Perceptual awareness in infants during the first year of life is understudied, despite the philosophical, scientific, and clinical importance of understanding how and when consciousness emerges during human brain development. Although parents are undoubtedly convinced that their infant is conscious, the lack of adequate experimental paradigms to address this question in preverbal infants has been a hindrance to research on this topic. However, recent behavioral and brain imaging studies have shown that infants are engaged in complex learning from an early age and that their brains are more structured than traditionally thought. I will present a rapid overview of these results, which might provide indirect evidence of early perceptual awareness and then describe how a more systematic approach to this question could stand within the framework of global workspace theory, which identifies specific signatures of conscious perception in adults. Relying on these brain signatures as a benchmark for conscious perception, we can deduce that it exists in the second half of the first year, whereas the evidence before the age of 5 months is less solid, mainly because of the paucity of studies. The question of conscious perception before term remains open, with the possibility of short periods of conscious perception, which would facilitate early learning. Advances in brain imaging and growing interest in this subject should enable us to gain a better understanding of this important issue in the years to come.

Speech is not a purely auditory signal. From around 2 months of age, infants are able to correctly match the vowel they hear with the appropriate articulating face. However, there is no behavioral evidence of integrated audiovisual perception until 4 months of age, at the earliest, when an illusory percept can be created by the fusion of the auditory stimulus and of the facial cues (McGurk effect). To understand how infants initially match the articulatory movements they see with the sounds they hear, we recorded high-density ERPs in response to auditory vowels that followed a congruent or incongruent silently articulating face in 10-week-old infants. In a first experiment, we determined that auditory–visual integration occurs during the early stages of perception as in adults. The mismatch response was similar in timing and in topography whether the preceding vowels were presented visually or aurally. In the second experiment, we studied audiovisual integration in the linguistic (vowel perception) and nonlinguistic (gender perception) domain. We observed a mismatch response for both types of change at similar latencies. Their topographies were significantly different demonstrating that cross-modal integration of these features is computed in parallel by two different networks. Indeed, brain source modeling revealed that phoneme and gender computations were lateralized toward the left and toward the right hemisphere, respectively, suggesting that each hemisphere possesses an early processing bias. We also observed repetition suppression in temporal regions and repetition enhancement in frontal regions. These results underscore how complex and structured is the human cortical organization which sustains communication from the first weeks of life on.

Most studies on visual perception of human beings have focused on perception of faces. However, bodies are another important visual element, which help us to identify a member of our species in the visual scene. In order to study whether similar configural information processing is used in body and face perception, we recorded high-density even-related potentials (ERPs) to normal and distorted faces and bodies in adults and 3-month-old infants. In adults, the N1 responses evoked by bodies and faces were similar in amplitude but differed slightly in latency. The voltage topography of N1 also differed in concordance with fMRI data showing that two distinct areas are involved in face and body perception. Distortion affected ERPs to faces and bodies similarly from N1 on, although the effect was significant earlier for bodies than for faces. These results suggest that fast processing of configural information is not specific to faces but it also occurs for bodies. In 3-month-old infants, distortion decreased the amplitude of P400 around 450 msec, showing no interaction with image category. This result demonstrates that infants are not only able to recognize the normal configuration of faces, but also that of bodies. This could either be related to an innate knowledge of this particular type of biological object, or to fast learning through intense exposure during the first months of life.