Ben Tatler

17 janvier 2014

School of Psychology, University of Dundee, Dundee, UK

Saccadic decisions in space and time

invité par Sara Spotorno et Anna Montagnini

Abstract : Much has been learnt about the neural mechanisms of decision by studying reaction times, notably of saccadic eye movements in response to suddenly-presented visual targets. However, in real life, most saccades are not evoked in this way, but made spontaneously while viewing complex visual scenes. Here saccadic decisions are described using likelihood theory, where decisions to move the eyes are made when the evidence in favour of moving to a new location in the scene outweighs the evidence for not moving to that location sufficiently. This decision process is implemented using the LATER (Linear Approach to Threshold with Ergodic Rate) model. The present work considers how the dynamics of the decision processes underlying saccade timing in natural scenes are influenced by different aspects of the visual scene. It shows that saccade timings are sensitive to information both at the current fixation location and at the target of the next saccade. While both low- and high-level visual information influence decision times, higher-level semantic information dominates. From these findings this study proposes a decision-map framework for explaining fixation selection in space and time when viewing complex images.

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