Arm-body adaptation with passive arm movements

Abstract

Two experiments investigated the aftereffects of pointing with passive movements during exposure to 15-deg laterally displacing wedge pnsms. Experiment 1 compared exposure with passive and active supported movements when the aftereffects were measured with the arm still in the passive movement device. Following passive exposure and active supported exposure, 5.6 and 7.9 deg, respectively, of arm-body adaptation were measured. In Experiment 2, the passive and active supported exposure tasks were compared with a third task in which similar movements were made with the arm fully supported by the muscles. Aftereffects were measured with active test movements. The amount of arm-body adaptation measured following passive exposure was decreased to 2.8 deg, and following active supported exposure it was decreased to 2.8 deg, while following exposure with normal active movements, 5.3 deg of arm-body adaptation was found. The results suggest that when the arm remains outstretched during prism exposure, adaptation is specific to this extended posture. © 1972 Psychonomic Society, Inc.