VISUAL AND KINESTHETIC CONTROL OF GOAL-DIRECTED MOVEMENTS TO VISUALLYAND KINESTHETICALLY PRESENTED TARGETS

The study investigated the contribution of kinesthetic and visual inpu t to the performance of reaching movements and identified rules govern ing the transformation of information between these two sensory modali ties. The study examined the accuracy by which 39 subjects reproduced locations of five targets in a horizontal plane. Mode of target presen tation and feedback during reproduction of a target's location was eit her visual, kinesthetic or a combination of both modalities. Thus, it was possible to examine performance when target presentation and repro duction involved feedback from the same sensory modality (intramodal) as well as from different sensory modalities (intermodal). Errors in t arget reproduction were calculated in terms of distance and systematic biases in movement extent. The major findings of the study are (1) In tramodal reproduction of a target's location on the basis of kinesthet ic feedback is somewhat less accurate than intramodal reproduction on the basis of visual feedback. (2) Intermodal performance is significan tly less accurate than intramodal performance. (3) Accuracy of perform ance does not depend on the direction of information transfer between sensory modalities. (4) Intermodal performance is characterized by sys tematic biases in extent of movement which are dependent on the direct ion of information transfer between modalities. (5) When presentation of the target's location is bimodal, reproduction is adversely affecte d by the conflicting input. The results suggest that transformation ru les, used to combine input from Various sensory modalities, depend on environmental conditions and attention.