An inborn predisposition to attend to biological motion has long been theorized, but had so far been demonstrated only in one animal species (the domestic chicken). In particular, no preference for biological motion was reported for human infants of <3 months of age. We tested 2-day-old babies' discrimination after familiarization and their spontaneous preferences for biological vs. nonbiological point-light animations. Newborns were shown to be able to discriminate between two different patterns of motion (Exp. 1) and, when first exposed to them, selectively preferred to look at the biological motion display (Exp. 2). This preference was also orientation-dependent: newborns looked longer at upright displays than upside-down displays (Exp. 3). These data support the hypothesis that detection of biological motion is an intrinsic capacity of the visual system, which is presumably part of an evolutionarily ancient and nonspecies-specific system predisposing animals to preferentially attend to other animals.

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Numbers are represented as ordered magnitudes along a spatially oriented number line. While culture and formal education modulate the direction of this number-space mapping, it is a matter of debate whether its emergence is entirely driven by cultural experience. By registering 8-9-month-old infants' eye movements, this study shows that numerical cues are critical in orienting infants' visual attention towards a peripheral region of space that is congruent with the number's relative position on a left-to-right oriented representational continuum. This finding provides the first direct evidence that, in humans, the association between numbers and oriented spatial codes occurs before the acquisition of symbols or exposure to formal education, suggesting that the number line is not merely a product of human invention.

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Recent data demonstrate a perceptual processing advantage for adult faces in both adults and young children, suggesting that face representation is shaped by visual experience accumulated with different face-age groups. As for species and race, this age bias may emerge during the first year of life as part of the general process of perceptual narrowing, given the extensive amount of social and perceptual experience accumulated with caregivers and/or other adult individuals. Using infant-controlled habituation and visual-paired comparison at test, two experiments were carried out to examine 3- and 9-month-olds' ability to discriminate within adult and infant faces. Results showed that, when they are provided with adequate time to visually compare the stimuli during test trials (Experiment 2), 3-month-olds exhibit above-chance discrimination of adult and infant faces. Instead, 9-month-olds discriminate adult faces but not infant faces (Experiments 1 and 2). Results provide the first evidence of age-related face processing biases in infancy, and show that by 9 months face representations tune to adult human faces.