Is the asymmetry in young infants' categorization of humans versus nonhuman animals based on head, body, or global gestalt information?

Quinn and Eimas (1998) reported an asymmetry in the exclusivity of the category representations that young infants form for humans and nonhuman animals: category representations for nonhuman animal species were found to exclude humans, whereas a category representation for humans was found to include nonhuman animal species (i.e., cats, horses). The present experiment utilized the familiarization/novelty-preference procedure with 3- and 4-month-olds to determine the perceptual cues (i.e., whole stimulus, head alone, body alone) that provided the basis for this asymmetry. The data revealed the asymmetry to be observable only with the whole animal stimuli and not when infants were provided with information from just the head or the body of the exemplars. The results indicate that the incorporation of nonhuman animal species into a category representation for humans is based on holistic information.