Reinforcement effects in anticipatory smooth eye movements

group statistics
Boxplots of anticipatory eye velocity for the whole group of participants in all direction-bias sessions and reinforcement conditions of Experiment 1. Individual mean velocities and 95% confidence interval are also presented with black symbols connected by thin lines. The individual data points' abscissae are randomly jittered on the x-axis in order to avoid the superposition of the symbols.

When predictive information about target motion is available, anticipatory smooth pursuit eye movements (aSPEM) are consistently generated before target appearance, thereby reducing the typical sensorimotor delay between target motion onset and foveation. By manipulating the probability for target motion direction, we were able to bias the direction and mean velocity of aSPEM. This suggests that motion-direction expectancy has a strong effect on the initiation of anticipatory movements. To further understand the nature of anticipatory smooth eye movements, we investigated different effects of reinforcement on aSPEM. In a first experiment, the reinforcement was contingent to a particular anticipatory behavior. A monetary reward was associated to a criterion-matching anticipatory velocity as estimated online during the gap before target motion onset. Our results showed a small but significant effect of behavior-contingent monetary reward on aSPEM. In a second experiment, the proportion of rewarded trials was manipulated across motion directions (right vs. left) independently from participants' behavior. Our results indicate that a bias in expected reward does not systematically affect anticipatory eye movements. Overall, these findings strengthen the notion that anticipatory eye movements can be considered as an operant behavior (similar to visually guided ones), whereas the expectancy for a noncontingent reward cannot efficiently bias them.


All material (c) L. Perrinet. Please check the copyright notice.

This work was supported by ANR project ANR-13-APPR-0008 "ANR R.E.M.".
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