Perceptual Narrowing in Speech and Face Recognition: Evidence for Intra-individual Cross-Domain Relations

Older infants' social learning behavior under uncertainty is modulated by the interaction of face and speech processing

The origin of face or language influences infants' perceptual processing and social learning behavior. However, it remains unclear how infants' social learning behavior is affected when both information are provided simultaneously. Hence, the current study investigated whether and how infants' social learning in terms of gaze following is influenced by face race and language origin of an interaction partner in an uncertain situation. Our sample consisted of 91 Caucasian infants from German speaking families. They were divided into 2 age groups: Younger infants were 5- to 8-month-old (n = 46) and the older infants 11- to 20-month-old (n = 45). We used a modified online version of the gaze following paradigm by Xiao and colleagues by varying face race (Caucasian, and Asian faces) and language (German and French) of a female actor. We recorded infants looking behavior via webcam and coded it offline. Our results revealed that older but not younger infants were biased to follow the gaze of own-race adults speaking their native language. Our findings show that older infants are clearly influenced by adults' ethnicity and language in social learning situations of uncertainty.

The effect of face orientation on audiovisual speech integration in infancy: An electrophysiological study

Humans pay special attention to faces and speech from birth, but the interplay of developmental processes leading to specialization is poorly understood. We investigated the effects of face orientation on audiovisual (AV) speech perception in two age groups of infants (younger: 5- to 6.5-month-olds; older: 9- to 10.5-month-olds) and adults. We recorded event-related potentials (ERP) in response to videos of upright and inverted faces producing /ba/ articulation dubbed with auditory syllables that were either matching /ba/ or mismatching /ga/ the mouth movement. We observed an increase in the amplitude of audiovisual mismatch response (AVMMR) to incongruent visual /ba/-auditory /ga/ syllable in comparison to other stimuli in younger infants, while the older group of infants did not show a similar response. AV mismatch response to inverted visual /ba/-auditory /ga/ stimulus relative to congruent stimuli was also detected in the right frontal areas in the younger group and the left and right frontal areas in adults. We show that face configuration affects the neural response to AV mismatch differently across all age groups. The novel finding of the AVMMR in response to inverted incongruent AV speech may potentially imply the featural face processing in younger infants and adults when processing inverted faces articulating incongruent speech. The lack of visible differential responses to upright and inverted incongruent stimuli obtained in the older group of infants suggests a likely functional cortical reorganization in the processing of AV speech.

A review of the characteristics, mechanisms and clinical significance of habituation in foetuses and newborn infants

Habituation has been a topic of interest since the early 20th century. We summarise the characteristics of habituation, the proposed habituation mechanisms, the associated cortical responses and the link between habituation and cognitive development. Behavioural and neuroimaging studies have highlighted the early sensory abilities of foetuses and newborn infants, with preterm newborn infants exhibiting decreased habituation and dishabituation capabilities that increase their environmental vulnerability. Habituation provides a foundation for the learning and cognition on which higher functions are constructed. It has been suggested that it is efficient for predicting cognitive developmental outcomes in term and preterm newborn infants.

Can language modulate perceptual narrowing for faces? Other-race face recognition in infants is modulated by language experience

Between 6 and 9 months, while infant’s ability to discriminate faces within their own racial group is maintained, discrimination of faces within other-race groups declines to a point where 9-month-old infants fail to discriminate other-race faces. Such face perception narrowing can be overcome in various ways at 9 or 12 months of age, such as presenting faces with emotional expressions. Can language itself modulate face narrowing? Many adult studies suggest that language has an impact on the recognition of individuals. For example, adults remember faces previously paired with their native language more accurately than faces paired with a non-native language. We have previously found that from 9 months of age, own-race faces associated with the native language can be learned and recognized whereas own-race faces associated with a non-native language cannot. Based on the language familiarity effect, we hypothesized that the native language could restore recognition of other-race faces after perceptual narrowing has happened. We tested 9- and 12-month-old Caucasian infants. During a familiarization phase, infants were shown still photographs of an Asian face while audio was played either in the native or in the non-native language. Immediately after the familiarization, the familiar face and a novel one were displayed side-by-side for the recognition test. We compared the proportional looking time to the new face to the chance level. Both 9- and 12-month-old infants exhibited recognition memory for the other-race face when familiarized with non-native speech, but not with their native speech. Native language did not facilitate recognition of other-race faces after 9 months of age but a non-native language did, suggesting that 9- and 12-month-olds already have expectations about which language an individual should talk (or at least not talk). Our results confirm the strong links between face and speech processing during infancy.

The Origins of Social Knowledge in Altricial Species

Human infants are altricial, born relatively helpless and dependent on parental care for an extended period of time. This protracted time to maturity is typically regarded as a necessary epiphenomenon of evolving and developing large brains. We argue that extended altriciality is itself adaptive, as a prolonged necessity for parental care allows extensive social learning to take place. Human adults possess a suite of complex social skills, such as language, empathy, morality, and theory of mind. Rather than requiring hardwired, innate knowledge of social abilities, evolution has outsourced the necessary information to parents. Critical information for species-typical development, such as species recognition, may originate from adults rather than from genes, aided by underlying perceptual biases for attending to social stimuli and capacities for statistical learning of social actions. We draw on extensive comparative findings to illustrate that, across species, altriciality functions as an adaptation for social learning from caregivers.

Perceptual narrowing in face- and speech-perception domains in infancy: A longitudinal approach

During the first year of life, infants undergo a process known as perceptual narrowing, which reduces their sensitivity to classes of stimuli which the infants do not encounter in their environment. It has been proposed that perceptual narrowing for faces and speech may be driven by shared domain-general processes. To investigate this theory, our study longitudinally tested 50 German Caucasian infants with respect to these domains first at 6 months of age followed by a second testing at 9 months of age. We used an infant-controlled habituation-dishabituation paradigm to test the infants' ability to discriminate among other-race Asian faces and non-native Cantonese speech tones, as well as same-race Caucasian faces as a control. We found that while at 6 months of age infants could discriminate among all stimuli, by 9 months of age they could no longer discriminate among other-race faces or non-native tones. However, infants could discriminate among same-race stimuli both at 6 and at 9 months of age. These results demonstrate that the same infants undergo perceptual narrowing for both other-race faces and non-native speech tones between the ages of 6 and 9 months. This parallel development of perceptual narrowing occurring in both the face and speech perception modalities over the same period of time lends support to the domain-general theory of perceptual narrowing in face and speech perception.

Language familiarity influences own-race face recognition in 9- and 12-month-old infants

During their first year, infants attune to the faces and language(s) that are frequent in their environment. The present study investigates the impact of language familiarity on how French-learning 9- and 12-month-olds recognize own-race faces. In Experiment 1, infants were familiarized with the talking face of a Caucasian bilingual German-French speaker reciting a nursery rhyme in French (native condition) or in German (non-native condition). In the test phase, infants' face recognition was tested by presenting a picture of the speaker's face they were familiarized with, side by side with a novel face. At 9 and 12 months, neither infants in the native condition nor the ones in the non-native condition clearly recognized the speaker's face. In Experiment 2, we familiarized infants with the still picture of the speaker's face, along with the auditory speech stream. This time, both 9- and 12-month-olds recognized the face of the speaker they had been familiarized with, but only if she spoke in their native language. This study shows that at least from 9 months of age, language modulates the way faces are recognized.

Environmental convergence in facial preferences: a cross-group comparison of Asian Vietnamese, Czech Vietnamese, and Czechs

It has been demonstrated that sociocultural environment has a significant impact on human behavior. This contribution focuses on differences in the perception of attractiveness of European (Czech) faces as rated by Czechs of European origin, Vietnamese persons living in the Czech Republic and Vietnamese who permanently reside in Vietnam. We investigated whether attractiveness judgments and preferences for facial sex-typicality and averageness in Vietnamese who grew up and live in the Czech Republic are closer to the judgements and preferences of Czech Europeans or to those of Vietnamese born and residing in Vietnam. We examined the relative contribution of sexual shape dimorphism and averageness to the perception of facial attractiveness across all three groups of raters. Czech Europeans, Czech Vietnamese, and Asian Vietnamese raters of both sexes rated facial portraits of 100 Czech European participants (50 women and 50 men, standardized, non-manipulated) for attractiveness. Taking Czech European ratings as a standard for Czech facial attractiveness, we showed that Czech Vietnamese assessments of attractiveness were closer to this standard than assessments by the Asian Vietnamese. Among all groups of raters, facial averageness positively correlated with perceived attractiveness, which is consistent with the "average is attractive" hypothesis. A marginal impact of sexual shape dimorphism on attractiveness rating was found only in Czech European male raters: neither Czech Vietnamese nor Asian Vietnamese raters of either sex utilized traits associated with sexual shape dimorphism as a cue of attractiveness. We thus conclude that Vietnamese people permanently living in the Czech Republic converge with Czechs of Czech origin in perceptions of facial attractiveness and that this population adopted some but not all Czech standards of beauty.

Bimodal familiarization re-sensitizes 12-month-old infants to other-race faces

Perceptual narrowing in the domain of face perception typically begins to reduce infants' sensitivity to differences distinguishing other-race faces from approximately 6 months of age. The present study investigated whether it is possible to re-sensitize Caucasian 12-month-old infants to other-race Asian faces through statistical learning by familiarizing them with different statistical distributions of these faces. The familiarization faces were created by generating a morphed continuum from one Asian face identity to another. In the unimodal condition, infants were familiarized with a frequency distribution wherein they saw the midpoint face of the morphed continuum the most frequently. In the bimodal condition, infants were familiarized with a frequency distribution wherein they saw faces closer to the endpoints of the morphed continuum the most frequently. After familiarization, infants were tested on their discrimination of the two original Asian faces. The infants' looking times during the test indicated that infants in the bimodal condition could discriminate between the two faces, while infants in the unimodal condition could not. These findings therefore suggest that 12-month-old Caucasian infants could be re-sensitized to Asian faces by familiarizing them with a bimodal frequency distribution of such faces.

The Other-Race-Effect on Audiovisual Speech Integration in Infants: A NIRS Study

Previous studies have revealed perceptual narrowing for the own-race-face in face discrimination, but this phenomenon is poorly understood in face and voice integration. We focused on infants' brain responses to the McGurk effect to examine whether the other-race effect occurs in the activation patterns. In Experiment 1, we conducted fNIRS measurements to find the presence of a mapping of the McGurk effect in Japanese 8- to 9-month-old infants and to examine the difference between the activation patterns in response to own-race-face and other-race-face stimuli. We used two race-face conditions, own-race-face (East Asian) and other-race-face (Caucasian), each of which contained audiovisual-matched and McGurk-type stimuli. While the infants (N = 34) were observing each speech stimulus for each race, we measured cerebral hemoglobin concentrations in bilateral temporal brain regions. The results showed that in the own-race-face condition, audiovisual-matched stimuli induced the activation of the left temporal region, and the McGurk stimuli induced the activation of the bilateral temporal regions. No significant activations were found in the other-race-face condition. These results mean that the McGurk effect occurred only in the own-race-face condition. In Experiment 2, we used a familiarization/novelty preference procedure to confirm that the infants (N = 28) could perceive the McGurk effect in the own-race-face condition but not that of the other-race-face. The behavioral data supported the results of the fNIRS data, implying the presence of narrowing for the own-race face in the McGurk effect. These results suggest that narrowing of the McGurk effect may be involved in the development of relatively high-order processing, such as face-to-face communication with people surrounding the infant. We discuss the hypothesis that perceptual narrowing is a modality-general, pan-sensory process.