An analysis of human adaptation to prismatically displaced vision

Abstract

Experiments were undertaken on prism adaptation in humans. Two treatment conditions were used. The restricted, where only localising movements of the arm were allowed and the free situation, where the subject was free to walk about. In the first situation: a) Adaptation takes place in effect at the level of the position sensors of the used joint. This is a change in felt limb position. b) Movement of the joint is a prerequisite condition. c) The sensory channel feeding in the error information is a passive instrument. d) Adaptation does not affect automatic movements: these take place without using information about joint position. In the second situation: a) Adaptation takes place in the positioning system of the eye; i.e., a change in the appreciated eye position. b) This form of adaptation takes place when the limbs are inspected, with or without repeated voluntary positioning movements of the eye. Immobility of the limbs favours this type of adaptation, but it will occur when gross limb movements are taking place.