Categorization of real and replica objects by 14- and 18-month-old infants.

In studies of infant categorization (especially sequential touching), replicas of real objects are often utilized on the assumption that infants treat replicas as they do reals. Do infants categorize replicas of objects in the same way as they categorize real objects? This question was addressed in a sequential touching task, where 14- and 18-month-olds were presented with four sets of objects: real telephones and hairbrushes, real lemons and pears, replica telephones and hairbrushes, and replica lemons and pears. On the whole, mean run length, number of contacts, and appropriate actions did not differ between real and replica objects. Moreover, mean run length was significantly greater than chance for telephones and hairbrushes, but not for lemons and pears; both ages categorized the former sets but not the latter. Infants of this age appear to treat replicas as equivalent to reals, and replicas are appropriate stimuli to use in the sequential touching procedure to address questions of infants' categorization.