All EyeLink Publications
All 11,000+ peer-reviewed EyeLink research publications up until 2022 (with some early 2023s) are listed below by year. You can search the publications library using keywords such as Visual Search, Smooth Pursuit, Parkinson’s, etc. You can also search for individual author names. Eye-tracking studies grouped by research area can be found on the solutions pages. If we missed any EyeLink eye-tracking papers, please email us!
Taosheng Liu; Irida Mance
Constant spread of feature-based attention across the visual field Journal Article
In: Vision Research, vol. 51, no. 1, pp. 26–33, 2011.
Attending to a feature in one location can produce feature-specific modulation in a different location. This global feature-based attention effect has been demonstrated using two stimulus locations. Although the spread of feature-based attention is presumed to be constant across spatial locations, it has not been tested empirically. We examined the spread of feature-based attention by measuring attentional modulation of the motion aftereffect (MAE) at remote locations. Observers attended to one of two directions in a compound motion stimulus (adapter) and performed a speed-increment task. MAE was measured via a speed nulling procedure for a test stimulus at different distances from the adapter. In Experiment 1, the adapter was at fixation, while the test stimulus was located at different eccentricities. We also measured the magnitude of baseline MAE for each location in two control conditions that did not require feature-based selection necessitated by a compound stimulus. In Experiment 2, the adapter and test stimuli were all located in the periphery at the same eccentricity. Our results showed that attention induced MAE spread completely across the visual field, indicating a genuine global effect. These results add to our understanding of the deployment of feature-based attention and provide empirical constraints on theories of visual attention.
Taosheng Liu; Timothy J. Pleskac
Neural correlates of evidence accumulation in a perceptual decision task Journal Article
In: Journal of Neurophysiology, vol. 106, no. 5, pp. 2383–2398, 2011.
Sequential sampling models provide a useful framework for understanding human decision making. A key component of these models is an evidence accumulation process in which information is accrued over time to a threshold, at which point a choice is made. Previous neurophysiological studies on perceptual decision making have suggested accumulation occurs only in sensorimotor areas involved in making the action for the choice. Here we investigated the neural correlates of evidence accumulation in the human brain using functional magnetic resonance imaging (fMRI) while manipulating the quality of sensory evidence, the response modality, and the foreknowledge of the response modality. We trained subjects to perform a random dot motion direction discrimination task by either moving their eyes or pressing buttons to make their responses. In addition, they were cued about the response modality either in advance of the stimulus or after a delay. We isolated fMRI responses for perceptual decisions in both independently defined sensorimotor areas and task-defined nonsensorimotor areas. We found neural signatures of evidence accumulation, a higher fMRI response on low coherence trials than high coherence trials, primarily in saccade-related sensorimotor areas (frontal eye field and intraparietal sulcus) and nonsensorimotor areas in anterior insula and inferior frontal sulcus. Critically, such neural signatures did not depend on response modality or foreknowledge. These results help establish human brain areas involved in evidence accumulation and suggest that the neural mechanism for evidence accumulation is not specific to effectors. Instead, the neural system might accumulate evidence for particular stimulus features relevant to a perceptual task.
Anil Kumar; Irene Gottlob; Rebecca J. Mclean; Shery Thomas; Mervyn G. Thomas; Frank A. Proudlock
Clinical and oculomotor characteristics of albinism compared to FRMD7 associated infantile nystagmus Journal Article
In: Investigative Ophthalmology & Visual Science, vol. 52, no. 5, pp. 2306–2313, 2011.
PURPOSE. Previous studies have found no difference between nystagmus characteristics associated with idiopathic infantile nystagmus (IIN) and that associated with albinism. The present aim is to compare the oculomotor characteristics and other associated clinical features of albinism and a genetically homogenous group of IIN volunteers where the nystagmus is associated with FRMD7 mutations. METHODS. Oculomotor characteristics and related clinical features between albinism (n ⫽ 52) and idiopathic nystag- mus associated with FRMD7 mutations (FRMD7-IIN
Victor Kuperman; Julie A. Van Dyke
Effects of individual differences in verbal skills on eye-movement patterns during sentence reading Journal Article
In: Journal of Memory and Language, vol. 65, no. 1, pp. 42–73, 2011.
This study is a large-scale exploration of the influence that individual reading skills exert on eye-movement behavior in sentence reading. Seventy-one non-college-bound 16-24. year-old speakers of English completed a battery of 18 verbal and cognitive skill assessments, and read a series of sentences as their eye-movements were monitored. Statistical analyses were performed to establish what tests of reading abilities were predictive of eye-movement patterns across this population and how strong the effects were. We found that individual scores in rapid automatized naming and word identification tests (i) were the only participant variables with reliable predictivity throughout the time-course of reading; (ii) elicited effects that superceded in magnitude the effects of established predictors like word length or frequency; and (iii) strongly modulated the influence of word length and frequency on fixation times. We discuss implications of our findings for testing reading ability, as well as for research of eye-movements in reading.
Eric Lambert; Denis Alamargot; Denis Larocque; Gilles Caporossi
Dynamics of the spelling process during a copy task: Effects of regularity and frequency Journal Article
In: Canadian Journal of Experimental Psychology, vol. 65, no. 3, pp. 141–150, 2011.
This study investigated the time course of spelling, and its influence on graphomotor execution, in a successive word copy task. According to the cascade model, these two processes may be engaged either sequentially or in parallel, depending on the cognitive demands of spelling. In this experiment, adults were asked to copy a series of words varying in frequency and spelling regularity. A combined analysis of eye and pen movements revealed periods where spelling occurred in parallel with graphomotor execution, but concerned different processing units. The extent of this parallel processing depended on the words' orthographic characteristics. Results also highlighted the specificity of word recognition for copying purposes compared with recognition for reading tasks. The results confirm the validity of the cascade model and clarify the nature of the dependence between spelling and graphomotor processes.
Martijn J. M. Lamers; Ardi Roelofs
Attention and gaze shifting in dual-task and go/no-go performance with vocal responding Journal Article
In: Acta Psychologica, vol. 137, no. 3, pp. 261–268, 2011.
Evidence from go/no-go performance on the Eriksen flanker task with manual responding suggests that individuals gaze at stimuli just as long as needed to identify them (e.g., Sanders, 1998). In contrast, evidence from dual-task performance with vocal responding suggests that gaze shifts occur after response selection (e.g., Roelofs, 2008a). This difference in results may be due to the nature of the task situation (go/no-go vs. dual task) or the response modality (manual vs. vocal). We examined this by having participants vocally respond to congruent and incongruent flanker stimuli and shift gaze to left- or right-pointing arrows. The arrows required a manual response (dual task) or determined whether the vocal response to the flanker stimuli had to be given or not (go/no-go). Vocal response and gaze shift latencies were longer on incongruent than congruent trials in both dual-task and go/no-go performance. The flanker effect was also present in the manual response latencies in dual-task performance. Ex-Gaussian analyses revealed that the flanker effect on the gaze shifts consisted of a shift of the entire latency distribution. These results suggest that gaze shifts occur after response selection in both dual-task and go/no-go performance with vocal responding.
Wolf Gero Lange; Kathrin Heuer; Oliver Langner; Ger P. J. Keijsers; Eni S. Becker; Mike Rinck
Face value: Eye movements and the evaluation of facial crowds in social anxiety Journal Article
In: Journal of Behavior Therapy and Experimental Psychiatry, vol. 42, no. 3, pp. 355–363, 2011.
Scientific evidence is equivocal on whether Social Anxiety Disorder (SAD) is characterized by a biased negative evaluation of (grouped) facial expressions, even though it is assumed that such a bias plays a crucial role in the maintenance of the disorder. To shed light on the underlying mechanisms of face evaluation in social anxiety, the eye movements of 22 highly socially anxious (SAs) and 21 non-anxious controls (NACs) were recorded while they rated the degree of friendliness of neutral-angry and smiling-angry face combinations. While the Crowd Rating Task data showed no significant differences between SAs and NACs, the resultant eye-movement patterns revealed that SAs, compared to NACs, looked away faster when the face first fixated was angry. Additionally, in SAs the proportion of fixated angry faces was significantly higher than for other expressions. Independent of social anxiety, these fixated angry faces were the best predictor of subsequent affect ratings for either group. Angry faces influence attentional processes such as eye movements in SAs and by doing so reflect biased evaluations. As these processes do not correlate with explicit ratings of faces, however, it remains unclear at what point implicit attentional behaviors lead to anxiety-prone behaviors and the maintenance of SAD. The relevance of these findings is discussed in the light of the current theories.
Georgia Laretzaki; Sotiris Plainis; Ioannis Vrettos; Anna Chrisoulakis; Ioannis G. Pallikaris; Panos Bitsios
Threat and trait anxiety affect stability of gaze fixation Journal Article
In: Biological Psychology, vol. 86, no. 3, pp. 330–336, 2011.
Threat accelerates early visual information processing, as shown by shorter P100 latencies of pattern Visual Evoked Potentials in subjects with low trait anxiety, but the opposite is true for high anxious subjects. We sought to determine if, and how, threat and trait anxiety interact to affect stability of gaze fixation. We used video oculography to record gaze position in the presence and in the absence of a fixational stimulus, in a safe and a verbal threat condition in subjects characterised for their trait anxiety. Trait anxiety significantly predicted fixational instability in the threat condition. An extreme tertile analysis revealed that fixation was less stable in the high anxiety group, especially under threat or in the absence of a stimulus. The effects of anxiety extend to perceptual and sensorimotor processes. These results have implications for the understanding of individual differences in occulomotor planning and visually guided behavior.
Louisa Lavergne; Dorine Vergilino-Perez; Christelle Lemoine; Thérèse Collins; Karine Doré-Mazars
Exploring and targeting saccades dissociated by saccadic adaptation Journal Article
In: Brain Research, vol. 1415, pp. 47–55, 2011.
Saccadic adaptation maintains saccade accuracy and has been studied with targeting saccades, i.e. saccades that bring the gaze to a target, with the classical intra-saccadic step procedure in which the target systematically jumps to a new position during saccade execution. Post-saccadic visual feedback about the error between target position and the saccade landing position is crucial to establish and maintain adaptation. However, recent research focusing on two-saccade sequences has shown that exploring saccades, i.e. saccades that explore an object, resists this classical intra-saccadic step procedure but can be adapted by systematically changing the main parameter used for their coding: stimulus size. Here, we adapted an exploring saccade and a targeting saccade in two separate experiments, using the appropriate adaptation procedure, and we tested whether the adaptation induced on one saccade type transferred to the other. We showed that whereas classical targeting saccade adaptation does not transfer to exploring saccades, the reciprocal transfer (i.e., from exploring to targeting saccades) occurred when targeting saccades aimed for a spatially extended stimulus, but not when they aimed for an isolated target. These results show that, in addition to position errors, size errors can drive adaptation, and confirm that exploring vs. targeting a stimulus leads to two different motor planning modes.
Casimir J. H. Ludwig; J. Rhys Davies
Estimating the growth of internal evidence guiding perceptual decisions Journal Article
In: Cognitive Psychology, vol. 63, no. 2, pp. 61–92, 2011.
Perceptual decision-making is thought to involve a gradual accrual of noisy evidence. Temporal integration of the evidence reduces the relative contribution of dynamic internal noise to the decision variable, thereby boosting its signal-to-noise ratio. We aimed to estimate the internal evidence guiding perceptual decisions over time, using a novel combination of external noise and the response signal methods. Observers performed orientation discrimination of patterns presented in external noise. We varied the contrast of the patterns and the delay at which observers were forced to signal their decision. Each test stimulus (patterns and noise sample) was presented twice. Across two experiments we varied the avail- ability of the visual stimulus for processing. Observer model anal- yses of discrimination accuracy and response consistency to two passes of the same stimulus, suggested that there was very little growth in the internal evidence. The improvement in accuracy over time characterised by the speed-accuracy trade-off function pre- dominantly reflected a decreasing proportion of non-visual deci- sions, or pure guesses. There was no advantage to having the visual patterns visible for longer than 80 ms, indicating that only the visual information in a short window after display onset was used to drive the decisions. The remarkable constancy of the inter- nal evidence over time suggests that temporal integration of the sensory information was very limited. Alternatively, more extended integration of the evidence from memory could have taken place, provided that the dominant source of internal noise limiting performance occurs between-trials, which cannot be reduced by prolonged evidence integration.
Arthur J. Lugtigheid; Eli Brenner; Andrew E. Welchman
Speed judgments of three-dimensional motion incorporate extraretinal information Journal Article
In: Journal of Vision, vol. 11, no. 13, pp. 1–11, 2011.
When tracking an object moving in depth, the visual system should take changes of eye vergence into account to judge the object's 3D speed correctly. Previous work has shown that extraretinal information about changes in eye vergence is exploited when judging the sign of 3D motion. Here, we ask whether extraretinal signals also affect judgments of 3D speed. Observers judged the speed of a small target surrounded by a large background. To manipulate extraretinal information, we varied the vergence demand of the entire stimulus sinusoidally over time. At different phases of vergence pursuit, we changed the disparity of the target relative to the background, leading observers to perceive approaching target motion. We determined psychometric functions for the target's approach speed when the eyes were (1) converging, (2) diverging, (3) maximally converged (near), and (4) maximally diverged (far). The target's motion was reported as faster during convergence and slower during divergence but perceived speed was little affected at near or far vergence positions. Thus, 3D speed judgments are affected by extraretinal signals about changes in eye rotation but appear unaffected by the absolute orientation of the eyes. We develop a model that accounts for observers' judgments by taking a weighted average of the retinal and extraretinal signals to target motion.
Antonio F. Macedo; Michael D. Crossland; Gary S. Rubin
Investigating unstable fixation in patients with macular disease Journal Article
In: Investigative Ophthalmology & Visual Science, vol. 52, no. 3, pp. 1275–1280, 2011.
PURPOSE. To assess the effect on visual acuity of compensating fixation instability by controlling retinal image motion in people with macular disease. METHODS. Ten patients with macular disease participated in this study. Crowded and noncrowded visual acuity were measured using an eye tracking system to compensate for fixation instability. Four conditions, corresponding to four levels of retinal image motion, were tested: no compensation (normal motion), partial compensation (reduced motion), total compensation (no motion), and overcompensation (increased motion). Fixation stability and the number of preferred retinal loci were also measured. RESULTS. Modulating retinal image motion had the same effect on crowded and noncrowded visual acuity (P ⫽ 0.601). When fixation instability was overcompensated, acuity worsened by 0.1 logMAR units (P ⬍ 0.001) compared with baseline (no compensation) and remained equal to baseline for all other conditions. CONCLUSIONS. In people with macular disease, retinal image motion caused by fixation instability does not reduce either crowded or noncrowded visual acuity. Acuity declines when fixation instability is overcompensated, showing limited tolerance to increased retinal image motion. The results provide evidence that fixation instability does not improve visual acuity and may be a consequence of poor oculomotor control.
Jessica Maryott; Abigail L. Noyce; Robert Sekuler
Eye movements and imitation learning: Intentional disruption of expectation Journal Article
In: Journal of Vision, vol. 11, no. 1, pp. 1–16, 2011.
Over repeated viewings of motion along a quasi-random path, ability to reproduce that path from memory improves. To assess the role of expectations and sequence context on such learning, subjects eye movements were measured while trajectories were viewed for subsequent reproduction. As a sequence of motions was repeated, subjects' eye movements became anticipatory, leading the stimulus' motions. To investigate how prediction errors affected eye movements and imitation learning, we injected an occasional deviant motion into a well-learned stimulus sequence, violating subjects' expectation about the motion that would be seen. This unexpected direction of motion in the stimulus sequence did not impair reproduction of the sequence. The externally induced prediction errors promoted one-shot learning: During the very next stimulus presentation, their eye movements showed that subjects now expected the new sequence item to reappear. A second experiment showed that an associative mismatch can facilitate accurate reproduction of an unexpected stimulus. After a deviant sequence item was presented, imitation accuracy for sequences that contained the deviant direction of motion was reduced relative to sequences that restored the original direction of motions. These findings demonstrate that in the context of a familiar sequence, unexpected events can play an important role in learning the sequence.
Kazunaga Matsuki; Tracy Chow; Mary Hare; Jeffrey L. Elman; Christoph Scheepers; Ken McRae
Event-based plausibility immediately influences on-line language comprehension Journal Article
In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 37, no. 4, pp. 913–934, 2011.
In some theories of sentence comprehension, linguistically relevant lexical knowledge, such as selectional restrictions, is privileged in terms of the time-course of its access and influence. We examined whether event knowledge computed by combining multiple concepts can rapidly influence language understanding even in the absence of selectional restriction violations. Specifically, we investigated whether instruments can combine with actions to influence comprehension of ensuing patients of (as in Rayner, Warren, Juhuasz, & Liversedge, 2004; Warren & McConnell, 2007). Instrument-verb-patient triplets were created in a norming study designed to tap directly into event knowledge. In self-paced reading (Experiment 1), participants were faster to read patient nouns, such as hair, when they were typical of the instrument-action pair (Donna used the shampoo to wash vs. the hose to wash). Experiment 2 showed that these results were not due to direct instrument-patient relations. Experiment 3 replicated Experiment 1 using eyetracking, with effects of event typicality observed in first fixation and gaze durations on the patient noun. This research demonstrates that conceptual event-based expectations are computed and used rapidly and dynamically during on-line language comprehension. We discuss relationships among plausibility and predictability, as well as their implications. We conclude that selectional restrictions may be best considered as event-based conceptual knowledge rather than lexical-grammatical knowledge.
Michi Matsukura; James R. Brockmole; Walter R. Boot; John M. Henderson
Oculomotor capture during real-world scene viewing depends on cognitive load Journal Article
In: Vision Research, vol. 51, no. 6, pp. 546–552, 2011.
It has been claimed that gaze control during scene viewing is largely governed by stimulus-driven, bottom-up selection mechanisms. Recent research, however, has strongly suggested that observers' top-down control plays a dominant role in attentional prioritization in scenes. A notable exception to this strong top-down control is oculomotor capture, where visual transients in a scene draw the eyes. One way to test whether oculomotor capture during scene viewing is independent of an observer's top-down goal setting is to reduce observers' cognitive resource availability. In the present study, we examined whether increasing observers' cognitive load influences the frequency and speed of oculomotor capture during scene viewing. In Experiment 1, we tested whether increasing observers' cognitive load modulates the degree of oculomotor capture by a new object suddenly appeared in a scene. Similarly, in Experiment 2, we tested whether increasing observers' cognitive load modulates the degree of oculomotor capture by an object's color change. In both experiments, the degree of oculomotor capture decreased as observers' cognitive resources were reduced. These results suggest that oculomotor capture during scene viewing is dependent on observers' top-down selection mechanisms.
Hideyuki Matsumoto; Yasuo Terao; Toshiaki Furubayashi; Akihiro Yugeta; Hideki Fukuda; Masaki Emoto; Ritsuko Hanajima; Yoshikazu Ugawa
Small saccades restrict visual scanning area in Parkinson's disease Journal Article
In: Movement Disorders, vol. 26, no. 9, pp. 1619–1626, 2011.
The purpose of this study wasto investigate abnormalities in visual scanning when Parkinson's disease patients view images of varying complexity. Eighteen nondemented Parkinson's disease patients and 18 normal subjects participated in the study. The ocular fixation position during viewing visual images was recorded using an eye-tracking device. The number of saccades, duration of fixation, amplitude of saccades, and scanned area in Parkinson's disease patients were compared with those in normal subjects. We also investigated whether the number of saccades, duration of fixation, or amplitude of saccades influenced the scanned area. While scanning images of varying complexity, Parkinson's disease patients made fewer saccades with smaller amplitude and longer fixation compared with normal subjects. As image complexity increased, the number of saccades and duration of fixation gradually approached those of normal subjects. Nevertheless, the scanned area in Parkinson's disease patients was consistently smaller than that in normal subjects. The scanned area significantly correlated with saccade amplitude in most images. Importantly, although Parkinson's disease patients cannot make frequent saccades when viewing simple figures, they can increase the saccade number and reduce their fixation duration when viewing more complex figures, making use of the abundant visual cues in such figures, suggesting the existence of ocular kinesie paradoxale. Nevertheless, both the saccade amplitude and the scanned area were consistently smaller than those of normal subjects for all levels of visual complexity. This indicates that small saccade amplitude is the main cause of impaired visual scanning in Parkinson's disease patients.
Hideyuki Matsumoto; Yasuo Terao; Akihiro Yugeta; Hideki Fukuda; Masaki Emoto; Toshiaki Furubayashi; Tomoko Okano; Ritsuko Hanajima; Yoshikazu Ugawa
Where do neurologists look when viewing brain CT images? An eye-tracking study involving stroke cases Journal Article
In: PLoS ONE, vol. 6, no. 12, pp. e28928, 2011.
The aim of this study was to investigate where neurologists look when they view brain computed tomography (CT) images and to evaluate how they deploy their visual attention by comparing their gaze distribution with saliency maps. Brain CT images showing cerebrovascular accidents were presented to 12 neurologists and 12 control subjects. The subjects' ocular fixation positions were recorded using an eye-tracking device (Eyelink 1000). Heat maps were created based on the eye-fixation patterns of each group and compared between the two groups. The heat maps revealed that the areas on which control subjects frequently fixated often coincided with areas identified as outstanding in saliency maps, while the areas on which neurologists frequently fixated often did not. Dwell time in regions of interest (ROI) was likewise compared between the two groups, revealing that, although dwell time on large lesions was not different between the two groups, dwell time in clinically important areas with low salience was longer in neurologists than in controls. Therefore it appears that neurologists intentionally scan clinically important areas when reading brain CT images showing cerebrovascular accidents. Both neurologists and control subjects used the "bottom-up salience" form of visual attention, although the neurologists more effectively used the "top-down instruction" form.
Ali Mazaheri; Nicholas E. DiQuattro; Jesse Bengson; Joy J. Geng
Pre-stimulus activity predicts the winner of top-down vs. bottom-up attentional selection Journal Article
In: PLoS ONE, vol. 6, no. 2, pp. e16243, 2011.
Our ability to process visual information is fundamentally limited. This leads to competition between sensory information that is relevant for top-down goals and sensory information that is perceptually salient, but task-irrelevant. The aim of the present study was to identify, from EEG recordings, pre-stimulus and pre-saccadic neural activity that could predict whether top-down or bottom-up processes would win the competition for attention on a trial-by-trial basis. We employed a visual search paradigm in which a lateralized low contrast target appeared alone, or with a low (i.e., non-salient) or high contrast (i.e., salient) distractor. Trials with a salient distractor were of primary interest due to the strong competition between top-down knowledge and bottom-up attentional capture. Our results demonstrated that 1) in the 1-sec pre-stimulus interval, frontal alpha (8-12 Hz) activity was higher on trials where the salient distractor captured attention and the first saccade (bottom-up win); and 2) there was a transient pre-saccadic increase in posterior-parietal alpha (7-8 Hz) activity on trials where the first saccade went to the target (top-down win). We propose that the high frontal alpha reflects a disengagement of attentional control whereas the transient posterior alpha time-locked to the saccade indicates sensory inhibition of the salient distractor and suppression of bottom-up oculomotor capture.
Kathryn L. McCabe; Dominique Rich; Carmel M. Loughland; Ulrich Schall; Linda E. Campbell
Visual scanpath abnormalities in 22q11.2 deletion syndrome: Is this a face specific deficit? Journal Article
In: Psychiatry Research, vol. 189, no. 2, pp. 292–298, 2011.
People with 22q11.2 deletion syndrome (22q11DS) have deficits in face emotion recognition. However, it is not known whether this is a deficit specific to faces, or represents maladaptive information processing strategies to complex stimuli in general. This study examined the specificity of face emotion processing deficits in 22q11DS by exploring recognition accuracy and visual scanpath performance to a Faces task compared to a Weather Scene task. Seventeen adolescents with 22q11DS (11. =females
Helmut Leder; Michael Forster; Gernot Gerger
The glasses stereotype revisited: Effects of eyeglasses on perception, recognition, and impression of faces Journal Article
In: Swiss Journal of Psychology, vol. 70, no. 4, pp. 211–222, 2011.
In face perception, besides physiognomic changes, accessories like eyeglasses can influence facial appearance. According to a stereotype, people who wear glasses are more intelligent, but less attractive. In a series of four experiments, we showed how full-rim and rimless glasses, differing with respect to the amount of face they cover, affect face perception, recognition, distinctiveness, and the attribution of stereotypes. Eyeglasses generally directed observers' gaze to the eye regions; rimless glasses made faces appear less distinctive and resulted in reduced distinctiveness in matching and in recognition tasks. Moreover, the stereotype was confirmed but depended on the kind of glasses—rimless glasses yielded an increase in perceived trustworthiness, but not a decrease in attractiveness. Thus, glasses affect how we perceive the faces of the people wearing them and, in accordance with an old stereotype, they can lower how attractive, but increase how intelligent and trustworthy people wearing them appear. These effects depend on the kind of glasses worn.
Eun Ju Lee; Gusang Kwon; Aekyoung Lee; Jamshid Ghajar; Minah Suh
Individual differences in working memory capacity determine the effects of oculomotor task load on concurrent word recall performance Journal Article
In: Brain Research, vol. 1399, pp. 59–65, 2011.
In this study, the interaction between individual differences in working memory capacity, which were assessed by the Korean version of the California Verbal Learning Test (K-CVLT), and the effects of oculomotor task load on word recall performance are examined in a dual-task experiment. We hypothesized that varying levels of oculomotor task load should result in different demands on cognitive resources. The verbal working memory task used in this study involved a brief exposure to seven words to be remembered, followed by a 30-second delay during which the subject carried out an oculomotor task. Then, memory performance was assessed by having the subjects recall as many words as possible. Forty healthy normal subjects with no vision-related problems carried out four separate dual-tasks over four consecutive days of participation, wherein word recall performances were tested under unpredictable random SPEM (smooth pursuit eye movement), predictive SPEM, fixation, and eyes-closed conditions. The word recall performance of subjects with low K-CVLT scores was significantly enhanced under predictive SPEM conditions as opposed to the fixation and eyes-closed conditions, but performance was reduced under the random SPEM condition, thus reflecting an inverted-U relationship between the oculomotor task load and word recall performance. Subjects with high K-CVLT scores evidenced steady word recall performances, regardless of the type of oculomotor task performed. The concurrent oculomotor performance measured by velocity error did not differ significantly among the K-CVLT groups. However, the high-scoring subjects evidenced smaller phase errors under predictive SPEM conditions than did the low-scoring subjects; this suggests that different resource allocation strategies may be adopted, depending on individuals' working memory capacity.
Jiyeon Lee; Cynthia K. Thompson
Real-time production of unergative and unaccusative sentences in normal and agrammatic speakers: An eyetracking study Journal Article
In: Aphasiology, vol. 25, no. 6-7, pp. 813–825, 2011.
Background: Speakers with agrammatic aphasia have greater difficulty producing unaccusative (float) compared to unergative (bark) verbs (Kegl, 1995; Lee & Thompson, 2004; Thompson, 2003), putatively because the former involve movement of the theme to the subject position from the post-verbal position, and are therefore more complex than the latter (Burzio, 1986; Perlmutter, 1978). However, it is unclear if and how sentence production processes are affected by the linguistic distinction between these two types of verbs in normal and impaired speakers. Aims: This study examined real-time production of sentences with unergative (the black dog is barking) vs unaccusative (the black tube is floating) verbs in healthy young speakers and individuals with agrammatic aphasia, using eyetracking. Methods & Procedures: Participants' eye movements and speech were recorded while they produced a sentence using computer displayed written stimuli (e.g., black, dog, is barking). Outcomes & Results: Both groups of speakers produced numerically fewer unaccusative sentences than unergative sentences. However, the eye movement data revealed significant differences in fixations between the adjective (black) vs the noun (tube) when producing unaccusatives, but not when producing unergatives for both groups. Interestingly, whereas healthy speakers showed this difference during speech, speakers with agrammatism showed this difference prior to speech onset. Conclusions: These findings suggest that the human sentence production system differentially processes unaccusatives vs unergatives. This distinction is preserved in individuals with agrammatism; however, the time course of sentence planning appears to differ from healthy speakers (Lee & Thompson, 2010).
Carly J. Leonard; Steven J. Luck
The role of magnocellular signals in oculomotor attentional capture Journal Article
In: Journal of Vision, vol. 11, no. 13, pp. 1–12, 2011.
While it is known that salient distractors often capture covert and overt attention, it is unclear whether salience signals that stem from magnocellular visual input have a more dominant role in oculomotor capture than those that result from parvocellular input. Because of the direct anatomical connections between the magnocellular pathway and the superior colliculus, salience signals generated from the magnocellular pathway may produce greater oculomotor capture than those from the parvocellular pathway, which could be potentially harder to overcome with "top-down," goal-directed guidance. Although previous research has addressed this with regard to magnocellular transients, in the current research, we investigated whether a static singleton distractor defined along a dimension visible to the magnocellular pathway would also produce enhanced oculomotor capture. In two experiments, we addressed this possibility by comparing a parvo-biased singleton condition, in which the distractor was defined by isoluminant chromatic color contrast, with a magno + parvo singleton condition, in which the distractor also differed in luminance from the surrounding objects. In both experiments, magno + parvo singletons elicited faster eye movements than parvo-only singletons, presumably reflecting faster information transmission in the magnocellular pathway, but magno + parvo singletons were not significantly more likely to produce oculomotor capture. Thus, although magnocellular salience signals are available more rapidly, they have no sizable advantage over parvocellular salience signals in controlling oculomotor orienting when all stimuli have a common onset.
Benjamin D. Lester; Paul Dassonville
Attentional control settings modulate susceptibility to the induced Roelofs effect Journal Article
In: Attention, Perception, and Psychophysics, vol. 73, no. 5, pp. 1398–1406, 2011.
When a visible frame is offset laterally from an observer's objective midline, the subjective midline is pulled toward the frame's center, causing the frame and any enclosed targets to be misperceived as being shifted somewhat in the opposite direction. This illusion, the Roelofs effect, is driven by environmental (bottom-up) visual cues, but whether it can be modulated by top-down (e.g., task-relevant) information is unknown. Here, we used an attentional manipulation (i.e., the color-contingency effect) to test whether attentional filtering can modulate the magnitude of the illusion. When observers were required to report the location of a colored target, presented within an array of differently colored distractors, there was a greater effect of the illusion when the Roelofs-inducing frame was the same color as the target. These results indicate that feature-based attentional processes can modulate the impact of contextual information on an observer's perception of space.
N. Gorgoraptis; R. F. G. Catalao; Paul M. Bays; Masud Husain
Dynamic updating of working memory resources for visual objects Journal Article
In: Journal of Neuroscience, vol. 31, no. 23, pp. 8502–8511, 2011.
Recent neurophysiological and imaging studies have investigated how neural representations underlying working memory (WM) are dynamically updated for objects presented sequentially. Although such studies implicate information encoded in oscillatory activity across distributed brain networks, interpretation of findings depends crucially on the underlying conceptual model of how memory resources are distributed. Here, we quantify the fidelity of human memory for sequences of colored stimuli of different orientation. The precision with which each orientation was recalled declined with increases in total memory load, but also depended on when in the sequence it appeared. When one item was prioritized, its recall was enhanced, but with corresponding decrements in precision for other objects. Comparison with the same number of items presented simultaneously revealed an additional performance cost for sequential display that could not be explained by temporal decay. Memory precision was lower for sequential compared with simultaneous presentation, even when each item in the sequence was presented at a different location. Importantly, stochastic modeling established this cost for sequential display was due to misbinding object features (color and orientation). These results support the view that WM resources can be dynamically and flexibly updated as new items have to be stored, but redistribution of resources with the addition of new items is associated with misbinding object features, providing important constraints and a framework for interpreting neural data.
Dan J. Graham; Robert W. Jeffery
Location, location, location: Eye-tracking evidence that consumers preferentially view prominently positioned nutrition information Journal Article
In: Journal of the American Dietetic Association, vol. 111, no. 11, pp. 1704–1711, 2011.
Background: Nutrition Facts labels can keep consumers better informed about their diets' nutritional composition, however, consumers currently do not understand these labels well or use them often. Thus, modifying existing labels may benefit public health. Objective: The present study tracked the visual attention of individuals making simulated food-purchasing decisions to assess Nutrition Facts label viewing. Primary research questions were how self-reported viewing of Nutrition Facts labels and their components relates to measured viewing and whether locations of labels and specific label components relate to viewing. Design: The study involved a simulated grocery shopping exercise conducted on a computer equipped with an eye-tracking camera. A post-task survey assessed self-reported nutrition information viewing, health behaviors, and demographics. Subjects/setting: Individuals 18 years old and older and capable of reading English words on a computer (n=203) completed the 1-hour protocol at the University of Minnesota during Spring 2010. Statistical analyses: Primary analyses included X2, analysis of variance, and t tests comparing self-reported and measured viewing of label components in different presentation configurations. Results: Self-reported viewing of Nutrition Facts label components was higher than objectively measured viewing. Label components at the top of the label were viewed more than those at the bottom, and labels positioned in the center of the screen were viewed more than those located on the sides. Conclusions: Nutrition Facts label position within a viewing area and position of specific components on a label relate to viewing. Eye tracking is a valuable technology for evaluating consumers' attention to nutrition information, informing nutrition labeling policy (eg, front-of-pack labels), and designing labels that best support healthy dietary decisions.
Sven-Thomas Graupner; Sebastian Pannasch; Boris M. Velichkovsky
Saccadic context indicates information processing within visual fixations: Evidence from event-related potentials and eye-movements analysis of the distractor effect Journal Article
In: International Journal of Psychophysiology, vol. 80, no. 1, pp. 54–62, 2011.
Attention, visual information processing, and oculomotor control are integrated functions of closely related brain mechanisms. Recently, it was shown that the processing of visual distractors appearing during a fixation is modulated by the amplitude of its preceding saccade (Pannasch & Velichkovsky, 2009). So far, this was demonstrated only at the behavioral level in terms of saccadic inhibition. The present study investigated distractor-related brain activity with cortical eye fixation-related potentials (EFRPs). Moreover, the following saccade was included as an additional classification criterion. Eye movements and EFRPs were recorded during free visual exploration of paintings. During some of the fixations, a visual distractor was shown as an annulus around the fixation position, 100. ms after the fixation onset. The saccadic context of a fixation was classified by its preceding and following saccade amplitudes with the cut-off criterion set to 4° of visual angle. The prolongation of fixation duration induced by distractors was largest for fixations preceded and followed by short saccades. EFRP data revealed a difference in distractor-related P2 amplitude between the saccadic context conditions, following the same trend as in eye movements. Furthermore, influences of the following saccade amplitude on the latency of the saccadic inhibition and on the N1 amplitude were found. The EFRP results cannot be explained by the influence of saccades per se since this bias was removed by subtracting the baseline from the distractor EFRP. Rather, the data suggest that saccadic context indicates differences in how information is processed within single visual fixations.
Katherine Guérard; Jean Saint-Aubin; Pierre Boucher; Sébastien Tremblay
The role of awareness in anticipation and recall performance in the hebb repetition paradigm: Implications for sequence learning Journal Article
In: Memory and Cognition, vol. 39, no. 6, pp. 1012–1022, 2011.
Sequence learning has notably been studied using the Hebb repetition paradigm (Hebb, 1961) and the serial reaction time (SRT) task (Nissen & Bullemer, Cognitive Psychology 19:1-32, 1987). These two paradigms produce robust learning effects but differ with regard to the role of awareness: Awareness does not affect learning a repeated sequence in the Hebb repetition paradigm, as is evidenced by recall performance, whereas in the SRT task, awareness helps to anticipate the location of the next stimulus. In this study, we examined the role of awareness in anticipation and recall performance, using the Hebb repetition paradigm. Eye movements were monitored during a spatial reconstruction task where participants had to memorize sequences of dot locations. One sequence was repeated every four trials. Results showed that recall performance for the repeated sequence improved across repetitions for all participants but that anticipation increased only for participants aware of the repetition.
Maria J. S. Guerreiro; Pascal W. M. Van Gerven
Now you see it, now you don't: Evidence for age-dependent and age-independent cross-modal distraction Journal Article
In: Psychology and Aging, vol. 26, no. 2, pp. 415–426, 2011.
Age-related deficits in selective attention have often been demonstrated in the visual modality and, to a lesser extent, in the auditory modality. In contrast, a mounting body of evidence has suggested that cross-modal selective attention is intact in aging, especially in visual tasks that require ignoring the auditory modality. Our goal in this study was to investigate age-related differences in the ability to ignore cross-modal auditory and visual distraction and to assess the role of cognitive control demands thereby. In a set of two experiments, 30 young (mean age = 23.3 years) and 30 older adults (mean age = 67.7 years) performed a visual and an auditory n-back task (0 ≤ n ≤ 2), with and without cross-modal distraction. The results show an asymmetry in cross-modal distraction as a function of sensory modality and age: Whereas auditory distraction did not disrupt performance on the visual task in either age group, visual distraction disrupted performance on the auditory task in both age groups. Most important, however, visual distraction was disproportionately larger in older adults. These results suggest that age-related distraction is modality dependent, such that suppression of cross-modal auditory distraction is preserved and suppression of cross-modal visual distraction is impaired in aging.
Tuomo Häikiö; Raymond Bertram; Jukka Hyönä
The development of whole-word representations in compound word processing: Evidence from eye fixation patterns of elementary school children Journal Article
In: Applied Psycholinguistics, vol. 32, no. 3, pp. 533–551, 2011.
The role of morphology in reading development was examined by measuring participants' eye movements while they read sentences containing either a hyphenated (e.g., ulko-ovi “front door”) or concatenated (e.g., autopeli “racing game”) compound. The participants were Finnish second, fourth, and sixth graders (aged 8, 10, and 12 years, respectively). Fast second graders and all four and sixth graders read concatenated compounds faster than hyphenated compounds. This suggests that they resort to slower morpheme-based processing for hyphenated compounds but prefer to process concatenated compounds via whole-word representations. In contrast, slow second graders' fixation durations were shorter for hyphenated than concatenated compounds. This implies that they process all compounds via constituent morphemes and that hyphenation comes to aid in this process.
Timothy D. Hanks; Mark E. Mazurek; Roozbeh Kiani; Elisabeth Hopp; Michael N. Shadlen
Elapsed decision time affects the weighting of prior probability in a perceptual decision task Journal Article
In: Journal of Neuroscience, vol. 31, no. 17, pp. 6339–6352, 2011.
Decisions are often based on a combination of new evidence with prior knowledge of the probable best choice. Optimal combination requires knowledge about the reliability of evidence, but in many realistic situations, this is unknown. Here we propose and test a novel theory: the brain exploits elapsed time during decision formation to combine sensory evidence with prior probability. Elapsed time is useful because (1) decisions that linger tend to arise from less reliable evidence, and (2) the expected accuracy at a given decision time depends on the reliability of the evidence gathered up to that point. These regularities allow the brain to combine prior information with sensory evidence by weighting the latter in accordance with reliability. To test this theory, we manipulated the prior probability of the rewarded choice while subjects performed a reaction-time discrimination of motion direction using a range of stimulus reliabilities that varied from trial to trial. The theory explains the effect of prior probability on choice and reaction time over a wide range of stimulus strengths. We found that prior probability was incorporated into the decision process as a dynamic bias signal that increases as a function of decision time. This bias signal depends on the speed-accuracy setting of human subjects, and it is reflected in the firing rates of neurons in the lateral intraparietal area (LIP) of rhesus monkeys performing this task.
Till S. Hartmann; Frank Bremmer; Thomas D. Albright; Bart Krekelberg
Receptive field positions in area MT during slow eye movements Journal Article
In: Journal of Neuroscience, vol. 31, no. 29, pp. 10437–10444, 2011.
Perceptual stability requires the integration of information across eye movements. We first tested the hypothesis that motion signals are integrated by neurons whose receptive fields (RFs) do not move with the eye but stay fixed in the world. Specifically, we measured the RF properties of neurons in the middle temporal area (MT) of macaques (Macaca mulatta) during the slow phase of optokinetic nystagmus. Using a novel method to estimate RF locations for both spikes and local field potentials, we found that the location on the retina that changed spike rates or local field potentials did not change with eye position; RFs moved with the eye. Second, we tested the hypothesis that neurons link information across eye positions by remapping the retinal location of their RFs to future locations. To test this, we compared RF locations during leftward and rightward slow phases of optokinetic nystagmus. We found no evidence for remapping during slow eye movements; the RF location was not affected by eye-movement direction. Together, our results show that RFs of MT neurons and the aggregate activity reflected in local field potentials are yoked to the eye during slow eye movements. This implies that individual MT neurons do not integrate sensory information from a single position in the world across eye movements. Future research will have to determine whether such integration, and the construction of perceptual stability, takes place in the form of a distributed population code in eye-centered visual cortex or is deferred to downstream areas.
Andreas Hartwig; W. Neil Charman; Hema Radhakrishnan
Accommodative response to peripheral stimuli in myopes and emmetropes Journal Article
In: Ophthalmic and Physiological Optics, vol. 31, no. 1, pp. 91–99, 2011.
Purpose: It has been suggested that peripheral refractive error may influence eye growth and the development of axial refractive error, implying that the peripheral retina is sensitive to defocus. This study aimed to evaluate the steady-state accommodative response to peripheral stimuli in 10 young, adult myopes (mean spherical equivalent error -2.10 ± 1.72 D, median -1.63 D, range -0.83 to -6.00 D) and 10 emmetropes (mean spherical equivalent error -0.02 ± 0.35 D, median +0.08 D, range -0.50 to +0.50 D). Methods: The subjects were asked to view monocularly the centre of a screen displaying each of a series of eccentric accommodative targets placed at 5, 10 and 15°. An axial target was viewed for comparison purposes. Accommodation was measured using an open-field autorefractor, each stimulus being varied between about 0 and 4 D with spherical trial lenses placed in front of the viewing eye. Results: The results confirm that the peripheral retina is sensitive to optical focus, up to field angles of at least 15°, with accommodative responses weakening as the peripheral angle increases. There is some evidence that peripheral accommodation may be less effective in myopes than emmetropes. Conclusions: Although peripheral accommodation can be demonstrated in the absence of a central stimulus, the accommodation response is normally dominated by the central stimulus and it seems unlikely that peripheral accommodation effects play an important role in refractive development.
Andreas Hartwig; Emma Gowen; W. Neil Charman; Hema Radhakrishnan
Analysis of head position used by myopes and emmetropes when performing a near-vision reading task Journal Article
In: Vision Research, vol. 51, no. 14, pp. 1712–1717, 2011.
The aim of the study was to compare head posture in young, adult emmetropes and corrected myopes during a reading task. Thirty-two (32) myopes (mean spherical equivalent: -3.46 ± 2.35. D) and 22 emmetropes (mean spherical equivalent: -0.03 ± 0.36. D) participated in the study. Of the myopes, 16 were progressing (rate of progression ≥-0.5. D over the previous 2. years), 12 were stable (changes of -0.25. D or less over 2. years) and four could not be classified. Seated subjects were asked to read a text binocularly in their habitual posture. To measure head posture, two simultaneous images were recorded from different directions. In a separate study with the same subjects and conditions, a motion monitor was used to track head posture for 1. min. The habitual reading distance was measured in both studies, together with the stereoscopic acuity and fixation disparity for each subject.The results of the photographic study showed no significant differences in head posture or reading distance between the myopic and emmetropic groups (p>0.05) but there was some evidence that downward pitch angles were greater in progressing myopes than in non-progressing myopes (p=0.03). No correlations were observed between the binocular parameters and head posture. Reading distances were systematically shorter with the helmet-mounted eye tracker and it was concluded that posture was affected by the weight of the equipment. With this reservation, it appeared that the rate of change of downward pitch angle over the 1-min recording session increased with the subject's rate of myopia progression (correlation between myopia progression and slope of pitch: r2=-0.69
Andreas Hartwig; Emma Gowen; W. Neil Charman; Hema Radhakrishnan
Working distance and eye and head movements during near work in myopes and non-myopes Journal Article
In: Clinical and Experimental Optometry, vol. 94, no. 6, pp. 536–544, 2011.
PURPOSE: Reasons for the development and progression of myopia remain unclear. Some studies show a high prevalence of myopia in certain occupational groups. This might imply that certain head and eye movements lead to ocular elongation, perhaps as a result of forces from the extraocular muscles, lids or other structures. The present study aims to analyse head and eye movements in myopes and non-myopes for near-vision tasks. METHODS: The study analysed head and eye movements in a cohort of 14 myopic and 16 non-myopic young adults. Eye and head movements were monitored by an eye tracker and a motion sensor while the subjects performed three near tasks, which included reading on a screen, reading a book and writing. Horizontal eye and head movements were measured in terms of angular amplitudes. Vertical eye and head movements were analysed in terms of the range of the whole movement during the recording. Values were also assessed as a ratio based on the width of the printed text, which changed between participants due to individual working distances. RESULTS: Horizontal eye and head movements were significantly different among the three tasks (p = 0.03 and p = 0.014, for eye and head movements, respectively, repeated measures ANOVA). Horizontal and vertical eye and head movements did not differ significantly between myopes and non-myopes. As expected, eye movements preponderated over head movements for all tasks and in both meridians. A positive correlation was found between mean spherical equivalent and the working distance for reading a book (r = 0.41; p = 0.025). CONCLUSIONS: The results show a similar pattern of eye movements in all participating subjects, although the amplitude of these movements varied considerably between the individuals. It is likely that some individuals when exposed to certain occupational tasks might show different eye and head movement patterns.
Ben M. Harvey; Serge O. Dumoulin
The relationship between cortical magnification factor and population receptive field size in human visual cortex: Constancies in cortical architecture Journal Article
In: Journal of Neuroscience, vol. 31, no. 38, pp. 13604–13612, 2011.
Receptive field (RF) sizes and cortical magnification factor (CMF) are fundamental organization properties of the visual cortex. At increasing visual eccentricity, RF sizes increase and CMF decreases. A relationship between RF size and CMF suggests constancies in cortical architecture, as their product, the cortical representation of an RF (point image), may be constant. Previous animal neurophysiology studies of this question yield conflicting results. Here, we use fMRI to determine the relationship between the population RF (pRF) and CMF in humans. In average and individual data, the product of CMF and pRF size, the population point image, is near constant, decreasing slightly with eccentricity in V1. Interhemisphere and subject variations in CMF, pRF size, and V1 surface area are correlated, and the population point image varies less than these properties. These results suggest a V1 cortical processing architecture of approximately constant size between humans. Up the visual hierarchy, to V2, V3, hV4, and LO1, the population point image decreases with eccentricity, and both the absolute values and rate of change increase. PRF sizes increase between visual areas and with eccentricity, but when expressed in V1 cortical surface area (i.e., corticocortical pRFs), they are constant across eccentricity in V2/V3. Thus, V2/V3, and to some degree hV4, sample from a constant extent of V1. This may explain population point image changes in later areas. Consequently, the constant factor determining pRF size may not be the relationship to the local CMF, but rather pRF sizes and CMFs in visual areas from which the pRF samples.
Katharina Havermann; Eckart Zimmermann; Markus Lappe
Eye position effects in saccadic adaptation Journal Article
In: Journal of Neurophysiology, vol. 106, no. 5, pp. 2536–2545, 2011.
Saccades are used by the visual system to explore visual space with the high accuracy of the fovea. The visual error after the saccade is used to adapt the control of subsequent eye movements of the same amplitude and direction in order to keep saccades accurate. Saccadic adaptation is thus specific to saccade amplitude and direction. In the present study we show that saccadic adaptation is also specific to the initial position of the eye in the orbit. This is useful, because saccades are normally accompanied by head movements and the control of combined head and eye movements depends on eye position. Many parts of the saccadic system contain eye position information. Using the intrasaccadic target step paradigm, we adaptively reduced the amplitude of reactive saccades to a suddenly appearing target at a selective position of the eyes in the orbitae and tested the resulting amplitude changes for the same saccade vector at other starting positions. For central adaptation positions the saccade amplitude reduction transferred completely to eccentric starting positions. However, for adaptation at eccentric starting positions, there was a reduced transfer to saccades from central starting positions or from eccentric starting positions in the opposite hemifield. Thus eye position information modifies the transfer of saccadic amplitude changes in the adaptation of reactive saccades. A gain field mechanism may explain the eye position dependence found.
Benjamin Y. Hayden; Sarah R. Heilbronner; John M. Pearson; Michael L. Platt
Surprise signals in anterior cingulate cortex: Neuronal encoding of unsigned reward prediction errors driving adjustment in behavior Journal Article
In: Journal of Neuroscience, vol. 31, no. 11, pp. 4178–4187, 2011.
In attentional models of learning, associations between actions and subsequent rewards are stronger when outcomes are surprising, regardless of their valence. Despite the behavioral evidence that surprising outcomes drive learning, neural correlates of unsigned reward prediction errors remain elusive. Here we show that in a probabilistic choice task, trial-to-trial variations in preference track outcome surprisingness. Concordant with this behavioral pattern, responses of neurons in macaque (Macaca mulatta) dorsal anterior cingulate cortex (dACC) to both large and small rewards were enhanced when the outcome was surprising. Moreover, when, on some trials, probabilities were hidden, neuronal responses to rewards were reduced, consistent with the idea that the absence of clear expectations diminishes surprise. These patterns are inconsistent with the idea that dACC neurons track signed errors in reward prediction, as dopamine neurons do. Our results also indicate that dACC neurons do not signal conflict. In the context of other studies of dACC function, these results suggest a link between reward-related modulations in dACC activity and attention and motor control processes involved in behavioral adjustment. More speculatively, these data point to a harmonious integration between reward and learning accounts of ACC function on one hand, and attention and cognitive control accounts on the other.
Benjamin Y. Hayden; John M. Pearson; Michael L. Platt
Neuronal basis of sequential foraging decisions in a patchy environment Journal Article
In: Nature Neuroscience, vol. 14, no. 7, pp. 933–939, 2011.
Deciding when to leave a depleting resource to exploit another is a fundamental problem for all decision makers. The neuronal mechanisms mediating patch-leaving decisions remain unknown. We found that neurons in primate (Macaca mulatta) dorsal anterior cingulate cortex, an area that is linked to reward monitoring and executive control, encode a decision variable signaling the relative value of leaving a depleting resource for a new one. Neurons fired during each sequential decision to stay in a patch and, for each travel time, these responses reached a fixed threshold for patch-leaving. Longer travel times reduced the gain of neural responses for choosing to stay in a patch and increased the firing rate threshold mandating patch-leaving. These modulations more closely matched behavioral decisions than any single task variable. These findings portend an understanding of the neural basis of foraging decisions and endorse the unification of theoretical and experimental work in ecology and neuroscience.
Taylor R. Hayes; Alexander A. Petrov; Per B. Sederberg
A novel method for analyzing sequential eye movements reveals strategic influence on Raven's Advanced Progressive Matrices Journal Article
In: Journal of Vision, vol. 11, no. 10, pp. 1–11, 2011.
Eye movements are an important data source in vision science. However, the vast majority of eye movement studies ignore sequential information in the data and utilize only first-order statistics. Here, we present a novel application of a temporal-difference learning algorithm to construct a scanpath successor representation (SR; P. Dayan, 1993) that captures statistical regularities in temporally extended eye movement sequences. We demonstrate the effectiveness of the scanpath SR on eye movement data from participants solving items from Raven's Advanced Progressive Matrices Test. Analysis of the SRs revealed individual differences in scanning patterns captured by two principal components that predicted individual Raven scores much better than existing methods. These scanpath SR components were highly interpretable and provided new insight into the role of strategic processing on the Raven test. The success of the scanpath SR in terms of prediction and interpretability suggests that this method could prove useful in a much broader context.
L. Elliot Hong; Gunvant K. Thaker; Robert P. McMahon; Ann Summerfelt; Jill RachBeisel; Rebecca L. Fuller; Ikwunga Wonodi; Robert W. Buchanan; Carol Myers; Stephen J. Heishman; Jeff Yang; Adrienne Nye
Effects of moderate-dose treatment with varenicline on neurobiological and cognitive biomarkers in smokers and nonsmokers with schizophrenia or schizoaffective disorder Journal Article
In: Archives of General Psychiatry, vol. 68, no. 12, pp. 1195–1206, 2011.
CONTEXT: The administration of nicotine transiently improves many neurobiological and cognitive functions in schizophrenia and schizoaffective disorder. It is not yet clear which nicotinic acetylcholine receptor (nAChR) subtype or subtypes are responsible for these seemingly pervasive nicotinic effects in schizophrenia and schizoaffective disorder. OBJECTIVE: Because $alpha$4$beta$2 is a key nAChR subtype for nicotinic actions, we investigated the effect of varenicline tartrate, a relatively specific $alpha$4$beta$2 partial agonist and antagonist, on key biomarkers that are associated with schizophrenia and are previously shown to be responsive to nicotinic challenge in humans. DESIGN: A double-blind, parallel, randomized, placebo-controlled trial of patients with schizophrenia or schizoaffective disorder to examine the effects of varenicline on biomarkers at 2 weeks (short-term treatment) and 8 weeks (long-term treatment), using a slow titration and moderate dosing strategy for retaining $alpha$4$beta$2-specific effects while minimizing adverse effects. SETTING: Outpatient clinics. PARTICIPANTS: A total of 69 smoking and nonsmoking patients; 64 patients completed week 2, and 59 patients completed week 8. Intervention Varenicline. MAIN OUTCOME MEASURES: Prepulse inhibition, sensory gating, antisaccade, spatial working memory, eye tracking, processing speed, and sustained attention. RESULTS: A moderate dose of varenicline (1) significantly reduced the P50 sensory gating deficit in nonsmokers after long-term treatment (P = .006), (2) reduced startle reactivity (P = .02) regardless of baseline smoking status, and (3) improved executive function by reducing the antisaccadic error rate (P = .03) regardless of smoking status. A moderate dose of varenicline had no significant effect on spatial working memory, predictive and maintenance pursuit measures, processing speed, or sustained attention by Conners' Continuous Performance Test. Clinically, there was no evidence of exacerbation of psychiatric symptoms, psychosis, depression, or suicidality using a gradual titration (1-mg daily dose). CONCLUSIONS: Moderate-dose treatment with varenicline has a unique treatment profile on core schizophrenia-related biomarkers. Further development is warranted for specific nAChR compounds and dosing and duration strategies to target subgroups of schizophrenic patients with specific biological deficits.
Lorelei R. Howard; Dharshan Kumaran; Hauður F. Ólafsdóttir; Hugo J. Spiers
Double dissociation between hippocampal and parahippocampal responses to object-background context and scene novelty Journal Article
In: Journal of Neuroscience, vol. 31, no. 14, pp. 5253–5261, 2011.
Several recent models of medial temporal lobe (MTL) function have proposed that the parahippocampal cortex processes context information, the perirhinal cortex processes item information, and the hippocampus binds together items and contexts. While evidence for a clear functional distinction between the perirhinal cortex and other regions within the MTL has been well supported, it has been less clear whether such a dissociation exists between the hippocampus and parahippocampal cortex. In the current study, we use a novel approach applying a functional magnetic resonance imaging adaptation paradigm to address these issues. During scanning, human subjects performed an incidental target detection task while viewing trial-unique sequentially presented pairs of natural scenes, each containing a single prominent object. We observed a striking double dissociation between the hippocampus and parahippocampal cortex, with the former showing a selective sensitivity to changes in the spatial relationship between objects and their background context and the latter engaged only by scene novelty. Our findings provide compelling support for the hypothesis that rapid item-context binding is a function of the hippocampus, rather than the parahippocampal cortex, with the former acting to detect relational novelty of this nature through its function as a match-mismatch detector.
Yanbo Hu; Robin Walker
The neural basis of parallel saccade programming: An fMRI study Journal Article
In: Journal of Cognitive Neuroscience, vol. 23, no. 11, pp. 3669–3680, 2011.
The neural basis of parallel saccade programming was examined in an event-related fMRI study using a variation of the double-step saccade paradigm. Two double-step conditions were used: one enabled the second saccade to be partially programmed in parallel with the first saccade while in a second condition both saccades had to be prepared serially. The inter-saccadic interval, observed in the parallel programming (PP) condition, was significantly reduced compared with latency in the serial programming (SP) condition and also to the latency of single saccades in control conditions. The fMRI analysis revealed greater activity (BOLD response) in the frontal and parietal eye fields for the PP condition compared with the SP double-step condition and when compared with the single-saccade control conditions. By contrast, activity in the supplementary eye fields was greater for the double-step condition than the single-step condition but did not distinguish between the PP and SP requirements. The role of the frontal eye fields in PP may be related to the advanced temporal preparation and increased salience of the second saccade goal that may mediate activity in other downstream structures, such as the superior colliculus. The parietal lobes may be involved in the preparation for spatial remapping, which is required in double-step conditions. The supplementary eye fields appear to have a more general role in planning saccade sequences that may be related to error monitoring and the control over the execution of the correct sequence of responses.
Yi Ting Huang; Peter C. Gordon
Distinguishing the time course of lexical and discourse processes through context, coreference, and quantified expressions Journal Article
In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 37, no. 4, pp. 966–978, 2011.
How does prior context influence lexical and discourse-level processing during real-time language comprehension? Experiment 1 examined whether the referential ambiguity introduced by a repeated, anaphoric expression had an immediate or delayed effect on lexical and discourse processing, using an eye-tracking-while-reading task. Eye movements indicated facilitated recognition of repeated expressions, suggesting that prior context can rapidly influence lexical processing. However, context effects at the discourse level affected later processing, appearing in longer regression-path durations 2 words after the anaphor and in greater rereading times of the antecedent expression. Experiments 2 and 3 explored the nature of this delay by examining the role of the preceding context in activating relevant representations. Offline and online interpretations confirmed that relevant referents were activated following the critical context. Nevertheless, their initial unavailability during comprehension suggests a robust temporal division between lexical and discourse-level processing.
Yu-feng Huang; Feng-yang Kuo
An eye-tracking investigation of internet consumers' decision deliberateness Journal Article
In: Internet Research, vol. 21, no. 5, pp. 541–561, 2011.
Purpose – Because presentation formats, i.e. table v. graph, in shopping web sites may promote or inhibit deliberate consumer decision making, it is important to understand the effects of information presentation on deliberateness. This paper seeks to empirically test whether the table format enhances deliberate decision making, while the web map weakens the process. In addition, deliberateness can be influenced by the decision orientation, i.e. emotionally charged or accuracy oriented. Thus, the paper further examines the effect of presentations across these two decision orientations. Design/methodology/approach – Objective and detailed description of the decision process is used to examine the effects. A two (decision orientation: positive emotion v. accuracy) by two (presentation: map v. table) eye-tracking experiment is designed. Deliberateness is quantified with the information processing pattern summarized from eye movement data. Participants are required to make preferential choices from simple decision tasks. Findings – The results confirm that the table strengthens while the map weakens deliberateness. In addition, this effect is mostly evident across the two decision orientations. An explorative factor analysis further reveals that there are two major attention distribution functions (global v. local) underlying the decision process. Research limitations/implications – Only simple decision tasks are used in the present study and therefore complex tasks should be introduced to examine the effects in the future. Practical implications – For consumers, they should become aware that the table facilitates while the map diminishes deliberateness. For web businesses, they may try to strengthen the impulsivity in a web map filled with emotional stimuli. Originality/value – This research is one of the first attempts to investigate the joint effects of presentations and decision orientations on decision deliberateness in the internet domain. The eye movement data are also valuable because previous studies seldom provided such detailed description of the decision process.
Mackenzie G. Glaholt; Eyal M. Reingold
Eye movement monitoring as a process tracing methodology in decision making research Journal Article
In: Journal of Neuroscience, Psychology, and Economics, vol. 4, no. 2, pp. 125–146, 2011.
Over the past half century, research on human decision making has expanded from a purely behaviorist approach that focuses on decision outcomes, to include a more cognitive approach that focuses on the decision processes that occur prior to the response. This newer approach, known as process tracing, has employed various methods, such as verbal protocols, information search displays, and eye movement monitoring, to identify and track psychological events that occur prior to the response (such as cognitive states, stages, or processes). In the present article, we review empirical studies that have employed eye movement monitoring as a process tracing method in decision making research, and we examine the potential of eye movement monitoring as a process tracing methodology. We also present an experiment that further illustrates the experimental manipulations and analysis techniques that are possible with modern eye tracking technology. In this experiment, a gaze-contingent display was used to manipulate stimulus exposure during decision making, which allowed us to test a specific hypothesis about the role of eye movements in preference decisions (the Gaze Cascade model; Shimojo, Simion, Shimojo, & Scheier, 2003). The results of the experiment did not confirm the predictions of the Gaze Cascade model, but instead support the idea that eye movements in these decisions reflect the screening and evaluation of decision alternatives. In summary, we argue that eye movement monitoring is a valuable tool for capturing decision makers' information search behaviors, and that modern eye tracking technology is highly compatible with other process tracing methods such as retrospective verbal protocols and neuroimaging techniques, and hence it is poised to be an integral part of the next wave of decision research.
Davis M. Glasser; James M. G. Tsui; Christopher C. Pack; Duje Tadin
Perceptual and neural consequences of rapid motion adaptation Journal Article
In: Proceedings of the National Academy of Sciences, vol. 108, no. 45, pp. E1080–E1088, 2011.
Nervous systems adapt to the prevailing sensory environment, and the consequences of this adaptation can be observed in the responses of single neurons and in perception. Given the variety of timescales underlying events in the natural world, determining the temporal characteristics of adaptation is important to understanding how perception adjusts to its sensory environment. Previous work has shown that neural adaptation can occur on a timescale of milliseconds, but perceptual adaptation has generally been studied over relatively long timescales, typically on the order of seconds. This disparity raises important questions. Can perceptual adaptation be observed at brief, functionally relevant timescales? And if so, how do its properties relate to the rapid adaptation seen in cortical neurons? We address these questions in the context of visual motion processing, a perceptual modality characterized by rapid temporal dynamics. We demonstrate objectively that 25 ms of motion adaptation is sufficient to generate a motion aftereffect, an illusory sensation of movement experienced when a moving stimulus is replaced by a stationary pattern. This rapid adaptation occurs regardless of whether the adapting motion is perceived. In neurophysiological recordings from the middle temporal area of primate visual cortex, we find that brief motion adaptation evokes direction-selective responses to subsequently presented stationary stimuli. A simple model shows that these neural responses can explain the consequences of rapid perceptual adaptation. Overall, we show that the motion aftereffect is not merely an intriguing perceptual illusion, but rather a reflection of rapid neural and perceptual processes that can occur essentially every time we experience motion.
Tamar H. Gollan; Timothy J. Slattery; Diane Goldenberg; Eva Van Assche; Wouter Duyck; Keith Rayner
Frequency drives lexical access in reading but not in speaking: The frequency-lag hypothesis Journal Article
In: Journal of Experimental Psychology: General, vol. 140, no. 2, pp. 186–209, 2011.
To contrast mechanisms of lexical access in production versus comprehension we compared the effects of word frequency (high, low), context (none, low constraint, high constraint), and level of English proficiency (monolingual, Spanish-English bilingual, Dutch-English bilingual) on picture naming, lexical decision, and eye fixation times. Semantic constraint effects were larger in production than in reading. Frequency effects were larger in production than in reading without constraining context but larger in reading than in production with constraining context. Bilingual disadvantages were modulated by frequency in production but not in eye fixation times, were not smaller in low-constraint contexts, and were reduced by high-constraint contexts only in production and only at the lowest level of English proficiency. These results challenge existing accounts of bilingual disadvantages and reveal fundamentally different processes during lexical access across modalities, entailing a primarily semantically driven search in production but a frequency-driven search in comprehension. The apparently more interactive process in production than comprehension could simply reflect a greater number of frequency-sensitive processing stages in production.
Becky Heaver; Samuel B. Hutton
Keeping an eye on the truth? pupil size changes associated with recognition memory Journal Article
In: Memory, vol. 19, no. 4, pp. 398–405, 2011.
During recognition memory tests participants' pupils dilate more when they view old items compared to novel items. We sought to replicate this "pupil old/new effect" and to determine its relationship to participants' responses. We compared changes in pupil size during recognition when participants were given standard recognition memory instructions, instructions to feign amnesia, and instructions to report all items as new. Participants' pupils dilated more to old items compared to new items under all three instruction conditions. This finding suggests that the increase in pupil size that occurs when participants encounter previously studied items is not under conscious control. Given that pupil size can be reliably and simply measured, the pupil old/new effect may have potential in clinical settings as a means for determining whether patients are feigning memory loss.
Sarah R. Heilbronner; Benjamin Y. Hayden; Michael L. Platt
Decision salience signals in posterior cingulate cortex Journal Article
In: Frontiers in Neuroscience, vol. 5, pp. 55, 2011.
Despite its phylogenetic antiquity and clinical importance, the posterior cingulate cortex (CGp) remains an enigmatic nexus of attention, memory, motivation, and decision making. Here we show that CGp neurons track decision salience - the degree to which an option differs from a standard - but not the subjective value of a decision. To do this, we recorded the spiking activity of CGp neurons in monkeys choosing between options varying in reward-related risk, delay to reward, and social outcomes, each of which varied in level of decision salience. Firing rates were higher when monkeys chose the risky option, consistent with their risk-seeking preferences, but were also higher when monkeys chose the delayed and social options, contradicting their preferences. Thus, across decision contexts, neuronal activity was uncorrelated with how much monkeys valued a given option, as inferred from choice. Instead, neuronal activity signaled the deviation of the chosen option from the standard, independently of how it differed. The observed decision salience signals suggest a role for CGp in the flexible allocation of neural resources to motivationally significant information, akin to the role of attention in selective processing of sensory inputs.
Stephen J. Heinen; Z. Jin; Scott N. J. Watamaniuk
Flexibility of foveal attention during ocular pursuit Journal Article
In: Journal of Vision, vol. 11, no. 2, pp. 1–12, 2011.
Smooth pursuit of natural objects requires flexible allocation of attention to inspect features. However, it has been reported that attention is focused at the fovea during pursuit. We ask here if foveal attention is obligatory during pursuit, or if it can be disengaged. Observers tracked a stimulus composed of a central dot surrounded by four others and identified one of the dots when it dimmed. Extinguishing the center dot before the dimming improved task performance, suggesting that attention was released from it. To determine if the center dot automatically usurped attention, we provided the pursuit system with an alternative sensory signal by adding peripheral motion that moved with the stimulus. This also improved identification performance, evidence that a central target does not necessarily require attention during pursuit. Identification performance at the central dot also improved, suggesting that the spatial extent of the background did not attract attention to the periphery; instead, peripheral motion freed pursuit attention from the central dot, affording better identification performance. The results show that attention can be flexibly allocated during pursuit and imply that attention resources for pursuit of small and large objects come from different sources.
Jennifer J. Heisz; Jennifer D. Ryan
The effects of prior exposure on face processing in younger and older adults Journal Article
In: Frontiers in Aging Neuroscience, vol. 3, pp. 15, 2011.
Older adults differ from their younger counterparts in the way they view faces. We assessed whether older adults can use past experience to mitigate these typical face-processing differences; that is, we examined whether there are age-related differences in the use of memory to support current processing. Eye movements of older and younger adults were monitored as they viewed faces that varied in the type/amount of prior exposure. Prior exposure was manipulated by including famous and novel faces, and by presenting faces up to five times. We expected that older adults may have difficulty quickly establishing new representations to aid in the processing of recently presented faces, but would be able to invoke face representations that have been stored in memory long ago to aid in the processing of famous faces. Indeed, younger adults displayed effects of recent exposure with a decrease in the total fixations to the faces and a gradual increase in the proportion of fixations to the eyes. These effects of recent exposure were largely absent in older adults. In contrast, the effect of fame, revealed by a subtle increase in fixations to the inner features of famous compared to non-famous faces, was similar for younger and older adults. Our results suggest that older adults' current processing can benefit from lifetime experience, however the full benefit of recent experience on face processing is not realized in older adults.
Richard W. Hertle; Dongsheng Yang; Kenneth Adams; Roxanne Caterino
Surgery for the treatment of vertical head posturing associated with infantile nystagmus syndrome: Results in 24 patients Journal Article
In: Clinical and Experimental Ophthalmology, vol. 39, no. 1, pp. 37–46, 2011.
Background: The study of the clinical and electrophysiological effects of eye muscle surgery on patients with infantile nystagmus has broadened our knowledge of the disease and its interventions. Design: Prospective, comparative, interventional case series. Participants: Twenty-four patients with a vertical head posture because of electrophysiologically diagnosed infantile nystagmus syndrome. The ages ranged from 2.5 to 38 years and follow up averaged 14.0 months. Methods: Thirteen patients with a chin-down posture had a bilateral superior rectus recession, inferior oblique myectomy and a horizontal rectus recession or tenotomy. Those 11 with a chin-up posture had a bilateral superior oblique tenectomy, inferior rectus recession and a horizontal rectus recession or tenotomy. Main Outcome Measures: Outcome measures included: demography, eye/systemic conditions and preoperative and postoperative; binocular, best optically corrected, null zone acuity, head posture, null zone foveation time and nystagmus waveform changes. Results: Associated conditions were strabismus in 66%, ametropia in 96%, amblyopia in 46% and optic nerve, foveal dysplasia or albinism in 54%. Null zone acuity increased at least 0.1 logMAR in 20 patients (P < 0.05 group mean change). Patients had significant (P < 0.05) improvements in degrees of head posture, average foveation time in milliseconds and infantile nystagmus syndrome waveform improvements. Conclusions: This study illustrates a successful surgical approach to treatment and provides expectations of ocular motor and visual results after vertical head posture surgery because of an eccentric gaze null in patients with infantile nystagmus syndrome.
Arvid Herwig; Gernot Horstmann
Action-effect associations revealed by eye movements Journal Article
In: Psychonomic Bulletin & Review, vol. 18, no. 3, pp. 531–537, 2011.
We move our eyes not only to get information, but also to supply information to our fellows. The latter eye movements can be considered as goal-directed actions to elicit changes in our counterparts. In two eye-tracking experiments, participants looked at neutral faces that changed facial expression 100 ms after the gaze fell upon them. We show that participants anticipate a change in facial expression and direct their first saccade more often to the mouth region of a neutral face about to change into a happy one and to the eyebrows region of a neutral face about to change into an angry expression. Moreover, saccades in response to facial expressions are initiated more quickly to the position where the expression was previously triggered. Saccade-effect associations are easily acquired and are used to guide the eyes if participants freely select where to look next (Experiment 1), but not if saccades are triggered by external stimuli (Experiment 2).
Masahiro Hirai; Daniel R. Saunders; Nikolaus F. Troje
Allocation of attention to biological motion: Local motion dominates global shape Journal Article
In: Journal of Vision, vol. 11, no. 3, pp. 1–11, 2011.
Directional information can be retrieved from a point-light walker (PLW) in two different ways: either from recovering the global shape of the articulated body or from signals in the local motion of individual dots. Here, we introduce a voluntary eye movement task to assess how the direction of a centrally presented, task-irrelevant PLW affects the onset latency and accuracy of saccades to peripheral targets. We then use this paradigm to design experiments to study which aspects of biological motion-the global form mediated by the motion of the walker or the local movements of critical features-drive the observed attentional effects. Putting the two cues into conflict, we show that saccade latency and accuracy were affected by the local motion of the dots representing the walker's feet-but only if they retain their familiar, predictable location within the display.
Margit Höfler; Iain D. Gilchrist; Christof Körner
Inhibition of return functions within but not across searches Journal Article
In: Attention, Perception, and Psychophysics, vol. 73, no. 5, pp. 1385–1397, 2011.
Inhibition of return (IOR) facilitates visual search by discouraging the reinspection of recently processed items. We investigated whether IOR operates across two consecutive searches of the same display for different targets. In Experiment 1, we demonstrated that IOR is present within each of the two searches. In Experiment 2, we found no evidence for IOR across searches. In Experiment 3, we showed that IOR is present across the two searches when the first search is interrupted, suggesting that the completion of the search is what causes the resetting of IOR. We concluded that IOR is a partially flexible process that can be reset when the task completes, but not necessarily when it changes. When resetting occurs, this flexibility ensures that the inhibition of previously visited locations does not interfere with the new search.
Stacey E. Parrott; Brian R. Levinthal; Steven L. Franconeri
Complex attentional control settings Journal Article
In: Quarterly Journal of Experimental Psychology, vol. 63, no. 12, pp. 2297–2304, 2011.
The visual system prioritizes information through a variety of mechanisms, including “attentional control settings” that specify features (e.g., colour) that are relevant to current goals. Recent work shows that these control settings may be more complex than previously thought, such that participants can monitor for independent features at different locations (Adamo, Pun, Pratt, & Ferber, 2008). However, this result leaves unclear whether these control settings affect early attentional selection or later target processing. We dissociated between these possibilities in two ways. In Experiment 1, participants were asked to determine whether a target object, which was preceded by an uninformative cue, matched one of two target templates (e.g., a blue vertical object or a green horizontal object). Participants monitored for independent features in the same location, but in different objects, which should reduce the effectiveness of the control setting if it is due to early attentional selection, but not if it is due to later target processing. In Experiment 2, we removed the ability of the cue to prime the target identity, which makes the opposite prediction. Together, the results suggest that complex attentional control settings primarily affect later target identity processing, and not early attentional selection.
Nikole D. Patson; Tessa Warren
Building complex reference objects from dual sets Journal Article
In: Journal of Memory and Language, vol. 64, no. 4, pp. 443–459, 2011.
There has been considerable psycholinguistic investigation into the conditions that allow separately introduced individuals to be joined into a plural set and represented as a complex reference object (e.g., Eschenbach et al., 1989; Garrod & Sanford, 1982; Koh & Clifton, 2002; Koh et al., 2008; Moxey, Sanford, Sturt, & Morrow, 2004; Sanford & Lockhart, 1990). The current paper reports three eye-tracking experiments that investigate the less-well understood question of what conditions allow pointers to be assigned to the individuals within a previously undifferentiated set, turning it into a complex reference object. The experiments made use of a methodology used in Patson and Ferreira (2009) to distinguish between complex reference objects and undifferentiated sets. Experiments 1 and 2 demonstrated that assigning different properties to the members of an undifferentiated dual set via a conjoined modifier or a comparative modifier transformed it into a complex reference object. Experiment 3 indicated that assigning a property to only one member of an undifferentiated dual set introduced pointers to both members. These results demonstrate that pointers can be established to referents within a plural set without picking them out via anaphors; they set boundaries on the kinds of implicit contrasts between referents that establish pointers; and they illustrate that extremely subtle properties of the semantic and referential context can affect early parsing decisions.
Manuel Perea; Chie Nakatani; Cees Leeuwen
Transposition effects in reading Japanese Kana: Are they orthographic in nature? Journal Article
In: Memory and Cognition, vol. 39, no. 4, pp. 700–707, 2011.
One critical question for the front end of models of visual-word recognition and reading is whether the stage of letter position coding is purely orthographic or whether phonology is (to some degree) involved. To explore this issue, we conducted a silent reading experiment in Japanese Kana--a script in which orthography and phonology can be easily separated--using a technique that is highly sensitive to phonological effects (i.e., Rayner's (1975) boundary technique). Results showed shorter fixation times on the target word when the parafoveal preview was a transposed-mora nonword (a.ri.me.ka [アリメカ]-a.me.ri.ka [アメリカ]) than when the preview was a replacement-mora nonword (a.ka.ho.ka [アカホカ] -a.me.ri.ka [アメリカ]). More critically, fixation times on the target word were remarkably similar when the parafoveal preview was a transposed-consonant nonword (a.re.mi.ka [アレミカ]-a.ri.me.ka [アリメカ]) and when the parafoveal preview was an orthographic control nonword (a.ke.hi.ka [アケヒカ]-a.me.ri.ka [アメリカ]). Thus, these findings offer strong support for the view that letter/mora position coding during silent reading is orthographic in nature.
Gerald Pfeffer; Mathias Abegg; A. Talia Vertinsky; Isabella Ceccherini; Francesco Caroli; Jason J. S. Barton
The ocular motor features of adult-onset alexander disease: A case and review of the literature Journal Article
In: Journal of Neuro-Ophthalmology, vol. 31, no. 2, pp. 155–159, 2011.
A 51-year-old Chinese man presented with gaze-evoked nystagmus, impaired smooth pursuit and vestibular ocular reflex cancellation, and saccadic dysmetria, along with a family history suggestive of late-onset autosomal dominant parkinsonism. MRI revealed abnormalities of the medulla and cervical spinal cord typical of adult-onset Alexander disease, and genetic testing showed homozygosity for the p.D295N polymorphic allele in the gene encoding the glial fibrillary acidic protein. A review of the literature shows that ocular signs are frequent in adult-onset Alexander disease, most commonly gaze-evoked nystagmus, pendular nystagmus, and/or oculopalatal myoclonus, and less commonly ptosis, miosis, and saccadic dysmetria. These signs are consistent with the propensity of adult-onset Alexander disease to cause medullary abnormalities on neuroimaging.
Tobias Pflugshaupt; Julia Suchan; Marc André Mandler; Alexander N. Sokolov; Susanne Trauzettel-Klosinski; Hans-Otto Karnath
Do patients with pure alexia suffer from a specific word form processing deficit? Evidence from 'wrods with trasnpsoed letetrs' Journal Article
In: Neuropsychologia, vol. 49, no. 5, pp. 1294–1301, 2011.
It is widely accepted that letter-by-letter reading and a pronounced increase in reading time as a function of word length are the hallmark features of pure alexia. Why patients show these two phenomena with respect to underlying cognitive mechanisms is, however, much less clear. Two main hypotheses have been proposed, i.e. impaired discrimination of letters and deficient processing of word forms. While the former deficit can easily be investigated in isolation, previous findings favouring the latter seem confounded. Applying a word reading paradigm with systematically manipulated letter orders in two patients with pure alexia, we demonstrate a word form processing deficit that is not attributable to sublexical letter discrimination difficulties. Moreover, pure alexia-like fixation patterns could be induced in healthy adults by having them read sentences including words with transposed letters, so-called 'jumbled words'. This further corroborates a key role of deficient word form processing in pure alexia. With regard to basic reading research, the present study extends recent evidence for relative, rather than precise, encoding of letter position in the brain..
Elmar H. Pinkhardt; Jan Kassubek
Ocular motor abnormalities in Parkinsonian syndromes Journal Article
In: Parkinsonism and Related Disorders, vol. 17, no. 4, pp. 223–230, 2011.
Oculomotor abnormalities can be observed in all Parkinsonian syndromes (PS). Nevertheless, due to the considerable overlap of oculomotor pathology in Parkinsonism, oculomotor changes are not generally considered to contribute substantially to the differential diagnosis of PS. Here we review the characteristics of oculomotor disturbances in the major PS, we provide a survey of the current concepts of the underlying neural physiology of oculomotor control and a summary of the major recording techniques for eye movements. The main focus of this review is to outline the subtle differences between apparently similar oculomotor alterations in Parkinson's disease (PD) and atypical neurodegenerative PS that can contribute to the early differential diagnosis of these entities.
L. Pisella; N. Alahyane; A. Blangero; F. Thery; S. Blanc; Denis Pelisson
Right-hemispheric dominance for visual remapping in humans Journal Article
In: Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 366, pp. 572–585, 2011.
We review evidence showing a right-hemispheric dominance for visuo-spatial processing and representation in humans. Accordingly, visual disorganization symptoms (intuitively related to remapping impairments) are observed in both neglect and constructional apraxia. More specifically, we review findings from the intervening saccade paradigm in humans--and present additional original data--which suggest a specific role of the asymmetrical network at the temporo-parietal junction (TPJ) in the right hemisphere in visual remapping: following damage to the right dorsal posterior parietal cortex (PPC) as well as part of the corpus callosum connecting the PPC to the frontal lobes, patient OK in a double-step saccadic task exhibited an impairment when the second saccade had to be directed rightward. This singular and lateralized deficit cannot result solely from the patient's cortical lesion and, therefore, we propose that it is due to his callosal lesion that may specifically interrupt the interhemispheric transfer of information necessary to execute accurate rightward saccades towards a remapped target location. This suggests a specialized right-hemispheric network for visuo-spatial remapping that subsequently transfers target location information to downstream planning regions, which are symmetrically organized.
Alexander Pollatsek; Raymond Bertram; Jukka Hyönä
Processing novel and lexicalised Finnish compound words Journal Article
In: Journal of Cognitive Psychology, vol. 23, no. 7, pp. 795–810, 2011.
Participants read sentences in which novel and lexicalized two-constituent compound words appeared while their eye movements were measured. The frequency of the first constituent of the compounds was also varied factorially and the frequency of the lexicalized compounds was equated over the two conditions. The sentence frames prior to the target word were matched across conditions. Both lexicality and first constituent frequency had large and significant effects on gaze durations on the target word; moreover the constituent frequency effect was significantly larger for the novel words. These results indicate that first constituent frequency has an effect in two stages: in the initial encoding of the compound and in the construction of meaning for the novel compound. The difference between this pattern of results and those for English prefixed words (Pollatsek, Slattery, & Juhasz, 2008) is apparently due to differences in the construction of meaning stage. A general model of the relationship of the processing of polymorphemic words to how they are fixated is presented.
Katharine B. Porter; Gideon P. Caplovitz; Peter J. Kohler; Christina M. Ackerman; Peter U. Tse
Rotational and translational motion interact independently with form Journal Article
In: Vision Research, vol. 51, no. 23-24, pp. 2478–2487, 2011.
Do the mechanisms that underlie the perception of translational and rotational object motion show evidence of independent processing? By probing the perceived speed of translating and/or rotating objects, we find that an object's form contributes in independent ways to the processing of translational and rotational motion: In the context of translational motion, it has been shown that the more elongated an object is along its direction of motion, the faster it is perceived to translate; in the context of rotational motion, it has been shown that the sharper the maxima of curvature along an object's contour, the faster it appears to rotate. Here we demonstrate that such rotational form-motion interactions are due solely to the rotational component of combined rotational and translational motion. We conclude that the perception of rotational motion relies on form-motion interactions that are independent of the processing underlying translational motion.
Elsie Premereur; Wim Vanduffel; Peter Janssen
Functional heterogeneity of macaque lateral intraparietal neurons Journal Article
In: Journal of Neuroscience, vol. 31, no. 34, pp. 12307–12317, 2011.
The macaque lateral intraparietal area (LIP) has been implicated in manycognitive processes, ranging from saccade planning and spatial attention to timing and categorization. Importantly, different research groups have used different criteria for including LIP neurons in their studies. While some research groups have selected LIP neurons based on the presence of memory-delay activity, other research groups have used other criteria such as visual, presaccadic, and/or memory activity. We recorded from LIP neurons that were selected based on spatially selective saccadic activity but regardless ofmemory-delay activity in macaque monkeys. To test anticipatory climbing activity, we used a delayed visually guided saccade task with a unimodal schedule ofgo-times, for which the conditional probability that the go-signal will occur rises monotonically as a function of time. A subpopulation of LIP neurons showed anticipatory activity that mimicked the subjective hazard rate ofthe go-signal when the animal was planning a saccade toward the receptive field. Alarge subgroup ofLIP neurons, however, did not modulate their firing rates according to the subjective hazard function. These non-anticipatory neurons were strongly influenced by salient visual stimuli appearing in their receptive field, but less so by the direction ofthe impending saccade. Thus, LIP contains a heterogeneous population ofneurons related to saccade planning or visual salience, and these neurons are spatially intermixed.Our results suggest that between-study differences in neuronal selectionmayhave contributed significantly to the findings of different research groups with respect to the functional role ofarea LIP.
Kerstin Preuschoff; Bernard Marius Hart; Wolfgang Einhäuser
Pupil dilation signals surprise: Evidence for noradrenaline's role in decision making Journal Article
In: Frontiers in Neuroscience, vol. 5, pp. 115, 2011.
Our decisions are guided by the rewards we expect. These expectations are often based on incomplete knowledge and are thus subject to uncertainty. While the neurophysiology of expected rewards is well understood, less is known about the physiology of uncertainty. We hypothesize that uncertainty, or more specifically errors in judging uncertainty, are reflected in pupil dilation, a marker that has frequently been associated with decision-making, but so far has remained largely elusive to quantitative models. To test this hypothesis, we measure pupil dilation while observers perform an auditory gambling task. This task dissociates two key decision variables – uncertainty and reward – and their errors from each other and from the act of the decision itself. We first demonstrate that the pupil does not signal expected reward or uncertainty per se, but instead signals surprise, that is, errors in judging uncertainty. While this general finding is independent of the precise quantification of these decision variables, we then analyze this effect with respect to a specific mathematical model of uncertainty and surprise, namely risk and risk prediction error. Using this quantification, we find that pupil dilation and risk prediction error are indeed highly correlated. Under the assumption of a tight link between noradrenaline (NA) and pupil size under constant illumination, our data may be interpreted as empirical evidence for the hypothesis that NA plays the same role for uncertainty as dopamine does for reward, namely the encoding of error signals.
Rachael D. Rubin; Sarah Brown-Schmidt; Melissa C. Duff; Daniel Tranel; Neal J. Cohen
How do I remember that I know you know that I know? Journal Article
In: Psychological Science, vol. 22, no. 12, pp. 1574–1582, 2011.
Communication is aided greatly when speakers and listeners take advantage of mutually shared knowledge (i.e., common ground). How such information is represented in memory is not well known. Using a neuropsychological-psycholinguistic approach to real-time language understanding, we investigated the ability to form and use common ground during conversation in memory-impaired participants with hippocampal amnesia. Analyses of amnesics' eye fixations as they interpreted their partner's utterances about a set of objects demonstrated successful use of common ground when the amnesics had immediate access to common-ground information, but dramatic failures when they did not. These findings indicate a clear role for declarative memory in maintenance of common-ground representations. Even when amnesics were successful, however, the eye movement record revealed subtle deficits in resolving potential ambiguity among competing intended referents; this finding suggests that declarative memory may be critical to more basic aspects of the on-line resolution of linguistic ambiguity.
Adam J. Sachs; Paul S. Khayat; Robert Niebergall; Julio C. Martinez-Trujillo
A metric-based analysis of the contribution of spike timing to contrast and motion direction coding by single neurons in macaque area MT Journal Article
In: Brain Research, vol. 1368, pp. 163–184, 2011.
Spike timing is thought to contribute to the coding of motion direction information by neurons in macaque area MT. Here, we examined whether spike timing also contributes to the coding of stimulus contrast. We applied a metric-based approach to spike trains fired by MT neurons in response to stimuli that varied in contrast, or direction. We assessed the performance of three metrics, Dspikeand Dproduct(containing spike count and timing information), and the spike count metric Dcount. We analyzed responses elicited during the first 200 msec of stimulus presentation from 205 neurons. For both contrast and direction, the large majority of neurons showed the highest mutual information using Dspike, followed by Dproduct, and Dcount. This was corroborated by the performance of a theoretical observer model at discriminating contrast and direction using the three metrics. Our results demonstrate that spike timing can contribute to contrast coding in MT neurons, and support previous reports of its potential contribution to direction coding. Furthermore, they suggest that a combination of spike count with periodic and non-periodic spike timing information (contained in Dspike, but not in Dproductand Dcountwhich are insensitive to spike counts and timing respectively) provides the largest coding advantage in spike trains fired by MT neurons during contrast and direction discrimination.
Navid G. Sadeghi; Vani Pariyadath; Sameer Apte; David M. Eagleman; Erik P. Cook
Neural correlates of subsecond time distortion in the middle temporal area of visual cortex Journal Article
In: Journal of Cognitive Neuroscience, vol. 23, no. 12, pp. 3829–3840, 2011.
How does the brain represent the passage of time at the subsecond scale? Although different conceptual models for time perception have been proposed, its neurophysiological basis remains unknown. We took advantage of a visual duration illusion produced by stimulus novelty to link changes in cortical activity in monkeys with distortions of duration perception in humans. We found that human subjects perceived the duration of a subsecond motion pulse with a novel direction longer than a motion pulse with a repeated direction. Recording from monkeys viewing identical motion stimuli but performing a different behavioral task, we found that both the duration and amplitude of the neural response in the middle temporal area of visual cortex were positively correlated with the degree of novelty of the motion direction. In contrast to previous accounts that attribute distortions in duration perception to changes in the speed of a putative internal clock, our results suggest that the known adaptive properties of neural activity in visual cortex contributes to subsecond temporal distortions.
Anne Pier Salverda; Gerry T. M. Altmann
Attentional capture of objects referred to by spoken language Journal Article
In: Journal of Experimental Psychology: Human Perception and Performance, vol. 37, no. 4, pp. 1122–1133, 2011.
Participants saw a small number of objects in a visual display and performed a visual detection or visual-discrimination task in the context of task-irrelevant spoken distractors. In each experiment, a visual cue was presented 400 ms after the onset of a spoken word. In experiments 1 and 2, the cue was an isoluminant color change and participants generated an eye movement to the target object. In experiment 1, responses were slower when the spoken word referred to the distractor object than when it referred to the target object. In experiment 2, responses were slower when the spoken word referred to a distractor object than when it referred to an object not in the display. In experiment 3, the cue was a small shift in location of the target object and participants indicated the direction of the shift. Responses were slowest when the word referred to the distractor object, faster when the word did not have a referent, and fastest when the word referred to the target object. Taken together, the results demonstrate that referents of spoken words capture attention.
Sarah Risse; Reinhold Kliegl
Adult age differences in the perceptual span during reading Journal Article
In: Psychology and Aging, vol. 26, no. 2, pp. 451–460, 2011.
Following up on research suggesting an age-related reduction in the rightward extent of the perceptual span during reading (Rayner, Castelhano, & Yang, 2009), we compared old and young adults in an N + 2-boundary paradigm in which a nonword preview of word N + 2 or word N + 2 itself is replaced by the target word once the eyes cross an invisible boundary located after word N. The intermediate word N + 1 was always three letters long. Gaze durations on word N + 2 were significantly shorter for identical than nonword N + 2 preview both for young and for old adults, with no significant difference in this preview benefit. Young adults, however, did modulate their gaze duration on word N more strongly than old adults in response to the difficulty of the parafoveal word N + 1. Taken together, the results suggest a dissociation of preview benefit and parafoveal-on-foveal effect. Results are discussed in terms of age-related decline in resilience towards distributed processing while simultaneously preserving the ability to integrate parafoveal information into foveal processing. As such, the present results relate to proposals of regulatory compensation strategies older adults use to secure an overall reading speed very similar to that of young adults.
Attention, exposure duration, and gaze shifting in naming performance Journal Article
In: Journal of Experimental Psychology: Human Perception and Performance, vol. 37, no. 3, pp. 860–873, 2011.
Two experiments are reported in which the role of attribute exposure duration in naming performance was examined by tracking eye movements. Participants were presented with color-word Stroop stimuli and left- or right-pointing arrows on different sides of a computer screen. They named the color attribute and shifted their gaze to the arrow to manually indicate its direction. The color attribute (Experiment 1) or the complete color-word stimulus (Experiment 2) was removed from the screen 100 ms after stimulus onset. Compared with presentation until trial offset, removing the color attribute diminished Stroop interference, as well as facilitation effects in color naming latencies, whereas removing the complete stimulus diminished interference only. Attribute and stimulus removal reduced the latency of gaze shifting, which suggests decreased rather than increased attentional demand. These results provide evidence that limiting exposure duration contributes to attribute naming performance by diminishing the extent to which irrelevant attributes are processed, which reduces attentional demand.
Martin Rolfs; Donatas Jonikaitis; Heiner Deubel; Patrick Cavanagh
Predictive remapping of attention across eye movements Journal Article
In: Nature Neuroscience, vol. 14, no. 2, pp. 252–258, 2011.
Many cells in retinotopic brain areas increase their activity when saccades (rapid eye movements) are about to bring stimuli into their receptive fields. Although previous work has attempted to look at the functional correlates of such predictive remapping, no study has explicitly tested for better attentional performance at the future retinal locations of attended targets. We found that, briefly before the eyes start moving, attention drawn to the targets of upcoming saccades also shifted to those retinal locations that the targets would cover once the eyes had moved, facilitating future movements. This suggests that presaccadic visual attention shifts serve to both improve presaccadic perceptual processing at the target locations and speed subsequent eye movements to their new postsaccadic locations. Predictive remapping of attention provides a sparse, efficient mechanism for keeping track of relevant parts of the scene when frequent rapid eye movements provoke retinal smear and temporal masking.
Nicholas M. Ross; Linda J. Lanyon; Jaya Viswanathan; Dara S. Manoach; Jason J. S. Barton
Human prosaccades and antisaccades under risk: Effects of penalties and rewards on visual selection and the value of actions Journal Article
In: Neuroscience, vol. 196, pp. 168–177, 2011.
Monkey studies report greater activity in the lateral intraparietal area and more efficient saccades when targets coincide with the location of prior reward cues, even when cue location does not indicate which responses will be rewarded. This suggests that reward can modulate spatial attention and visual selection independent of the "action value" of the motor response. Our goal was first to determine whether reward modulated visual selection similarly in humans, and next, to discover whether reward and penalty differed in effect, if cue effects were greater for cognitively demanding antisaccades, and if financial consequences that were contingent on stimulus location had spatially selective effects. We found that motivational cues reduced all latencies, more for reward than penalty. There was an "inhibition-of-return"-like effect at the location of the cue, but unlike the results in monkeys, cue valence did not modify this effect in prosaccades, and the inhibition-of-return effect was slightly increased rather than decreased in antisaccades. When financial consequences were contingent on target location, locations without reward or penalty consequences lost the benefits seen in noncontingent trials, whereas locations with consequences maintained their gains. We conclude that unlike monkeys, humans show reward effects not on visual selection but on the value of actions. The human saccadic system has both the capacity to enhance responses to multiple locations simultaneously, and the flexibility to focus motivational enhancement only on locations with financial consequences. Reward is more effective than penalty, and both interact with the additional attentional demands of the antisaccade task.
Rodrigo Quian Quiroga; Carlos Pedreira
How do we see art: An eye-tracker study Journal Article
In: Frontiers in Human Neuroscience, vol. 5, pp. 98, 2011.
We describe the pattern of fixations of subjects looking at figurative and abstract paintings from different artists (Molina, Mondrian, Rembrandt, della Francesca) and at modified versions in which different aspects of these art pieces were altered with simple digital manipulations. We show that the fixations of the subjects followed some general common principles (e.g., being attracted to saliency regions) but with a large variability for the figurative paintings, according to the subject's personal appreciation and knowledge. In particular, we found different gazing patterns depending on whether the subject saw the original or the modified version of the painting first. We conclude that the study of gazing patterns obtained by using the eye-tracker technology gives a useful approach to quantify how subjects observe art.
Stefan Rach; Adele Diederich; Hans Colonius
On quantifying multisensory interaction effects in reaction time and detection rate Journal Article
In: Psychological Research, vol. 75, no. 2, pp. 77–94, 2011.
Both mean reaction time (RT) and detection rate (DR) are important measures for assessing the amount of multisensory interaction occurring in crossmodal experiments, but they are often applied separately. Here we demonstrate that measuring multisensory performance using either RT or DR alone misses out on important information. We suggest an integration of RT and DR into a single measure of multisensory performance: the first index (MRE*) is based on an arithmetic combination of RT and DR, the second (MPE) is constructed from parameters derived from fitting a sequential sampling model to RT and DR data simultaneously. Our approach is illustrated by data from two audio-visual experiments. In the first, a redundant targets detection experiment using stimuli of different intensity, both measures yield similar pattern of results supporting the "principle of inverse effectiveness". The second experiment, introducing stimulus onset asynchrony and differing instructions (focused attention vs. redundant targets task) further supports the usefulness of both indices. Statistical properties of both measures are investigated via bootstrapping procedures.
M. Raemaekers; Douwe P. Bergsma; Richard J. A. Wezel; G. J. Wildt; Albert V. Berg
Effects of vision restoration training on early visual cortex in patients with cerebral blindness investigated with functional magnetic resonance imaging Journal Article
In: Journal of Neurophysiology, vol. 105, no. 2, pp. 872–882, 2011.
Cerebral blindness is a loss of vision as a result of postchiasmatic damage to the visual pathways. Parts of the lost visual field can be restored through training. However, the neuronal mechanisms through which training effects occur are still unclear. We therefore assessed training-induced changes in brain function in eight patients with cerebral blindness. Visual fields were measured with perimetry and retinotopic maps were acquired with functional magnetic resonance imaging (fMRI) before and after vision restoration training. We assessed differences in hemodynamic responses between sessions that represented changes in amplitudes of neural responses and changes in receptive field locations and sizes. Perimetry results showed highly varied visual field recovery with shifts of the central visual field border ranging between 1 and 7°. fMRI results showed that, although retinotopic maps were mostly stable over sessions, there was a small shift of receptive field locations toward a higher eccentricity after training in addition to increases in receptive field sizes. In patients with bilateral brain activation, these effects were stronger in the affected than in the intact hemisphere. Changes in receptive field size and location could account for limited visual field recovery (± 1°), although it could not account for the large increases in visual field size that were observed in some patients. Furthermore, the retinotopic maps strongly matched perimetry measurements before training. These results are taken to indicate that local visual field enlargements are caused by receptive field changes in early visual cortex, whereas large-scale improvement cannot be explained by this mechanism.
Keith Rayner; Timothy J. Slattery; Denis Drieghe; Simon P. Liversedge
Eye movements and word skipping during reading: Effects of word length and predictability Journal Article
In: Journal of Experimental Psychology: Human Perception and Performance, vol. 37, no. 2, pp. 514–528, 2011.
Eye movements were monitored as subjects read sentences containing high- or low-predictable target words. The extent to which target words were predictable from prior context was varied: Half of the target words were predictable, and the other half were unpredictable. In addition, the length of the target word varied: The target words were short (4–6 letters), medium (7–9 letters), or long (10–12 letters). Length and predictability both yielded strong effects on the probability of skipping the target words and on the amount of time readers fixated the target words (when they were not skipped). However, there was no interaction in any of the measures examined for either skipping or fixation time. The results demonstrate that word predictability (due to contextual constraint) and word length have strong and independent influences on word skipping and fixation durations. Furthermore, because the long words extended beyond the word identification span, the data indicate that skipping can occur on the basis of partial information in relation to word identity.
Eva Reinisch; Alexandra Jesse; James M. McQueen
Speaking rate from proximal and distal contexts is used during word segmentation Journal Article
In: Journal of Experimental Psychology: Human Perception and Performance, vol. 37, no. 3, pp. 978–996, 2011.
A series of eye-tracking and categorization experiments investigated the use of speaking-rate information in the segmentation of Dutch ambiguous-word sequences. Juncture phonemes with ambiguous durations (e.g., [s] in 'eens (s)peer,' "once (s)pear," [t] in 'nooit (t)rap,' "never staircase/quick") were perceived as longer and hence more often as word-initial when following a fast than a slow context sentence. Listeners used speaking-rate information as soon as it became available. Rate information from a context proximal to the juncture phoneme and from a more distal context was used during on-line word recognition, as reflected in listeners' eye movements. Stronger effects of distal context, however, were observed in the categorization task, which measures the off-line results of the word-recognition process. In categorization, the amount of rate context had the greatest influence on the use of rate information, but in eye tracking, the rate information's proximal location was the most important. These findings constrain accounts of how speaking rate modulates the interpretation of durational cues during word recognition by suggesting that rate estimates are used to evaluate upcoming phonetic information continuously during prelexical speech processing.
Benedikt Reuter; David Möllers; Julia Bender; Asysa Schwehn; Juliane Ziemek; Jürgen Gallinat; Norbert Kathmann
Volitional saccades and attentional mechanisms in schizophrenia patients and healthy control subjects Journal Article
In: Psychophysiology, vol. 48, no. 10, pp. 1333–1339, 2011.
Schizophrenia (SZ) patients showed increased volitional saccade latencies, suggesting deficient volitional initiation of action. Yet increased volitional saccade latencies may also result from deficits in attention shifts. To dissociate attention shifting and saccade initiation, we asked 25 SZ patients and 25 healthy subjects to make saccades toward newly appearing (onset) targets and toward the loci of disappearing (offset) targets. Similar onsets and offsets were also used as attention cues in a Posner-type manual task. As expected, onsets and offsets had similar effects on attention. In contrast, saccade latencies were considerably longer with offset compared to onset targets, reflecting additional time for volitional saccade initiation. Unexpectedly, SZ patients had normal saccade latencies. Presumably, the expected deficit was compensated by decreased fixation-related neural activity, which was induced by the disappearance of fixation stimuli.
Helen J. Richards; Julie A. Hadwin; Valerie Benson; Michael J. Wenger; Nick Donnelly
The influence of anxiety on processing capacity for threat detection Journal Article
In: Psychonomic Bulletin & Review, vol. 18, no. 5, pp. 883–889, 2011.
In the present study, we explored the proposition that an individual's capacity for threat detection is related to his or her trait anxiety. Using a redundant signals paradigm with concurrent measurements of reaction times and eye movements, participants indicated the presence or absence of an emotional target face (angry or happy) in displays containing no targets, one target, or two targets. We used estimates of the orderings on the hazard functions of the RT distributions as measures of processing capacity (Townsend & Ashby, 1978; Wenger & Gibson, Journal of Experimental Psychology. Human Perception and Performance, 30, 708–719, 2004) to assess whether self-reported anxiety and the affective state of the face interacted with the level of perceptual load (i.e., the number of targets). Results indicated that anxiety was associated with fewer eye movements and increased processing capacity to detect multiple (vs. single) threatening faces. The data are consistent with anxiety influencing threat detection via a broadly tuned attentional mechanism (Eysenck, Derakshan, Santos, & Calvo, Emotion, 7, 336–353, 2007).
Brian A. Richardson; Anusha Ratneswaran; James Lyons; Ramesh Balasubramaniam
The time course of online trajectory corrections in memory-guided saccades Journal Article
In: Experimental Brain Research, vol. 212, no. 3, pp. 457–469, 2011.
Recent investigations have revealed the kinematics of horizontal saccades are less variable near the end of the trajectory than during the course of execution. Converging evidence indicates that oculomotor networks use online sensorimotor feedback to correct for initial trajectory errors. It is also known that oculomotor networks express saccadic corrections with decreased efficiency when responses are made toward memorized locations. The present research investigated whether repetitive motor timekeeping influences online feedback-based corrections in predictive saccades. Predictive saccades are a subclass of memory-guided saccades and are observed when one makes series of timed saccades. We hypothesized that cueing predictive saccades in a sequence would facilitate the expression of trajectory corrections. Seven participants produced a number of single unpaced, visually guided saccades, and also sequences of timed predictive saccades. Kinematic and trajectory variability were used to measure the expression of online saccadic corrections at a number of time indices in saccade trajectories. In particular, we estimated the minimum time required to implement feedback-based corrections, which was consistently 37 ms. Our observations demonstrate that motor commands in predictive memory-guided saccades can be parameterized by spatial working memory and retain the accuracy of online trajectory corrections typically associated with visually guided behavior. In contrast, untimed memory-guided saccades exhibited diminished kinematic evidence for online corrections. We conclude that motor timekeeping and sequencing contributed to efficient saccadic corrections. These results contribute to an evolving view of the interactions between motor planning and spatial working memory, as they relate to oculomotor control.
Lily Riggs; Douglas A. McQuiggan; Adam K. Anderson; Jennifer D. Ryan
Evaluation of anti bacterial activity of fruit rind extract of Garcinia mangostana Linn on enteric pathogens-an in vitro study Journal Article
In: Frontiers in Psychology, vol. 4, pp. 205, 2011.
Research shows that memory for emotional aspects of an event may be enhanced at the cost of impaired memory for surrounding peripheral details. However, this has only been assessed directly via verbal reports which reveal the outcome of a long stream of processing but cannot shed light on how/when emotion may affect the retrieval process. In the present experiment, eye movement monitoring (EMM) was used as an indirect measure of memory as it can reveal aspects of online memory processing. For example, do emotions modulate the nature of memory representations or the speed with which such memories can be accessed? Participants viewed central negative and neutral scenes surrounded by three neutral objects and after a brief delay, memory was assessed indirectly via EMM and then directly via verbal reports. Consistent with the previous literature, emotion enhanced central and impaired peripheral memory as indexed by eye movement scanning and verbal reports. This suggests that eye movement scanning may contribute and/or is related to conscious access of memory. However, the central/peripheral tradeoff effect was not observed in an early measure of eye movement behavior, i.e., participants were faster to orient to a critical region of change in the periphery irrespective of whether it was previously studied in a negative or neutral context. These findings demonstrate emotion's differential influences on different aspects of retrieval. In particular, emotion appears to affect the detail within, and/or the evaluation of, stored memory representations, but it may not affect the initial access to those representations.
Lily Riggs; Douglas A. McQuiggan; Norman A. S. Farb; Adam K. Anderson; Jennifer D. Ryan
The role of overt attention in emotion-modulated memory Journal Article
In: Emotion, vol. 11, no. 4, pp. 776–785, 2011.
The presence of emotional stimuli results in a central/peripheral tradeoff effect in memory: memory for central details is enhanced at the cost of peripheral items. It has been assumed that emotion-modulated differences in memory are the result of differences in attention, but this has not been tested directly. The present experiment used eye movement monitoring as an index of overt attention allocation and mediation analysis to determine whether differences in attention were related to subsequent memory. Participants viewed negative and neutral scenes surrounded by three neutral objects and were then given a recognition memory test. The results revealed evidence in support of a central/peripheral tradeoff in both attention and memory. However, contrary with previous assumptions, whereas attention partially mediated emotion-enhanced memory for central pictures, it did not explain the entire relationship. Further, although centrally presented emotional stimuli led to decreased number of eye fixations toward the periphery, these differences in viewing did not contribute to emotion-impaired memory for specific details pertaining to the periphery. These findings suggest that the differential influence of negative emotion on central versus peripheral memory may result from other cognitive influences in addition to overt visual attention or on postencoding processes.
Learning to parse liaison-initial words: An eye-tracking study Journal Article
In: Bilingualism: Language and Cognition, vol. 14, no. 3, pp. 257–279, 2011.
This study investigates the processing of resyllabified words by native English speakers at three proficiency levels in French and by native French speakers. In particular, it examines non-native listeners' development of a parsing procedure for recognizing vowel-initial words in the context of liaison, a process that creates a misalignment of the syllable and word boundaries in French. The participants completed an eye-tracking experiment in which they identified liaison- and consonant-initial real and nonce words in auditory stimuli. The results show that the non-native listeners had little difficulty recognizing liaison-initial real words, and they recognized liaison-initial nonce words more rapidly than consonant-initial ones. By contrast, native listeners recognized consonant-initial real and nonce words more rapidly than liaison-initial ones. These results suggest that native and non-native listeners used different parsing procedures for recognizing liaison-initial words in the task, with the non-native listeners' ability to segment liaison-initial words being phonologically abstract rather than lexical. textcopyright Copyright Cambridge University Press 2011.
Leanne Trick; Lee Hogarth; Theodora Duka
Prediction and uncertainty in human Pavlovian to instrumental transfer Journal Article
In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 37, no. 3, pp. 757–765, 2011.
Attentional capture and behavioral control by conditioned stimuli have been dissociated in animals. The current study assessed this dissociation in humans. Participants were trained on a Pavlovian schedule in which 3 visual stimuli, A, B, and C, predicted the occurrence of an aversive noise with 90%, 50%, or 10% probability, respectively. Participants then went on to separate instrumental training in which a key-press response canceled the aversive noise with a .5 probability on a variable interval schedule. Finally, in the transfer phase, the 3 Pavlovian stimuli were presented in this instrumental schedule and were no longer differentially predictive of the outcome. Observing times and gaze dwell time indexed attention to these stimuli in both training and transfer. Aware participants acquired veridical outcome expectancies in training--that is, A > B > C, and these expectancies persisted into transfer. Most important, the transfer effect accorded with these expectancies, A > B > C. By contrast, observing times accorded with uncertainty--that is, they showed B > A = C during training, and B < A = C in the transfer phase. Dwell time bias supported this association between attention and uncertainty, although these data showed a slightly more complicated pattern. Overall, the study suggests that transfer is linked to outcome prediction and is dissociated from attention to conditioned stimuli, which is linked to outcome uncertainty.
Cara Tsang; Craig G. Chambers
Appearances aren't everything: Shape classifiers and referential processing in cantonese Journal Article
In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 37, no. 5, pp. 1065–1080, 2011.
Cantonese shape classifiers encode perceptual information that is characteristic of their associated nouns, although certain nouns are exceptional. For example, the classifier tiu occurs primarily with nouns for long-narrow-flexible objects (e.g., scarves, snakes, and ropes) and also occurs with the noun for a (short, rigid) key. In 3 experiments, we explored how the semantic information encoded in shape classifiers influences language comprehension. When judging the fit between classifiers and depicted objects in an explicit ranking task, Cantonese speakers evaluated classifier-noun pairings solely in terms of grammatical well-formedness and showed no separate sensitivity to the shape features of objects. In an eye-tracking task (Experiment 2), we also found little sensitivity to shape classifier semantics during real-time comprehension. However, in a subsequent experiment in which referent objects lacked the prototypical features for their accompanying classifiers (Experiment 3), an influence of shape semantics was found in participants' incidental fixations to nontarget objects. We conclude that shape classifiers influence referential interpretation primarily through their grammatical constraints, consistent with the agreementlike nature of classifiers in general. The role of shape classifiers' semantics on processing is apparent only in specific circumstances.
James M. G. Tsui; Christopher C. Pack
Contrast sensitivity of MT receptive field centers and surrounds Journal Article
In: Journal of Neurophysiology, vol. 106, no. 4, pp. 1888–1900, 2011.
Neurons throughout the visual system have receptive fields with both excitatory and suppressive components. The latter are responsible for a phenomenon known as surround suppression, in which responses decrease as a stimulus is extended beyond a certain size. Previous work has shown that surround suppression in the primary visual cortex depends strongly on stimulus contrast. Such complex center-surround interactions are thought to relate to a variety of functions, although little is known about how they affect responses in the extrastriate visual cortex. We have therefore examined the interaction of center and surround in the middle temporal (MT) area of the macaque (Macaca mulatta) extrastriate cortex by recording neuronal responses to stimuli of different sizes and contrasts. Our findings indicate that surround suppression in MT is highly contrast dependent, with the strongest suppression emerging unexpectedly at intermediate stimulus contrasts. These results can be explained by a simple model that takes into account the nonlinear contrast sensitivity of the neurons that provide input to MT. The model also provides a qualitative link to previous reports of a topographic organization of area MT based on clusters of neurons with differing surround suppression strength. We show that this organization can be detected in the gamma-band local field potentials (LFPs) and that the model parameters can predict the contrast sensitivity of these LFP responses. Overall our results show that surround suppression in area MT is far more common than previously suspected, highlighting the potential functional importance of the accumulation of nonlinearities along the dorsal visual pathway.
Geoffrey Underwood; Katherine Humphrey; Editha M. Loon
Decisions about objects in real-world scenes are influenced by visual saliency before and during their inspection Journal Article
In: Vision Research, vol. 51, no. 18, pp. 2031–2038, 2011.
Evidence from eye-tracking experiments has provided mixed support for saliency map models of inspection, with the task set for the viewer accounting for some of the discrepancies between predictions and observations. In the present experiment viewers inspected pictures of road scenes with the task being to decide whether or not they would enter a highway from a junction. Road safety observations have concluded that highly visible road users are less likely to be involved in crashes, suggesting that saliency is important in real-world tasks. The saliency of a critical vehicle was varied in the present task, as was the type of vehicle and the preferred vehicle of the viewer. Decisions were influenced by saliency, with more risky decisions when low saliency motorcycles were present. Given that the vehicles were invariably inspected, this may relate to the high incidence of "looked-but-failed-to-see" crashes involving motorcycles and to prevalence effects in visual search. Eye-tracking measures indicated effects of saliency on the fixation preceding inspection of the critical vehicle (as well as effects on inspection of the vehicle itself), suggesting that high saliency can attract an early fixation. These results have implications for recommendations about the conspicuity of vulnerable road users.
Gurmit Uppal; Mary P. Feely; Michael D. Crossland; Luke Membrey; John Lee; Lyndon Cruz; Gary S. Rubin
Assessment of reading behavior with an infrared eye tracker after 360° macular translocation for age-related macular degeneration Journal Article
In: Investigative Ophthalmology & Visual Science, vol. 52, no. 9, pp. 6486–6496, 2011.
Purpose. Macular translocation (MT360) is complex surgery used to restore reading in exudative age-related macular degeneration (AMD). MT360 involves retinal rotation and subsequent oculomotor globe counterrotation and is not without significant surgical risk. This study attempts to gauge the optimal potential of MT360 in restoring reading ability and describe the quality and extent of recovery. Methods. The six best outcomes were examined from a consecutive series of 23 MT360 cases. Reading behavior and fixation characteristics were examined with an infrared eye tracker. Results were compared to age-matched normal subjects and patients with untreated exudative and nonexudative AMD. Retinal sensitivity was examined with microperimetry to establish threshold visual function. Results. MT360 produced significant improvements in visual function over untreated disease and approximated normal function for reading speed and fixation quality. Relative to the comparative groups, eye tracking revealed the MT360 cohort generated a greater number of horizontal and vertical saccades, of longer latency and reduced velocity. In contrast, saccadic behavior when reading (forward and regressive saccades) closely matched normal function. Microperimetry revealed a reduction in the central scotoma with three patients recovering normal foveal sensitivity. Conclusions. Near normal reading function is recovered despite profound surgical disruption to the anatomy (retinal/oculomotor). MT360 restores foveal function sufficient to produce a single stable locus of fixation, with marked reduction of the central scotoma. Despite the limitations on saccadic function, the quality of reading saccadic behavior is maintained with good reading ability. Oculomotor surgery appears not to limit reading ability, and the results of retinal surgery approximate normal macular function.
Sarah Uzzaman; Steve Joordens
The eyes know what you are thinking: Eye movements as an objective measure of mind wandering Journal Article
In: Consciousness and Cognition, vol. 20, no. 4, pp. 1882–1886, 2011.
Paralleling the recent work by Reichle, Reineberg, and Schooler (2010), we explore the use of eye movements as an objective measure of mind wandering while participants performed a reading task. Participants were placed in a self-classified probe-caught mind wandering paradigm while their eye movements were recorded. They were randomly probed every 2-3. min and were required to indicate whether their mind had been wandering. The results show that eye movements were generally less complex when participants reported mind wandering episodes, with both duration and frequency of within-word regressions, for example, becoming significantly reduced. This is consistent with the theoretical claim that the cognitive processes that normally influence eye movements to enhance semantic processing during reading exert less control during mind wandering episodes.
Seppo Vainio; Raymond Bertram; Anneli Pajunen; Jukka Hyönä
Processing modifier-head agreement in long Finnish words: Evidence from eye movements Journal Article
In: Acta Linguistica Hungarica, vol. 58, no. 1, pp. 134–156, 2011.
The present study investigates whether processing of an inflected Finnish noun is facilitated when preceded by a modifier in the same case ending. In Finnish, modifiers agree with their head nouns both in case and in number and the agreement is expressed by means of suffixes (e.g., vanha/ssa talo/ssa 'old/in house/in' --> 'in the old house'). Vainio et al. (2003; 2008) showed processing benefits for this kind of modifier-head agreement, when the head nouns were relatively short. However, the effect showed up relatively late in the processing stream, such that word n + 1, the word following the target noun talo/ssa, was read faster when it was preceded by an agreeing modifier (vanha/ssa) than when no modifier was present. This led Vainio et al. to the conclusion that agreement exerts its effect at a later stage, namely at the level of syntactic integration and not at the level of lexical access. The current study investigates whether the same holds when head nouns are considerably longer (e.g., kaupungin/talo/ssa 'city house/in' --> 'in the city hall'). Our results show that the effect of agreement is facilitative in case of longer head nouns as well, but -- in contrast to what was found for shorter words -- the effect not only appeared late, but was also observed in earlier processing measures. It thus seems that, in processing long words, benefits related to modifier-head agreement are not confined to post-lexical syntactic integration processes, but extend to lexical identification of the head. Adapted from the source document
Ye Wang; Bogdan F. Iliescu; Jianfu Ma; Kresimir Josic; Valentin Dragoi
Adaptive changes in neuronal synchronization in macaque V4 Journal Article
In: Journal of Neuroscience, vol. 31, no. 37, pp. 13204–13213, 2011.
A fundamental property of cortical neurons is the capacity to exhibit adaptive changes or plasticity. Whether adaptive changes in cortical responses are accompanied by changes in synchrony between individual neurons and local population activity in sensory cortex is unclear. This issue is important as synchronized neural activity is hypothesized to play an important role in propagating information in neuronal circuits. Here, we show that rapid adaptation (300 ms) to a stimulus of fixed orientation modulates the strength of oscillatory neuronal synchronization in macaque visual cortex (area V4) and influences the ability of neurons to distinguish small changes in stimulus orientation. Specifically, rapid adaptation increases the synchronization of individual neuronal responses with local population activity in the gamma frequency band (30-80 Hz). In contrast to previous reports that gamma synchronization is associated with an increase in firing rates in V4, we found that the postadaptation increase in gamma synchronization is associated with a decrease in neuronal responses. The increase in gamma-band synchronization after adaptation is functionally significant as it is correlated with an improvement in neuronal orientation discrimination performance. Thus, adaptive synchronization between the spiking activity of individual neurons and their local population can enhance temporally insensitive, rate-based-coding schemes for sensory discrimination.
Zheng Wang; Anna W. Roe
Trial-to-trial noise cancellation of cortical field potentials in awake macaques by autoregression model with exogenous input (ARX) Journal Article
In: Journal of Neuroscience Methods, vol. 194, no. 2, pp. 266–273, 2011.
Gamma band synchronization has drawn increasing interest with respect to its potential role in neuronal encoding strategy and behavior in awake, behaving animals. However, contamination of these recordings by power line noise can confound the analysis and interpretation of cortical local field potential (LFP). Existing denoising methods are plagued by inadequate noise reduction, inaccuracies, and even introduction of new noise components. To carefully and more completely remove such contamination, we propose an automatic method based on the concept of adaptive noise cancellation that utilizes the correlative features of common noise sources, and implement with AutoRegressive model with eXogenous Input (ARX). We apply this technique to both simulated data and LFPs recorded in the primary visual cortex of awake macaque monkeys. The analyses here demonstrate a greater degree of accurate noise removal than conventional notch filters. Our method leaves desired signal intact and does not introduce artificial noise components. Application of this method to awake monkey V1 recordings reveals a significant power increase in the gamma range evoked by visual stimulation. Our findings suggest that the ARX denoising procedure will be an important pre-processing step in the analysis of large volumes of cortical LFP data as well as high frequency (gamma-band related) electroencephalography/magnetoencephalography (EEG/MEG) applications, one which will help to convincingly dissociate this notorious artifact from gamma-band activity.
Zhong I. Wang; Louis F. Dell'Osso
A unifying model-based hypothesis for the diverse waveforms of infantile nystagmus syndrome Journal Article
In: Journal of Eye Movement Research, vol. 4, no. 1, pp. 1–18, 2011.
We expanded the original behavioral Ocular Motor System (OMS) model for Infantile Nystagmus Syndrome (INS) by incorporating common types of jerk waveforms within a unifying mechanism. Alexander's law relationships were used to produce desired INS null positions and sharpness. At various gaze angles, these relationships influenced the IN slow-phase amplitudes differently, thereby mimicking the gaze-angle effects of INS patients. Transitions from pseudopendular with foveating saccades to jerk waveforms required replacing braking saccades with foveating fast phases and adding a resettable neural integrator in the pursuit pre-motor circuitry. The robust simulations of accurate OMS behavior in the presence of diverse INS waveforms demonstrate that they can all be generated by a loss of pursuit-system damping, supporting this hypothetical origin.
Tessa Warren; Erik D. Reichle; Nikole D. Patson
Lexical and post-lexical complexity effects on eye movements Journal Article
In: Journal of Eye Movement Research, vol. 4, no. 1, pp. 1–10, 2011.
The current study investigated how a post-lexical complexity manipulation followed by a lexical complexity manipulation affects eye movements during reading. Both manipula- tions caused disruption in all measures on the manipulated words, but the patterns of spill- over differed. Critically, the effects of the two kinds of manipulations did not interact, and there was no evidence that post-lexical processing difficulty delayed lexical processing on the next word (c.f. Henderson & Ferreira, 1990). This suggests that post-lexical processing of one word and lexical processing of the next can proceed independently and likely in parallel. This finding is consistent with the assumptions of the E-Z Reader model of eye movement control in reading (Reichle, Warren, & McConnell, 2009).
Eva Van Assche; Denis Drieghe; Wouter Duyck; Marijke Welvaert; Robert J. Hartsuiker
The influence of semantic constraints on bilingual word recognition during sentence reading Journal Article
In: Journal of Memory and Language, vol. 64, no. 1, pp. 88–107, 2011.
The present study investigates how semantic constraint of a sentence context modulates language-non-selective activation in bilingual visual word recognition. We recorded Dutch-English bilinguals' eye movements while they read cognates and controls in low and high semantically constraining sentences in their second language. Early and late eye-movement measures yielded cognate facilitation, both for low- and high-constraint sentences. Facilitation increased gradually as a function of cross-lingual overlap between translation equivalents. A control experiment showed that the same stimuli did not yield cognate effects in English monolingual controls, ensuring that these effects were not due to any uncontrolled stimulus characteristics. The present study supports models of bilingual word recognition with a limited role for top-down influences of semantic constraints on lexical access in both early and later stages of bilingual word recognition.
Marije Beilen; Remco J. Renken; Erik S. Groenewold; Frans W. Cornelissen
Attentional window set by expected relevance of environmental signals Journal Article
In: PLoS ONE, vol. 6, no. 6, pp. e21262, 2011.
The existence of an attentional window--a limited region in visual space at which attention is directed--has been invoked to explain why sudden visual onsets may or may not capture overt or covert attention. Here, we test the hypothesis that observers voluntarily control the size of this attentional window to regulate whether or not environmental signals can capture attention. We have used a novel approach to test this: participants eye-movements were tracked while they performed a search task that required dynamic gaze-shifts. During the search task, abrupt onsets were presented that cued the target positions at different levels of congruency. The participant knew these levels. We determined oculomotor capture efficiency for onsets that appeared at different viewing eccentricities. From these, we could derive the participant's attentional window size as a function of onset congruency. We find that the window was small during the presentation of low-congruency onsets, but increased monotonically in size with an increase in the expected congruency of the onsets. This indicates that the attentional window is under voluntary control and is set according to the expected relevance of environmental signals for the observer's momentary behavioral goals. Moreover, our approach provides a new and exciting method to directly measure the size of the attentional window.
Goedele Van Belle; Thomas Busigny; Philippe Lefèvre; Sven Joubert; Olivier Felician; Francesco Gentile; Bruno Rossion; Philippe Lefèvre; Sven Joubert; Olivier Felician; Francesco Gentile; Bruno Rossion
Impairment of holistic face perception following right occipito-temporal damage in prosopagnosia: Converging evidence from gaze-contingency Journal Article
In: Neuropsychologia, vol. 49, no. 11, pp. 3145–3150, 2011.
Gaze-contingency is a method traditionally used to investigate the perceptual span in reading by selectively revealing/masking a portion of the visual field in real time. Introducing this approach in face perception research showed that the performance pattern of a brain-damaged patient with acquired prosopagnosia (PS) in a face matching task was reversed, as compared to normal observers: the patient showed almost no further decrease of performance when only one facial part (eye, mouth, nose, etc.) was available at a time (foveal window condition, forcing part-based analysis), but a very large impairment when the fixated part was selectively masked (mask condition, promoting holistic perception) (Van Belle, De Graef, Verfaillie, Busigny, & Rossion, 2010a; Van Belle, De Graef, Verfaillie, Rossion, & Lefèvre, 2010b). Here we tested the same manipulation in a recently reported case of pure prosopagnosia (GG) with unilateral right hemisphere damage (Busigny, Joubert, Felician, Ceccaldi, & Rossion, 2010). Contrary to normal observers, GG was also significantly more impaired with a mask than with a window, demonstrating impairment with holistic face perception. Together with our previous study, these observations support a generalized account of acquired prosopagnosia as a critical impairment of holistic (individual) face perception, implying that this function is a key element of normal human face recognition. Furthermore, the similar behavioral pattern of the two patients despite different lesion localizations supports a distributed network view of the neural face processing structures, suggesting that the key function of human face processing, namely holistic perception of individual faces, requires the activity of several brain areas of the right hemisphere and their mutual connectivity.