Color for Recognition and Action
Color vision is strongly associated with object perception and the ventral processing stream in primate cortex. There have been only few studies of the chromatic properties of neurons in cortical areas belonging to the dorsal stream, and few studies of the use of color in controlling the motor system. We ran several series of experiments to investigate how well color signals can be used to control eye and hand movements. In particular, we tested the precision of manual pointing towards objects defined by isoluminant color differences and the maximum preshape aperture of grasping movements towards isoluminant objects. In both of these tasks, performance for the colored objects was equal to performance with objects defined by luminance contrast. The same results were obtained for both the initiation and steady state phase of smooth pursuit eye movements. Overall, the only difference between color and luminance in motor control seems to be a 10 msec latency difference that seems to be due to an early stage of sensory processing. The results imply that the color signals can be efficiently used by the motor system for a variety of actions. Possible neural mechanisms will be discussed.