Abstract
Evidence of remarkable face discrimination abilities in neonates, perceptual narrowing and a critical period converge to argue for an innate representation that supports face individuation from birth. Previous studies have shown this initial representation encompasses monkey as well as human faces, but it has implicitly been assumed that it is of a face. Here, we consider the possibility that it is even broader. We tested individual level discrimination of whole animals (bay thoroughbred horses, shown in side view), at an age before any narrowing has been observed for faces (4-month-olds). Horses and human faces were equated for visual similarity as demonstrated by matched discrimination performance for the inverted orientation in adults. Using a novelty-preference procedure, results for 4-month-old infants (with no horse experience) then showed the babies discriminated individual upright horses; moreover, they did so at least as well as they discriminated upright human faces, and these findings were obtained despite adults showing the expected pattern of poor discrimination of upright horses relative to upright faces. Infants did not discriminate inverted horse stimuli. Together, the results imply that the innate representation capable of supporting individuation of upright biological stimuli is much broader in form than the previously proposed innate primate face representation. We argue the representation encompasses at least other mammal heads (in profile view), and possibly full bodies of all animals.
Supported by Australian Reseach Council grants DP0770923 & DP0984558.