Recognition of hand shape drawings on vertical and horizontal display.

Abstract

visual recognition of body parts activates somato-motor representations in the brain. In the present study, we investigate the influence of the plane in which hand drawings are displayed (Vertical or Horizontal) on mental rotations evoked by a handedness recognition task. Sixteen right-handed volunteers participated in an experiment where the task was to evaluate the handedness of drawings of the human hand presented in different perspectives and orientations while the Manual Reaction Time (MRT) was measured. For eight volunteers, the hand drawings were displayed on a vertical screen monitor, while for the remainder a mirror was employed and the same drawings appeared on the horizontal plan. Our main finding was that there are no differences in MRTs among the drawings displayed vertically or horizontally, with some exceptions. However, the MRTs were longer when the hands in the drawings assumed configurations that were more awkward to perform using real movements. These results show that the implicit movements involved with handedness recognition are mainly dependent on biomechanical constraints for distal (hand), but not proximal (shoulder) movements. Keywords: handedness recognition, motor imagery, manual reaction time, visual representations, sensorimotor representations.