No more top-heavy bias: infants and adults prefer upright faces but not top-heavy geometric or face-like patterns.

A non-specific "top-heavy" configuration bias has been proposed to explain neonatal face preference (F. Simion, E. Valenza, V. Macchi Cassia, C. Turati, & C. Umiltà, 2002). Using an eye tracker (Tobii T60), we investigated whether the top-heavy bias is still present in 3- to 5.5-month-old infants and in adults as a comparison group. Each infant and adult viewed three classes of stimuli: simple geometric patterns, face-like figures, and photographs of faces. Using area of interest analyses on fixation duration, we computed a top-heavy bias index (a number between -1 and 1) for each individual. Our results showed that the indices for the geometric and face-like patterns were about zero in infants, indicating no consistent bias for the "top-heavy" configuration. In adults, the indices for the geometric and face-like patterns were also close to zero except for the T-shaped figure and the ones that had higher rating on facedness. Moreover, the indices for photographs of faces were positive in both infants and adults, indicating significant preferences for upright natural faces over inverted ones. Taken together, we found no evidence for the top-heavy configuration bias in both infants and adults. The absence of top-heavy bias plus a clear preference for photographed upright faces in infants seem to suggest an early cognitive specialization process toward face representation.