08.01.2014

Talk @ NIP by Aenne Brielmann

Aenne Brielmann from the University of Konstanz will give a talk entitled "Effects of expected value on eye movement accuracy" at the AG NIP, Sand 6, on Wednesday the 19th of February, 2014, at 15:00 hrs.

Abstract

Expected value modulates behavioral choices and biases goal-oriented behavior, such as eye or hand movements, towards a location or stimulus associated with a higher reward. Moreover it has been shown to modulate basic visual processing. Here we investigated the effects of expected value on the accuracy and timing of human smooth pursuit eye movements. As pursuit represents a continuous readout of visual motion information we were able to examine the temporal dynamics of value effects. In three experiments, we measured humans' accuracy in tracking a moving visual target on a computer monitor with their eyes. In experiment 1 (n=11) a coin picture shown prior to target motion onset served as cue indicating whether participants could earn a 25-cent reward by tracking accurately, or whether the trial was unrewarded. Expected value significantly improved eye-movement accuracy. Improvements were seen even in the earliest phase of the eye movement, within 70 ms of tracking onset, indicating that expected value affects visual-motor processing at an early level. This result was replicated in experiment 2 (n=11) in which task difficulty was heightened by using a low-contrast stimulus. In experiment 3 (n=9), we used numerical cues to indicate high- or low-reward trials and found no effects of expected value, suggesting that cues with inherent incentive value are more effective than numerical cues.