A model of the uncertainty effects in choice reaction time that includes a major contribution from effector selection.

Hick's law describes the relation between choice reaction time (RT) and the number of stimulus-response alternatives (NA). For over half a century, this uncertainty effect has been ascribed primarily to the time taken to map a stimulus to its associated response. Here, data from 2 experiments suggests that selection of the appropriate effector-the particular body part to make a response-also contributes substantially to the uncertainty effect....