Is a Large Nut Like An Apple? Studies with Real and Modified Sized Objects

Two experiments investigate the role played in categorization by visual online information and information stored in memory. Participants categorized photographs of objects into artefacts or natural kinds. Before or near the object participants saw photographs of hands in a grasping posture (precision, power grip). Objects, manipulable either with a power or a precision grip, were presented in their real or modified size (e.g., strawberries were presented both in their real size and with the size of apples). RTs were faster with the power than with the precision posture, suggesting that visual hand stimuli activate a simulation of grasping. More importantly, participants categorized objects on the basis of their appearance rather than of their real size. This role of online information is remarkable in a task that implies the involvement of semantic knowledge. Results are discussed with regards to the distinction between the dorsal and ventral stream (Milner & Goodale, 1995).