Vision , Attention , and Action : Inhibition and Facilitation in Sensory - Motor Links Revealed by the Reaction Time and the Line Motion

REA CTI 0 N TIME AND A TTENTI 0N 23.1 To investigate critical factors for local inhibition and facilitation in visual-motor tasks, we randomized stimulus dimensions (location, color, and orientation) and response-stimulus interval across trials. The subject performed four different tasks'. Reaction times at the same location were longer, that is, "inhibition of return" (lOR) occurred, in the detection and location discrimination tasks. Reaction times at the same location were shorter in the color and orientation discrimination tasks. lOR was observed also in arm-reaching and saccadic eye movement tasks. Moreover , the task-dependent difference of RTs was observed also with popout displays. The results indicate a dissociation of two visual functions: detection/orienting and fine feature analysis. To investigate whether motor readiness could draw attention to the target location and have an influence on visual information processing, we employed the "line motion" illusion; we showed that mere preparation for a motor response, such as arm reaching or saccade , would be sufficient to yield local facilitation at the prepared target location. In this chapter , we discuss issues related to functional links between the visual and the motor systems . For this purpose , we will present two sets of findings : one employing the reaction time paradigm and indicating functional segrega tion of two visual functions , and the other employing the " line motion " paradigm and indicating effects of motor readiness on the visual information processIng . Vision , Attention , and Action : Inhibition and Facilitation in Sensory -Motor Links Revealed by the Reaction Time and the Line Motion Shinsuke Shimojo, Yasuto Tanaka, Okihide Hikosaka,