Involuntary grasping and groping responses to space-related visual stimuli

Involuntary groping-grasping responses to visual stimuli were studied in relation to the location of the stimuli in the space surrounding the patient. The following space-related patterns of stimulus-response were observed in four patients: (a) responses were evoked only by visual stimuli in the hemispace ipsilateral to the arm involved; (b) responses were evoked only by visual stimuli within the reach of maximal arm extension; (c) responses were evoked only by visual stimuli in the space around the hand; (d) all such patterns were variously combined. These findings are discussed in relation to the general problem of specific correlations between sensorimotor subsystems and peripersonal behavioral space.