Optimal planning of eye movements

Abstract

The capability of directing gaze to relevant parts in the environment is crucial for our survival. Computational models based on ideal-observer theory have provided quantitative accounts of human gaze selection in a range of visual search tasks. According to these models, gaze is directed to the position in a visual scene, at which uncertainty about task relevant properties will be reduced maximally with the next look. However, in tasks going beyond a single action, delayed rewards can play a crucial role thereby necessitating planning. Here we investigate whether humans are capable of planning more than the next single eye movement. We found evidence that our subjects' behavior was better explained by an ideal planner compared to the ideal observer. In particular, the location of the first fixation differed depending on the stimulus and the time available for the search. Overall, our results are the first evidence that our visual system is capable of planning.Actively deciding where to direct our eyes is an essential ability in fundamental 1 tasks, which rely on acquiring visual information for survival such as gathering 2 food, avoiding predators, making tools, and social interaction. As we can only 3 perceive a small proportion of our surroundings at any moment in time due to 4 the spatial distribution of our retinal receptor cells 1 , we are constantly forced to 5 bring task relevant parts of the visual scene into focus using eye movements 2 . 6Thus, vision is a sequential process of active decisions. These decisions have locations that are most salient 11 .