Action and perception: Evidence against converging selection processes

In a series of experiments we investigated whether identification of a lateralized visual target would benefit from concurrent execution of a reaching movement on the same side of space. Participants were tested in a dual-task paradigm. In one task, they performed a speeded reach movement towards a lateralized target button. The reach was cued by an auditory stimulus, and performed out of the participant's sight. In the other task, participants identified one of two simultaneous visual stimuli presented to the left and right visual fields, close to movement target locations. If motor activity were effective in modulating perceptual processes via a visuo-attentional shift, identification performance should have improved when the visual stimulus appeared at the movement target location. In fact, identification was not affected by the side of reach. Such results suggest substantially independent selection processes in motor and visual domains.