation in dual-task performance reveals late initiation of speech planning in turn-taking Journal Article In: Cognition, vol. 136, pp. 304–324, 2015. @article{sm15b,The smooth transitions between turns in natural conversation suggest that speakers often begin to plan their utterances while listening to their interlocutor. The presented study investigates whether this is indeed the case and, if so, when utterance planning begins. Two hypotheses were contrasted: that speakers begin to plan their turn as soon as possible (in our experiments less than a second after the onset of the interlocutor's turn), or that they do so close to the end of the interlocutor's turn. Turn-taking was combined with a finger tapping task to measure variations in cognitive load. We assumed that the onset of speech planning in addition to listening would be accompanied by deterioration in tapping performance. Two picture description experiments were conducted. In both experiments there were three conditions: (1) Tapping and Speaking, where participants tapped a complex pattern while taking over turns from a pre-recorded speaker, (2) Tapping and Listening, where participants carried out the tapping task while overhearing two pre-recorded speakers, and (3) Speaking Only, where participants took over turns as in the Tapping and Speaking condition but without tapping. The experiments differed in the amount of tapping training the participants received at the beginning of the session. In Experiment 2, the participants' eye-movements were recorded in addition to their speech and tapping. Analyses of the participants' tapping performance and eye movements showed that they initiated the cognitively demanding aspects of speech planning only shortly before the end of the turn of the preceding speaker. We argue that this is a smart planning strategy, which may be the speakers' default in many everyday situations. |
Antonia F. Ten Brink; Tanja C. W. Nijboer; Douwe P. Bergsma; Jason J. S. Barton; Stefan Van der Stigchel Lack of multisensory integration in hemianopia: No influence of visual stimuli on aurally guided saccades to the blind hemifield Journal Article In: PLoS ONE, vol. 10, no. 4, pp. e0122054, 2015. @article{Brink2015,In patients with visual hemifield defects residual visual functions may be present, a phenomenon called blindsight. The superior colliculus (SC) is part of the spared pathway that is considered to be responsible for this phenomenon. Given that the SC processes input from different modalities and is involved in the programming of saccadic eye movements, the aim of the present study was to examine whether multimodal integration can modulate oculomotor competition in the damaged hemifield. We conducted two experiments with eight patients who had visual field defects due to lesions that affected the retinogeniculate pathway but spared the retinotectal direct SC pathway. They had to make saccades to an auditory target that was presented alone or in combination with a visual stimulus. The visual stimulus could either be spatially coincident with the auditory target (possibly enhancing the auditory target signal), or spatially disparate to the auditory target (possibly competing with the auditory tar-get signal). For each patient we compared the saccade endpoint deviation in these two bi-modal conditions with the endpoint deviation in the unimodal condition (auditory target alone). In all seven hemianopic patients, saccade accuracy was affected only by visual stimuli in the intact, but not in the blind visual field. In one patient with a more limited quadrantano-pia, a facilitation effect of the spatially coincident visual stimulus was observed. We conclude that our results show that multisensory integration is infrequent in the blind field of patients with hemianopia. |
Eileen T. Crehan; Robert R. Althoff Measuring the stare-in-the-crowd effect: a new paradigm to study social perception Journal Article In: Behavior Research Methods, vol. 47, no. 4, pp. 994–1003, 2015. @article{Crehan2015,Social perceptual ability plays a key role in successful social functioning. Social interactions demand a number of simultaneous skills, one of which is the detection of self-directed gaze. This study demonstrates how the ability to accurately detect self-directed gaze, called the stare-in-the-crowd effect, can be studied using a new eye-tracking paradigm. A set of images was developed to test this effect using a group of healthy undergraduate students. Eye movements and pupil size were tracked while they viewed these images. Participants also completed behavioral measures about themselves. Results show that self-directed gaze results in significantly more looking by participants. Behavioral predictors of gaze behaviors were not identified, likely given the health of the sample. However, correlations with variables are reported to explore in future research. |
Thomas A. Farmer; Shaorong Yan; Klinton Bicknell; Michael K. Tanenhaus Form-to-expectation matching effects on first-pass eye movement measures during reading Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 41, no. 4, pp. 958–976, 2015. @article{Farmer2015,Recent Electroencephalography/Magnetoencephalography (EEG/MEG) studies suggest that when contextual information is highly predictive of some property of a linguistic signal, expectations generated from context can be translated into surprisingly low-level estimates of the physical form-based properties likely to occur in subsequent portions of the unfolding signal. Whether form-based expectations are generated and assessed during natural reading, however, remains unclear. We monitored eye movements while participants read phonologically typical and atypical nouns in noun-predictive contexts (Experiment 1), demonstrating that when a noun is strongly expected, fixation durations on furst-pass eye movement measures, including first fixation duration, gaze durations, and go-past times, are shorter for nouns with category typical form-based features. In Experiments 2 and 3, typical and atypical nouns were placed in sentential contexts normed to create expectations of variable strength for a noun. Context and typicality interacted significantly at gaze duration. These results suggest that during reading, form-based expectations that are translated from higher-level category-based expectancies can facilitate the processing of a word in context, and that their effect on lexical processing is graded based on the strength of category expectancy. |
R. Calen Walshe; Antje Nuthmann Mechanisms of saccadic decision making while encoding naturalistic scenes Journal Article In: Journal of Vision, vol. 15, no. 5, pp. 21, 2015. @article{Walshe2015,Saccadic eye movements are the primary vehicle by which human gaze is brought in alignment with vital visual information present in naturalistic scenes. Although numerous studies using the double-step paradigm have demonstrated that saccade preparation is subject to modification under certain conditions, this has yet to be studied directly within a naturalistic scene-viewing context. To reveal characteristic properties of saccade programming during naturalistic scene viewing, we contrasted behavior across three conditions. In the Static condition of the main experiment, double-step targets were presented following a period of stable fixation on a central cross. In a Scene condition, targets were presented while participants actively explored a naturalistic scene. During a Noise condition, targets were presented during active exploration of a 1/f noise-filtered scene. In Experiment 2, we measure saccadic responses in three Static conditions (Uniform, Scene, and Noise) in which the backgrounds are the same as Experiment 1 but scene exploration is no longer permitted. We find that the mechanisms underlying saccade modification generalize to both dynamic conditions. However, we show that a property of saccade programming known as the saccadic dead time (SDT), the interval prior to saccade onset during which a saccade may not be canceled or modified, is lower in the Static task than it is in the dynamic tasks. We also find a trend toward longer SDT in the Scene as compared with Noise conditions. We discuss the implication of these results for computational models of scene viewing, reading, and visual search tasks. |
Justine Cléry; Olivier Guipponi; Soline Odouard; Claire Wardak; Suliann Ben Hamed Impact prediction by looming visual stimuli enhances tactile detection Journal Article In: Journal of Neuroscience, vol. 35, no. 10, pp. 4179–4189, 2015. @article{Clery2015,From an ecological point of view, approaching objects are potentially more harmful than receding objects. A predator, a dominant conspecific, or a mere branch coming up at high speed can all be dangerous if one does not detect them and produce the appropriate escape behavior fast enough. And indeed, looming stimuli trigger stereotyped defensive responses in both monkeys and human infants. However, while the heteromodal somatosensory consequences of visual looming stimuli can be fully predicted by their spatiotemporal dynamics, few studies if any have explored whether visual stimuli looming toward the face predictively enhance heteromodal tactile sensitivity around the expected time of impact and at its expected location on the body. In the present study, we report that, in addition to triggering a defensive motor repertoire, looming stimuli toward the face provide the nervous system with predictive cues that enhance tactile sensitivity on the face. Specifically, we describe an enhancement of tactile processes at the expected time and location of impact of the stimulus on the face. We additionally show that a looming stimulus that brushes past the face also enhances tactile sensitivity on the nearby cheek, suggesting that the space close to the face is incorporated into the subjects' body schema. We propose that this cross-modal predictive facilitation involves multisensory convergence areas subserving the representation of a peripersonal space and a safety boundary of self. |
Alessio Fracasso; Lisandro N. Kaunitz; David Melcher Saccade kinematics modulate perisaccadic perception Journal Article In: Journal of Vision, vol. 15, no. 3, pp. 1–12, 2015. @article{Fracasso2015,Around the time of execution of an eye movement, participants systematically misperceive the spatial location of briefly flashed visual stimuli. This phenomenon, known as perisaccadic mislocalization, is thought to involve an active process that takes into account the motor plan (efference copy) of the upcoming saccade. While it has been proposed that the motor system anticipates and informs the visual system about the upcoming eye movements, at present the type and detail of information carried by this motor signal remains unclear. Some authors have argued that the efference copy conveys only coarse information about the direction of the eye movement, while a second theoretical view proposes that it provides specific details about the direction, amplitude, and velocity of the saccade to come. To test between these alternatives, we investigated the influence of saccade parameters on a perisaccadic unmasking task in which performance in discriminating the identity of a target (face or house) followed by a trailing mask is dramatically improved around the time of saccade onset. We found that the amplitude and peak velocity of the upcoming saccade modulated target perception, even for stimuli presented well before saccadic onset. We developed a predictive model for the generation of the efference copy that incorporates both saccade amplitude and saccade velocity planning prior to saccade execution. Overall, these results suggest that the efference copy stores specific information about the parameters of upcoming eye movement and that these parameters influence perception even prior to saccade onset |
Michele Graffeo; Luca Polonio; Nicolao Bonini Individual differences in competent consumer choice: The role of cognitive reflection and numeracy skills Journal Article In: Frontiers in Psychology, vol. 6, pp. 844, 2015. @article{Graffeo2015,In this paper, we investigate whether cognitive reflection and numeracy skills affect the quality of the consumers' decision-making process in a purchase decision context. In a first (field) experiment, an identical product was on sale in two shops with different initial prices and discounts. One of the two deals was better than the other and the consumers were asked to choose the best one and to describe which arithmetic operations they used to solve the problem; then they were asked to complete the numeracy scale (Lipkus et al., 2001). The choice procedures used by the consumers were classified as "complete decision approach" when all the arithmetic operations needed to solve the problem were computed, and as "partial decision approach" when only some operations were computed. A mediation model shows that higher numeracy is associated with use of the complete decision approach. In turn, this approach is positively associated with the quality of the purchase decision. Given that these findings highlight the importance of the decision processes, in a second (laboratory) experiment we used a supplementary method to study the type of information search used by the participants: eye-tracking. In this experiment the participants were presented with decision problems similar to those used in Experiment 1 and they completed the Lipkus numeracy scale and the Cognitive Reflection Test (CRT; Frederick, 2005). Participants with a high CRT score chose the best deal more frequently, and showed a more profound and detailed information search pattern compared to participants with a low CRT score. Overall, results indicate that higher levels of cognitive reflection and numeracy skills predict the use of a more thorough decision process (measured with two different techniques: retrospective verbal reports and eye movements). In both experiments the decision process is a crucial factor which greatly affects the quality of the purchase decision. |
Jamila Andoh; Reiko Matsushita; Robert J. Zatorre Asymmetric interhemispheric transfer in the auditory network: Evidence from TMS, resting-state fMRI, and diffusion imaging Journal Article In: Journal of Neuroscience, vol. 43, no. 43, pp. 14602–14611, 2015. @article{Andoh2015,Hemispheric asymmetries in human auditory cortical function and structure are still highly debated. Brain stimulation approaches can complement correlational techniques by uncovering causal influences. Previous studies have shown asymmetrical effects of transcranial magnetic stimulation (TMS) on task performance, but it is unclear whether these effects are task-specific or reflect intrinsic network properties. To test how modulation of auditory cortex (AC) influences functional networks and whether this influence is asymmetrical, the present study measured resting-state fMRI connectivity networks in 17 healthy volunteers before and immediately after TMS (continuous theta burst stimulation) to the left or right AC, and the vertex as a control. We also examined the relationship between TMS-induced interhemispheric signal propagation and anatomical properties of callosal auditory fibers as measured with diffusion-weighted MRI. We found that TMS to the right AC, but not the left, resulted in widespread connectivity decreases in auditory- and motor-related networks in the resting state. Individual differences in the degree of change in functional connectivity between auditory cortices after TMS applied over the right AC were negatively related to the volume of callosal auditory fibers. The findings show that TMS-induced network modulation occurs, even in the absence of an explicit task, and that the magnitude of the effect differs across individuals as a function of callosal structure, supporting a role for the corpus callosum in mediating functional asymmetry. The findings support theoretical models emphasizing hemispheric differences in network organization and are of practical significance in showing that brain stimulation studies need to take network-level effects into account. |
Kelvin Balcombe; Iain Fraser; Eugene McSorley Visual attention and attribute attendance in multi-attribute choice experiments Journal Article In: Journal of Applied Econometrics, vol. 30, pp. 447–467, 2015. @article{Balcombe2015,Decision strategies in multi-attribute choice experiments are investigated using eye-tracking. The visual attention towards, and attendance of, attributes is examined. Stated attendance is found to diverge substantively from visual attendance of attributes. However, stated and visual attendance are shown to be informative, non-overlapping sources of information about respondent utility functions when incorporated into model estimation. Eye-tracking also reveals systematic nonattendance of attributes only by a minority of respondents. Most respondents visually attend most attributes most of the time. We find no compelling evidence that the level of attention is related to respondent certainty, or that higher or lower value attributes receive more or less attention. |
Benedikt V. Ehinger; Peter Konig; José P. Ossandón Predictions of visual content across eye movements and their modulation by inferred information Journal Article In: Journal of Neuroscience, vol. 35, no. 19, pp. 7403–7413, 2015. @article{Ehinger2015,The brain is proposed to operate through probabilistic inference, testing and refining predictions about the world. Here, we search for neural activity compatible with the violation of active predictions, learned from the contingencies between actions and the consequent changes in sensory input. We focused on vision, where eye movements produce stimuli shifts that could, in principle, be predicted. We compared, in humans, error signals to saccade-contingent changes of veridical and inferred inputs by contrasting the electroencephalographic activity after saccades to a stimulus presented inside or outside the blind spot. We observed early (<250 ms) and late (>250 ms) error signals after stimulus change, indicating the violation of sensory and associative predictions, respectively. Remarkably, the late response was diminished for blind-spot trials. These results indicate that predictive signals occur across multiple levels of the visual hierarchy, based on generative models that differentiate between signals that originate from the outside world and those that are inferred. |
Hazel I. Blythe; Ascensión Pagán; Megan Dodd Beyond decoding: Phonological processing during silent reading in beginning readers Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 4, pp. 1244–1252, 2015. @article{Blythe2015,In this experiment, the extent to which beginning readers process phonology during lexical identification in silent sentence reading was investigated. The eye movements of children aged seven to nine years and adults were recorded as they read sentences containing either a correctly spelled target word (e.g., girl), a pseudohomophone (e.g., gerl), or a spelling control (e.g., garl). Both children and adults showed a benefit from the valid phonology of the pseudohomophone, compared to the spelling control during reading. This indicates that children as young as seven years old exhibit relatively skilled phonological processing during reading, despite having moved past the use of overt phonological decoding strategies. In addition, in comparison to adults, children's lexical processing was more disrupted by the presence of spelling errors, suggesting a developmental change in the relative dependence upon phonological and orthographic processing in lexical identification during silent sentence reading. |
Francisco López-Orozco; Luis D. Rodríguez-Vega Model of making decisions during an information search task Journal Article In: Research in Computing Science, vol. 105, pp. 157–166, 2015. @article{LopezOrozco2015,This paper presents a cognitive computational model of the way people read a paragraph with the task of quickly deciding whether it is related or not to a given goal. In particular, the model attempts to predict the time at which participants would decide to stop reading the paragraph because they have enough information to make their decision. Our model makes predictions at the level of words that are likely to be ?xated before the paragraph is abandoned. Human semantic judgments are mimicked by computing the semantic similarities between sets of words using Latent Semantic Analysis. A two-variable linear threshold is proposed to account for that decision, based on the rank of the ?xation and the semantic similarity between the paragraph and the goal. Model performance is compared to eyetracking data of 19 participants. |
Tuomo Häikiö; Jukka Hyönä; Raymond Bertram The role of syllables in word recognition among beginning Finnish readers: Evidence from eye movements during reading Journal Article In: Journal of Cognitive Psychology, vol. 27, no. 5, pp. 562–577, 2015. @article{Haeikioe2015,The eye movements of Finnish first and second graders were monitored as they read sentences where polysyllabic words were either hyphenated at syllable boundaries, alternatingly coloured (every second syllable black, every second red) or had no explicit syllable boundary cues (e.g., ta-lo vs. talo vs. talo = “house”). The results showed that hyphenation at syllable boundaries slows down reading of first and second graders even though syllabification by hyphens is very common in Finnish reading instruction, as all first-grade textbooks include hyphens at syllable boundaries. When hyphens were positioned within a syllable (t-alo vs. ta-lo), beginning readers were even more disrupted. Alternate colouring did not affect reading speed, no matter whether colours signalled syllable structure or not. The results show that beginning Finnish readers prefer to process polysyllabic words via syllables rather than letter by letter. At the same time they imply that hyphenation encourages sequential syllable processing, which slows down the reading of children, who are already capable of parallel syllable processing or recognising words directly via the whole-word route. |
Günter Kugler; Bernard Marius Hart; Stefan Kohlbecher; Wolfgang Einhäuser; Erich Schneider Gaze in visual search is guided more efficiently by positive cues than by negative cues Journal Article In: PLoS ONE, vol. 10, no. 12, pp. e0145910, 2015. @article{Kugler2015,Visual search can be accelerated when properties of the target are known. Such knowledge allows the searcher to direct attention to items sharing these properties. Recent work indicates that information about properties of non-targets (i.e., negative cues) can also guide search. In the present study, we examine whether negative cues lead to different search behavior compared to positive cues. We asked observers to search for a target defined by a certain shape singleton (broken line among solid lines). Each line was embedded in a colored disk. In "positive cue" blocks, participants were informed about possible colors of the target item. In "negative cue" blocks, the participants were informed about colors that could not contain the target. Search displays were designed such that with both the positive and negative cues, the same number of items could potentially contain the broken line ("relevant items"). Thus, both cues were equally informative. We measured response times and eye movements. Participants exhibited longer response times when provided with negative cues compared to positive cues. Although negative cues did guide the eyes to relevant items, there were marked differences in eye movements. Negative cues resulted in smaller proportions of fixations on relevant items, longer duration of fixations and in higher rates of fixations per item as compared to positive cues. The effectiveness of both cue types, as measured by fixations on relevant items, increased over the course of each search. In sum, a negative color cue can guide attention to relevant items, but it is less efficient than a positive cue of the same informational value. |
Alma Veenstra; Antje S. Meyer; Daniel J. Acheson Effects of parallel planning on agreement production Journal Article In: Acta Psychologica, vol. 162, pp. 29–39, 2015. @article{Veenstra2015,An important issue in current psycholinguistics is how the time course of utterance planning affects the generation of grammatical structures. The current study investigated the influence of parallel activation of the components of complex noun phrases on the generation of subject-verb agreement. Specifically, the lexical interference account (Gillespie & Pearlmutter, 2011b; Solomon & Pearlmutter, 2004) predicts more agreement errors (i.e., attraction) for subject phrases in which the head and local noun mismatch in number (e.g., the apple next to the pears) when nouns are planned in parallel than when they are planned in sequence. We used a speeded picture description task that yielded sentences such as the apple next to the pears is red. The objects mentioned in the noun phrase were either semantically related or unrelated. To induce agreement errors, pictures sometimes mismatched in number. In order to manipulate the likelihood of parallel processing of the objects and to test the hypothesized relationship between parallel processing and the rate of agreement errors, the pictures were either placed close together or far apart. Analyses of the participants' eye movements and speech onset latencies indicated slower processing of the first object and stronger interference from the related (compared to the unrelated) second object in the close than in the far condition. Analyses of the agreement errors yielded an attraction effect, with more errors in mismatching than in matching conditions. However, the magnitude of the attraction effect did not differ across the close and far conditions. Thus, spatial proximity encouraged parallel processing of the pictures, which led to interference of the associated conceptual and/or lexical representation, but, contrary to the prediction, it did not lead to more attraction errors. |
Mithun Diwakar; Deborah L. Harrington; Jun Maruta; Jamshid Ghajar; Fady El-Gabalawy; Laura Muzzatti; Maurizio Corbetta; Ming-Xiong X. Huang; Roland R. Lee Filling in the gaps: Anticipatory control of eye movements in chronic mild traumatic brain injury Journal Article In: NeuroImage: Clinical, vol. 8, pp. 210–223, 2015. @article{Diwakar2015,A barrier in the diagnosis of mild traumatic brain injury (mTBI) stems from the lack of measures that are adequately sensitive in detecting mild head injuries. MRI and CT are typically negative in mTBI patients with persistent symptoms of post-concussive syndrome (PCS), and characteristic difficulties in sustaining attention often go undetected on neuropsychological testing, which can be insensitive to momentary lapses in concentration. Conversely, visual tracking strongly depends on sustained attention over time and is impaired in chronic mTBI patients, especially when tracking an occluded target. This finding suggests deficient internal anticipatory control in mTBI, the neural underpinnings of which are poorly understood. The present study investigated the neuronal bases for deficient anticipatory control during visual tracking in 25 chronic mTBI patients with persistent PCS symptoms and 25 healthy control subjects. The task was performed while undergoing magnetoencephalography (MEG), which allowed us to examine whether neural dysfunction associated with anticipatory control deficits was due to altered alpha, beta, and/or gamma activity. Neuropsychological examinations characterized cognition in both groups. During MEG recordings, subjects tracked a predictably moving target that was either continuously visible or randomly occluded (gap condition). MEG source-imaging analyses tested for group differences in alpha, beta, and gamma frequency bands. The results showed executive functioning, information processing speed, and verbal memory deficits in the mTBI group. Visual tracking was impaired in the mTBI group only in the gap condition. Patients showed greater error than controls before and during target occlusion, and were slower to resynchronize with the target when it reappeared. Impaired tracking concurred with abnormal beta activity, which was suppressed in the parietal cortex, especially the right hemisphere, and enhanced in left caudate and frontaloral areas. Regional beta-amplitude demonstrated high classification accuracy (92%) compared to eye-tracking (65%) and neuropsychological variables (80%). These findings show that deficient internal anticipatory control in mTBI is associated with altered beta activity, which is remarkably sensitive given the heterogeneity of injuries. |
Gerulf Rieger; Brian M. Cash; Sarah M. Merrill; James Jones-Rounds; Sanjay Muralidharan Dharmavaram; Ritch C. Savin-Williams Sexual arousal: The correspondence of eyes and genitals Journal Article In: Biological Psychology, vol. 104, pp. 56–64, 2015. @article{Rieger2015,Men's, more than women's, sexual responses may include a coordination of several physiological indices in order to build their sexual arousal to relevant targets. Here, for the first time, genital arousal and pupil dilation to sexual stimuli were simultaneously assessed. These measures corresponded more strongly with each other, subjective sexual arousal, and self-reported sexual orientation in men than women. Bisexual arousal is more prevalent in women than men. We therefore predicted that if bisexual-identified men show bisexual arousal, the correspondence of their arousal indices would be more female-typical, thus weaker, than for other men. Homosexual women show more male-typical arousal than other women; hence, their correspondence of arousal indices should be stronger than for other women. Findings, albeit weak in effect, supported these predictions. Thus, if sex-specific patterns are reversed within one sex, they might affect more than one aspect of sexual arousal. Because pupillary responses reflected sexual orientation similar to genital responses, they offer a less invasive alternative for the measurement of sexual arousal. |
Peggy Gerardin; Judith Nicolas; Alessandro Farnè; Denis Pélisson Increasing attentional load boosts saccadic adaptation Journal Article In: Investigative Ophthalmology & Visual Science, vol. 56, no. 11, pp. 6304–6312, 2015. @article{Gerardin2015,PURPOSE: Visual exploration relies on saccadic eye movements and attention processes. Saccadic adaptation mechanisms, which calibrate the oculomotor commands to continuously maintain the accuracy of saccades, have been suggested to act at downstream (motor) and upstream (visuoattentional) levels of visuomotor transformation. Conversely, whether attention can directly affect saccadic adaptation remains unknown. To answer this question, we manipulated the level of attention engaged in a visual discrimination task performed during saccadic adaptation. METHODS: Participants performed low or high attention demanding orientation discrimination tasks on largely or faintly oriented Gabor patches, respectively, which served as targets for reactive saccades. Gabor patches systematically jumped backward during eye motion to elicit an adaptive shortening of saccades, and replaced 50 msec later (100 msec in two subjects) by a mask. Subjects judged whether Gabors' orientation was "nearly horizontal" versus "nearly vertical" (low attention demanding) or "slightly left" versus "slightly right" (high attention demanding), or made no discrimination (control task). RESULTS: We found that the build-up and the retention of adaptation of reactive saccades were larger in the "high attention demanding" condition than in the "low attention demanding" and the no-discrimination control conditions. CONCLUSIONS: These results indicate that increasing the level of attention to the perceptual processing of otherwise identical targets boosts saccadic adaptation, and suggest that saccadic adaptation mechanisms and attentional load effects may functionally share common neural substrates. |
Andrew Isaac Meso; Guillaume S. Masson Dynamic resolution of ambiguity during tri-stable motion perception Journal Article In: Vision Research, vol. 107, pp. 113–123, 2015. @article{Meso2015,Multi-stable perception occurs when an image falling onto the retina has multiple incompatible interpretations. We probed this phenomenon in psychophysical experiments using a moving barber-pole visual stimulus configured as a square to generate three competing perceived directions, horizontal, diagonal and vertical. We characterised patterns in reported switching type and percept duration, classifying switches into three groups related to the direction cues driving such transitions i.e. away from diagonal, towards diagonal and between cardinals. The proportions of each class reported by participants depended on contrast. The two including diagonals dominated at low contrast and those between cardinals increased in proportion as contrast was increased. At low contrasts, the less frequent cardinals persisted for shorter than the dominant diagonals and this was reversed at higher contrasts. This observed asymmetry between the dominance of transition classes appears to be driven by different underlying dynamics between cardinal and the oblique cues and their related transitions. At trial onset we found that transitions away from diagonal dominate, a tendency which later in the trial reverses to dominance by transitions excluding the diagonal, most prominently at higher contrasts. Thus ambiguity is resolved over a contrast dependent temporal integration similar to, but lasting longer than that observed when resolving the aperture problem to estimate direction. When the diagonal direction dominates perception, evidence is found for a noisier competition seen in broader duration distributions than during dominance of cardinal perception. There remain aspects of these identified differences in cardinal and oblique dynamics to be investigated in future. |
Mojtaba Seyedhosseini; S. Shushruth; Tyler Davis; Jennifer M. Ichida; Paul A. House; Bradley Greger; Alessandra Angelucci; Tolga Tasdizen Informative features of local field potential signals in primary visual cortex during natural image stimulation Journal Article In: Journal of Neurophysiology, vol. 113, no. 5, pp. 1520–1532, 2015. @article{ssdihgat15,The local field potential (LFP) is of growing importance in neurophysiology as a metric of network activity and as a readout signal for use in brain-machine interfaces. However, there are uncertainties regarding the kind and visual field extent of information carried by LFP signals, and the specific features of the LFP signal conveying such information, especially under naturalistic conditions. To address these questions, we recorded LFP responses to natural images in V1 of awake and anesthetized macaques using Utah multielectrode arrays. First, we show that it is possible to identify presented natural images from the LFP responses they evoke using trained Gabor wavelet (GW) models. Since GW models were devised to explain the spiking responses of V1 cells, this finding suggests that local spiking activity and LFPs (thought to reflect primarily local synaptic activity) carry similar visual information. Second, models trained on scalar metrics, like evoked LFP response range, provide robust image identification, supporting the informative nature of even simple LFP features. Third, image identification is robust only for the first 300ms following image presentation, and image information is not restricted to any of the spectral bands. This suggests that the short latency broadband LFP response carries most information during natural scene viewing. Finally, best image identification was achieved by GW models incorporating information at the scale of ~0.5° in size and trained using 4 different orientations. This suggests that during natural image viewing LFPs carry stimulus-specific information at spatial scales corresponding to few orientation columns in macaque V1. |
Ryosuke Tachibana; Yasuki Noguchi Unconscious analyses of visual scenes based on feature conjunctions Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 41, no. 3, pp. 639–648, 2015. @article{Tachibana2015,To efficiently process a cluttered scene, the visual system analyzes statistical properties or regularities of visual elements embedded in the scene. It is controversial, however, whether those scene analyses could also work for stimuli unconsciously perceived. Here we show that our brain performs the unconscious scene analyses not only using a single featural cue (e.g., orientation) but also based on conjunctions of multiple visual features (e.g., combinations of color and orientation information). Subjects foveally viewed a stimulus array (duration: 50 ms) where 4 types of bars (red-horizontal, red-vertical, greenhorizontal, and green-vertical) were intermixed. Although a conscious perception of those bars was inhibited by a subsequent mask stimulus, the brain correctly analyzed the information about color, orientation, and color-orientation conjunctions of those invisible bars. The information of those features was then used for the unconscious configuration analysis (statistical processing) of the central bars, which induced a perceptual bias and illusory feature binding in visible stimuli at peripheral locations. While statistical analyses and feature binding are normally 2 key functions of the visual system to construct coherent percepts of visual scenes, our results show that a high-level analysis combining those 2 functions is correctly performed by unconscious computations in the brain. |
Ming Yan; Jinger Pan; Nathalie N. Bélanger; Hua Shu Chinese deaf readers have early access to parafoveal semantics Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 1, pp. 254–261, 2015. @article{Yan2015c,In the present study, we manipulated different types of information available in the parafovea during the reading of Chinese sentences and examined how deaf readers make use of the parafoveal information. Results clearly indicate that although the reading-level matched hearing readers make greater use of orthographic information in the parafovea, parafoveal semantic information is obtained earlier among the deaf readers. In addition, a phonological preview benefit effect was found for the better deaf readers (relative to less-skilled deaf readers), although we also provide an alternative explanation for this effect. Providing evidence that Chinese deaf readers have higher efficiency when processing parafoveal semantics, the study indicates flexibility across individuals in the mechanisms underlying word recognition adapting to the inputs available in the linguistic environment. |
Steffi Zander; Maria Reichelt; Stefanie Wetzel; Frauke Kämmerer; Sven Bertel Does personalisation promote learners' attention? An eye-tracking study Journal Article In: Frontline Learning Research, vol. 3, no. 4, pp. 1–13, 2015. @article{Zander2015,The personalisation principle is a design recommendation and states that multimedia presentations using personalised language promote learning better than those using formal language (e.g., using ‘your' instead of ‘the'). It is often assumed that this design recommendation affects motivation and therefore allocation of attention. To gain further insight into the processes underlying personalisation effects we conducted an eye tracking experiment with 37 German university students who were presented with either personalised or formal learning materials. We examined group differences in attention allocation parameters (fixation count, fixation duration, transition count). The eye-tracking data was combined with self-reports concerning motivation, cognitive load, and learning outcomes. Eye-tracking data revealed a significantly higher reading depth for the main picture areas of interest in the personalised condition. Additionally, participants found the personalised version more appealing and inviting. For learning outcomes, there was a significant positive effect of personalisation for retention, not for transfer. We discuss additional explanatory variables as well as methodological and practical implications for instructional design. |
Tom A. Graaf; Felix Duecker; Martin H. P. Fernholz; Alexander T. Sack Spatially specific vs. unspecific disruption of visual orientation perception using chronometric pre-stimulus TMS Journal Article In: Frontiers in Behavioral Neuroscience, vol. 9, pp. 5, 2015. @article{Graaf2015,Transcranial magnetic stimulation (TMS) over occipital cortex can impair visual processing. Such ‘TMS masking' has repeatedly been shown at several stimulus onset asynchronies (SOAs), with TMS pulses generally applied after the onset of a visual stimulus. Following increased interest in the neuronal state-dependency of visual processing, we recently explored the efficacy of TMS at ‘negative SOAs', when no visual processing can yet occur. We could reveal pre-stimulus TMS disruption, with results moreover hinting at two separate mechanisms in occipital cortex biasing subsequent orientation perception. Here we extended this work, including a chronometric design to map the temporal dynamics of spatially specific and unspecific mechanisms of state-dependent visual processing, while moreover controlling for TMS-induced pupil covering. TMS pulses applied 60-40 ms prior to a visual stimulus decreased orientation processing independent of stimulus location, while a local suppressive effect was found for TMS applied 30-10 ms pre-stimulus. These results contribute to our understanding of spatiotemporal mechanisms in occipital cortex underlying the state-dependency of visual processing, providing a basis for future work to link pre-stimulus TMS suppression effects to other known visual biasing mechanisms. |
Simon P. Tiffin-Richards; Sascha Schroeder Children's and adults' parafoveal processes in German: Phonological and orthographic effects Journal Article In: Journal of Cognitive Psychology, vol. 27, no. 5, pp. 531–548, 2015. @article{TiffinRichards2015,Phonological and orthographic information has been shown to play an important role in parafoveal processing in skilled adult reading in English. In the present study, we investigated whether similar parafoveal effects can be found in children using the boundary eye tracking method. Children and adults read sentences in German with embedded target nouns which were presented in original, pseudohomophone (PsH), transposed-letter (TL), lower-case and control conditions to assess phonological and orthographic preview effects. We found evidence of PsH preview benefit effects for children. We also found TL preview benefit effects for adults, while children only showed these effects under specific conditions. Results are consistent with the developmental view that reading initially depends on phonological processes and that orthographic processes become increasingly important. |
Mark M. G. Walton; Michael J. Mustari Abnormal tuning of saccade-related cells in pontine reticular formation of strabismic monkeys Journal Article In: Journal of Neurophysiology, vol. 114, no. 2, pp. 857–868, 2015. @article{Walton2015,Strabismus is a common disorder, char- acterized by a chronic misalignment of the eyes and numerous visual and oculomotor abnormalities. For example, saccades are often highly disconjugate. For humans with pattern strabismus, the horizontal and vertical disconjugacies vary with eye position. In monkeys, manipula- tions that disturb binocular vision during the first several weeks of life result in a chronic strabismus with characteristics that closely match those in human patients. Early onset strabismus is associated with altered binocular sensitivity of neurons in visual cortex. Here we test the hypothesis that brain stem circuits specific to saccadic eye movements are abnormal. We targeted the pontine paramedian reticular formation, a structure that directly projects to the ipsilateral abducens nucleus. In normal animals, neurons in this structure are characterized by a high- frequency burst of spikes associated with ipsiversive saccades. We recorded single-unit activity from 84 neurons from four monkeys (two normal, one exotrope, and one esotrope), while they made saccades to a visual target on a tangent screen. All 24 neurons recorded from the normal animals had preferred directions within 30° of pure horizontal. For the strabismic animals, the distribution of preferred directions was normal on one side of the brain, but highly variable on the other. In fact, 12/60 neurons recorded from the strabismic animals preferred vertical saccades. Many also had unusually weak or strong bursts. These data suggest that the loss of corresponding binocular vision during infancy impairs the development of normal tuning characteristics for saccade- related neurons in brain stem. |
Mónika Gergelyfi; Benvenuto Jacob; Etienne Olivier; Alexandre Zénon Dissociation between mental fatigue and motivational state during prolonged mental activity Journal Article In: Frontiers in Behavioral Neuroscience, vol. 9, pp. 176, 2015. @article{Gergelyfi2015,Mental fatigue (MF) is commonly observed following prolonged cognitive activity and can have major repercussions on the daily life of patients as well as healthy individuals. Despite its important impact, the cognitive processes involved in MF remain largely unknown. An influential hypothesis states that MF does not arise from a disruption of overused neural processes but, rather, is caused by a progressive decrease in motivation-related task engagement. Here, to test this hypothesis, we measured various neural, autonomic, psychometric and behavioral signatures of MF and motivation (EEG, ECG, pupil size, eye blinks, Skin conductance responses (SCRs), questionnaires and performance in a working memory (WM) task) in healthy volunteers, while MF was induced by Sudoku tasks performed for 120 min. Moreover extrinsic motivation was manipulated by using different levels of monetary reward. We found that, during the course of the experiment, the participants' subjective feeling of fatigue increased and their performance worsened while their blink rate and heart rate variability (HRV) increased. Conversely, reward-induced EEG, pupillometric and skin conductance signal changes, regarded as indicators of task engagement, remained constant during the experiment, and failed to correlate with the indices of MF. In addition, MF did not affect a simple reaction time task, despite the strong influence of extrinsic motivation on this task. Finally, alterations of the motivational state through monetary incentives failed to compensate the effects of MF. These findings indicate that MF in healthy subjects is not caused by an alteration of task engagement but is likely to be the consequence of a decrease in the efficiency, or availability, of cognitive resources. |
Mariah Moore; Peter C. Gordon Reading ability and print exposure: item response theory analysis of the author recognition test Journal Article In: Behavior Research Methods, vol. 47, no. 4, pp. 1095–1109, 2015. @article{Moore2015,In the author recognition test (ART), participants are presented with a series of names and foils and are asked to indicate which ones they recognize as authors. The test is a strong predictor of reading skill, and this predictive ability is generally explained as occurring because author knowledge is likely acquired through reading or other forms of print exposure. In this large-scale study (1,012 college student participants), we used item response theory (IRT) to analyze item (author) characteristics in order to facilitate identification of the determinants of item difficulty, provide a basis for further test development, and optimize scoring of the ART. Factor analysis suggested a potential two-factor structure of the ART, differentiating between literary and popular authors. Effective and ineffective author names were identified so as to facilitate future revisions of the ART. Analyses showed that the ART is a highly significant predictor of the time spent encoding words, as measured using eyetracking during reading. The relationship between the ART and time spent reading provided a basis for implementing a higher penalty for selecting foils, rather than the standard method of ART scoring (names selected minus foils selected). The findings provide novel support for the view that the ART is a valid indicator of reading volume. Furthermore, they show that frequency data can be used to select items of appropriate difficulty, and that frequency data from corpora based on particular time periods and types of texts may allow adaptations of the test for different populations. |
Simon P. Tiffin-Richards; Sascha Schroeder Word length and frequency effects on children's eye movements during silent reading Journal Article In: Vision Research, vol. 113, pp. 33–43, 2015. @article{TiffinRichards2015a,In the present study we measured the eye movements of a large sample of 2nd grade German speaking children and a control group of adults during a silent reading task. To be able to directly investigate the interaction of word length and frequency effects we employed controlled sentence frames with embedded target words in an experimental design in which length and frequency were manipulated independently of one another. Unlike previous studies which have investigated the interaction of word length and frequency effects in children, we used age-appropriate word frequencies for children. We found significant effects of word length and frequency for both children and adults while effects were generally greater for children. The interaction of word length and frequency was significant for children in gaze duration and total viewing time eye movement measures but not for adults. Our results suggest that children rely on sublexical decoding of infrequent words, leading to greater length effects for infrequent than frequent words while adults do not show this effect when reading children's reading materials. |
Mark M. G. Walton; Michael J. Mustari; Christy L. Willoughby; Linda K. McLoon Abnormal activity of neurons in abducens nucleus of strabismic monkeys Journal Article In: Investigative Ophthalmology & Visual Science, vol. 56, no. 1, pp. 10–19, 2015. @article{Walton2015a,PURPOSE: Infantile strabismus is characterized by persistent misalignment of the eyes. Mounting evidence suggests that the disorder is associated with abnormalities at the neural level, but few details are known. This study investigated the signals carried by abducens neurons in monkeys with experimentally induced strabismus. We wanted to know whether the firing rates of individual neurons are exclusively related to the position and velocity of one eye and whether the overall level of activity of the abducens nucleus was in the normal range. METHODS: We recorded 58 neurons in right and left abducens nuclei while strabismic monkeys (one esotrope and one exotrope) performed a saccade task. We analyzed the firing rates associated with static horizontal eye position and saccades by fitting the data with a dynamic equation that included position and velocity terms for each eye. Results were compared to previously published data in normal monkeys. RESULTS: For both strabismic monkeys the overall tonic activity was 50 to 100 spikes/s lower, for every suprathreshold eye position, than what has previously been reported for normal monkeys. This was mostly the result of lower baseline activity; the slopes of rate-position curves were similar to those in previous reports in normal monkeys. The saccade velocity sensitivities were similar to those of normal monkeys, 0.35 for the esotrope and 0.40 for the exotrope. For most neurons the firing rate was more closely related to the position and velocity of the ipsilateral eye. CONCLUSIONS: These data suggest that strabismus can be associated with reduced neural activity in the abducens nucleus. |
Gustav Kuhn; Amber Pagano; Sumaya Maani; David Bunce Age-related decline in the reflexive component of overt gaze following Journal Article In: Quarterly Journal of Experimental Psychology, vol. 68, no. 6, pp. 1073–1081, 2015. @article{Kuhn2015,Previous research has found age-related declines in social perception tasks as well as the ability to engage in joint attention and orienting covert attention (i.e., absence of eye movements) in response to an eye gaze cue. We used an overt gaze following task to explore age differences in overt gaze following whilst people searched for a target. Participants were faster to detect targets appearing at the looked-at location, and although the gaze cue biased the direction in which saccades were executed, no age differences were found in overt gaze following. There were, however, age effects relating to involuntary eye movements. In the younger adults, anticipatory saccades were biased in the direction of the gaze cue, but this bias was not observed in the older group. Moreover, in the younger adults, saccades that followed the gaze were initiated more rapidly, illustrating the reflexive nature of gaze following. No such difference was observed in the older adults. Importantly, our results showed that whilst the general levels of gaze following were age invariant, there were age-related differences in the reflexive components of overt gaze following. |
Manuel Perea; María Jiménez; Miguel Martín-Suesta; Pablo Gómez Letter position coding across modalities: Braille and sighted reading of sentences with jumbled words Journal Article In: Psychonomic Bulletin & Review, vol. 22, no. 2, pp. 531–536, 2015. @article{Perea2015,This article explores how letter position coding is attained during braille reading and its implications for models of word recognition. When text is presented visually, the reading process easily adjusts to the jumbling of some letters (jugde-judge), with a small cost in reading speed. Two explanations have been proposed: One relies on a general mechanism of perceptual uncertainty at the visual level, and the other focuses on the activation of an abstract level of representation (i.e., bigrams) that is shared by all orthographic codes. Thus, these explanations make differential predictions about reading in a tactile modality. In the present study, congenitally blind readers read sentences presented on a braille display that tracked the finger position. The sentences either were intact or involved letter transpositions. A parallel experiment was conducted in the visual modality. Results revealed a substantially greater reading cost for the sentences with transposed-letter words in braille readers. In contrast with the findings with sighted readers, in which there is a cost of transpositions in the external (initial and final) letters, the reading cost in braille readers occurs serially, with a large cost for initial letter transpositions. Thus, these data suggest that the letter-position-related effects in visual word recognition are due to the characteristics of the visual stream. |
Dingcai Cao; Nathaniel Nicandro; Pablo A. Barrionuevo A five-primary photostimulator suitable for studying intrinsically photosensitive retinal ganglion cell functions in humans Journal Article In: Journal of Vision, vol. 15, no. 1, pp. 1–14, 2015. @article{Cao2015,Intrinsically photosensitive retinal ganglion cells (ipRGCs) can respond to light directly through self-contained photopigment, melanopsin. IpRGCs also receive synaptic inputs from rods and cones. Thus, studying ipRGC functions requires a novel photostimulating method that can account for all of the photoreceptor inputs. Here, we introduced an inexpensive LED-based five-primary photostimulator that can control the excitations of rods, S-, M-, L-cones, and melanopsin-containing ipRGCs in humans at constant background photoreceptor excitation levels, a critical requirement for studying the adaptation behavior of ipRGCs with rod, cone, or melanopsin input. We described the theory and technical aspects (including optics, electronics, software, and calibration) of the five-primary photostimulator. Then we presented two preliminary studies using the photostimulator we have implemented to measure melanopsin-mediated pupil responses and temporal contrast sensitivity function (TCSF). The results showed that the S-cone input to pupil responses was antagonistic to the L-, M- or melanopsin inputs, consistent with an S-OFF and (L + M)-ON response property of primate ipRGCs (Dacey et al., 2005). In addition, the melanopsin-mediated TCSF had a distinctive pattern compared with L + M or S-cone mediated TCSF. Other than controlling individual photoreceptor excitation independently, the five-primary photostimulator has the flexibility in presenting stimuli modulating any combination of photoreceptor excitations, which allows researchers to study the mechanisms by which ipRGCs combine various photoreceptor inputs. |
Pieter Moors; Filip Germeys; Iwona Pomianowska; Karl Verfaillie Perceiving where another person is looking: The integration of head and body information in estimating another person's gaze Journal Article In: Frontiers in Psychology, vol. 6, pp. 909, 2015. @article{Moors2015,The process through which an observer allocates his/her attention based on the attention of another person is known as joint attention. To be able to do this, the observer effectively has to compute where the other person is looking. It has been shown that observers integrate information from the head and the eyes to determine the gaze of another person. Most studies have documented that observers show a bias called the overshoot effect when eyes and head are misaligned. That is, when the head is not oriented straight to the observer, perceived gaze direction is sometimes shifted in the direction opposite to the head turn. The present study addresses whether body information is also used as a cue to compute perceived gaze direction. In Experiment 1, we observed a similar overshoot effect in both behavioral and saccadic responses when manipulating body orientation. In Experiment 2, we explored whether the overshoot effect was due to observers assuming that the eyes are oriented further than the head when head and body orientation are misaligned. We removed horizontal eye information by presenting the stimulus from a side view. Head orientation was now manipulated in a vertical direction and the overshoot effect was replicated. In summary, this study shows that body orientation is indeed used as a cue to determine where another person is looking. |
Jinger Pan; Hua Shu; Yuling Wang; Ming Yan Parafoveal activation of sign translation previews among deaf readers during the reading of Chinese sentences Journal Article In: Memory & Cognition, vol. 43, no. 6, pp. 964–972, 2015. @article{Pan2015,In the present study, we manipulated the different types of information available in the parafovea during the reading of Chinese sentences and examined whether deaf readers could activate sign translations of Chinese words during reading. The main finding was that, as compared to unrelated previews, the deaf readers had longer fixation durations on the target words when sign-phonologically related preview words were presented; this preview cost effect due to sign-phonological relatedness was absent for reading-level-matched hearing individuals. These results indicate that Chinese deaf readers activate sign language translations of parafoveal words during reading. We discuss the implications for notions of parafoveal processing in reading. |
Meaghan Clough; Laura Mitchell; Lynette Millist; Nathaniel Lizak; Shin Beh; Teresa C. Frohman; Elliot M. Frohman; Owen B. White; Joanne Fielding Ocular motor measures of cognitive dysfunction in multiple sclerosis I: Inhibitory control Journal Article In: Journal of Neurology, vol. 262, no. 5, pp. 1130–1137, 2015. @article{Clough2015,Our ability to control and inhibit behaviours that are inappropriate, unsafe, or no longer required is crucial for functioning successfully in complex environments. Here, we investigated whether a series of ocular motor (OM) inhibition tasks could dissociate deficits in patients with multiple sclerosis (MS), including patients with only a probable diagnosis (clinically isolated syndrome: CIS), from healthy individuals as well as a function of increasing disease duration. 25 patients with CIS, 25 early clinically definite MS patients (CDMS: ≤7 years of diagnosis), 24 late CDMS patients (>7 years from diagnosis), and 25 healthy controls participated. All participants completed a series of classic OM inhibition tasks [antisaccade (AS) task, memory-guided (MG) task, endogenous cue task], and a neuropsychological inhibition task [paced auditory serial addition test (PASAT)]. Clinical disability was characterised in CDMS patients using the Expanded Disability Severity Scale (EDSS). OM (latency and error) and PASAT performance were compared between patient groups and controls, as well as a function of disease duration. For CDMS patients only, results were correlated with EDSS score. All patient groups made more errors than controls on all OM tasks; error rate did not increase with increasing disease duration. In contrast, saccade latency (MG and endogenous cue tasks) was found to worsen with increasing disease duration. PASAT performance did not discriminate patient groups or disease duration. The EDSS did not correlate with any measure. These OM measures appear to dissociate deficit between patients at different disease durations. This suggests their utility as a measure of progression from the earliest inception of the disease. |
Joshua A. Granek; Lauren E. Sergio Evidence for distinct brain networks in the control of rule-based motor behavior Journal Article In: Journal of Neurophysiology, vol. 114, no. 2, pp. 1298–1309, 2015. @article{Granek2015,Reach guidance when the spatial location of the viewed target and hand movement are incongruent (i.e., decoupled) necessitates use of explicit cognitive rules (strategic control) or implicit recalibration of gaze and limb position (senso- rimotor recalibration). In a patient with optic ataxia (OA) and bilateral superior parietal lobule damage, we recently demonstrated an in- creased reliance on strategic control when the patient performed a decoupled reach (Granek JA, Pisella L, Stemberger J, Vighetto A, Rossetti Y, Sergio LE. PLoS One 8: e86138, 2013). To more generally understand the fundamental mechanisms of decoupled visuomotor control and to more specifically test whether we could distinguish these two modes of movement control, we tested healthy participants in a cognitively demanding dual task. Participants continuously counted backward while simultaneously reaching toward horizontal (left or right) or diagonal (equivalent to top-left or top-right) targets with either veridical or rotated (90°) cursor feedback. By increasing the overall neural load and selectively compromising potentially overlapping neural circuits responsible for strategic control, the com- plex dual task served as a noninvasive means to disrupt the integration of a cognitive rule into a motor action. Complementary to our previous results observed in patients with optic ataxia, here our dual task led to greater performance deficits during movements that re- quired an explicit rule, implying a selective disruption of strategic control in decoupled reaching. Our results suggest that distinct neural processing is required to control these different types of reaching because in considering the current results and previous patient results together, the two classes of movement could be differentiated depend- ing on the type of interference. |
Lena A. Jäger; Lena Benz; Jens Roeser; Brian W. Dillon; Shravan Vasishth Teasing apart retrieval and encoding interference in the processing of anaphors Journal Article In: Frontiers in Psychology, vol. 6, pp. 506, 2015. @article{Jaeger2015,Two classes of account have been proposed to explain the memory processes subserving the processing of reflexive-antecedent dependencies. Structure-based accounts assume that the retrieval of the antecedent is guided by syntactic tree-configurational information without considering other kinds of information such as gender marking in the case of English reflexives. By contrast, unconstrained cue-based retrieval assumes that all available information is used for retrieving the antecedent. Similarity-based interference effects from structurally illicit distractors which match a non-structural retrieval cue have been interpreted as evidence favoring the unconstrained cue-based retrieval account since cue-based retrieval interference from structurally illicit distractors is incompatible with the structure-based account. However, it has been argued that the observed effects do not necessarily reflect interference occurring at the moment of retrieval but might equally well be accounted for by interference occurring already at the stage of encoding or maintaining the antecedent in memory, in which case they cannot be taken as evidence against the structure-based account. We present three experiments (self-paced reading and eye-tracking) on German reflexives and Swedish reflexive and pronominal possessives in which we pit the predictions of encoding interference and cue-based retrieval interference against each other. We could not find any indication that encoding interference affects the processing ease of the reflexive-antecedent dependency formation. Thus, there is no evidence that encoding interference might be the explanation for the interference effects observed in previous work. We therefore conclude that invoking encoding interference may not be a plausible way to reconcile interference effects with a structure-based account of reflexive processing. |
Maria Matziridi; Eli Brenner; Jeroen B. J. Smeets The role of temporal information in perisaccadic mislocalization Journal Article In: PLoS ONE, vol. 10, no. 9, pp. e0134081, 2015. @article{Matziridi2015,In dynamic environments, it is crucial to accurately consider the timing of information. For instance, during saccades the eyes rotate so fast that even small temporal errors in relating retinal stimulation by flashed stimuli to extra-retinal information about the eyes' orientations will give rise to substantial errors in where the stimuli are judged to be. If spatial localization involves judging the eyes' orientations at the estimated time of the flash, we should be able to manipulate the pattern of mislocalization by altering the estimated time of the flash. We reasoned that if we presented a relevant flash within a short rapid sequence of irrelevant flashes, participants' estimates of when the relevant flash was presented might be shifted towards the centre of the sequence. In a first experiment, we presented five bars at different positions around the time of a saccade. Four of the bars were black. Either the second or the fourth bar in the sequence was red. The task was to localize the red bar. We found that when the red bar was presented second in the sequence, it was judged to be further in the direction of the saccade than when it was presented fourth in the sequence. Could this be because the red bar was processed faster when more black bars preceded it? In a second experiment, a red bar was either presented alone or followed by two black bars. When two black bars followed it, it was judged to be further in the direction of the saccade. We conclude that the spatial localization of flashed stimuli involves judging the eye orientation at the estimated time of the flash. |
Miguel A. Vadillo; Chris N. H. Street; Tom Beesley; David R. Shanks A simple algorithm for the offline recalibration of eye-tracking data through best-fitting linear transformation Journal Article In: Behavior Research Methods, vol. 47, no. 4, pp. 1365–1376, 2015. @article{Vadillo2015,Poor calibration and inaccurate drift correction can pose severe problems for eye-tracking experiments requiring high levels of accuracy and precision. We describe an algorithm for the offline correction of eye-tracking data. The algorithm conducts a linear transformation of the coordinates of fixations that minimizes the distance between each fixation and its closest stimulus. A simple implementation in MATLAB is also presented. We explore the performance of the correction algorithm under several conditions using simulated and real data, and show that it is particularly likely to improve data quality when many fixations are included in the fitting process. |
Juan D. Velásquez; Pablo Loyola; Gustavo Martinez; Kristofher Munoz; Pedro Maldanado; Andrés Andres Couve; Pedro E. Maldonado Combining eye tracking and pupillary dilation analysis to identify website key objects Journal Article In: Neurocomputing, vol. 168, pp. 179–189, 2015. @article{Velasquez2015,Identifying the salient zones from Web interfaces, namely the Website Key Objects, is an essential part of the personalization process that current Web systems perform to increase user engagement. While several techniques have been proposed, most of them are focused on the use of Web usage logs. Only recently has the use of data from users[U+05F3] biological responses emerged as an alternative to enrich the analysis. In this work, a model is proposed to identify Website Key Objects that not only takes into account visual gaze activity, such as fixation time, but also the impact of pupil dilation. Our main hypothesis is that there is a strong relationship in terms of the pupil dynamics and the Web user preferences on a Web page. An empirical study was conducted on a real Website, from which the navigational activity of 23 subjects was captured using an eye tracking device. Results showed that the inclusion of pupillary activity, although not conclusively, allows us to extract a more robust Web Object classification, achieving a 14% increment in the overall accuracy. |
Lena A. Jäger; Zhong Chen; Qiang Li; Chien-Jer Charles Lin; Shravan Vasishth The subject-relative advantage in Chinese: Evidence for expectation-based processing Journal Article In: Journal of Memory and Language, vol. 79-80, pp. 97–120, 2015. @article{Jaeger2015a,Chinese relative clauses are an important test case for pitting the predictions of expectation-based accounts against those of memory-based theories. The memory-based accounts predict that object relatives are easier to process than subject relatives because, in object relatives, the distance between the relative clause verb and the head noun is shorter. By contrast, expectation-based accounts such as surprisal predict that the less frequent object relative should be harder to process. In previous studies on Chinese relative clause comprehension, local ambiguities may have rendered a comparison between relative clause types uninterpretable. We designed experimental materials in which no local ambiguities confound the comparison. We ran two experiments (self-paced reading and eye-tracking) to compare reading difficulty in subject and object relatives which were placed either in subject or object modifying position. The evidence from our studies is consistent with the predictions of expectation-based accounts but not with those of memory-based theories. |
Franziska Geringswald; Anne Herbik; Wolfram Hofmüller; Michael B. Hoffmann; Stefan Pollmann Visual memory for objects following foveal vision loss Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 5, pp. 1471–1484, 2015. @article{Geringswald2015a,Allocation of visual attention is crucial for encoding items into visual long-term memory. In free vision, attention is closely linked to the center of gaze, raising the question whether foveal vision loss entails suboptimal deployment of attention and subsequent impairment of object encoding. To investigate this question, we examined visual long-term memory for objects in patients suffering from foveal vision loss due to age-related macular degeneration. We measured patients' change detection sensitivity after a period of free scene exploration monocularly with their worse eye when possible, and under binocular vision, comparing sensitivity and eye movements to matched normal-sighted controls. A highly salient cue was used to capture attention to a nontarget location before a target change occurred in half of the trials, ensuring that change detection relied on memory. Patients' monocular and binocular sensitivity to object change was comparable to controls, even after more than 4 intervening fixations, and not significantly correlated with visual impairment. We conclude that extrafoveal vision suffices for efficient encoding into visual long-term memory. |
Lena A. Jäger; Felix Engelmann; Shravan Vasishth Retrieval interference in reflexive processing: Experimental evidence from Mandarin, and computational modeling Journal Article In: Frontiers in Psychology, vol. 6, pp. 617, 2015. @article{Jaeger2015b,We conducted two eye-tracking experiments investigating the processing of the Mandarin reflexive ziji in order to tease apart structurally constrained accounts from standard cue-based accounts of memory retrieval. In both experiments, we tested whether structurally inaccessible distractors that fulfill the animacy requirement of ziji influence processing times at the reflexive. In Experiment 1, we manipulated animacy of the antecedent and a structurally inaccessible distractor intervening between the antecedent and the reflexive. In conditions where the accessible antecedent mismatched the animacy cue, we found inhibitory interference whereas in antecedent-match conditions, no effect of the distractor was observed. In Experiment 2, we tested only antecedent-match configurations and manipulated locality of the reflexive-antecedent binding (Mandarin allows non-local binding). Participants were asked to hold three distractors (animate vs. inanimate nouns) in memory while reading the target sentence. We found slower reading times when animate distractors were held in memory (inhibitory interference). Moreover, we replicated the locality effect reported in previous studies. These results are incompatible with structure-based accounts. However, the cue-based ACT-R model of Lewis and Vasishth (2005) cannot explain the observed pattern either. We therefore extend the original ACT-R model and show how this model not only explains the data presented in this article, but is also able to account for previously unexplained patterns in the literature on reflexive processing. |
James Lee; Jessica Manousakis; Joanne Fielding; Clare Anderson Alcohol and sleep restriction combined reduces vigilant attention, whereas sleep restriction alone enhances distractibility Journal Article In: Sleep, vol. 38, no. 5, pp. 765–775, 2015. @article{Lee2015a,STUDY OBJECTIVES: Alcohol and sleep loss are leading causes of motor vehicle crashes, whereby attention failure is a core causal factor. Despite a plethora of data describing the effect of alcohol and sleep loss on vigilant attention, little is known about their effect on voluntary and involuntary visual attention processes. DESIGN: Repeated-measures, counterbalanced design. SETTING: Controlled laboratory setting. PARTICIPANTS: Sixteen young (18-27 y; M = 21.90 ± 0.60 y) healthy males. INTERVENTIONS: Participants completed an attention test battery during the afternoon (13:00-14:00) under four counterbalanced conditions: (1) baseline; (2) alcohol (0.05% breath alcohol concentration); (3) sleep restriction (02:00-07:00); and (4) alcohol/sleep restriction combined. This test battery included a Psychomotor Vigilance Task (PVT) as a measure of vigilant attention, and two ocular motor tasks-visually guided and antisaccade-to measure the involuntary and voluntary allocation of visual attention. MEASUREMENTS AND RESULTS: Only the combined condition led to reductions in vigilant attention characterized by slower mean reaction time, fastest 10% responses, and increased number of lapses (P < 0.05) on the PVT. In addition, the combined condition led to a slowing in the voluntary allocation of attention as reflected by increased antisaccade latencies (P < 0.05). Sleep restriction alone however increased both antisaccade inhibitory errors [45.8% errors versus < 28.4% all others; P < 0.001] and the involuntary allocation of attention, as reflected by faster visually guided latencies (177.7 msec versus > 185.0 msec all others) to a peripheral target (P < 0.05). CONCLUSIONS: Our data reveal specific signatures for sleep related attention failure: the voluntary allocation of attention is impaired, whereas the involuntary allocation of attention is enhanced. This provides key evidence for the role of distraction in attention failure during sleep loss. |
Manuel Perea; Pilar Tejero; Heather Winskel Can colours be used to segment words when reading? Journal Article In: Acta Psychologica, vol. 159, pp. 8–13, 2015. @article{Perea2015a,Rayner, Fischer, and Pollatsek (1998, Vision Research) demonstrated that reading unspaced text in Indo-European languages produces a substantial reading cost in word identification (as deduced from an increased word-frequency effect on target words embedded in the unspaced vs. spaced sentences) and in eye movement guidance (as deduced from landing sites closer to the beginning of the words in unspaced sentences). However, the addition of spaces between words comes with a cost: nearby words may fall outside high-acuity central vision, thus reducing the potential benefits of parafoveal processing. In the present experiment, we introduced a salient visual cue intended to facilitate the process of word segmentation without compromising visual acuity: each alternating word was printed in a different colour (i.e., ). Results only revealed a small reading cost of unspaced alternating colour sentences relative to the spaced sentences. Thus, present data are a demonstration that colour can be useful to segment words for readers of spaced orthographies. |
Bertalan Polner; Désirée S. Aichert; Christine Macare; Anna Costa; Ulrich Ettinger Gently restless: Association of ADHD-like traits with response inhibition and interference control Journal Article In: European Archives of Psychiatry and Clinical Neuroscience, vol. 265, no. 8, pp. 689–699, 2015. @article{Polner2015,Impairment of inhibition-related functions is one of the most pronounced cognitive deficits found in attention-deficit/hyperactivity disorder (ADHD). Compelling evidence from studies of unaffected relatives of patients with ADHD and of ADHD-like traits in healthy subjects suggest the continuous distribution of ADHD symptoms in the population. A more subtle inhibitory deficit can also be found in healthy relatives of patients and in subjects with high ADHD-like traits. Here, we examined the relationship between inhibitory performance and ADHD-like traits, for the first time, in a large sample of healthy adults by applying multiple, widely used tests of inhibition-related functions. ADHD-like traits, in general, were independently predicted by Stroop interference score and, at trend level, by go/no-go commission error rate while controlling for socio-demographic factors, verbal intelligence and neuroticism. Additionally, higher inattentive traits were related to worse Stroop performance at trend level, and higher hyperactive/impulsive traits were significantly associated with more go/no-go commission errors. ADHD-like traits were strongly related to neuroticism. The study shows that individual differences in ADHD-like traits are related to variance in fundamental inhibition-related functions over and above effects of negative affect regulation, but the relationships tend to be small. The results suggest the quasi-dimensionality of ADHD and raise further questions about the relationship between genetic factors and the deficit of inhibition-related functions in the ADHD spectrum. |
Franziska Geringswald; Stefan Pollmann Central and peripheral vision loss differentially affects contextual cueing in visual search Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 5, pp. 1485–1496, 2015. @article{Geringswald2015,Visual search for targets in repeated displays is more efficient than search for the same targets in random distractor layouts. Previous work has shown that this contextual cueing is severely impaired under central vision loss. Here, we investigated whether central vision loss, simulated with gaze-contingent displays, prevents the incidental learning of contextual cues or the expression of learning, that is, the guidance of search by learned target-distractor configurations. Visual search with a central scotoma reduced contex-tual cueing both with respect to search times and gaze parameters. However, when the scotoma was subsequently removed, contextual cueing was observed in a comparable magnitude as for controls who had searched without scotoma simulation throughout the experiment. This indicated that search with a central scotoma did not prevent incidental context learning, but interfered with search guidance by learned contexts. We discuss the role of visuospatial working memory load as source of this interference. In contrast to central vision loss, peripheral vision loss was expected to prevent spatial configuration learning itself, because the restricted search window did not allow the integration of invariant local configurations with the global display layout. This expectation was confirmed in that visual search with a simulated peripheral scotoma eliminated contextual cueing not only in the initial learning phase with scotoma, but also in the subsequent test phase without scotoma. |
Leigh D. Grant; Alison C. Bowling Gambling attitudes and beliefs predict attentional bias in non-problem gamblers Journal Article In: Journal of Gambling Studies, vol. 31, no. 4, pp. 1487–1503, 2015. @article{Grant2015,Problem gambling has been identified as a public health concern in Australia, and a considerable proportion of regular gamblers may be at risk of developing gambling related problems. Attentional bias to salient cues has been observed in substance addictions, and to some extent, in problem gamblers. This bias appears to be indicative of an increase in sensitisation to salient cues as a result of continued reforcement of a related behaviour. To test for an attentional bias to gambling-related stimuli in non-problem gamblers, the relationships between gambling frequency, gambling attitudes and beliefs (GABS-23), and attentional bias were investigated. Participants (N = 38) viewed simultaneous pairs of gambling-related and neutral images and performed a dot probe task, during which their eye-movements were recorded. This enabled both direct and indirect measures of attentional bias to be obtained. Gambling frequency and GABS-23 scores predicted both direct and indirect measures of a bias in the maintenance of attention to gambling cues. No bias in attentional engagement was found. These results suggest that regular gamblers who have not yet developed any related problems show signs of sensitisation to gambling cues and may be at risk of progressing further towards problem gambling. |
Makoto Kobayashi Unidirectional ocular flutter: Report of a case with abnormal saccadic characteristics Journal Article In: Neurological Sciences, vol. 36, no. 7, pp. 1273–1276, 2015. @article{Kobayashi2015,Presents a case report of a unique case of unidirectional ocular flutter (OF) with event frequency much lower than in the previous unidirectional OF case, displacement magnitudes larger than observed in double saccadic pulses (another involuntary saccade syndrome), and saccadic peak velocities substantially slower than visually guided saccades (VGSs). The 38 year old male was referred to our department because of a 2-month history of involuntary eye movements. His medical history included depression, for which he was prescribed duloxetine hydrochloride, bromazepam, olanzapine, and zolpidem tartrate. The termed saccadic intrusions, usually occur horizontally with directional predominance in each normal individual. Perhaps, saccadic intrusions observed in normal subjects and unidirectional OF may share a common directional predominance mechanism. |
Luca Polonio; D. S. Guida; Giorgio Coricelli; Sibilla Di Guida; Giorgio Coricelli Strategic sophistication and attention in games: An eye-tracking study Journal Article In: Games and Economic Behavior, vol. 94, pp. 80–96, 2015. @article{Polonio2015,We used eye-tracking to measure the dynamic patterns of visual information acquisition in two-player normal-form games. Participants played one-shot games in which either, neither, or only one of the players had a dominant strategy. First, we performed a mixture models cluster analysis to group participants into types according to the pattern of visual information acquisition observed in a single class of games. Then, we predicted agents' choices in different classes of games and observed that patterns of visual information acquisition were game invariant. Our method allowed us to predict whether the decision process would lead to equilibrium choices or not, and to attribute out-of-equilibrium responses to limited cognitive capacities or social motives. Our results suggest the existence of individually heterogeneous-but-stable patterns of visual information acquisition based on subjective levels of strategic sophistication and social preferences. |
Avinash R. Vaidya; Lesley K. Fellows Testing necessary regional frontal contributions to value assessment and fixation-based updating Journal Article In: Nature Communications, vol. 6, pp. 10120, 2015. @article{Vaidya2015,Value-based decisions are biased by the time people spend viewing each option: Options fixated longer are chosen more often, even when previously rated as less appealing. This bias is thought to reflect /`value updating/' as new evidence is accumulated. Prior work has shown that ventromedial prefrontal cortex (PFC) carries a fixation-dependent value comparison signal, while other studies implicate dorsomedial PFC in representing the value of alternative options. Here, we test whether these regions are necessary for fixation-related value updating in 33 people with frontal lobe damage and 27 healthy controls performing a simple choice task. We show that damage to dorsomedial PFC leads to an exaggerated influence of fixations on choice, while damage to ventromedial or lateral PFC has no effect on this bias. These findings suggest a critical role for dorsomedial, and not ventromedial PFC, in mediating the relative influence of current fixations and a priori value on choice. |
Ming Yan; Werner Sommer Parafoveal-on-foveal effects of emotional word semantics in reading chinese sentences: Evidence from eye movements Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. 4, pp. 1237–1243, 2015. @article{Yan2015b,Despite the well-known influence of emotional meaning on cognition, relatively less is known about its effects on reading behavior. We investigated whether fixation behavior during the reading of Chinese sentences is influenced by emotional word meaning in the parafovea. Two-character target words embedded into the same sentence frames provided emotionally positive, negative, or neutral contents. Fixation durations on neutral pretarget words were prolonged for positive parafoveal words and for highly frequent negative parafoveal words. In addition, fixation durations on foveal emotional words were shorter than those on neutral words. We also found that the role of emotional words varied as a function of their valence during foveal and parafoveal processing. These findings suggest a processing advantage for emotional words relative to emotionally neutral stimuli in foveal and parafoveal vision. We discuss implications for the notion of attention attraction due to emotional content. |
Gerrit W. Maus; Elena Potapchuk; Scott N. J. Watamaniuk; Stephen J. Heinen Different time scales of motion integration for anticipatory smooth pursuit and perceptual adaptation Journal Article In: Journal of Vision, vol. 15, no. 2, pp. 16–16, 2015. @article{Maus2015,When repeatedly exposed to moving stimuli, the oculomotor system elicits anticipatory smooth pursuit (ASP) eye movements, even before the stimulus moves. ASP is affected oppositely to perceptual speed judgments of repetitive moving stimuli: After a sequence of fast stimuli, ASP velocity increases, whereas perceived speed decreases. These two effects-perceptual adaptation and oculomotor priming-could result from adapting a single common internal speed representation that is used for perceptual comparisons and for generating ASP. Here we test this hypothesis by assessing the temporal dependence of both effects on stimulus history. Observers performed speed discriminations on moving random dot stimuli, either while pursuing the movement or maintaining steady fixation. In both cases, responses showed perceptual adaptation: Stimuli preceded by fast speeds were perceived as slower, and vice versa. To evaluate oculomotor priming, we analyzed ASP velocity as a function of average stimulus speed in preceding trials and found strong positive dependencies. Interestingly, maximal priming occurred over short stimulus histories (~two trials), whereas adaptation was maximal over longer histories (~15 trials). The temporal dissociation of adaptation and priming suggests different underlying mechanisms. It may be that perceptual adaptation integrates over a relatively long period to robustly calibrate the operating range of the motion system, thereby avoiding interference from transient changes in stimulus speed. On the other hand, the oculomotor system may rapidly prime anticipatory velocity to efficiently match it to that of the pursuit target. |
Paul Metzner; Titus Malsburg; Shravan Vasishth; Frank Rösler Brain responses to world knowledge violations: A comparison of stimulus- and fixation-triggered event-related potentials and neural oscillations Journal Article In: Journal of Cognitive Neuroscience, vol. 27, no. 5, pp. 1017–1028, 2015. @article{Metzner2015,Recent research has shown that brain potentials time-locked to fixations in natural reading can be similar to brain potentials recorded during rapid serial visual presentation (RSVP). We attempted two replications of Hagoort, Hald, Bastiaansen, and Petersson [Hagoort, P., Hald, L., Bastiaansen, M., & Petersson, K. M. Integration of word meaning and world knowledge in language comprehension. Science, 304, 438-441, 2004] to determine whether this correspondence also holds for oscillatory brain responses. Hagoort et al. reported an N400 effect and synchronization in the theta and gamma range following world knowledge violations. Our first experiment (n = 32) used RSVP and replicated both the N400 effect in the ERPs and the power increase in the theta range in the time-frequency domain. In the second experiment (n = 49), participants read the same materials freely while their eye movements and their EEG were monitored. First fixation durations, gaze durations, and regression rates were increased, and the ERP showed an N400 effect. An analysis of time-frequency representations showed synchronization in the delta range (1-3 Hz) and desynchronization in the upper alpha range (11-13 Hz) but no theta or gamma effects. The results suggest that oscillatory EEG changes elicited by world knowledge violations are different in natural reading and RSVP. This may reflect differences in how representations are constructed and retrieved from memory in the two presentation modes. |
Helen F. Dodd; Jennifer L. Hudson; Tracey A. Williams; Talia Morris; Rebecca S. Lazarus; Yulisha Byrow Anxiety and attentional bias in preschool-aged children: An eyetracking study Journal Article In: Journal of Abnormal Child Psychology, vol. 43, no. 6, pp. 1055–1065, 2015. @article{Dodd2015,Extensive research has examined attentional bias for threat in anxious adults and school-aged children but it is unclear when this anxiety-related bias is first established. This study uses eyetracking technology to assess attentional bias in a sample of 83 children aged 3 or 4 years. Of these, 37 (19 female) met criteria for an anxiety disorder and 46 (30 female) did not. Gaze was recorded during a free-viewing task with angry-neutral face pairs presented for 1250 ms. There was no indication of between-group differences in threat bias, with both anxious and non-anxious groups showing vigilance for angry faces as well as longer dwell times to angry over neutral faces. Importantly, however, the anxious participants spent significantly less time looking at the faces overall, when compared to the non-anxious group. The results suggest that both anxious and non-anxious preschool-aged children preferentially attend to threat but that anxious children may be more avoidant of faces than non-anxious children. |
Harry H. Haladjian; Ella Wufong; Tamara L. Watson Spatial compression: Dissociable effects at the time of saccades and blinks Journal Article In: Journal of Vision, vol. 15, no. 9, pp. 1–19, 2015. @article{Haladjian2015,Various studies have identified systematic errors, such as spatial compression, when observers report the locations of objects displayed around the time of saccades. Localization errors also occur when holding spatial representations in visual working memory. Such errors, however, have not been examined in the context of eye blinks. In this study, we examined the effects of blinks and saccades when observers reproduced the locations of a set of briefly presented, randomly placed discs. Performance was compared with a fixation-only condition in which observers simply held these representations in working memory for the same duration; this allowed us to elucidate the relationship between the perceptual phenomena related to blinks, saccades, and visual working memory. Our results indicate that the same amount of spatial compression is experienced prior to a blink as is experienced in the control fixation-only condition, suggesting that blinks do not increase compression above that occurring from holding a spatial representation in visual memory. Saccades, however, tend to increase these compression effects and produce translational shifts both toward and away from saccade targets (depending on the time of the saccade onset in relation to the stimulus offset). A higher numerosity recall capacity was also observed when stimuli were presented prior to a blink in comparison with the other conditions. These findings reflect key differences underlying blinks and saccades in terms of spatial compression and translational shifts. Such results suggest that separate mechanisms maintain perceptual stability across these visual events. |
Lisette J. Schmidt; Artem V. Belopolsky; Jan Theeuwes Potential threat attracts attention and interferes with voluntary saccades Journal Article In: Emotion, vol. 15, no. 3, pp. 329–338, 2015. @article{sbt15,Several studies have shown that threatening stimuli are prioritized by the visual system. In the present study we investigated whether a stimulus associated with a threat of electrical shock attracts attention and accordingly interferes with the execution of voluntary eye movements to other locations. In 2 experiments, we showed that when a fear-conditioned and a neutral stimulus were presented simultaneously, voluntary saccades were initiated faster toward fear-conditioned compared with neutral stimuli. Moreover, saccades often erroneously went to the location of threat even when a saccade to a different location was required. This implies an automatic shift of attention to a fear-conditioned stimulus that interferes with saccade execution. The same pattern of results was found for a neutral stimulus that was always presented together with the fear-conditioned stimulus and consequently itself became associated with threat. The current results indicate that threatening stimuli attract visual attention and subsequently bias saccade target selection in a reflexive fashion. |
Moreno I. Coco; Frank Keller Integrating mechanisms of visual guidance in naturalistic language production Journal Article In: Cognitive Processing, vol. 16, no. 2, pp. 131–150, 2015. @article{Coco2015a,Situated language production requires the integration of visual attention and linguistic processing. Previous work has not conclusively disentangled the role of perceptual scene information and structural sentence information in guiding visual attention. In this paper, we present an eye-tracking study that demonstrates that three types of guidance, perceptual, conceptual, and structural, interact to control visual attention. In a cued language production experiment, we manipulate perceptual (scene clutter) and conceptual guidance (cue animacy) and measure structural guidance (syntactic complexity of the utterance). Analysis of the time course of language production, before and during speech, reveals that all three forms of guidance affect the complexity of visual responses, quantified in terms of the entropy of attentional landscapes and the turbulence of scan patterns, especially during speech. We find that perceptual and conceptual guidance mediate the distribution of attention in the scene, whereas structural guidance closely relates to scan pattern complexity. Furthermore, the eye-voice span of the cued object and its perceptual competitor are similar; its latency mediated by both perceptual and structural guidance. These results rule out a strict interpretation of structural guidance as the single dominant form of visual guidance in situated language production. Rather, the phase of the task and the associated demands of cross-modal cognitive processing determine the mechanisms that guide attention. |
Aaron Veldre; Sally Andrews Parafoveal lexical activation depends on skilled reading proficiency Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 41, no. March, pp. 586–595, 2015. @article{Veldre2015,The boundary paradigm was used to investigate individual differences in the extraction of lexical information from the parafovea in sentence reading. The preview of a target word was manipulated so that it was identical (e.g., sped), a higher frequency orthographic neighbor (seed), a nonword neighbor (sted), or an all-letter-different nonword (glat). Ninety-four skilled adult readers were assessed on measures of reading and spelling ability. The results showed that null effects of preview lexical status in the average data obscured systematic differences on the basis of proficiency and target neighborhood density. For targets from dense neighborhoods, inhibition from a higher frequency neighbor preview occurred among highly proficient readers, and particularly those with superior spelling ability, in early fixation measures. Poorer readers showed inhibition only in second-pass reading of the target. These data suggest that readers with precise lexical representations are more likely to extract lexical information from a word before it is fixated. The implications for computational models of eye movements in reading are discussed. |
Rick A. Adams; Eduardo Aponte; Louise Marshall; Karl J. Friston Active inference and oculomotor pursuit: The dynamic causal modelling of eye movements Journal Article In: Journal of Neuroscience Methods, vol. 242, pp. 1–14, 2015. @article{Adams2015,Background: This paper introduces a new paradigm that allows one to quantify the Bayesian beliefs evidenced by subjects during oculomotor pursuit. Subjects' eye tracking responses to a partially occluded sinusoidal target were recorded non-invasively and averaged. These response averages were then analysed using dynamic causal modelling (DCM). In DCM, observed responses are modelled using biologically plausible generative or forward models - usually biophysical models of neuronal activity. New method: Our key innovation is to use a generative model based on a normative (Bayes-optimal) model of active inference to model oculomotor pursuit in terms of subjects' beliefs about how visual targets move and how their oculomotor system responds. Our aim here is to establish the face validity of the approach, by manipulating the content and precision of sensory information - and examining the ensuing changes in the subjects' implicit beliefs. These beliefs are inferred from their eye movements using the normative model. Results: We show that on average, subjects respond to an increase in the 'noise' of target motion by increasing sensory precision in their models of the target trajectory. In other words, they attend more to the sensory attributes of a noisier stimulus. Conversely, subjects only change kinetic parameters in their model but not precision, in response to increased target speed. Conclusions: Using this technique one can estimate the precisions of subjects' hierarchical Bayesian beliefs about target motion. We hope to apply this paradigm to subjects with schizophrenia, whose pursuit abnormalities may result from the abnormal encoding of precision. |
Moreno I. Coco; Frank Keller The interaction of visual and linguistic saliency during syntactic ambiguity resolution Journal Article In: Quarterly Journal of Experimental Psychology, vol. 68, no. 1, pp. 46–74, 2015. @article{Coco2015,Psycholinguistic research using the visual world paradigm has shown that the processing ofsentences is constrained by the visual context in which they occur. Recently, there has been growing interest in the interactions observed when both language and vision provide relevant information during sentence pro- cessing. In three visual world experiments on syntactic ambiguity resolution, we investigate how visual and linguistic information influence the interpretation ofambiguous sentences. We hypothesize that (1) visual and linguistic information both constrain which interpretation is pursued by the sentence pro- cessor, and (2) the two types of information act upon the interpretation of the sentence at different points during processing. In Experiment 1, we show that visual saliency is utilized to anticipate the upcoming arguments ofa verb. In Experiment 2, we operationalize linguistic saliency using intonational breaks and demonstrate that these give prominence to linguistic referents. These results confirm pre- diction (1). In Experiment 3, we manipulate visual and linguistic saliency together and find that both types of information are used, but at different points in the sentence, to incrementally update its current interpretation. This finding is consistent with prediction (2). Overall, our results suggest an adaptive processing architecture in which different types of information are used when they become available, optimizing different aspects of situated language processing. |
Gerard M. Loughnane; John P. Shanley; Edmund C. Lalor; Redmond G. O'Connell Behavioral and electrophysiological evidence of opposing lateral visuospatial asymmetries in the upper and lower visual fields Journal Article In: Cortex, vol. 63, pp. 220–231, 2015. @article{Loughnane2015,Neurologically healthy individuals typically exhibit a subtle bias towards the left visual field during spatial judgments, known as "pseudoneglect". However, it has yet to be reliably established if the direction and magnitude of this lateral bias varies along the vertical plane. Here, participants were required to distribute their attention equally across a checkerboard array spanning the entire visual field in order to detect transient targets that appeared at unpredictable locations. Reaction times (RTs) were faster to left hemifield targets in the lower visual field but the opposite trend was observed for targets in the upper field. Electroencephalogram (EEG) analyses focused on the interval prior to target onset in order to identify endogenous neural correlates of these behavioral asymmetries. The relative hemispheric distribution of pre-target oscillatory alpha power was predictive of RT bias to targets in the lower visual field but not the upper field, indicating separate attentional mechanisms for the upper and lower visual fields. Analysis of multifocal visual-evoked potentials (MVEP) in the pre-target interval also indicated that the opposing upper and lower field asymmetries may impact on the magnitude of primary visual cortical responses. These results provide new evidence of a functional segregation of upper and lower field visuospatial processing. |
Ioannis Rigas; Oleg V. Komogortsev Eye movement-driven defense against iris print-attacks Journal Article In: Pattern Recognition Letters, vol. 68, no. 2, pp. 316–326, 2015. @article{rk15,This paper proposes a methodology for the utilization of eye movement cues for the task of iris print-attack detection. We investigate the fundamental distortions arising in the eye movement signal during an iris print-attack, due to the structural and functional discrepancies between a paper-printed iris and a natural eye iris. The performed experiments involve the execution of practical print-attacks against an eye-tracking device, and the collection of the resulting eye movement signals. The developed methodology for the detection of print-attack signal distortions is evaluated on a large database collected from 200 subjects, which contains both the real (‘live') eye movement signals and the print-attack (‘spoof') eye movement signals. The suggested methodology provides a sufficiently high detection performance, with a maximum average classification rate (ACR) of 96.5% and a minimum equal error rate (EER) of 3.4%. Due to the hardware similarities between eye tracking and iris capturing systems, we hypothesize that the proposed methodology can be adopted into the existing iris recognition systems with minimal cost. To further support this hypothesis we experimentally investigate the robustness of our scheme by simulating conditions of reduced sampling resolution (temporal and spatial), and of limited duration of the eye movement signals. |