The effect of expectations on slow oculomotor control—II. Single target displacements

Abstract It had previously been reported that when periodic target steps are tracked, the eye moves smoothly in the expected direction of the target step before the step occurs. Here we report anticipatory smooth eye movements with single target steps, with single ramps, and during smooth pursuit when a single target step is expected following a ramp. The direction and latency of anticipatory smooth eye movements depended on the expected direction and time of the step, but steps in unpredictable directions or at unpredictable times also influenced smooth eye movements. Anticipatory smooth eye movements require retinal error signals. They were not found in the absence of visual targets. Our demonstration that expected target motion need not be predictable nor periodic in order for anticipatory smooth eye movements to occur suggests that expectations about the future position of targets always influence slow eye movements.