Albatrosses, jackals and gaze shifts
Place: Large Lecture Room - CVC
Affiliation: Dipartimento di Scienze dell'Informazione, Universita di Milano, Italy
Gaze shifts are eye movements that play an important role: the Human Visual System (HVS) achieves highest resolution in the fovea and the succession of rapid eye movements (saccades) compensates the loss of visual acuity in the periphery when looking at an ob ject or a scene that spans more than several degrees in the observer’s ﬁeld of view.
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. Interestingly enough, one point that is not addressed by most models is one essential feature of gaze shifts: the ”noisy”, idiosyncratic variation of the random exploration exhibited by diﬀerent observers when viewing the same scene, or even by the same subject along diﬀerent trials. Such variations speak of the stochastic nature of scanpaths.
At the most general level one can assume any scanpath to be the result of a random walk performed to visually explore the environment under the constraints of both the physical information provided by the stimuli (saliency or conspicuity) and the internal state of the observer, shaped by cognitive task being involved) and emotional factors.
Apparently evolution has achieved eﬃcient eye movement strategies with minimal neural resources devoted to memory. This is in common with movement patterns and foraging behaviors of some biological organisms, e.g., spider monkey, albatrosses, jackals that indeed can be represented as random trajectories driven by alpha-stable distributions.
On such basis, in this talk, a diﬀerent view of the gaze-shift mechanism will be introduced as that of a motor system implementation of an active random sampling strategy of the surrounding visual world. Examples will be provided to show how such strategy can be exploited to carry on an attentive analysis of either static and dynamic scenes.