Sibling experience prevents neural tuning to adult faces in 10-month-old infants.

Early facial experience provided by the infant's social environment is known to shape face processing abilities, which narrow during the first year of life towards adult human faces of the most frequently encountered ethnic groups. Here we explored the hypothesis that natural variability in facial input may delay neural commitment to face processing by testing the impact of early natural experience with siblings on infants' brain responses. Event-Related Potentials (ERPs) evoked by upright and inverted adult and child faces were compared in two groups of 10-month-old infants with (N = 21) and without (N = 22) a child sibling. In first-born infants, P1 ERP component showed specificity to upright adult faces that carried over to the subsequent N290 and P400 components. In infants with siblings no inversion effects were observed. Results are discussed in the context of evidence from the language domain, showing that neural commitment to phonetic contrasts emerges later in bilinguals than in monolinguals, and that this delay facilitates subsequent learning of previously unencountered sounds of new languages.

Operational momentum for magnitude ordering in preschool children and adults.

When adding or subtracting quantities, adults tend to overestimate addition outcomes and underestimate subtraction outcomes. They also shift visuospatial attention to the right when adding and to the left when subtracting. These operational momentum phenomena are thought to reflect an underlying representation in which small magnitudes are associated with the left side of space and large magnitudes with the right side of space. Currently, there is limited research on operational momentum in early childhood or for operations other than addition and subtraction. The current study tested whether English-speaking 3- and 4-year-old children and college-aged adults exhibit operational momentum when ordering quantities. Participants were presented with two experimental blocks. In one block of trials, they were tasked with choosing the same quantity they had previously seen three times; in the other block, they were asked to generate the next quantity in a doubling sequence composed of three ascending quantities. A bias to shift attention to the right after an ascending operation was found in both age groups, and a bias to overestimate the next sequential quantity during an ascending ordering operation was found in adults under conditions of uncertainty. These data suggest that, for children, the spatial biases during operating are more pronounced than the mis-estimation biases. These findings highlight the spatial underpinnings of operational momentum and suggest that both very young children and adults conceptualize quantity along a horizontal continuum during ordering operations, even before formal schooling.

Discrimination of biomechanically possible and impossible hand movements at birth.

The development of human body perception has long been investigated, but little is known about its early origins. This study focused on how a body part highly relevant to the human species, namely the hand, is perceived a few days after birth. Using a preferential-looking paradigm, 24- to 48-hr-old newborns watched biomechanically possible and impossible dynamic hand gestures (Experiment 1, N = 15) and static hand postures (Experiment 2, N = 15). In Experiment 1, newborns looked longer at the impossible, compared to the possible, hand movement, whereas in Experiment 2 no visual preference emerged. These findings suggest that early in life the representation of the human body may be shaped by sensory-motor experience.

The early development of human mirror mechanisms: evidence from electromyographic recordings at 3 and 6 months.

In primates and adult humans direct understanding of others' action is provided by mirror mechanisms matching action observation and action execution (e.g. Casile, Caggiano & Ferrari, 2011). Despite the growing body of evidence detailing the existence of these mechanisms in the adult human brain, their origins and early development are largely unknown. In this study, for the first time, electromyographic (EMG) measures were used to shed light on the emergence of mirror motor mechanisms in infancy. EMG activity was recorded while 6- and 3-month-old infants watched two videos displaying an agent reaching for, grasping and bringing an object either to the mouth or to the head. Results indicate that the motor system of 6-month-olds, but not 3-month-olds, was recruited and selectively modulated during observation of the goal-directed actions, favoring the idea that mirror mechanisms driving action understanding gradually emerge during early development.

The neural correlates of processing newborn and adult faces in 3-year-old children.

The current study examines the processing of upright and inverted faces in 3-year-old children (n = 35). Event-related potentials (ERPs) were recorded during a passive looking paradigm including adult and newborn face stimuli. We observed three face-sensitive components, the P1, the N170 and the P400. Inverted faces elicited shorter P1 latency and larger P400 amplitude. P1 and N170 amplitudes were larger for adult faces. To examine the role of experience in the development of face processing, the processing of adult and newborn faces was compared for children with a younger sibling (n = 23) and children without a younger sibling (n = 12). Age of sibling at test correlated negatively with P1 amplitude for adult and newborn faces. This may indicate more efficient processing of different face ages in children with a younger sibling and potentially reflects a more flexible face representation.

Early experience predicts later plasticity for face processing: evidence for the reactivation of dormant effects.

Research has shown that experience acquired in infancy dramatically affects face-discrimination abilities. Yet much less is known about whether face processing retains any flexibility after the 1st year of life. Here, we show that early experience with an individual infant face can modulate the recognition performance of 3-year-old children and the perceptual processes they use to recognize infant faces (Experiment 1). Similar experience acquired in adulthood does not produce measurable effects (Experiment 2). We also show that the effects of early-acquired experience with an infant face become dormant during development in the absence of continued experience (Experiment 3) and can be reactivated in adulthood by reexposure to the original experience (Experiment 2). Overall, the results indicate that early experience can preserve the face-processing system from the loss of plasticity that would otherwise take place between childhood and adulthood.

Why mix-ups don't happen in the nursery: evidence for an experience-based interpretation of the other-age effect.

Adults' face recognition abilities vary across face types, as evidenced by the other-race and other-species effects. Recent evidence shows that face age is another dimension affecting adults' performance in face recognition tasks, giving rise to an other-age effect (OAE). By comparing recognition performance for adult and newborn faces in a group of maternity-ward nurses and a control group of novice participants, the current study provides evidence for an experience-based interpretation of the OAE. Novice participants were better at recognizing adult than newborn faces and showed an inversion effect for adult faces. Nurses manifested an inversion cost of equal magnitude for both adult and newborn faces and a smaller OAE in comparison to the novices. The results indicate that experience acquired exclusively in adulthood is capable of modulating the OAE and suggest that the visual processes involved in face recognition are still plastic in adulthood, granted that extensive experience with multiple faces is acquired.

Holistic processing for faces and cars in preschool-aged children and adults: evidence from the composite effect.

The current study compared the development of holistic processing for faces and non-face visual objects by testing for the composite effect for faces and frontal images of cars in 3- to 5-year-old children and adults in a series of four experiments using a two-alternative forced-choice recognition task. Results showed that a composite effect for faces was present as early as 3 1/2 years, and none of the age groups tested showed signs of a composite effect for cars. These findings provide the first demonstration that holistic processing is already selective for faces in early childhood, and confirm existing evidence that sensitivity to holistic information in faces does not increase from 4 years to adulthood.

The effect of inversion on 3- to 5-year-olds' recognition of face and nonface visual objects.

This study compared the effect of stimulus inversion on 3- to 5-year-olds' recognition of faces and two nonface object categories matched with faces for a number of attributes: shoes (Experiment 1) and frontal images of cars (Experiments 2 and 3). The inversion effect was present for faces but not shoes at 3 years of age (Experiment 1). Analogous results were found for boys when faces were compared with frontal images of cars. For girls, stimulus inversion impaired recognition of both faces and cars at 3 to 4 years of age, becoming specific to faces only at 5 years of age (Experiments 2 and 3). Evidence demonstrates that the ability to extract the critical cues that lead to adults' efficient face recognition is selectively tuned to faces during preschool years.

Congruency as a nonspecific perceptual property contributing to newborns' face preference.

Past research has shown that top-heaviness is a perceptual property that plays a crucial role in triggering newborns' preference toward faces. The present study examined the contribution of a second configural property, congruency, to newborns' face preference. Experiments 1 and 2 demonstrated that when embedded in nonfacelike stimuli, congruency induces a preference of the same strength as that induced by facedness. Experiments 3 and 4 demonstrated that the attentional biases toward facedness and congruency produce a cumulative effect on newborns' visual preferences according to an additive model. These findings were extended by those of Experiment 5, showing that the additive model holds true when congruency is added to top-heaviness in nonfacelike stimuli displaying more elements in the upper portion.

A behavioural and ERP investigation of 3-month-olds' face preferences.

Recent behavioural work suggests that newborns' face preferences are derived from a general, non-specific attentional bias toward patterns with more features in the upper versus lower half. In the current study, we predicted that selectivity for the specific geometry of the face may emerge during the first 3 months of life as a product of perceptual narrowing, leading to the construction of the first broadly defined face category segregating faces from other visual objects which may share with faces one or more visual properties. This was investigated behaviourally, using a standard preferential looking paradigm, and electrophysiologically, using high-density ERPs. Behavioural results indicated that, at 3 months, the top-heavy property is no longer a crucial factor in determining face preferences. ERP results showed evidence of differentiation between the two stimuli only for the N700. No differentiation was found for earlier components that are thought to reflect the adult-like structural encoding stage of face processing in infants (N290 and P400). Together, ERP and behavioural results suggest that, by 3 months, the perceptual narrowing process has led to a behavioural response specific to the geometry of the human face, but that this response is not purely perceptual in nature. Rather, it seems related to the acquired salience of this stimulus category, which may reflect the high degree of familiarity and/or the social value faces have gained over the infants' first 3 months of life.

Can a nonspecific bias toward top-heavy patterns explain newborns' face preference?

This study examined newborns' face preference using images of natural and scrambled faces in which the location of the inner features was distorted. The results demonstrate that newborns' face preference is not confined to schematic configurations, but can be obtained also with veridical faces. Moreover, this phenomenon is not produced by a specific bias toward the face geometry, but derives from a domain-general bias toward configurations with more elements in the upper than in the lower half (i.e., top-heavy patterns). These results suggest that it may be unnecessary to assume the existence of a prewired tendency to orient toward the face geometry, and support the idea that faces do not possess a special status in newborns' visual world.

Dominance of global visual properties at birth.

Six experiments are reported that were aimed at demonstrating the presence in newborns of a perceptual dominance of global over local visual information in hierarchical patterns, similar to that observed in adults (D. Navon, 1977, 1981). The first four experiments showed that, even though both levels of visual information were detectable by the newborn (Experiments 1A and 1B), global cues enjoyed some advantage over local cues (Experiments 2 and 3). Experiments 4A and 4B demonstrated that the global bias was strictly dependent on the low spatial frequency content of the stimuli and vanished after selective removal of low spatial frequencies. The results are interpreted as suggesting parallels between newborns' visual processing and processing later in development.