Redundancy gain with static versus moving hands: a test of the hemispheric coactivation model

A simple reaction time (RT) experiment was conducted to test the hypothesis that redundancy gain arises partly because of hemispheric coactivation. Stimuli were presented to the left or right of fixation, or redundantly to both, and the participants had to make keypress responses as rapidly as possible to stimulus onset. A "static" condition, in which the participants held their hands at rest, was compared with a "dynamic" condition, in which they moved their hands back and forth in an oscillating motion prior to stimulus onset. As predicted from the hypothesis of hemispheric coactivation, redundancy gain, measured as the decrease in mean RT to redundant stimuli as compared with single stimuli, was smaller in the dynamic condition than in the static one.