Visual hand primes and manipulable objects

In three experiments we assessed whether priming a hand shape facilitated categorization. Primes consisted of photographs of hands displaying one of four different postures (precision, power, ok, open hand). Targets consisted of photographs or words of manipulable objects, artifacts and natural kinds. Across experiments participants were asked to decide respond only to stimuli presented after the precision, the power, or the ok prime, while they had to avoid to respond to stimuli following the open hand prime. Their task consisted of pressing a different key to decide whether the target referred to an artifact or a natural kind object. In Experiments 1 and 2, artifacts were processed slower than natural kinds, and natural kinds graspable with a power grip were processed faster than those graspable with a precision grip. In addition in Experiment 2 precision primes were slower with artifacts, probably due to the activation of functional information. These results confirm that a visual prime activates motor information on objects. However, apparently the visual hand prime was not sufficient to associate a specific kind of grip and a specific kind of manipulable object. In Experiment 3 a motor training phase preceded the experiment; the results show that power primes followed by objects graspable with a precision grip lead to longer RTs. Results are discussed in the framework of theories suggesting that vision and motor information are strictly interwoven and with theories assuming that object concepts are grounded in sensorimotor experience.