Suprasegmental information affects processing of talking faces at birth

Is That You I Hear? Speaker Familiarity Modulates Neural Signatures of Lexical-semantic Activation in 18-month-old Infants

Developmental language studies have shown that lexical-semantic organization develops between 18 and 24 months of age in monolingual infants. In the present study, we aimed to examine whether voice familiarity facilitates lexical-semantic activation in the infant brain. We recorded the brain activity of 18-month-old, French-learning infants using EEG while they listened to taxonomically related and unrelated spoken word pairs by one voice with which they were familiarized with before the experiment, and one voice with which they were not familiarized. The ERPs were measured in response to related and unrelated target words. Our results showed an N400 effect (greater amplitudes for unrelated as opposed to related target words) over the left hemisphere, only for the familiar voice, suggesting that the voice familiarity facilitated lexical-semantic activation. For unfamiliar voices, we observed an earlier congruence effect (greater amplitudes for related than for unrelated target words). This suggests that although 18-month-olds process lexical-semantic information from unfamiliar speakers, their neural signatures of lexical-semantic processing are less mature. Our results show that even in the absence of personal relation with a speaker, familiarity with a voice augments infant lexical-semantic processing. This supports the idea that extralinguistic information plays a role in infant lexical-semantic activation.

How do human newborns come to understand the multimodal environment?

For a long time, newborns were considered as human beings devoid of perceptual abilities who had to learn with effort everything about their physical and social environment. Extensive empirical evidence gathered in the last decades has systematically invalidated this notion. Despite the relatively immature state of their sensory modalities, newborns have perceptions that are acquired, and are triggered by, their contact with the environment. More recently, the study of the fetal origins of the sensory modes has revealed that in utero all the senses prepare to operate, except for the vision mode, which is only functional starting from the first minutes after birth. This discrepancy between the maturation of the different senses leads to the question of how human newborns come to understand our multimodal and complex environment. More precisely, how the visual mode interacts with the tactile and auditory modes from birth. After having defined the tools that newborns use to interact with other sensory modalities, we review studies across different fields of research such as the intermodal transfer between touch and vision, auditory-visual speech perception, and the existence of links between the dimensions of space, time, and number. Overall, evidence from these studies supports the idea that human newborns are spontaneously driven, and cognitively equipped, to link information collected by the different sensory modes in order to create a representation of a stable world.

Mouth Movements as Possible Cues of Social Interest at Birth: New Evidences for Early Communicative Behaviors

Previous studies evidenced that different interactive contexts modulate the visual attention of newborns. In the present study, we investigated newborns' motor feedback as an additional cue to neonates' expression of interest. Using videos of interactive faces and a familiarization-test procedure, three different groups of newborns were assigned to three different conditions (i.e., one condition with a talking face during familiarization and silently moving faces at test, silently moving/silently moving condition, or talking/static condition). Following studies on neonatal imitation, mouth movements were analyzed as indicators of social interest. We expected the occurrence of mouth movements in the newborns to differ according to different conditions: (a) whether or not the face in front of them was talking and (b) if the person had been already seen or was new. Results revealed that a talking face elicited more motor feedback from the newborns than a silent one and that there was no difference in front of the familiar face or the novel one. Finally, frequencies of mouth movements were greater, and latencies of appearance of the first mouth movement were shorter, in front of a static vs. a dynamic face. These results are congruent with the idea of the existence of "a sense" for interaction at birth, and therefore new approaches in newborn studies are discussed.

Labels and object categorization in six- and nine-month-olds: tracking labels across varying carrier phrases

Language shapes object categorization in infants. This starts as a general enhanced attentional effect of language, which narrows to a specific link between labels and categories by twelve months. The current experiments examined this narrowing effect by investigating when infants track a consistent label across varied input. Six-month-old infants (N = 48) were familiarized to category exemplars, each presented with the exact same labeling phrase or the same label in different phrases. Evidence of object categorization at test was only found with the same phrase, suggesting that infants were not tracking the label's consistency, but rather that of the entire input. Nine-month-olds (N = 24) did show evidence of categorization across the varied phrases, suggesting that they were tracking the consistent label across the varied input.

Premises of social cognition: Newborns are sensitive to a direct versus a faraway gaze

Previous studies evidenced that already from birth, newborns can perceive differences between a direct versus an averted gaze in faces both presented in static and interactive situations. It has been hypothesized that this early sensitivity would rely on modifications of the location of the iris (i.e. the darker part of the eye) in the sclera (i.e. the white part), or that it would be an outcome of newborns' preference for configurations of faces with the eye region being more contrasted. One question still remains: What happens when the position of the iris is not modified in the sclera, but the look is 'faraway', that is when the gaze is toward the newborns' face but above his or her own eyes? In the present study, we tested the influence of a direct versus a faraway gaze (i.e., two gazes that only differed slightly in the position of the iris on the vertical axis and not on the horizontal axis) on newborns' face recognition. The procedure was identical to that used in previous studies: using a familiarization-test procedure, we familiarized two groups of newborns (N = 32) with videos of different talking faces that were presented with either a direct or a faraway gaze. Newborns were then tested with photographs of the face seen previously and of a new one. Results evidenced that newborns looked longer at the familiar face, but only in the direct gaze condition. These results suggest that, already from birth, infants can perceive slight differences of gazes when someone is addressing to them.

Active sleep is associated with the face preference in the newborns who familiarized with a responsive face

Aim of this study was to investigate the preferential looking behaviour, subsequent to a familiarization task (8-min) with a previously responsive or motionless face, before and after a sleep cycle. Moreover, the role of the active sleep in memory consolidation of the responsive or motionless faces was explored. Hypotheses were that the newborns undergoing a motionless familiarization will exhibit a novelty effect (preference for the novel face) whereas the newborns undergoing a responsive familiarization will show a familiarity effect (preference for the known face) before and after the sleep cycle; moreover, the amount of active sleep will be associated with the looking time at the known face after a sleep cycle. Forty-five healthy full-term newborns were randomly assigned to two groups (group 1: motionless-familiarization and group 2: responsive-familiarization); in both groups newborns were video-recorded during four post-familiarization face-preference tasks, two of them performed before and two after a sleep cycle. During the pre-sleep-trials, there was not a significant preference for one face in both groups. During the post-sleep trials, the newborns showed a clear preference for the novel face. This effect was more evident in group 1. Only in group 2 there was a significant positive correlation between the active sleep duration and the looking duration at the known-face during the post-sleep trials (r=0.41; p=0.040). Multiple regression confirmed that only in the group 2 the total duration of the active sleep was associated with the looking duration at the known-face during the post-sleep trials (Adjusted R²=0.13; β=0.41; t=2.2; p=0.040). Findings showed that in newborns the face representation can be recalled after a sleep cycle. Moreover, the amount of the active sleep predicted the post-sleep looking toward the known-face only in the newborns who interactively familiarized with the face.