Decision urgency invigorates movement in humans
Résumé
Recent work in highly trained monkeys suggests that decision-making and motor control are linked processeswhose regulation by urgency allows reward rate optimization. However, such urgency-based mechanism mightbe species-specific and/or a consequence of practice. Here I show that the unified regulation hypothesis exists innaïve human subjects. Seventeen volunteers performed a reach decision task in which blocks of trials encouragedeither risky or conservative choices. Participants performed at least two sessions in which they were indirectlymotivated to maximize their reward rate. Results show that subjects’ accuracy criterion decreased over timewithin each trial, and that decisions were earlier and less accurate in fast than slow blocks, with a larger differencein session #2 compared to session #1. A simple model in which sensory information is combined with agrowing urgency signal captured these effects. Crucially, arm and eye movement vigor systematically increasedas decision duration increased within blocks and the block-dependent decision policy strongly predicted thekinematics of reaching movements. These results suggest a practice-independent mechanistic link for establishingthe unified control of human decision timing and action vigor in order to optimize the rate of reward.
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