Fixational Eye Movements Research Articles

Surviving blind decomposition: A distributional analysis of the time-course of complex word recognition.

The current study addresses a discrepancy in the psycholinguistic literature about the chronology of information processing during the visual recognition of morphologically complex words. Form-then-meaning accounts of complex word recognition claim that morphemes are processed as units of form prior to any influence of their meanings, whereas form-and-meaning models posit that recognition of complex word forms involves the simultaneous access of morphological and semantic information. The study reported here addresses this theoretical discrepancy by applying a nonparametric distributional technique of survival analysis (Reingold & Sheridan, 2014) to 2 behavioral measures of complex word processing. Across 7 experiments reported here, this technique is employed to estimate the point in time at which orthographic, morphological, and semantic variables exert their earliest discernible influence on lexical decision RTs and eye movement fixation durations. Contrary to form-then-meaning predictions, Experiments 1-4 reveal that surface frequency is the earliest lexical variable to exert a demonstrable influence on lexical decision RTs for English and Dutch derived words (e.g., badness; bad + ness), English pseudoderived words (e.g., wander; wand + er) and morphologically simple control words (e.g., ballad; ball + ad). Furthermore, for derived word processing across lexical decision and eye-tracking paradigms (Experiments 1-2; 5-7), semantic effects emerge early in the time-course of word recognition, and their effects either precede or emerge simultaneously with morphological effects. These results are not consistent with the premises of the form-then-meaning view of complex word recognition, but are convergent with a form-and-meaning account of complex word recognition. (PsycINFO Database Record

Spatiotemporal Pixelization to Increase the Recognition Score of Characters for Retinal Prostheses.

Most of the retinal prostheses use a head-fixed camera and a video processing unit. Some studies proposed various image processing methods to improve visual perception for patients. However, previous studies only focused on using spatial information. The present study proposes a spatiotemporal pixelization method mimicking fixational eye movements to generate stimulation images for artificial retina arrays by combining spatial and temporal information. Input images were sampled with a resolution that was four times higher than the number of pixel arrays. We subsampled this image and generated four different phosphene images. We then evaluated the recognition scores of characters by sequentially presenting phosphene images with varying pixel array sizes (6 × 6, 8 × 8 and 10 × 10) and stimulus frame rates (10 Hz, 15 Hz, 20 Hz, 30 Hz, and 60 Hz). The proposed method showed the highest recognition score at a stimulus frame rate of approximately 20 Hz. The method also significantly improved the recognition score for complex characters. This method provides a new way to increase practical resolution over restricted spatial resolution by merging the higher resolution image into high-frame time slots.

Spatiotemporal Pixelization to Increase the Recognition Score of Characters for Retinal Prostheses

Most of the retinal prostheses use a head-fixed camera and a video processing unit. Some studies proposed various image processing methods to improve visual perception for patients. However, previous studies only focused on using spatial information. The present study proposes a spatiotemporal pixelization method mimicking fixational eye movements to generate stimulation images for artificial retina arrays by combining spatial and temporal information. Input images were sampled with a resolution that was four times higher than the number of pixel arrays. We subsampled this image and generated four different phosphene images. We then evaluated the recognition scores of characters by sequentially presenting phosphene images with varying pixel array sizes (6 × 6, 8 × 8 and 10 × 10) and stimulus frame rates (10 Hz, 15 Hz, 20 Hz, 30 Hz, and 60 Hz). The proposed method showed the highest recognition score at a stimulus frame rate of approximately 20 Hz. The method also significantly improved the recognition score for complex characters. This method provides a new way to increase practical resolution over restricted spatial resolution by merging the higher resolution image into high-frame time slots.

A Subconscious Interaction between Fixation and Anticipatory Pursuit.

Ocular smooth pursuit and fixation are typically viewed as separate systems, yet there is evidence that the brainstem fixation system inhibits pursuit. Here we present behavioral evidence that the fixation system modulates pursuit behavior outside of conscious awareness. Human observers (male and female) either pursued a small spot that translated across a screen, or fixated it as it remained stationary. As shown previously, pursuit trials potentiated the oculomotor system, producing anticipatory eye velocity on the next trial before the target moved that mimicked the stimulus-driven velocity. Randomly interleaving fixation trials reduced anticipatory pursuit, suggesting that a potentiated fixation system interacted with pursuit to suppress eye velocity in upcoming pursuit trials. The reduction was not due to passive decay of the potentiated pursuit signal because interleaving "blank" trials in which no target appeared did not reduce anticipatory pursuit. Interspersed short fixation trials reduced anticipation on long pursuit trials, suggesting that fixation potentiation was stronger than pursuit potentiation. Furthermore, adding more pursuit trials to a block did not restore anticipatory pursuit, suggesting that fixation potentiation was not overridden by certainty of an imminent pursuit trial but rather was immune to conscious intervention. To directly test whether cognition can override fixation suppression, we alternated pursuit and fixation trials to perfectly specify trial identity. Still, anticipatory pursuit did not rise above that observed with an equal number of random fixation trials. The results suggest that potentiated fixation circuitry interacts with pursuit circuitry at a subconscious level to inhibit pursuit.SIGNIFICANCE STATEMENT When an object moves, we view it with smooth pursuit eye movements. When an object is stationary, we view it with fixational eye movements. Pursuit and fixation are historically regarded as controlled by different neural circuitry, and alternating between invoking them is thought to be guided by a conscious decision. However, our results show that pursuit is actively suppressed by prior fixation of a stationary object. This suppression is involuntary, and cannot be avoided even if observers are certain that the object will move. The results suggest that the neural fixation circuitry is potentiated by engaging stationary objects, and interacts with pursuit outside of conscious awareness.

A self-avoiding walk with neural delays as a model of fixational eye movements

Fixational eye movements show scaling behaviour of the positional mean-squared displacement with a characteristic transition from persistence to antipersistence for increasing time-lag. These statistical patterns were found to be mainly shaped by microsaccades (fast, small-amplitude movements). However, our re-analysis of fixational eye-movement data provides evidence that the slow component (physiological drift) of the eyes exhibits scaling behaviour of the mean-squared displacement that varies across human participants. These results suggest that drift is a correlated movement that interacts with microsaccades. Moreover, on the long time scale, the mean-squared displacement of the drift shows oscillations, which is also present in the displacement auto-correlation function. This finding lends support to the presence of time-delayed feedback in the control of drift movements. Based on an earlier non-linear delayed feedback model of fixational eye movements, we propose and discuss different versions of a new model that combines a self-avoiding walk with time delay. As a result, we identify a model that reproduces oscillatory correlation functions, the transition from persistence to antipersistence, and microsaccades.

固視微動の確率的振る舞いを再現する数学モデル(視聴覚技術,ヒューマンインタフェースおよび一般)

固視微動の確率的振る舞いを再現する数学モデル(視聴覚技術,ヒューマンインタフェースおよび一般)

弱視者の固視微動に見られる特徴の解析(視聴覚技術,ヒューマンインタフェースおよび一般)

弱視者の固視微動に見られる特徴の解析(視聴覚技術,ヒューマンインタフェースおよび一般)

Microsaccades and interest areas during free-viewing sport task

ABSTRACTMicrosaccades are important fixation eye movements for visual scene perception. Compared to novices, athletes make fewer fixations of longer duration toward limited interest areas crucial for action prediction. Thus, our aim was to study the microsaccade features during those fixations. Gaze behaviour of expert and novice table tennis players was recorder during a task in which subjects were instructed to predict the direction of the ball after the opponent’s throw. Three interest areas from the opponent’s body and one from the ball trajectory were identified. We analysed correctness of predictions, fixations, microsaccades and saccades to estimate the relationship between eye movements toward interest areas and success in the task. Compared to novices, experts fixated more on hand-racket during forehand and on trunk during backhand drive technique. Longer fixations on hand-racket and trunk were associated with higher microsaccade rate with a narrower directional distribution of them. It probably means that athletes focused their gaze on these small areas, suggesting enhanced attention mainly to them, and fewer consideration for the surrounding regions. We can assume that microsaccade rate and average direction could be related to the salience of interest areas during performance.

Enhancing discrimination of fine spatial details with fixational eye movements: Is there an extra-retinal component?

Enhancing discrimination of fine spatial details with fixational eye movements: Is there an extra-retinal component?

Reading speed during a mesopic visual acuity task

Corrected myopes demonstrate reduced visual acuity and less stable fixational eye movements under mesopic conditions, compared to subjects without refractive error (Coletta et al., ARVO, 2007; Coletta et al., ARVO, 2016; FVM, 2016). Reduced acuity in myopia may be related to fixation instability, perhaps analogous to amblyopia, where less stable eye movements are associated with reductions in acuity and reading speed (Kanonidou et al., IOVS, 2010). In this study, we examined whether a subject's acuity and fixation stability were related to the time they spent to read an acuity line. Measurements were made on 31 subjects, mean age 25.7 years. Spherical equivalent refractions ranged from +2.25 to -10.88 D. Mesopic (0.28 cd/m2) and photopic (325 cd/m2) acuity was measured with high contrast letters, five per line, while eye position was recorded at 500 Hz using an EyeLink 1000 video-based eye tracker. Fixations were analyzed for letter sizes corresponding to the mesopic and photopic acuity limits. Fixation stability is reported as the bivariate contour ellipse area (BCEA), taken over a 2-sec interval, representing the area of fixation for 68% of the time. At the mesopic condition, subjects who took longer to read a line at their acuity limit had higher mesopic acuity (p=0.001) and smaller loss of acuity relative to their photopic acuity (p=0.025). However, there was no correlation between reading duration at the photopic acuity limit and photopic acuity (p>0.05), nor between reading duration and refractive error (p>0.05). When the mesopic acuity letter size was read at the photopic light level, BCEA decreased with increasing reading duration (p=0.032). For an acuity task in dim light, reading speed was correlated with acuity, but in an opposite direction to that reported for amblyopia; slower reading speed was associated instead with increased visual performance. Reading speed was not associated with refractive error. Meeting abstract presented at VSS 2017

Fixational eye movements in Tourette syndrome.

Studies of saccadic eye movements in subjects with Tourette syndrome (TS) have provided additional evidence that there is a link between TS symptoms and deficits in fronto-striato-thalamic networks. These studies revealed impaired timing and inhibition of saccades. We compared fixational eye movements, such as microsaccades and ocular drifts, in subjects with TS and healthy controls.We measured horizontal and vertical eye positions with video-oculography in 14 subjects with Tourette syndrome. We found reduced microsaccade amplitude but increased time between adjacent microsaccades (intersaccadic interval). Hence, the rate of microsaccades was reduced in subjects with TS compared to controls. Measure of ocular stability during intersaccadic intervals revealed increased drift velocity and increased variance in eye position. We hypothesize that increased activity of the direct fronto-striatal pathway and the resulting reduction in basal ganglia outflow targeting the superior colliculus fixation zone affect the rate and amplitude of microsaccades in subjects with TS. The resulting impairment in frontal eye field fixation leads to increased drifts during intersaccadic interval in subjects with TS. Possible clinical implication for these results is that fixational eye movements can be objective biological markers of TS.

Microsaccade-rate indicates absorption by music listening.

The power of music is a literary topos, which can be attributed to intense and personally significant experiences, one of them being the state of absorption. Such phenomenal states are difficult to grasp objectively. We investigated the state of musical absorption by using eye tracking. We utilized a load related definition of state absorption: multimodal resources are committed to create a unified representation of music. Resource allocation was measured indirectly by microsaccade rate, known to indicate cognitive processing load. We showed in Exp. 1 that microsaccade rate also indicates state absorption. Hence, there is cross-modal coupling between an auditory aesthetic experience and fixational eye movements. When removing the fixational stimulus in Exp. 2, saccades are no longer generated upon visual input and the cross-modal coupling disappeared. Results are interpreted in favor of the load hypothesis of microsaccade rate and against the assumption of general slowing by state absorption.

Masking of random-walk motion by flicker, and its role in the allocation of motion in the on-line jitter illusion

Typically, perceptual stabilization mechanisms make us unaware of the retinal image motion produced by the small, involuntary eye movements our eyes constantly make during fixation. The breakdown of perceptual stability is demonstrated by the on-line jitter illusion, in which a circular static pattern appears to jitter coherently when surrounded by a flickering annular pattern. Although both regions of the stimulus are subject to retinal motion from eye movements, the visual system attributes this motion to the central static region in the form of visual jitter, while the surrounding flickering region remains perceptually stable. We investigated factors influencing this allocation of motion and reference frame in the on-line jitter illusion. The flickering of the surround was found to impair the detection of simultaneous random-walk motion in this area, giving a detection reliability of around 80% for motion approximating that from fixational eye movements. Changes to spatial texture and location of flicker (centre vs. surrounding annulus) had little effect on the final percept. However, use of a nonconcentric stimulus resulted in a marked reduction in apparent jitter in all subjects. Our results suggest for the on-line jitter illusion, allocation of motion and reference frame is influenced by the general principle that, if one region surrounds another, the surrounding region tends to be allocated as the frame of reference. When this factor is controlled for, spatial textures, location of flicker, and the masking of motion by flicker have a smaller but measurable influence on the final percept.

Abnormal fixational eye movements in strabismus

IntroductionFixational saccades are miniature eye movements that constantly change the gaze during attempted visual fixation. Visually guided saccades and fixational saccades represent an oculomotor continuum and are produced by common...

Towards understanding addiction factors of mobile devices: An eye tracking study on effect of screen size.

Mobile devices addiction has been an important research topic in cognitive science, mental health, and human-machine interaction. Previous works observed mobile device addiction by logging mobile devices activity. Although immersion has been linked as a significant predictor of video game addiction, investigation on addiction factors of mobile device with behavioral measurement has never been done before. In this research, we demonstrated the usage of eye tracking to observe effect of screen size on experience of immersion. We compared subjective judgment with eye movements analysis. Non-parametric analysis on immersion score shows that screen size affects experience of immersion (p<;0.05). Furthermore, our experimental results suggest that fixational eye movements may be used as an indicator for future investigation of mobile devices addiction. Our experimental results are also useful to develop a guideline as well as intervention strategy to deal with smartphone addiction.

10-1 固視微動型カメラ運動に基づく微分型奥行復元アルゴリズムの実装と評価(第10部門 メディア工学(AR・画像認識))

10-1 固視微動型カメラ運動に基づく微分型奥行復元アルゴリズムの実装と評価(第10部門 メディア工学(AR・画像認識))

Fixational eye movements in a visual acuity task

Introduction: Corrected myopes exhibit larger visual acuity loss at low luminance (1, 2) and less precise fixational eye movements (3) than emmetropes. We examined the relationship between fixation stability and acuity at two light levels.

Recording fixational eye movements with a new AOSLO: simulation, measurement and evaluation

Recording fixational eye movements with a new AOSLO: simulation, measurement and evaluation

3-4 固視微動型カメラ回転による画像ボケからの3D復元における低周波成分抑圧の効果(第3部門 コンピュータビジョン)

3-4 固視微動型カメラ回転による画像ボケからの3D復元における低周波成分抑圧の効果(第3部門 コンピュータビジョン)

3-2 固視微動を模擬するカメラ運動からの形状復元における空間周波数の選択的利用(第3部門コンピュータビジョン)

3-2 固視微動を模擬するカメラ運動からの形状復元における空間周波数の選択的利用(第3部門コンピュータビジョン)