Enhanced detection of visual targets on the hand and familiar tools

This study investigated whether or not the simple detection of visual stimuli is better when those stimuli are presented on the hand than on other objects, and whether or not detection on other objects improves when people are trained to use them as tools. Participants performed a speeded visual detection task to targets presented on either side of their own left hand, a fake left hand, and a small garden rake. They were then trained to use either the fake hand or the rake as a tool with their left hand. Participants initially responded faster to stimuli projected onto their real hand than to stimuli presented on the fake hand or the tool, but they did not respond faster to stimuli on one side of the hand than on the other. After training, participants showed better detection of the visual stimuli presented on the object that they had been trained to use than they did for stimuli presented on the other object. Moreover, participants responded faster to stimuli presented on the upper side of the object that they had been trained to use than they did to stimuli on the other side. These findings demonstrate that an enhanced visual detection can be induced for stimuli presented on tools and other inanimate objects with training, suggesting that these objects have been incorporated into the body schema.