Statistical patterns of visual search for hidden objects

TL;DR

This study analyzes eye movement patterns during visual search for hidden objects, revealing distinct statistical signatures in saccades and fixations, and how search strategies shift with task difficulty.

Contribution

It uncovers the statistical properties of eye movements in visual search tasks and how search behavior transitions with increasing difficulty.

Findings

Saccadic jumps follow a log-normal distribution.

Fixation step lengths follow a power-law distribution.

Search strategies shift from directional to random with increased difficulty.

Abstract

The movement of the eyes has been the subject of intensive research as a way to elucidate inner mechanisms of cognitive processes. A cognitive task that is rather frequent in our daily life is the visual search for hidden objects. Here we investigate through eye-tracking experiments the statistical properties associated with the search of target images embedded in a landscape of distractors. Specifically, our results show that the twofold process of eye movement, composed of sequences of fixations (small steps) intercalated by saccades (longer jumps), displays characteristic statistical signatures. While the saccadic jumps follow a log normal distribution of distances, which is typical of multiplicative processes, the lengths of the smaller steps in the fixation trajectories are consistent with a power-law distribution. Moreover, the present analysis reveals a clear transition between a directional serial search to an isotropic random movement as the difficulty level of the searching task is increased.