Infant-directed Communication Research Articles

Soundscapes of infant care and infant-directed communication in two hunter-gatherer societies

This study contributes an ethnographic perspective to the study of infant-directed (ID) communicative activities. We compare soundscapes of infant care and ID vocal communication in two egalitarian, forest-dwelling, mobile hunter-gatherer groups: Mbendjele BaYaka/Aka in Northern Congo-Brazzaville and the Maniq of Southern Thailand. Across the unique patterns of speech and song specific to these different cultures, common threads emerged in infants’ soundscapes that suggest the centrality of musically enriched ID-speech for communication with infants. A conspicuous under-elaboration of music among Maniq people suggests that while musical activity in a culture may vary greatly, ID-speech does not. The ID-speech register thus emerges as more central to childhood socialisation and development in these hunter-gatherer societies than does the ID-song register. Although the use of lullabies (ID-song) by mothers has been claimed to be a human universal ( Trehub 2001 ; Mehr et al 2019 ) the ethnography from these hunter-gatherer societies supports Takada’s (2020:139–142) conclusion that ID-speech and song demonstrate important cultural diversity. This paper contributes to ethnographic accounts of the diversity of ways that cultures organise communicative exchanges with children.

Infant-directed communication: Examining the many dimensions of everyday caregiver-infant interactions.

Everyday caregiver-infant interactions are dynamic and multidimensional. However, existing research underestimates the dimensionality of infants' experiences, often focusing on one or two communicative signals (e.g., speech alone, or speech and gesture together). Here, we introduce "infant-directed communication" (IDC): the suite of communicative signals from caregivers to infants including speech, action, gesture, emotion, and touch. We recorded 10min of at-home play between 44 caregivers and their 18- to 24-month-old infants from predominantly white, middle-class, English-speaking families in the United States. Interactions were coded for five dimensions of IDC as well as infants' gestures and vocalizations. Most caregivers used all five dimensions of IDC throughout the interaction, and these dimensions frequently overlapped. For example, over 60% of the speech that infants heard was accompanied by one or more non-verbal communicative cues. However, we saw marked variation across caregivers in their use of IDC, likely reflecting tailored communication to the behaviors and abilities of their infant. Moreover, caregivers systematically increased the dimensionality of IDC, using more overlapping cues in response to infant gestures and vocalizations, and more IDC with infants who had smaller vocabularies. Understanding how and when caregivers use all five signals-together and separately-in interactions with infants has the potential to redefine how developmental scientists conceive of infants' communicative environments, and enhance our understanding of the relations between caregiver input and early learning. RESEARCH HIGHLIGHTS: Infants' everyday interactions with caregivers are dynamic and multimodal, but existing research has underestimated the multidimensionality (i.e., the diversity of simultaneously occurring communicative cues) inherent in infant-directed communication. Over 60% of the speech that infants encounter during at-home, free play interactions overlap with one or more of a variety of non-speech communicative cues. The multidimensionality of caregivers' communicative cues increases in response to infants' gestures and vocalizations, providing new information about how infants' own behaviors shape their input. These findings emphasize the importance of understanding how caregivers use a diverse set of communicative behaviors-both separately and together-during everyday interactions with infants.

Individual variation and plasticity in the infant-directed communication of orang-utan mothers.

Between-individual variation in behavioural expression, such as social responsiveness, has been shown to have important eco-evolutionary consequences. However, most comparative research on non-human primate communication has focused on species- or population-level variation, while among- and within-individual variation has been largely ignored or considered as noise. Here, we apply a behavioural reaction norm framework to repeated observations of mother–offspring interactions in wild and zoo-housed orang-utans (Pongo abelii, P. pygmaeus) to tease apart variation on the individual level from population-level and species-level differences. Our results showed that mothers not only differed in the composition of their infant-directed gestural repertoires, but also in communicative tactics, such as gestural redoings (i.e. persistence) and responsiveness to infants' requests. These differences remained after controlling for essential moderators, including species, setting, parity and infant age. Importantly, mothers differed in how they adjusted their behaviour across social contexts, making a strong case for investigating within-individual variation. Our findings highlight that partitioning behavioural variation into its within-individual, between-individual and environmental sources allows us to estimate the extent of plastic responses to the immediate environment in great ape communication.

Maternal input and infants' response to infant-directed speech.

Caregivers typically use an exaggerated speech register known as infant-directed speech (IDS) in communication with infants. Infants prefer IDS over adult-directed speech (ADS) and IDS is functionally relevant in infant-directed communication. We examined interactions among maternal IDS quality, infants' preference for IDS over ADS, and the functional relevance of IDS at 6 and 13months. While 6-month-olds showed a preference for IDS over ADS, 13-month-olds did not. Differences in gaze following behavior triggered by speech register (IDS vs. ADS) were found in both age groups. The degree of infants' preference for IDS (relative to ADS) was linked to the quality of maternal IDS infants were exposed to. No such relationship was found between gaze following behavior and maternal IDS quality and infants' IDS preference. The results speak to a dynamic interaction between infants' preference for different kinds of social signals and the social cues available to them.

Motherese, affect, and vocabulary development: dyadic communicative interactions in infants and toddlers.

Responsive parental communication during an infant's first year has been positively associated with later language outcomes. This study explores responsivity in mother-infant communication by modeling how change in guiding language between 7 and 11 months influences toddler vocabulary development. In a group of 32 mother-child dyads, change in early maternal guiding language positively predicted child language outcomes measured at 18 and 24 months. In contrast, a number of other linguistic variables - including total utterances and non-guiding language - did not correlate with toddler vocabulary development, suggesting a critical role of responsive change in infant-directed communication. We further assessed whether maternal affect during early communication influenced toddler vocabulary outcomes, finding that dominant affect during early mother-infant communications correlated to lower child language outcomes. These findings provide evidence that responsive parenting should not only be assessed longitudinally, but unique contributions of language and affect should also be concurrently considered in future study.

Multimodal infant-directed communication: how caregivers combine tactile and linguistic cues.

Both touch and speech independently have been shown to play an important role in infant development. However, little is known about how they may be combined in the input to the child. We examined the use of touch and speech together by having mothers read their 5-month-olds books about body parts and animals. Results suggest that speech+touch multimodal events are characterized by more exaggerated touch and speech cues. Further, our results suggest that maternal touches are aligned with speech and that mothers tend to touch their infants in locations that are congruent with names of body parts. Thus, our results suggest that tactile cues could potentially aid both infant word segmentation and word learning.

Putting the "Joy" in joint attention: affective-gestural synchrony by parents who point for their babies.

Despite a growing body of work examining the expression of infants’ positive emotion in joint attention contexts, few studies have examined the moment-by-moment dynamics of emotional signaling by adults interacting with babies in these contexts. We invited 73 parents of infants (three fathers) to our laboratory, comprising parent-infant dyads with babies at 6 (n = 15), 9 (n = 15), 12 (n = 15), 15 (n = 14), and 18 (n = 14) months of age. Parents were asked to sit in a chair centered on the long axis of a room and to point to distant dolls (2.5 m) when the dolls were animated, while holding their children in their laps. We found that parents displayed the highest levels of smiling at the same time that they pointed, thus demonstrating affective/referential synchrony in their infant-directed communication. There were no discernable differences in this pattern among parents with children of different ages. Thus, parents spontaneously encapsulated episodes of joint attention with positive emotion.

Melodic versus intonational coding of communicative functions: A comparison of tonal contours in infant-directed song and speech.

ABSTRACT - Global intonational contours of infantdirected speech are said to serve effective communicative functions. For example, steep rising contours are thought to arouse an infant while smoothly falling contours are thought to be soothing. Several researchers (e.g., Cordes, 2005; Papousek, 1996; Unyk, Trehub, Trainar, & Schellenberg, 1992) proposed that the melodic contours in nursery songs should fallow the same communicative principles as in speech. In this study, melodic and intonational contours in play contexts were compared in three languages in order to determine 1) whether infant-directed speech and song are similar in the composition of their typical contours, and 2) whether there are differences across languages. Evidence from soothing contexts is also taken into account. The material was collected from 43 German-, Frenchand Russian-speaking parents singing or speaking to their 2- to 12- month-old infants. Tonal contour types in each register were assessed adopting protocols based on Cordes (2005). The results confirm the similarity between infant-directed speech and song in play contexts, but some differences occur in soothing contexts. Languagespecific patterns are discussed, and it is put forward that it would be valuable to intensify research into the language-specific basis of infant-directed communication. KEYWORDS - Infant-directed speech, song, contour forms, communicative function In the presence of an infant, adults often unconsciously change their way of talking and singing. They slow down in tempo, use a higher overall pitch level, show more pitch variability, make more pauses and repeat their utterances (overview in Cruttenden, 1994; Trehub, 2003). In their first year of life, infants clearly prefer to listen to infant-directed speech (or motherese) and song than to adult-directed speech and song (Cooper, Abraham, Berman, & Staska, 1997; Fernald, 1984; Fernald & Kuhl, 1987; Nakata & Trehub, 2004; Trainor, 1996; Trehub & Trainor, 1998). Infants' preference for infant-directed speech is thought to be mostly due to the tonal structure of the signal (Fernald & Kuhl, 1987): adults use a wider frequency range, a higher speech register and salient tonal contours when addressing children (Fernald & Simon, 1984; Fernald et al., 1989; Gavrilova, 2001; Stern, Spieker, & MacKain, 1982). Infant-directed songs are also sung at a higher pitch level (Trainor & Zacharias, 1998), in a smiling tone and with more jitter and shimmer in the voice (Trainor, 1996; Trainor, Clark, Huntley, & Adams, 1997), which might be due to a higher emotional involvement of the singer (Trehub & Trainor, 1998). Fernald (1989), Papousek (1996), and Papousek, Papousek, and Symmes (1991) showed that there is a narrow inventory of tonal contour types in infant-directed speech used by parents to fulfill distinct communicative functions. Rising contours encourage a turn or elicit attention (especially at the age of 2 and 3 months, see Henning, Striano, and Lieven, 2005), bell-shaped contours close a turn or signal approval, steeply falling contours with abrupt onsets are used for warnings, disapproval and prohibitions whereas smoothly falling contours soothe and comfort the infant (see Figure 1). These functions were initially taken to be cross-linguistic universale (Grieser & Kuhl, 1988; Papousek et al., 1991), though further research showed some variations in tonal features and in the frequency of contour types across language and cultural context, sex and age of the infant (Kitamura & Burnham, 2003; Kitamura, Thanavishuth, Burnham, & Luksaneeyanawin, 2001; Lam & Kitamura, 2006; Rabain-Jamin & Sabeau-Jouannet, 1997). In the first year of life, infants attend particularly to the global shape of tonal/melodic contours in speech and song (Fernald & Kuhl, 1987; Trehub, Bull, & Thorpe, 1984). Thus, tonal contours with communicative functions might help infants to establish a first semantic-pragmatic relation between phonetic form and global referential meaning. …

Communication-induced memory biases in preverbal infants

Human teaching, a highly specialized form of cooperative information transmission, depends not only on the presence of benevolent communicators in the environment, but also on the preparedness of the students to learn from communication when it is addressed to them. We tested whether 9-month-old human infants can distinguish between communicative and noncommunicative social contexts and whether they retain qualitatively different information about novel objects in these contexts. We found that in a communicative context, infants devoted their limited memory resources to encoding the identity of novel objects at the expense of encoding their location, which is preferentially retained in noncommunicative contexts. We propose that infants' sensitivity to, and interpretation of, the social cues distinguishing infant-directed communication events represent important mechanisms of social learning by which others can help determine what information even preverbal human observers retain in memory.

A cross-language investigation of infant preference for infant-directed communication

Virtually all the research to date on infant preference for infant-directed talk has been conducted with English-learning infants. This study was designed to test whether the preference for native infant-directed (ID) communication extends to a language group other than English, and whether infants' preference for ID communication extends to a nonnative language. English- and Cantonese-learning infants 4.5 and 9.0 months of age were tested on their preference for filmed displays of a Cantonese-speaking female addressing either her own infant (ID) or an adult (AD). Both groups of infants showed a robust attentional and affective preference for ID over AD in Cantonese. These results strengthen the claim that the special properties evident in ID communication may have universal attentional and affective significance.