Processing spatial information in the sensorimotor branch of the visual system.
We distinguish two representations of visual space: a cognitive representation drives perception, and a sensorimotor representation controls visually guided behavior. Spatial values in the two representations are separated with the Roelofs effect: a target within an off-center frame appears biased in a location opposite the direction of the frame. The effect appears for a verbal measure (cognitive) but not for a jab at the target (sensorimotor). A 2-s response delay induces a Roelofs effect in the motor measure, showing the limit of motor memory. Motor error is not correlated with reaction time. Subjects could strike one of two identical targets, a process involving choice, without intrusion of a Roelofs effect, showing that the sensorimotor system can use its own coordinates even when a cognitive choice initiates the motor processing.
Bridgeman
B
B
Department of Psychology, University of California, Santa Cruz, CA 95064, USA. bruceb@cats.ucsc.edu
Gemmer
A
A
Forsman
T
T
Huemer
V
V
D003071:Cognition / Q000502:physiology; D006801:Humans; D009903:Optical Illusions; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time; D014795:Visual Pathways / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*