Anticipating uncertain events: estimates of probability driving anticipatory eye movements

Abstract

Introduction Animal and human sensorimotor behavior is influenced by expecting that a particular event will occur. Such expectancy is likely to rely on an internal estimation of the probability of occurrence of different events. Furthermore, expectancy can affect several aspects of the behavioral response, like reaction times [1], visuomotor gain [2] and anticipatory motor responses [3]. In this study, we analyze anticipatory smooth pursuit eye movements as a function of the relative probability of occurrence of different target motion types. Smooth pursuit eye movements (SPEM) permit the stabilization of the image of moving targets on the retina. In humans, visually guided SPEM start typically with a 100 ms latency with respect to target motion onset, leading to an initial lag of the eye relative to the target position (retinal error) and speed (retinal slip). Anticipatory SPEM (aSPEM) can be initiated some hundreds of milliseconds before target onset when the motion characteristics are totally or partially predictable and they might help reduce retinal error and slip.