Motor awareness without perceptual awareness.
The control of action has traditionally been described as "automatic". In particular, movement control may occur without conscious awareness, in contrast to normal visual perception. Studies on rapid visuomotor adjustment of reaching movements following a target shift have played a large part in introducing such distinctions. We suggest that previous studies of the relation between motor performance and perceptual awareness have confounded two separate dissociations. These are: (a) the distinction between motoric and perceptual representations, and (b) an orthogonal distinction between conscious and unconscious processes. To articulate these differences more clearly, we propose a new measure of motor awareness, based on subjects' ability to reproduce the spatial details of reaching movements they have just made. Here we focus on the dissociation between motor awareness and perceptual awareness that may occur when subjects make rapid visuomotor adjustments to reaching movements following a target shift. In experiment 1, motor awareness was dissociated from perceptual awareness of a target shift during reaching movement. Participants' reproduction of movement endpoints following visuomotor adjustment was independent of whether they saw the target shift or not. Experiment 2 replicated this result, and further showed that neither motor awareness nor motor performance were disrupted by TMS over the parietal cortex. The neural mechanisms underlying motor awareness, and the implications for theories of consciousness, are discussed.
Johnson
Helen
H
Institute of Cognitive Neuroscience and Department of Psychology, University College London, Alexandra House, 17 Queen Square, London WC1N 3AR, UK.
Haggard
Patrick
P
D000328:Adult; D001364:Awareness / Q000502:physiology*; D001696:Biomechanical Phenomena; D004574:Electromagnetic Fields; D005260:Female; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology; D010465:Perception / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D012438:Saccades / Q000502:physiology