It's the journey,not the destination: Locomotor exploration in infants

What incites infant locomotion? Recent research suggests that locomotor exploration is not primarily directed toward distant people, places, or things. However, this question has not been addressed experimentally. In the current study, we asked whether a room filled with toys designed to encourage locomotion (stroller, ball, etc.) elicits different quantities or patterns of exploration than a room with no toys. Caregivers were present but did not interact with infants. Although most walking bouts in the toy‐filled room involved toys, to our surprise, 15‐month‐olds in both rooms produced the same quantity of locomotion. This finding suggests that mere space to move is sufficient to elicit locomotion. However, infants' patterns of locomotor exploration differed: Infants in the toy‐filled room spent a smaller percent of the session within arms' reach of their caregiver and explored more locations in the room. Real‐time analyses show that infants in the toy‐filled room took an increasing number of steps per bout and covered more area as the session continued, whereas infants in the no‐toy room took fewer and fewer steps per bout and traveled repeatedly over the same ground. Although not required to elicit locomotion, moving with toys encouraged infants to travel farther from their caregivers and to explore new areas.     

Reinforcement of vocalizations through contingent vocal imitation

Maternal vocal imitation of infant vocalizations is highly prevalent during face-to-face interactions of infants and their caregivers. Although maternal vocal imitation has been associated with later verbal development, its potentially reinforcing effect on infant vocalizations has not been explored experimentally. This study examined the reinforcing effect of maternal vocal imitation of infant vocalizations using a reversal probe BAB design. Eleven 3- to 8-month-old infants at high risk for developmental delays experienced contingent maternal vocal imitation during reinforcement conditions. Differential reinforcement of other behavior served as the control condition. The behavior of 10 infants showed evidence of a reinforcement effect. Results indicated that vocal imitations can serve to reinforce early infant vocalizations.     

Differences in object sharing between infants at risk for autism and typically developing infants from 9 to 15 months of age

Object sharing abilities of infants at risk for autism (AR infants) and typically developing (TD) infants were compared from 9 to 15 months of age. Specifically, we examined the effects of infants’ locomotor abilities on their object sharing skills. 16 TD infants and 16 AR infants were observed during an “object sharing” paradigm at crawling and walking ages. Overall, AR walking infants demonstrated lower rates of object sharing with caregivers compared to TD walking infants. Specifically, AR walking infants had lower rates of giving and approaches toward caregivers compared to TD walking infants. AR walking infants also had lower step rates toward task-appropriate targets, i.e. caregivers and objects compared to TD walking infants. No group differences in object sharing were observed at crawling ages. Object sharing could be a valuable context for early identification of delays in infants at risk for developing Autism spectrum disorder.     

The role of crawling and walking experience in infant spatial memory

This research explored infants' use of place learning and cue learning in a locomotor task across the transition from crawling to walking. Novice and expert crawling and walking infants were observed in a novel locomotor task-finding a hidden goal location in a large space. In Experiment 1, infants were tested with distal landmarks. Infants with fewer than 6 weeks of experience, either crawling or walking, could not find the goal location. All infants with more locomotor experience were more successful. Learning did not transfer across the transition to walking. In Experiment 2, novice and expert crawlers and walkers were tested with a direct landmark. Again, novice crawlers and walkers with fewer than 6 weeks of experience could not find the goal, whereas those with more experience could. Taken together, these findings suggest that infants' spatial learning is inextricably linked to mode of locomotion.     

The effect of different soothing interventions on infant crying and on parent–infant interaction

Conducted in the home environment, this study examines the effects of three complementary soothing techniques on the duration of infant crying and on caregiver–infant interaction. In one group, the caregivers apply massage; in another, they provide supplemental carrying to their infants, and in the last, the caregivers both massage and provide supplemental carrying. Measurements, for the one control and three treatment groups took place prenatally (third trimester) and in the first 16 weeks postpartum for parental perception of infant temperament, parental sense of competence, parent–infant interaction, and the duration of infant crying. Whereas analyses indicate no statistically significant differences between groups in reducing infant crying, results approached significance (p ≤ .06) in favor of the combined supplemental carrying/massage group. These results challenge accepted beliefs that tactile stimulation and/or supplemental carrying enhance parental sense of competence, positive parental perceptions, and interactions with infants. Practitioners can apply these conclusions when counselling parents on the advisability of selecting any one complementary soothing technique. ©2002 Michigan Association for Infant Mental Health.     

Unweighting infants reveals hidden motor skills

We investigated the role of rate limiting factors in development using walking as a model system. The achievement of bipedal posture and locomotion are among the most significant achievements in an infant's first year, with poor balance and weak muscles long proposed as the rate limiting factors. Compensating for either may reveal upright motor skill that has not yet emerged in the infant's natural repertoire. To probe this question, we unweighted prewalking infants and measured their performance in various standing and walking behaviors while unweighted compared to baseline. Our secondary objective was to determine if the influence of unweighting was related to infants’ locomotor experience. Infants stood unsupported for longer durations with 20% or 40% unweighting. Infants took more independent steps and more steps with one hand held with 40% unweighting. No differences in transition to/from standing were observed. Locomotor experience was related to the influence of unweighting during cruising and walking with a push toy. This is the first report of more advanced motor skills—longer periods of unsupported standing and the emergence of independent walking—revealed by unweighting infants. We interpret our observations to suggest that the refinement of motor control needed to support bipedal posture and locomotion precedes the functional emergence of these skills in infants. In other words, the musculoskeletal components required for walking are slower to develop than the neurological factors – and consequently may be the rate limiters. We further suggest that training regimens including unweighting should be explored in infants with motor delays.     

Development of self‐produced locomotion in the first year: changes in parent perceptions and infant behaviour

Self‐produced locomotion is regarded as a setting event for other developmental transitions in infancy with important implications for socioemotional development and parent–child interaction. Using an age‐held‐constant design, this study examined changes in reported infant behaviour and maternal proactive/reactive control and compared them with direct observations of infant and maternal behaviour associated with the development of self‐produced locomotion. Maternal reports were obtained prior to the locomotor transition and, for half the sample, after infants had transitioned to effective mobility. Observations of all infants were conducted shortly after the second interview. Prelocomotor and transitioning infants showed none of the expected behavioural differences (e.g. emotionality and compliance) associated with the locomotor transition. There was modest confirmation of expected differences in maternal behaviour, particularly in the use of reactive control techniques, and mothers of transitioning infants showed higher proactive controls before their infants began to crawl. These findings suggest that the changes in parent–child interaction associated with the locomotor transition may have as much to do with parental expectations than with changes in infant socioemotional behaviour. 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.     

Coincidence or cascade? The temporal relation between locomotor behaviors and the emergence of stranger anxiety

Two infant milestones, self-propelled locomotion and stranger anxiety, tend to emerge at a similar age in development. An adaptive relation may exist in which the onset of one influences the development of the other in individual children. We examine whether these milestones systematically co-occur and whether one reliably precedes the other. In the current study, 104 parents completed weekly online surveys between 6 and 12 months, noting milestones as they occurred. Onset ages for locomotor behaviors were correlated with onset of stranger anxiety over and above a milestone in a third domain, namely consonant-vowel babbling. These data suggest that infants’ earliest locomotor behaviors may play a role in galvanizing the development of stranger anxiety.     

Role of motor imitation in traversability of surfaces by walking infants.

The ecological approach by Gibson stressed the role of visual cues in toddlers' locomotor activities. In particular, a rigid surface offers more traversability "affordances" to walkers (13-16 mo. old) than a deformable surface. On the other hand, imitation plays a relevant role in human behaviors. In our study a group of 17 walking infants (12-19 mo.) were asked to choose between locomoting on a rigid versus a deformable surface after having seen an older child walking on the deformable surface. A control group of 19 infants were asked to do the same task without having seen a model. The task was repeated three times. No relevant differences appeared between the two groups as to the choice of surfaces: the rigid surface was preferred by both groups. Some slight differences in the behavior of the experimental group were seen as a result of observing the model. Clearly, however, social stimulus. such as the sight of an older child performing a specific task, does not overcome the affordances which induce infants not to walk on the deformable surface.     

Learning to Move

ABSTRACT— Locomotion—moving the body from place to place—is one of infants' greatest achievements. In addition to conquering gravity, infants must cope with variable and novel constraints on balance and propulsion. At the same time that they are learning to move, changes in infants' bodies, skills, and environments change the biomechanical constraints on movement. Recent work highlights both flexibility and specificity in infants' responses to novel and variable situations, demonstrating that infants are learning to learn as they master locomotion. Within sitting, crawling, cruising, and walking postures, experienced infants adapt their locomotor responses to the current biomechanical constraints on movement. However, what infants have learned about coping with variability and novelty in earlier-developing postures does not transfer to later-developing postures.     

On-Line Updating of Spatial Information Druing Locomotion Without Vision

Two experiments are reported in which the control of locomotion without vision was investigated. In Experiment 1, subjects (N = 10) made similar, although less functional, locomotor adjustments when walking without vision to a target than they did when walking with vision. That result suggests that while walking without vision, the subjects updated their positions on-line with respect to a representation of the target rather than operating from a preformulated action plan. In Experiment 2, there was a significant weakening and loss of functionality of the locomotor adjustments when subjects (N = 10) had to walk without vision the correct distance to the target but in a direction opposite to its true location, as compared with when they walked without vision directly to the target. That finding suggests that the subjects were nonvisually updating their positions not with respect to an abstract representation of the target's distance but with respect to a representation of its relative location within the task environment.     

Behavioral Control Dynamics and Developmental Outcomes in Infants Prenatally Exposed to Cocaine

This study longitudinally examined the associations between mother–infant interactions at 15 months and behavioral and cognitive outcomes at 36 months of age in a sample of at‐risk, young children. Participants for the current study were 58 infants/toddlers prenatally exposed to cocaine and their maternal caregivers. These infants were from a low socioeconomic status background and were part of an intervention setting. When the children were 12, 15, and 36 months, they participated in research sessions with their maternal caregivers. Cognitive development at 12 months and maternal and infant behavior at 15 months were measured to predict behavioral and cognitive outcome at 36 months. Higher levels of maternal control at 15 months were marginally significant in predicting higher levels of problem behavior at 36 months whereas higher levels of infant resistance to control predicted lower levels of problem behavior. Furthermore, control‐resistant behavior displayed by infants was a unique buffer against problem behavior, even after controlling for maternal factors and cognitive abilities. These findings suggest that maternal control attempts and infant reactions to those maternal control behaviors play an important role in the development of adaptive and maladaptive behavior patterns during early childhood.     

Learning to walk changes infants’ social interactions

The onset of crawling marks a motor, cognitive and social milestone. The present study investigated whether independent walking marks a second milestone for social behaviors. In Experiment 1, the social and exploratory behaviors of crawling infants were observed while crawling and in a baby-walker, resulting in no differences based on posture. In Experiment 2, the social behaviors of independently walking infants were compared to age-matched crawling infants in a baby-walker. Independently walking infants spent significantly more time interacting with the toys and with their mothers, and also made more vocalizations and more directed gestures compared to infants in the walker. Experiment 3 tracked infants’ social behaviors longitudinally across the transition from crawling and walking. Even when controlled for age, the transition to independent walking marked increased interaction time with mothers, as well as more sophisticated interactions, including directing mothers’ attention to particular objects. The results suggest a developmental progression linking social interactions with milestones in locomotor development.     

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.     

The role of oxytocin in early mother-infant interactions: Variations in maternal affect attunement

The aim of the present research was to investigate the relationship between oxytocin and maternal affect attunement, as well as the role of affect attunement in the relationship between oxytocin and infant social engagement during early mother-infant interactions. Forty-three mother-infant dyads participated in the present study when infants were 4 months. They were observed during (1) a situation where no communication took place and (2) a natural interaction between mother and infant. During this procedure, three saliva samples from mothers and their infants were collected to determine their levels of oxytocin at different time points. Maternal affect attunement (maintaining attention, warm sensitivity) and infant interactive behaviors (gaze, positive, and negative affect) were coded during the natural interaction. Results indicated that overall maternal oxytocin functioning was negatively related to her warm sensitivity, while infant oxytocin reactivity together with maternal affect attunement were associated with infant positive social engagement with their mothers. Specifically, infant oxytocin reactivity was significantly related to their gazes at mother, but only for infants of highly attuned mothers. These results point to the complex role oxytocin plays in parent-infant interactions while emphasizing the need to analyze both overall oxytocin functioning as well as reactivity as different indices of human affiliative behavior.     

Neonatal imitation predicts how infants engage with faces

In human infants, neonatal imitation and preferences for eyes are both associated with later social and communicative skills, yet the relationship between these abilities remains unexplored. Here we investigated whether neonatal imitation predicts facial viewing patterns in infant rhesus macaques. We first assessed infant macaques for lipsmacking (a core affiliative gesture) and tongue protrusion imitation in the first week of life. When infants were 10–28 days old, we presented them with an animated macaque avatar displaying a still face followed by lipsmacking or tongue protrusion movements. Using eye tracking technology, we found that macaque infants generally looked equally at the eyes and mouth during gesture presentation, but only lipsmacking‐imitators showed significantly more looking at the eyes of the neutral still face. These results suggest that neonatal imitation performance may be an early measure of social attention biases and might potentially facilitate the identification of infants at risk for atypical social development.     

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.     

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.