-
Attention, Perception & Psychophysics Nov 2013Previous research on eye guidance in reading has investigated systematic tendencies with respect to horizontal fixation locations on letters within words and the...
Previous research on eye guidance in reading has investigated systematic tendencies with respect to horizontal fixation locations on letters within words and the relationship between fixation location in a word and the duration of the fixation. The present study investigates where readers place their eyes vertically on the line of text and how vertical fixation location is related to fixation duration. Analyses were based on a large corpus of eye movement recordings from single-sentence reading. The vertical preferred viewing location was found to be within the vertical extent of the font, but fixations beyond the vertical boundaries of the text also frequently occurred. Analyzing fixation duration as a function of vertical fixation location revealed a vertical optimal viewing position (vOVP) effect: Fixations were shortest when placed optimally on the line of text, and fixation duration gradually increased for fixations that fell above or below the line of text. The vOVP effect can be explained by the limits of visual resolution along the vertical meridian. It is concluded that vertical and horizontal landing positions in single-sentence reading are associated with differences in fixation durations in opposite ways.
Topics: Fixation, Ocular; Humans; Language; Pattern Recognition, Visual; Reading; Visual Acuity
PubMed: 24189941
DOI: 10.3758/s13414-013-0581-3 -
Journal of Neurophysiology Feb 2000It is well known that, typically, saccadic eye movements precede goal-directed hand movements to a visual target stimulus. Also pointing in general is more accurate when...
It is well known that, typically, saccadic eye movements precede goal-directed hand movements to a visual target stimulus. Also pointing in general is more accurate when the pointing target is gazed at. In this study, it is hypothesized that saccades are not only preceding pointing but that gaze also is stabilized during pointing in humans. Subjects, whose eye and pointing movements were recorded, had to make a hand movement and a saccade to a first target. At arm movement peak velocity, when the eyes are usually already fixating the first target, a new target appeared, and subjects had to make a saccade toward it (dynamical trial type). In the statical trial type, a new target was offered when pointing was just completed. In a control experiment, a sequence of two saccades had to be made, with two different interstimulus intervals (ISI), comparable with the ISIs found in the first experiment for dynamic and static trial types. In a third experiment, ocular fixation position and pointing target were dissociated, subjects pointed at not fixated targets. The results showed that latencies of saccades toward the second target were on average 155 ms longer in the dynamic trial types, compared with the static trial types. Saccades evoked during pointing appeared to be delayed with approximately the remaining deceleration time of the pointing movement, resulting in "normal" residual saccadic reaction times (RTs), measured from pointing movement offset to saccade movement onset. In the control experiment, the latency of the second saccade was on average only 29 ms larger when the two targets appeared with a short ISI compared with trials with long ISIs. Therefore the saccadic refractory period cannot be responsible for the substantially bigger delays that were found in the first experiment. The observed saccadic delay during pointing is modulated by the distance between ocular fixation position and pointing target. The largest delays were found when the targets coincided, the smallest delays when they were dissociated. In sum, our results provide evidence for an active saccadic inhibition process, presumably to keep steady ocular fixation at a pointing target and its surroundings. Possible neurophysiological substrates that might underlie the reported phenomena are discussed.
Topics: Adolescent; Adult; Fingers; Fixation, Ocular; Humans; Movement; Neural Inhibition; Optics and Photonics; Psychomotor Performance; Reaction Time; Saccades
PubMed: 10669480
DOI: 10.1152/jn.2000.83.2.639 -
Psychonomic Bulletin & Review Jun 2024When looking at faces, humans invariably move their eyes to a consistent preferred first fixation location on the face. While most people have the preferred fixation...
When looking at faces, humans invariably move their eyes to a consistent preferred first fixation location on the face. While most people have the preferred fixation location just below the eyes, a minority have it between the nose-tip and mouth. Not much is known about whether these long-term differences in the preferred fixation location are associated with distinct neural representations of faces. To study this, we used a gaze-contingent face adaptation aftereffect paradigm to test in two groups of observers, one with their mean preferred fixation location closer to the eyes (upper lookers) and the other closer to the mouth (lower lookers). In this task, participants were required to maintain their gaze at either their own group's mean preferred fixation location or that of the other group during adaptation and testing. The two possible fixation locations were 3.6° apart on the face. We measured the face adaptation aftereffects when the adaptation and testing happened while participants maintained fixation at either the same or different locations on the face. Both groups showed equally strong adaptation effects when the adaptation and testing happened at the same fixation location. Crucially, only the upper lookers showed a partial transfer of the FAE across the two fixation locations, when adaptation occurred at the eyes. Lower lookers showed no spatial transfer of the FAE irrespective of the adaptation position. Given the classic finding that neural tuning is increasingly position invariant as one moves higher in the visual hierarchy, this result suggests that differences in the preferred fixation location are associated with distinct neural representations of faces.
Topics: Humans; Adult; Facial Recognition; Fixation, Ocular; Male; Young Adult; Female; Figural Aftereffect; Adaptation, Physiological
PubMed: 37930609
DOI: 10.3758/s13423-023-02412-0 -
Proceedings of the National Academy of... Sep 2021Conversation is the platform where minds meet: the venue where information is shared, ideas cocreated, cultural norms shaped, and social bonds forged. Its frequency and...
Conversation is the platform where minds meet: the venue where information is shared, ideas cocreated, cultural norms shaped, and social bonds forged. Its frequency and ease belie its complexity. Every conversation weaves a unique shared narrative from the contributions of independent minds, requiring partners to flexibly move into and out of alignment as needed for conversation to both cohere and evolve. How two minds achieve this coordination is poorly understood. Here we test whether eye contact, a common feature of conversation, predicts this coordination by measuring dyadic pupillary synchrony (a corollary of shared attention) during natural conversation. We find that eye contact is positively correlated with synchrony as well as ratings of engagement by conversation partners. However, rather than elicit synchrony, eye contact commences as synchrony peaks and predicts its immediate and subsequent decline until eye contact breaks. This relationship suggests that eye contact signals when shared attention is high. Furthermore, we speculate that eye contact may play a corrective role in disrupting shared attention (reducing synchrony) as needed to facilitate independent contributions to conversation.
Topics: Adult; Attention; Communication; Concept Formation; Eye Movements; Female; Fixation, Ocular; Humans; Interpersonal Relations; Male; Young Adult
PubMed: 34504001
DOI: 10.1073/pnas.2106645118 -
Journal of Vision Jun 2012During visual fixation, microscopic eye movements shift the image on the retina over a large number of photoreceptors. Although these movements have been investigated... (Comparative Study)
Comparative Study
During visual fixation, microscopic eye movements shift the image on the retina over a large number of photoreceptors. Although these movements have been investigated for almost a century, the amount of retinal image motion they create remains unclear. Currently available estimates rely on assumptions about the probability distributions of eye movements that have never been tested. Furthermore, these estimates were based on data collected with only a few, highly experienced and motivated observers and may not be representative of the instability of naive and inexperienced subjects in experiments that require steady fixation. In this study, we used a high-resolution eye-tracker to estimate the probability distributions of gaze position in a relatively large group of human observers, most of whom were untrained, while they were asked to maintain fixation at the center of a uniform field in the presence/absence of a fixation marker. In all subjects, the probability distribution of gaze position deviated from normality, the underlying assumption of most previous studies. The resulting fixational dispersion of gaze was much larger than previously reported and varied greatly across individuals. Unexpectedly, the precision by which different observers maintained fixation on the marker was best predicted by the properties of ocular drift rather than those of microsaccades. Our results show that, during fixation, the eyes move by larger amounts and at higher speeds than commonly assumed and highlight the importance of ocular drift in maintaining accurate fixation.
Topics: Adult; Attention; Conditioning, Psychological; Fixation, Ocular; Humans; Linear Models; Models, Neurological; Photic Stimulation; Saccades; Young Adult
PubMed: 22728680
DOI: 10.1167/12.6.31 -
Proceedings of the National Academy of... Dec 2021The learning of first object names is deemed a hard problem due to the uncertainty inherent in mapping a heard name to the intended referent in a cluttered and variable...
The learning of first object names is deemed a hard problem due to the uncertainty inherent in mapping a heard name to the intended referent in a cluttered and variable world. However, human infants readily solve this problem. Despite considerable theoretical discussion, relatively little is known about the uncertainty infants face in the real world. We used head-mounted eye tracking during parent-infant toy play and quantified the uncertainty by measuring the distribution of infant attention to the potential referents when a parent named both familiar and unfamiliar toy objects. The results show that infant gaze upon hearing an object name is often directed to a single referent which is equally likely to be a wrong competitor or the intended target. This bimodal gaze distribution clarifies and redefines the uncertainty problem and constrains possible solutions.
Topics: Fixation, Ocular; Humans; Infant; Language Development; Learning; Uncertainty
PubMed: 34933998
DOI: 10.1073/pnas.2107019118 -
Journal of Vision Jul 2010Two contrasting views of visual attention in scenes are the visual salience and the cognitive relevance hypotheses. They fundamentally differ in their conceptualization... (Comparative Study)
Comparative Study
Two contrasting views of visual attention in scenes are the visual salience and the cognitive relevance hypotheses. They fundamentally differ in their conceptualization of the visuospatial representation over which attention is directed. According to the saliency model, this representation is image-based, while the cognitive relevance framework advocates an object-based representation. Previous research has shown that (1) viewers prefer to look at objects over background and that (2) the saliency model predicts human fixation locations significantly better than chance. However, it could be that saliency mainly acts through objects. To test this hypothesis, we investigated where people fixate within real objects and saliency proto-objects. To this end, we recorded eye movements of human observers while they inspected photographs of natural scenes under different task instructions. We found a preferred viewing location (PVL) close to the center of objects within naturalistic scenes. Compared to the PVL for real objects, there was less evidence for a PVL for human fixations within saliency proto-objects. There was no evidence for a PVL when only saliency proto-objects that did not spatially overlap with annotated real objects were analyzed. The results suggest that saccade targeting and, by inference, attentional selection in scenes is object-based.
Topics: Attention; Female; Fixation, Ocular; Humans; Male; Pattern Recognition, Visual; Photic Stimulation; Saccades; Young Adult
PubMed: 20884595
DOI: 10.1167/10.8.20 -
Vision Research Apr 2016While it is known that scleral search coils-measuring the rotation of the eye globe--and modern, video based eye trackers-tracking the center of the pupil and the...
While it is known that scleral search coils-measuring the rotation of the eye globe--and modern, video based eye trackers-tracking the center of the pupil and the corneal reflection (CR)--produce signals with different properties, the mechanisms behind the differences are less investigated. We measure how the size of the pupil affects the eye-tracker signal recorded during saccades with a common pupil-CR eye-tracker. Eye movements were collected from four healthy participants and one person with an aphakic eye while performing self-paced, horizontal saccades at different levels of screen luminance and hence pupil size. Results show that pupil-, and gaze-signals, but not the CR-signal, are affected by the size of the pupil; changes in saccade peak velocities in the gaze signal of more than 30% were found. It is important to be aware of this pupil size dependent change when comparing fine grained oculomotor behavior across participants and conditions.
Topics: Adult; Eye Movements; Female; Fixation, Ocular; Humans; Male; Pupil; Saccades; Young Adult
PubMed: 26940030
DOI: 10.1016/j.visres.2016.01.009 -
Vision Research 2001Two recent studies have investigated the relations of eye and hand movements in extended food preparation tasks, and here the results are compared. The tasks could be... (Review)
Review
Two recent studies have investigated the relations of eye and hand movements in extended food preparation tasks, and here the results are compared. The tasks could be divided into a series of actions performed on objects. The eyes usually reached the next object in the sequence before any sign of manipulative action, indicating that eye movements are planned into the motor pattern and lead each action. The eyes usually fixated the same object throughout the action upon it, although they often moved on to the next object in the sequence before completion of the preceding action. The specific roles of individual fixations could be identified as locating (establishing the locations of objects for future use), directing (establishing target direction prior to contact), guiding (supervising the relative movements of two or three objects) and checking (establishing whether some particular condition is met, prior to the termination of an action). It is argued that, at the beginning of each action, the oculomotor system is supplied with the identity of the required object, information about its location, and instructions about the nature of the monitoring required during the action. The eye movements during this kind of task are nearly all to task-relevant objects, and thus their control is seen as primarily 'top-down', and influenced very little by the 'intrinsic salience' of objects.
Topics: Eye Movements; Fixation, Ocular; Food Handling; Humans; Psychomotor Performance
PubMed: 11718795
DOI: 10.1016/s0042-6989(01)00102-x -
The Journal of Neuroscience : the... Feb 2014Classical image statistics, such as contrast, entropy, and the correlation between central and nearby pixel intensities, are thought to guide ocular fixation targeting....
Classical image statistics, such as contrast, entropy, and the correlation between central and nearby pixel intensities, are thought to guide ocular fixation targeting. However, these statistics are not necessarily task relevant and therefore do not provide a complete picture of the relationship between informativeness and ocular targeting. Moreover, it is not known whether either informativeness or classical image statistics affect microsaccade production; thus, the role of microsaccades in information acquisition is also unknown. The objective quantification of the informativeness of a scene region is a major challenge, because it can vary with both image features and the task of the viewer. Thus, previous definitions of informativeness suffered from subjectivity and inconsistency across studies. Here we developed an objective measure of informativeness based on fixation consistency across human observers, which accounts for both bottom-up and top-down influences in ocular targeting. We then analyzed fixations in more versus less informative image regions in relation to classical statistics. Observers generated more microsaccades on more informative than less informative image regions, and such regions also exhibited low redundancy in their classical statistics. Increased microsaccade production was not explained by increased fixation duration, suggesting that the visual system specifically uses microsaccades to heighten information acquisition from informative regions.
Topics: Algorithms; Blinking; Entropy; Face; Female; Fixation, Ocular; Humans; Male; Photic Stimulation; Saccades; Vision, Ocular; Visual Perception; Young Adult
PubMed: 24553936
DOI: 10.1523/JNEUROSCI.4448-13.2014