Action for perception: A motor-visual attentional effect

Five experiments investigated whether preparation of a grasping movement af fects detection and discrimination of visual stimuli. Normal human particip ants were required to prepare to grasp a bar and then to grasp it as fast a s possible on presentation of a visual stimulus. On the basis of the degree of sharing of their intrinsic properties with those of the to-be-grasped b ar, visual stimuli were categorized as "congruent" or "incongruent." Result s showed that grasping reaction times to congruent visual stimuli were fast er than reaction times to incongruent ones. These data indicate that prepar ation to act on an object produces faster processing of stimuli congruent w ith that object. The same facilitation was present also when, after the pre paration of hand grasping, participants were suddenly instructed to inhibit the prepared grasping movement and to respond with a different motor effec tor. The authors suggest that these findings could represent an extension o f the premotor theory of attention, from orienting of attention to spatial locations to orienting of attention to graspable objects.