Social touch alters newborn monkey behavior

In humans, infants respond positively to slow, gentle stroking—processed by C-tactile (CT) nerve fibers—by showing reductions in stress and increases in eye contact, smiling, and positive vocalizations. More frequent maternal touch is linked to greater activity and connectivity strength in social brain regions, and increases children’s attention to and learning of faces. It has been theorized that touch may prime children for social interactions and set them on a path towards healthy social cognitive development. However, less is known about the effects of touch on young infants’ psychological development, especially in the newborn period, a highly sensitive period of transition with rapid growth in sensory and social processing. It remains untested whether newborns can distinguish CT-targeted touch from other types of touch, or whether there are benefits of touch for newborns’ social, emotional, or cognitive development. In the present study, we experimentally investigated the acute effects of touch in newborn monkeys, a common model for human social development. Rhesus macaques (Macaca mulatta), like humans, are highly social, have complex mother-infant interactions with frequent body contact for the first weeks of life, making them an excellent model of infant sociality. Infant monkeys in the present study were reared in a neonatal nursery, enabling control over their early environment, including all caregiver interactions. One-week-old macaque infants (N = 27) participated in three 5-minute counter-balanced caregiver interactions, all with mutual gaze: stroking head and shoulders (CT-targeted touch), stroking palms of hands and soles of feet (Non-CT touch), or no stroking (No-touch). Immediately following the interaction, infants watched social and nonsocial videos and picture arrays including faces and objects, while we tracked their visual attention with remote eye tracking. We found that, during the caregiver interactions, infants behaved differently while being touched compared to the no-touch condition, irrespective of the body part touched. Most notably, in both touch conditions, infants exhibited fewer stress-related behaviors—self-scratching, locomotion, and contact time with a comfort object—compared to when they were not touched. Following CT-targeted touch, infants were faster to orient to the picture arrays compared to the other interaction conditions, suggesting CT-targeted touch may activate or prime infants’ attentional orienting system. In the No-touch condition infants attended longer to the nonsocial compared to the social video, possibly reflecting a baseline preference for nonsocial stimuli. In contrast, in both touch conditions, infants’ looked equally to the social and nonsocial videos, suggesting that touch may influence the types of visual stimuli that hold infants’ attention. Collectively, our results reveal that newborn macaques responded positively to touch, and touch appeared to influence some aspects of their subsequent attention, although we found limited evidence that these effects are mediated by CT fibers. These findings suggest that newborn touch may broadly support infants’ psychological development, and may have early evolutionary roots, shared across primates. This study illustrates the unique insight offered by nonhuman primates for exploring early infant social touch, revealing that touch may positively affect emotional and attentional development as early as the newborn period.     

Infants’ intentionally communicative vocalizations elicit responses from caregivers and are the best predictors of the transition to language: A longitudinal investigation of infants’ vocalizations,gestures and word production

What aspects of infants’ prelinguistic communication are most valuable for learning to speak, and why? We test whether early vocalizations and gestures drive the transition to word use because, in addition to indicating motoric readiness, they (a) are early instances of intentional communication and (b) elicit verbal responses from caregivers. In study 1, 11 month olds (N = 134) were observed to coordinate vocalizations and gestures with gaze to their caregiver's face at above chance rates, indicating that they are plausibly intentionally communicative. Study 2 tested whether those infant communicative acts that were gaze‐coordinated best predicted later expressive vocabulary. We report a novel procedure for predicting vocabulary via multi‐model inference over a comprehensive set of infant behaviours produced at 11 and 12 months (n = 58). This makes it possible to establish the relative predictive value of different behaviours that are hierarchically organized by level of granularity. Gaze‐coordinated vocalizations were the most valuable predictors of expressive vocabulary size up to 24 months. Study 3 established that caregivers were more likely to respond to gaze‐coordinated behaviours. Moreover, the dyadic combination of infant gaze‐coordinated vocalization and caregiver response was by far the best predictor of later vocabulary size. We conclude that practice with prelinguistic intentional communication facilitates the leap to symbol use. Learning is optimized when caregivers respond to intentional vocalizations with appropriate language.     

Touch by Intrusive and Withdrawn Mothers with Depressive Symptoms

Interaction behaviours of 88 adolescent mothers with depressive symptoms and their 3-month-old infants were videotaped and coded for different types of touch. The ‘depressed’ mothers were classified as intrusive, withdrawm or good by one observer and another observer coded rough tickling, poking, tugging and pulling as negative touch behaviours and gentle stroking and rubbing as positive touch behaviours. The mothers with depressive symptoms were more likely to touch their infants in a negative way and more likely to be classified as intrusive.     

Marked referential communicative behaviours,but no differentiation of the “knowledge state” of humans in untrained pet dogs versus 1-year-old infants

The study examines whether untrained dogs and infants take their caregiver’s visual experience into account when communicating with them. Fifteen adult dogs and 15 one-year-old infants were brought into play with their caregivers with one of their own toys. The caregiver gave the toy to the experimenter, who, in different conditions, placed it either above or under one of two containers, with both the infant or dog and the caregiver witnessing the positioning; in a third condition, the caregiver left the room before the toy was placed under one of the two containers and later returned. Afterwards, for each condition, the caregiver asked the participant to indicate the location of the toy. Neither dogs nor infants—untrained to the use of the partner’s knowledge state—showed much difference of behaviour between the three conditions. However, dogs showed more persistence for most behaviours (gaze at the owner, gaze at the toy and gaze alternation) and conditions, suggesting that the situation made more demands on dogs’ communicative behaviours than on those of infants. When all deictic behaviours of infants (arm points towards the toy and gaze at the toy) were taken into account, dogs and infants did not differ. Phylogeny, early experience and ontogeny may all play a role in the ways that both species communicate with adult humans.     

Infant brain responses to felt and observed touch of hands and feet: an MEG study

There is growing interest concerning the ways in which the human body, both one's own and that of others, is represented in the developing human brain. In two experiments with 7‐month‐old infants, we employed advances in infant magnetoencephalography (MEG) brain imaging to address novel questions concerning body representations in early development. Experiment 1 evaluated the spatiotemporal organization of infants’ brain responses to being touched. A punctate touch to infants’ hands and feet produced significant activation in the hand and foot areas of contralateral primary somatosensory cortex as well as in other parietal and frontal areas. Experiment 2 explored infant brain responses to visually perceiving another person's hand or foot being touched. Results showed significant activation in early visual regions and also in regions thought to be involved in multisensory body and self–other processing. Furthermore, observed touch of the hand and foot activated the infant's own primary somatosensory cortex, although less consistently than felt touch. These findings shed light on aspects of early social cognition, including action imitation, which may build, at least in part, on infant neural representations that map equivalences between the bodies of self and other.     

Infants’ behaviours elicit different verbal,nonverbal, and multimodal responses from caregivers during early play

Caregivers use a range of verbal and nonverbal behaviours when responding to their infants. Previous studies have typically focused on the role of the caregiver in providing verbal responses, while communication is inherently multimodal (involving audio and visual information) and bidirectional (exchange of information between infant and caregiver). In this paper, we present a comprehensive study of caregivers’ verbal, nonverbal, and multimodal responses to 10-month-old infants’ vocalisations and gestures during free play. A new coding scheme was used to annotate 2036 infant vocalisations and gestures of which 87.1 % received a caregiver response. Most caregiver responses were verbal, but 39.7 % of all responses were multimodal. We also examined whether different infant behaviours elicited different responses from caregivers. Infant bimodal (i.e., vocal-gestural combination) behaviours elicited high rates of verbal responses and high rates of multimodal responses, while infant gestures elicited high rates of nonverbal responses. We also found that the types of verbal and nonverbal responses differed as a function of infant behaviour. The results indicate that infants influence the rates and types of responses they receive from caregivers. When examining caregiver-child interactions, analysing caregivers’ verbal responses alone undermines the multimodal richness and bidirectionality of early communication.     

Past and present experiences with maternal touch affect infants’ attention toward emotional faces

Maternal touch is considered crucial in regulating infants’ internal states when facing unknown or distressing situations. Here, we explored the effects of maternal touch on 7-month-old infants’ preferences towards emotions. Infants’ looking times were measured through a two-trial preferential looking paradigm, while infants observed dynamic videos of happy and angry facial expressions. During the observation, half of the infants received an affective touch (i.e., stroke), while the other half received a non-affective stimulation (i.e., fingertip squeeze) from their mother. Further, we assessed the frequency of maternal touch in the mother-infant dyad through The Parent-Infant Caregiving Touch Scale (PICTS). Our results have shown that infants’ attention to angry and happy facial expressions varied as a function of both present and past experiences with maternal touch. Specifically, in the affective touch condition, as the frequency of previous maternal affective tactile care increased (PICTS), the avoidance of angry faces decreased. Conversely, in the non-affective touch condition, as the frequency of previous maternal affective tactile care increased (PICTS), the avoidance of angry faces increased as well. Thus, past experience with maternal affective touch is a crucial predictor of the regulatory effects that actual maternal touch exerts on infants’ visual exploration of emotional stimuli.     

Infant touching behaviour during mother–infant face‐to‐face interactions

The study of infant communication during mother–infant interactions has largely focused on infants' distal behaviours, while neglecting their more proximal behaviours, such as touch. Yet, touch is an important modality through which infants and mothers communicate; it is also a vital means through which infants self‐regulate and explore their surroundings. The present study was designed to investigate the touching behaviours of 44, 51/2‐month‐old, healthy, full‐term infants during face‐to‐face mother–infant interactions. A still‐face (SF) procedure was used in order to examine differences in the types and locations of infant touch across normal and perturbed interaction periods, when mothers exhibit changes in their emotional availability. Results revealed that infant touch varied with changes in maternal availability. During the SF period, when mothers were unavailable, infants used more active, soothing, and reactive tactile behaviours (stroke, finger, pat, and pull), and they spent more time touching themselves. In contrast, infants used mostly passive touch (static) during the Normal periods, when their mothers were available. They also spent a significant portion of time touching their mothers. The variations in infant touch across periods suggest that infants communicate their affective states through touch. The findings also support the regulatory and exploratory roles of infant touch, especially during periods of maternal unavailability. Copyright © 2007 John Wiley & Sons, Ltd.     

Early interactions and the socioemotional development of deaf infants

Studies of the early face-to-face interactions and later attachment behaviours between infants and their caregivers are reviewed, with a particular focus on implications for deaf infants. Since the majority of deaf infants are born to hearing parents, it is to be expected that many parental responses will rely on vocalizations which are inaccessible to the deaf infant. Are other sensory modalities enhanced or used in a compensatory manner by hearing parents so as to make their communication with a deaf infant more effective? Is the deaf infant's heightened need for visual and tactile input adequately met during normal interactions with their caregivers? Does the deaf infant develop the same strategies for signalling distress and coping with separation as does the hearing infant? Although the research literature on this population is sparse, there are beginning to be more reports addressing these questions as early identification becomes increasingly possible. Therefore, this paper will cover issues of the role of eye contact and mutual coordination in early interactions, compensatory parenting behaviours from the perspective of the ‘intuitive parenting’ model, and precursors to later attachment behaviours in deaf infants.     

Mutual touch during mother–infant face-to-face still-face interactions: Influences of interaction period and infant birth status

Contact behaviours such as touch, have been shown to be influential channels of nonverbal communication between mothers and infants. While existing research has examined the communicative roles of maternal or infant touch in isolation, mutual touch, whereby touching behaviours occur simultaneously between mothers and their infants, has yet to be examined. The present study was designed to investigate mutual touch during face-to-face interactions between mothers and their 5½-month-old fullterm (n = 40), very low birth weight/preterm (VLBW/preterm; n = 40) infants, and infants at psychosocial risk (n = 41). Objectives were to examine: (1) how the quantitative and qualitative aspects of touch employed by mothers and their infants varied across the normal periods of the still-face (SF) procedure, and (2) how these were associated with risk status. Mutual touch was systematically coded using the mother–infant touch scale. Interactions were found to largely consist of mutual touch and one-sided touch plus movement, highlighting that active touching is pervasive during mother–infant interactions. Consistent with the literature, while the SF period did not negatively affect the amount of mutual touch engaged in for mothers and their fullterm infants and mothers and their infants at psychosocial risk, it did for mothers and their VLBW/preterm infants. Together, results illuminate how both mothers and infants participate in shaping and co-regulating their interactions through the use of touch and underscore the contribution of examining the influence of birth status on mutual touch.     

What Is the Buzz About Iconicity? How Iconicity in Caregiver Speech Supports Children's Word Learning

One cue that may facilitate children's word learning is iconicity, or the correspondence between a word's form and meaning. Some have even proposed that iconicity in the early lexicon may serve to help children learn how to learn words, supporting the acquisition of even noniconic, or arbitrary, word–referent associations. However, this proposal remains untested. Here, we investigate the iconicity of caregivers’ speech to young children during a naturalistic free-play session with novel stimuli and ask whether the iconicity of caregivers’ speech facilitates children's learning of the noniconic novel names of those stimuli. Thirty-four 1.5-2-year-olds (19 girls; half monolingual English learners and half bilingual English-Spanish learners) participated in a naturalistic free-play task with their caregivers followed by a test of word-referent retention. We found that caregivers’ use of iconicity, particularly in utterances in which they named the novel stimuli, was associated with the likelihood that children learned that novel name. This result held even when controlling for other factors associated with word learning, such as the concreteness and frequency of words in caregiver speech. Together, the results demonstrate that iconicity not only can serve to help children identify the referent of novel words (as in previous research) but can also support their ability to retain even noniconic word-referent mappings.     

See and be seen: Infant–caregiver social looking during locomotor free play

Face‐to‐face interaction between infants and their caregivers is a mainstay of developmental research. However, common laboratory paradigms for studying dyadic interaction oversimplify the act of looking at the partner's face by seating infants and caregivers face to face in stationary positions. In less constrained conditions when both partners are freely mobile, infants and caregivers must move their heads and bodies to look at each other. We hypothesized that face looking and mutual gaze for each member of the dyad would decrease with increased motor costs of looking. To test this hypothesis, 12‐month‐old crawling and walking infants and their parents wore head‐mounted eye trackers to record eye movements of each member of the dyad during locomotor free play in a large toy‐filled playroom. Findings revealed that increased motor costs decreased face looking and mutual gaze: Each partner looked less at the other's face when their own posture or the other's posture required more motor effort to gain visual access to the other's face. Caregivers mirrored infants' posture by spending more time down on the ground when infants were prone, perhaps to facilitate face looking. Infants looked more at toys than at their caregiver's face, but caregivers looked at their infant's face and at toys in equal amounts. Furthermore, infants looked less at toys and faces compared to studies that used stationary tasks, suggesting that the attentional demands differ in an unconstrained locomotor task. Taken together, findings indicate that ever‐changing motor constraints affect real‐life social looking.     

Cultural Differences in Physical Contact Between Hispanic and Anglo Mother–Infant Dyads Living in the United States

This is a study of differences in physical contact and tactile interpersonal behaviours between Hispanic and Anglo mothers and infants living in the United States. Infants were 9 months old and 52 mother–infant dyads, 26 Hispanic and 26 Anglo, were videotaped during free play without toys in a university laboratory playroom. Coders judged the interpersonal distance, physical contact and affectionate touch from the videotapes and mothers responded to a questionnaire about the importance of physical contact and affectionate touch in their relationship with their infant. From questionnaire data we found that Hispanic and Anglo mothers both touch their infants on a daily basis, although Hispanic mothers report touching more frequently, being more affectionate with their infants and having more skin-to-skin contact. From videotaped observations we found that there were no overall differences in mother–infant touch between the two cultures; however, the Hispanic mothers showed more close touch and more close and affectionate touch compared to Anglo mothers, who showed more distal touch. The results are discussed in terms of the role of touch in infant development and cultural differences in the evaluation of close physical contact and touch.     

Demystifying infant vocal imitation: The roles of mouth looking and speaker’s gaze

Vocal imitation plays a fundamental role in human language acquisition from infancy. Little is known, however, about how infants imitate other's sounds. We focused on three factors: (a) whether infants receive information from upright faces, (b) the infant's observation of the speaker's mouth and (c) the speaker directing their gaze towards the infant. We recorded the eye movements of 6‐month‐olds who participated in experiments watching videos of a speaker producing vowel sounds. We found that an infants’ tendency to vocally imitate such videos increased as a function of (a) seeing upright rather than inverted faces, (b) their increased looking towards the speaker's mouth and (c) whether the speaker directed their gaze towards, rather than away from infants. These latter findings are consistent with theories of motor resonance and natural pedagogy respectively. New light has been shed on the cues and underlying mechanisms linking infant speech perception and production.     

Investigating Maternal Touch and Infants' Self‐Regulatory Behaviours during a Modified Face‐to‐Face Still‐Face with Touch Procedure

Maternal touch and infants' self‐regulatory behaviours were examined during a modified Still‐Face with Touch (SF + T) procedure. Mothers and their 5½‐month‐old infants participated in one period of Normal interaction followed by three SF + T periods. Maternal functions of touch, and infants' self‐regulatory behaviour, affect, and attention were evaluated. Contrary to a typical SF procedure, the amount of smiling remained high while fretting remained low. High levels of maternal touching and variations in the functions of maternal touch were observed across periods. Playful touch remained high while there was an increase in nurturing touch and a decrease in attention‐getting touch from the Normal to all SF + T periods. Similar amounts of self‐regulatory behaviours were observed across periods with the exception of a decrease in bidirectional exchanges during the SF + T periods. Finally, across periods, maternal touch and infants' self‐regulatory behaviours were found to be temporally organized with infants' affect and attention. Examining how mothers use touch when other forms of communication are absent increased our understanding of the role of touch in infants' emotion regulation. Copyright © 2014 John Wiley & Sons, Ltd.     

Early tactile experience of low birth weight children: links to later mental health and social adaptation

The purpose of this study was twofold: to determine (1) the degree to which specific qualities of maternal touch may contribute to the low birth weight infant's emotional and behavioural problems as well as social adaptation, and (2) the relationship between maternal touch and a mother's other caregiving behaviour. The sample included 114 socioculturally diverse infants and their mothers who were videotaped during an infant feeding when the baby was 3 months old. This videotape was analysed to assess dimensions of mother–infant interaction, including maternal touch. Data on perinatal risk and the mother's acceptance versus rejection of the infant were also acquired. Social adaptation and emotional/behavioural problems were measured when the child was 2 years of age. Hierarchical regression analyses indicated that maternal touch accounted for 15% of the variance in the likelihood of a child having emotional/behavioural problems at age 2. Children who received more nurturing touch had significantly fewer internalizing problems (such as depression) while children receiving both more frequent touch and harsh touch had more externalizing problems (such as aggressive behaviour). Infants who were less responsive to their caregivers were especially at risk of developing aggressive/destructive behaviour as a result of frequent touch. But less responsive infants also appeared to benefit most from greater use of diverse types of maternal touch, accounting for 6% of the variance in superior adaptive behaviour at age 2. Nurturing touch was the only quality that showed even a modest relationship to other caregiving behaviour, suggesting that touch may play a distinct role in the infant's psychosocial development. Copyright © 2001 John Wiley & Sons, Ltd.     

Uncertainty matters: impact of stimulus ambiguity on infant social referencing

Most infant social referencing studies have assumed that infants would be more likely to engage in social looking and be influenced by adults' message when a context is ambiguous. The present study empirically tested the effect of stimulus ambiguity on infants' referencing behaviours, with three different stimuli (positive, ambiguous, and negative), two different messages (happy and fearful), two different message providers (mother and stranger), and in two age groups (12 and 16 month olds). A typical social referencing paradigm was used and infants' social looking and regulation were measured. Infants looked at adults more frequently and faster during ambiguous situations than during unambiguous situations. They also tended to regulate their affect and behaviour based on adults' message only towards ambiguous toys. Older infants tended to look at adults faster, and showed stronger reactions towards ambiguous stimuli than younger infants, suggesting that infants' social development may moderate the effect of stimulus ambiguity on social referencing. Overall, results indicated that the ambiguity postulate is a legitimate assumption for infant social referencing. Copyright © 2010 John Wiley & Sons, Ltd.     

The social functions of babbling: acoustic and contextual characteristics that facilitate maternal responsiveness

What is the social function of babbling? An important function of prelinguistic vocalizing may be to elicit parental behavior in ways that facilitate the infant's own learning about speech and language. Infants use parental feedback to their babbling to learn new vocal forms, but the microstructure of parental responses to babbling has not been studied. To enable precise manipulation of the proximal infant cues that may influence maternal behavior, we used a playback paradigm to assess mothers’ responsiveness to prerecorded audiovisual clips of unfamiliar infants’ noncry prelinguistic vocalizations and actions. Acoustic characteristics and directedness of vocalizations were manipulated to test their efficacy in structuring social interactions. We also compared maternal responsiveness in the playback paradigm and in free play with their own infants. Maternal patterns of reactions to babbling were stable across both tasks. In the playback task, we found specific vocal cues, such as the degree of resonance and the transition timing of consonant‐vowel syllables, predicted contingent maternal responding. Vocalizations directed at objects also facilitated increased responsiveness. The responses mothers exhibited, such as sensitive speech and vocal imitation, are known to facilitate vocal learning and development. Infants, by influencing the behavior of their caregivers with their babbling, create social interactions that facilitate their own communicative development.     

Exploring maternal touch in the infant’s first 18 months of Life: A study on an Italian sample

Affective touch is a crucial component of caregiving in early life and constitutes a key factor with a significant impact on infant later-life outcomes. The Parent-Infant Caregiving Touch Scale (PICTS) allows to quantify and qualify the caregiver's self-perception of touch in the first months of an infant’s life. In the current study, we contributed to validation of the PICTS in the Italian language in order to explore whether early maternal touch would be associated with maternal emotional state, maternal history of affective touch experiences throughout the lifespan, and infants’ sex and age. Data analyses were run on a sample of 377 Italian mothers (mean age = 33.29; SD = 4.79) participating in an online survey. Confirmatory factor analysis was applied. A three-dimensional structure of PICTS (i.e., stroking, affective communication, and holding) after removing one item out resulted in the best model in our sample. Maternal emotional state did not affect PICTS factor scores while maternal comfort and amount of affective touch experienced during adulthood was significantly associated with the stroking, affective communication, and holding factors. Regarding infants’ dimensions, infants’ sex and age were not associated with PICTS factor scores. Findings suggest that the PICTS Italian version is a good measurement of caregiver's self-perception of touch in early infancy and that maternal history of touch is associated with a mother’s current use of touch.