scholarly journals Looking for symmetry: fixational eye movements are biased by image mirror symmetry

2016 ◽  
Vol 116 (3) ◽  
pp. 1250-1260 ◽  
Author(s):  
Andrew Isaac Meso ◽  
Anna Montagnini ◽  
Jason Bell ◽  
Guillaume S. Masson
Keyword(s):  
Eye Movements ◽  
Mirror Symmetry ◽  
Stimulus Onset ◽  
Orientation Discrimination ◽  
Automatic Process ◽  
Spatial Correlations ◽  
Fixational Eye Movements ◽  
Free Exploration ◽  
Highly Sensitive ◽  
Active Exploration

Humans are highly sensitive to symmetry. During scene exploration, the area of the retina with dense light receptor coverage acquires most information from relevant locations determined by gaze fixation. We characterized patterns of fixational eye movements made by observers staring at synthetic scenes either freely (i.e., free exploration) or during a symmetry orientation discrimination task (i.e., active exploration). Stimuli could be mirror-symmetric or not. Both free and active exploration generated more saccades parallel to the axis of symmetry than along other orientations. Most saccades were small (<2°), leaving the fovea within a 4° radius of fixation. Analysis of saccade dynamics showed that the observed parallel orientation selectivity emerged within 500 ms of stimulus onset and persisted throughout the trials under both viewing conditions. Symmetry strongly distorted existing anisotropies in gaze direction in a seemingly automatic process. We argue that this bias serves a functional role in which adjusted scene sampling enhances and maintains sustained sensitivity to local spatial correlations arising from symmetry.

Impact of microsaccades on visual shape processing

2020 ◽  
Author(s):  
Ken W. S. Tan ◽  
Chris Scholes ◽  
Neil W Roach ◽  
Elizabeth M. Haris ◽  
Paul V McGraw
Keyword(s):  
Eye Movements ◽  
Stimulus Onset ◽  
Local Form ◽  
Global Integration ◽  
Fixational Eye Movements ◽  
Spatial Pooling ◽  
Steady Fixation ◽  
Shape Processing ◽  
Radial Frequency ◽  
Visual Shape

Sensitivity to subtle changes in the shape of visual objects has been attributed to the existence of global pooling mechanisms that integrate local form information across space. While global pooling is typically demonstrated under steady fixation, other work suggests prolonged fixation can lead to a collapse of global structure. Here we ask whether small ballistic eye movements that naturally occur during periods of fixation affect the global processing of radial frequency (RF) patterns - closed contours created by sinusoidally modulating the radius of a circle. Observers were asked to discriminate the shapes of circular and RF modulated patterns while fixational eye movements were recorded binocularly at 500Hz. Microsaccades were detected using a velocity-based algorithm, allowing trials to be sorted according to the relative timing of stimulus and microsaccade onset. Results revealed clear peri-saccadic changes in shape discrimination thresholds. Performance was impaired when microsaccades occurred close to stimulus onset, but facilitated when they occurred shortly afterwards. In contrast, global integration of shape was unaffected by the timing of microsaccades. These findings suggest that microsaccades alter the discrimination sensitivity to briefly presented shapes but do not disrupt the spatial pooling of local form signals.

scholarly journals Lexical Processes and Eye Movements in Neglect Dyslexia

2002 ◽  
Vol 13 (1-2) ◽  
pp. 61-74 ◽  
Author(s):  
Giuseppe di Pellegrino ◽  
Elisabetta Làdavas ◽  
Claudio Galletti
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Letter String ◽  
Stimulus Onset ◽  
Superiority Effect ◽  
Unilateral Brain Damage ◽  
Highly Sensitive ◽  
Neglect Dyslexia ◽  
Lexical Processes ◽  
Contralesional Side

Neglect dyslexia is a disturbance in the allocation of spatial attention over a letter string following unilateral brain damage. Patients with this condition may fail to read letters on the contralesional side of an orthographic string. In some of these cases, reading is better with words than with non-words. This word superiority effect has received a variety of explanations that differ, among other things, with regard to the spatial distribution of attention across the letter string during reading. The primary goal of the present study was to explore the interaction between attention and lexical processes by recording eye movements in a patient (F.C.) with severe left neglect dyslexia who was required to read isolated word and non-word stimuli of various length.F.C.’s ocular exploration of orthographic stimuli was highly sensitive to the lexical status of the letter string. We found that: (1) the location to which F.C. directed his initial saccade (obtained approximately 230 ms post-stimulus onset) differed between word and non-word stimuli; (2) the patient spent a greater amount of time fixating the contralesional side of word than non-word strings. Moreover, we also found that F.C. failed to identify the left letters of a string despite having fixated them, thus showing a clear dissociation between eye movement responses and conscious access to orthographic stimuli.Our data suggest the existence of multiple interactions between lexical, attentional and eye movement systems that occur from very initial stages of visual word recognition.

scholarly journals Decorrelation of retinal response to natural scenes by fixational eye movements

2015 ◽  
Vol 112 (10) ◽  
pp. 3110-3115 ◽  
Author(s):  
Irina Yonit Segal ◽  
Chen Giladi ◽  
Michael Gedalin ◽  
Michele Rucci ◽  
Mor Ben-Tov ◽  
...  
Keyword(s):  
Eye Movements ◽  
Retinal Ganglion Cells ◽  
Visual Information ◽  
Ganglion Cells ◽  
Natural World ◽  
Natural Scenes ◽  
Retinal Ganglion ◽  
Spatial Correlations ◽  
Fixational Eye Movements ◽  
Spatiotemporal Signal

Under natural viewing conditions the input to the retina is a complex spatiotemporal signal that depends on both the scene and the way the observer moves. It is commonly assumed that the retina processes this input signal efficiently by taking into account the statistics of the natural world. It has recently been argued that incessant microscopic eye movements contribute to this process by decorrelating the input to the retina. Here we tested this theory by measuring the responses of the salamander retina to stimuli replicating the natural input signals experienced by the retina in the presence and absence of fixational eye movements. Contrary to the predictions of classic theories of efficient encoding that do not take behavior into account, we show that the response characteristics of retinal ganglion cells are not sufficient in themselves to disrupt the broad correlations of natural scenes. Specifically, retinal ganglion cells exhibited strong and extensive spatial correlations in the absence of fixational eye movements. However, the levels of correlation in the neural responses dropped in the presence of fixational eye movements, resulting in effective decorrelation of the channels streaming information to the brain. These observations confirm the predictions that microscopic eye movements act to reduce correlations in retinal responses and contribute to visual information processing.

scholarly journals The Role of Symmetry in the Aesthetics of Residential Building Façades Using Cognitive Science Methods

Symmetry ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1438
Author(s):  
Hamidreza Azemati ◽  
Fatemeh Jam ◽  
Modjtaba Ghorbani ◽  
Matthias Dehmer ◽  
Reza Ebrahimpour ◽  
...  
Keyword(s):  
Eye Movements ◽  
Mirror Symmetry ◽  
Aesthetic Experience ◽  
Residential Building ◽  
Science Methods ◽  
Fixational Eye Movements ◽  
Significant Difference ◽  
Building Facades ◽  
The Aesthetic

Symmetry is an important visual feature for humans and its application in architecture is completely evident. This paper aims to investigate the role of symmetry in the aesthetics judgment of residential building façades and study the pattern of eye movement based on the expertise of subjects in architecture. In order to implement this in the present paper, we have created images in two categories: symmetrical and asymmetrical façade images. The experiment design allows us to investigate the preference of subjects and their reaction time to decide about presented images as well as record their eye movements. It was inferred that the aesthetic experience of a building façade is influenced by the expertise of the subjects. There is a significant difference between experts and non-experts in all conditions, and symmetrical façades are in line with the taste of non-expert subjects. Moreover, the patterns of fixational eye movements indicate that the horizontal or vertical symmetry (mirror symmetry) has a profound influence on the observer’s attention, but there is a difference in the points watched and their fixation duration. Thus, although symmetry may attract the same attention during eye movements on façade images, it does not necessarily lead to the same preference between the expert and non-expert groups.

Orienting and Focusing in Voluntary and Involuntary Visuospatial Attention Conditions

2010 ◽  
Vol 24 (3) ◽  
pp. 198-209 ◽  
Author(s):  
Yan Wang ◽  
Jianhui Wu ◽  
Shimin Fu ◽  
Yuejia Luo
Keyword(s):  
Gain Control ◽  
Event Related Potentials ◽  
Stimulus Onset ◽  
Orientation Discrimination ◽  
Involuntary Attention ◽  
Attention Condition ◽  
Voluntary Attention ◽  
Visual Spatial ◽  
Related Potentials ◽  
Underlying Mechanisms

In the present study, we used event-related potentials (ERPs) and behavioral measurements in a peripherally cued line-orientation discrimination task to investigate the underlying mechanisms of orienting and focusing in voluntary and involuntary attention conditions. Informative peripheral cue (75% valid) with long stimulus onset asynchrony (SOA) was used in the voluntary attention condition; uninformative peripheral cue (50% valid) with short SOA was used in the involuntary attention condition. Both orienting and focusing were affected by attention type. Results for attention orienting in the voluntary attention condition confirmed the “sensory gain control theory,” as attention enhanced the amplitude of the early ERP components, P1 and N1, without latency changes. In the involuntary attention condition, compared with invalid trials, targets in the valid trials elicited larger and later contralateral P1 components, and smaller and later contralateral N1 components. Furthermore, but only in the voluntary attention condition, targets in the valid trials elicited larger N2 and P3 components than in the invalid trials. Attention focusing in the involuntary attention condition resulted in larger P1 components elicited by targets in small-cue trials compared to large-cue trials, whereas in the voluntary attention condition, larger P1 components were elicited by targets in large-cue trials than in small-cue trials. There was no interaction between orienting and focusing. These results suggest that orienting and focusing of visual-spatial attention are deployed independently regardless of attention type. In addition, the present results provide evidence of dissociation between voluntary and involuntary attention during the same task.

scholarly journals Fixation eye movement abnormalities and stereopsis recovery following strabismus repair

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Talora L. Martin ◽  
Jordan Murray ◽  
Kiran Garg ◽  
Charles Gallagher ◽  
Aasef G. Shaikh ◽  
...  
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Functional Improvement ◽  
Slow Phase ◽  
Fixational Eye Movements ◽  
Movement Characteristics ◽  
Adaptive Mechanisms ◽  
Before And After ◽  
Gaze Holding ◽  
Fixational Saccades

AbstractWe evaluated the effects of strabismus repair on fixational eye movements (FEMs) and stereopsis recovery in patients with fusion maldevelopment nystagmus (FMN) and patients without nystagmus. Twenty-one patients with strabismus, twelve with FMN and nine without nystagmus, were tested before and after strabismus repair. Eye-movements were recorded during a gaze-holding task under monocular viewing conditions. Fast (fixational saccades and quick phases of nystagmus) and slow (inter-saccadic drifts and slow phases of nystagmus) FEMs and bivariate contour ellipse area (BCEA) were analyzed in the viewing and non-viewing eye. Strabismus repair improved the angle of strabismus in subjects with and without FMN, however patients without nystagmus were more likely to have improvement in stereoacuity. The fixational saccade amplitudes and intersaccadic drift velocities in both eyes decreased after strabismus repair in subjects without nystagmus. The slow phase velocities were higher in patients with FMN compared to inter-saccadic drifts in patients without nystagmus. There was no change in the BCEA after surgery in either group. In patients without nystagmus, the improvement of the binocular function (stereopsis), as well as decreased fixational saccade amplitude and intersaccadic drift velocity, could be due, at least partially, to central adaptive mechanisms rendered possible by surgical realignment of the eyes. The absence of improvement in patients with FMN post strabismus repair likely suggests the lack of such adaptive mechanisms in patients with early onset infantile strabismus. Assessment of fixation eye movement characteristics can be a useful tool to predict functional improvement post strabismus repair.

scholarly journals Control and coordination of fixational eye movements in the Snellen acuity test

2019 ◽  
Vol 19 (10) ◽  
pp. 145a
Author(s):  
Janis Intoy ◽  
Michele A Cox ◽  
Michele Rucci
Keyword(s):  
Eye Movements ◽  
Fixational Eye Movements ◽  
Snellen Acuity ◽  
Acuity Test

scholarly journals What is the best fixation target? The effect of target shape on stability of fixational eye movements

2013 ◽  
Vol 76 ◽  
pp. 31-42 ◽  
Author(s):  
L. Thaler ◽  
A.C. Schütz ◽  
M.A. Goodale ◽  
K.R. Gegenfurtner
Keyword(s):  
Eye Movements ◽  
Fixation Target ◽  
Target Shape ◽  
Fixational Eye Movements
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