The ecology of gaze shifts

Brockmann, Dirk; Geisel, Theo

doi:10.1016/s0925-2312(00)00227-7

Cited by 94 publications

(97 citation statements)

References 8 publications

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“…2A). To further test the hypothesis of a bimodal distribution underlying microsaccade and saccade generation, we implemented a model of oculomotor behavior derived from known human oculomotor function (22,23). We generated random scanpaths within each image size (see This article is a PNAS Direct Submission.…”

Section: Resultsmentioning

confidence: 99%

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An oculomotor continuum from exploration to fixation

Otero‐Millan

Macknik

Langston

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

109

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During visual exploration, saccadic eye movements scan the scene for objects of interest. During attempted fixation, the eyes are relatively still but often produce microsaccades. Saccadic rates during exploration are higher than those of microsaccades during fixation, reinforcing the classic view that exploration and fixation are two distinct oculomotor behaviors. An alternative model is that fixation and exploration are not dichotomous, but are instead two extremes of a functional continuum. Here, we measured the eye movements of human observers as they either fixed their gaze on a small spot or scanned natural scenes of varying sizes. As scene size diminished, so did saccade rates, until they were continuous with microsaccadic rates during fixation. Other saccadic properties varied as function of image size as well, forming a continuum with microsaccadic parameters during fixation. This saccadic continuum extended to nonrestrictive, ecological viewing conditions that allowed all types of saccades and fixation positions. Eye movement simulations moreover showed that a single model of oculomotor behavior can explain the saccadic continuum from exploration to fixation, for images of all sizes. These findings challenge the view that exploration and fixation are dichotomous, suggesting instead that visual fixation is functionally equivalent to visual exploration on a spatially focused scale.free-viewing | fixational eye movements | miniature eye movements | fixational saccades | natural images C lassic and current vision studies distinguish between visual exploration, characterized by the alternation of saccades and brief fixation periods, and attempted visual fixation, where subjects maintain relative gaze stability despite continuous but minute fixational eye movements (i.e., microsaccades, slow drift, and oculomotor tremor) (1-7). The theoretical separation between exploratory gaze shifts and attempted fixation dates back to the discovery of fixational eye movements in the early 1900s (2-4), and remains central to contemporary discourse in visual, cognitive, and oculomotor research (8). However, mounting evidence in support of a common generator for both exploratory saccades and fixational microsaccades (refs. 9-12 but see ref. 13) brings into question whether such a dichotomy is justified. Instead, it may be that saccades and microsaccades form an oculomotor continuum along the entire spectrum of exploratory scales, with classical exploratory saccades at one end and classical fixational microsaccades at the other end. In that case, it might be baseless to distinguish between fixational and exploratory behaviors. Recent studies have identified abnormal dynamics of saccades and microsaccades as potential diagnostic markers of neurological disease (14-16); thus, the frame of reference proposed here may have important clinical implications concerning the role of the affected brain centers in the patients' oculomotor behavior.To establish such a framework, one must first reconcile any known discrepancy between the ...

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Section: Resultsmentioning

confidence: 99%

“…Second, small saccades have a higher likelihood of occurrence than large saccades (22,23). Further, neural activity maps in the superior colliculus are responsible, at least in part, for both saccadic and microsaccadic targeting (34).…”

Section: Methodsmentioning

confidence: 99%

An oculomotor continuum from exploration to fixation

Otero‐Millan

Macknik

Langston

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

109

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“…The use of such oculomotor constraints allows us to improve the modelling of scanpaths. (Brockmann & Geisel, 2000) used a Lévy flight to simulate the scanpaths. This approach has also been followed in (Boccignone & Ferraro, 2004), where gaze shifts were modeled by using Lévy flights constrained by salience.…”

Section: Introductionmentioning

confidence: 99%

Introducing context-dependent and spatially-variant viewing biases in saccadic models

Meur

Coutrot

2016

Vision Research

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Previous research showed the existence of systematic tendencies in viewing behavior during scene exploration. For instance, saccades are known to follow a positively skewed, long-tailed distribution, and to be more frequently initiated in the horizontal or vertical directions. In this study, we hypothesize that these viewing biases are not universal, but are modulated by the semantic visual category of the stimulus. We show that the joint distribution of saccade amplitudes and orientations significantly varies from one visual category to another. These joint distributions are in addition spatially variant within the scene frame. We demonstrate that a saliency model based on this better understanding of viewing behavioral biases and blind to any visual information outperforms well-established saliency models. We also propose a saccadic model that takes into account classical low-level features and spatially-variant and context-dependent viewing biases. This model outperforms state-of-the-art saliency models, and provides scanpaths in close agreement with human behavior. The better description of viewing biases will not only improve current models of visual attention but could also influence many other applications such as the design of human-computer interfaces, patient diagnosis or image/video processing applications.

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“…In a seminal paper [6], Brockmann and Geisel have shown that a visual system producing Lévy flights implements an efficient strategy of shifting gaze in a random visual environment than any strategy employing a typical scale in gaze shift magnitudes. Lévy flights provide a model of diffusion characterized by the occurrence of long jumps interleaved with local walk.…”

Section: Introductionmentioning

confidence: 99%

“…The fact that a visual system producing Lévy flights implements an efficient strategy of shifting gaze in a visual environment should not be surprizing [6,3]. Indeed, movements of some biological organisms can be represented as a trajectory constructed as a Random Walk Model (a simplified version of Eq.…”

Section: Introductionmentioning

confidence: 99%

The Active Sampling of Gaze-Shifts

Boccignone

Ferraro

2011

Image Analysis and Processing – ICIAP 2011

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Abstract. The ability to predict, given an image or a video, where a human might fixate elements of a viewed scene has long been of interest in the vision community.In this note we propose a different view of the gaze-shift mechanism as that of a motor system implementation of an active random sampling strategy that the Human Visual System has evolved in order to efficiently and effectively infer properties of the surrounding world. We show how it can be exploited to carry on an attentive analysis of dynamic scenes.

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The ecology of gaze shifts

Cited by 94 publications

References 8 publications

An oculomotor continuum from exploration to fixation

An oculomotor continuum from exploration to fixation

Introducing context-dependent and spatially-variant viewing biases in saccadic models

The Active Sampling of Gaze-Shifts

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