Effects of short-term hand immobilization on anticipatory mechanism for tool use.

The short-term immobilization of a limb such as the right arm can impair sensorimotor mechanisms, which in turn reduces motor control of this arm. However, it is not known whether immobilization also impairs the anticipatory mechanism for tool use without actual enactment. In two experiments, we asked participants to judge how they would use a tool in a particular environment (e.g., "Take the pencil to write on a sheet of paper"). Prior to this tool-use judgment task, some participants had been immobilized (right arm) for 24 h. Results revealed that compared to controls, immobilized participants performed more poorly on the tool-use judgment task (accuracy and response time) as well as in a manual dexterity task. As our tool-use judgment task involved anticipating the expected perceptual effect of using a tool to achieve an environmental goal (e.g., writing on a sheet of paper), our data are discussed in line with theories of motor control (e.g., ideomotor theory) that emphasize the expected perceptual consequences of the action.