The Influence of Mouthing on Infant Vocalization

Although vocalization and mouthing are behaviors frequently performed by infants, little is known about the characteristics of vocalizations that occur with objects, hands, or fingers in infants' mouths. The purpose of this research was to investigate characteristics of vocalizations associated with mouthing in 6‐ to 9‐month‐old infants during play with a primary caregiver. Results suggest that mouthing may influence the phonetic characteristics of vocalizations by introducing vocal tract closure and variation in consonant production.     

Multiple Coordination Patterns in Infant and Adult Vocalizations

The study of vocal coordination between infants and adults has led to important insights into the development of social, cognitive, emotional, and linguistic abilities. We used an automatic system to identify vocalizations produced by infants and adults over the course of the day for fifteen infants studied longitudinally during the first 2 years of life. We measured three different types of vocal coordination: coincidence‐based, rate‐based, and cluster‐based. Coincidence‐based coordination and rate‐based coordination are established measures in the developmental literature. Cluster‐based coordination is new and measures the strength of matching in the degree to which vocalization events occur in hierarchically nested clusters. We investigated whether various coordination patterns differ as a function of vocalization type, whether different coordination patterns provide unique information about the dynamics of vocal interaction, and how the various coordination patterns each relate to infant age. All vocal coordination patterns displayed greater coordination for infant speech‐related vocalizations, adults adapted the hierarchical clustering of their vocalizations to match that of infants, and each of the three coordination patterns had unique associations with infant age. Altogether, our results indicate that vocal coordination between infants and adults is multifaceted, suggesting a complex relationship between vocal coordination and the development of vocal communication.     

Crawling Experience Predicts Avoidance of Real Cliffs and Water Cliffs: Insights from a New Paradigm

This study examined the influence of age, crawling‐onset age, and crawling experience on infants’ adaptive behavior in situations that can lead to dangerous falls. Thirty‐one infants with variable amounts of crawling experience were tested in a new paradigm that used a real cliff and a water cliff, with a harness system to guarantee safety. Consistent with previous findings obtained in studies with real and visual cliffs, infants with more crawling experience were more likely to avoid the real cliff. More importantly, greater crawling experience was associated with a greater likelihood of avoiding the water cliff. The new paradigm offers exciting opportunities to study the development of adaptive behavior in risky environments.     

Crawling is Associated with Mental Rotation Ability by 9‐Month‐Old Infants

The present experiment examined whether 9‐month‐old infants’ mental rotation ability was related to their crawling ability. Forty‐eight 9‐month‐old infants were tested; half of them crawled for 7.1 weeks on average. Infants were habituated to a video of a simplified Shepard–Metzler object rotating back and forth through a 240° angle around the longitudinal axis of the object. Infants were tested with videos of the same object rotating through the previously unseen 120° angle and with the mirror image of that display. The results showed that the crawlers looked significantly longer at the mirror object than at the familiar object. The results support the interpretation that crawling experience is associated with 9‐month‐old infants’ mental rotation ability.     

Individual Differences in Infants’ Joint Attention Behaviors With Mother and a New Social Partner

Relations between infant–mother attachment security at 15 months and infants’ (N = 206) joint attention behaviors (a) with an experimenter at 8 and 15 months, and (b) with their mothers at 15 months were investigated. No concurrent or longitudinal relations were observed between attachment security and infants’ tendency to respond to an experimenter’s bids for joint attention. Higher levels of initiating joint attention with an experimenter at 15 months were associated with insecure‐avoidant attachment. Insecure‐avoidant attachment was also associated with lower scores for initiating high‐level joint attention behaviors (pointing, showing, and giving) with the mother at age 15 months. The fact that security‐related differences in initiating joint attention with an experimenter were observed only once the attachment relationship was consolidated suggests that (a) attachment security may influence infants’ active engagement with new social partners, and (b) insecure‐avoidant infants may compensate for reduced social contact with the caregiver by initiating more interaction with other social partners.     

Avoidance of Heights on the Visual Cliff in Newly Walking Infants

Work with infants on the “visual cliff” links avoidance of drop‐offs to experience with self‐produced locomotion. Adolph's (2002) research on infants' perception of slope and gap traversability suggests that learning to avoid falling down is highly specific to the postural context in which it occurs. Infants, for example, who have learned to avoid crossing risky slopes while crawling must learn anew such avoidance when they start walking. Do newly walking infants avoid crossing the drop‐off of the visual cliff? Twenty prewalking but experienced crawling infants were compared with 20 similarly aged newly walking infants on their reactions to the visual cliff. Newly walking infants avoided moving onto the cliff's deep side even more consistently than did the prewalking crawlers. Thus, in the context of drop‐offs in visual texture, our results show that once avoidance of drop‐offs is established under conditions of crawling, it is developmentally maintained once infants begin walking.     

Maternal Talk About Mental States and the Emergence of Joint Visual Attention

Twenty‐four infants were tested monthly for gaze and point following between 9 and 15 months of age and mother‐infant free play sessions were also conducted at 9, 12, and 15 months (Carpenter, Nagell, & Tomasello, 1998). Using this data set, this study explored relations between maternal talk about mental states during mothers' free play with their infants and the emergence of joint visual attention in infants. Contrary to hypothesis, mothers' comments about their infants' perceptual states significantly declined after their infants began to engage in joint visual attention. Comments about other mental states did not change relative to acquisition of joint visual attention skill. We speculate that after infants begin to reliably follow gaze and points, mothers may switch the focus of their conversation from their infants' visual behavior and experiences to the object of their mutual attention.     

The role of prosody in infants’ preference for speech: A comparison between speech and birdsong

Speech preferences emerge very early in infancy, pointing to a special status for speech in auditory processing and a crucial role of prosody in driving infant preferences. Recent theoretical models suggest that infant auditory perception may initially encompass a broad range of human and nonhuman vocalizations, then tune in to relevant sounds for the acquisition of species‐specific communication sounds. However, little is known about sound properties eliciting infants’ tuning‐in to speech. To address this issue, we presented a group of 4‐month‐olds with segments of non‐native speech (Mandarin Chinese) and birdsong, a nonhuman vocalization that shares some prosodic components with speech. A second group of infants was presented with the same segment of birdsong paired with Mandarin played in reverse. Infants showed an overall preference for birdsong over non‐native speech. Moreover, infants in the Backward condition preferred birdsong over backward speech whereas infants in the Forward condition did not show clear preference. These results confirm the prominent role of prosody in early auditory processing and suggest that infants’ preferences may privilege communicative vocalizations featured by certain prosodic dimensions regardless of the biological source of the sound, human or nonhuman.     

The Development of Anticipatory Smiling

When do infants begin to communicate positive affect about physical objects to their social partners? We examined developmental changes in the timing of smiles during episodes of initiating joint attention that involved an infant gazing between an object and a social partner. Twenty‐six typically developing infants were observed at 8, 10, and 12 months during the Early Social‐Communication Scales, a semistructured assessment for eliciting initiating joint attention and related behaviors. The proportion of infant smiling during initiating joint attention episodes did not change with age, but there was a change in the timing of the smiles. The likelihood of infants smiling at an object and then gazing at the experimenter while smiling (anticipatory smiling) increased between 8 and 10 months and remained stable between 10 and 12 months. The increase in the number of infants who smiled at an object and then made eye contact suggests a developing ability to communicate positive affect about an object.     

Developmental Change in Action Perception: Is Motor Experience the Cause?

Human actions are complex stimuli containing several perceptual dimensions an observer could attend to. Research indicates that attention to the perceptual dimensions of action undergoes a process of perceptual narrowing between 4 and 10 months, during which infants’ attention to configural and temporal information in action decreases over time, while attention to hand information is maintained. This research explored whether infants’ active experience with grasping is related to perceptual narrowing in action. Across two studies, we tested 6‐month‐old infants’ attention to changes in these action dimensions and also assessed their grasping ability. Infants who were more proficient at grasping showed a pattern more consistent with perceptual narrowing (decreasing attention to configural and temporal information) relative to those less proficient at grasping, especially for attention to configural information. In addition, attention to hand information appears to undergo U‐shaped development between 4 and 10 months, as 6‐month‐olds did not recover attention to the hand change. These findings add to a growing body of research showing that infants’ motor experience broadly influences their perception of others’ action and may follow a complex developmental pathway that diverges from perceptual narrowing over the first year.     

Effects of Contingent Reinforcement of Actions on Infants' Object‐Directed Reaching

The role of contingency learning was examined in 3‐month‐old infants' reaching movements. Infants in the experimental group experienced 9 min of active training during which they could move their arms in a reach‐like fashion to pull and move a mobile. Infants in the control group experienced 9 min of passive training during which they watched a mobile move. Prior to (pre‐training) and following the mobile experience (post‐training), infants in both conditions were given an opportunity to interact with a rattle placed within and out of their reach. Compared with infants in the control condition, infants in the experimental condition produced reach‐like movements more frequently during the mobile experience; they also showed a greater increase in reaching attempts from pre‐ to post‐training assessments with the rattle. These findings show that reinforcement of arm extensions and retractions increases the frequency of infants' reaching behaviors. This result suggests that the reinforcement of components of infants' behaviors may contribute to the successful assembly of these behaviors. This process could help keep infants engaged during the lengthy transition from prereaching to independent reaching.     

Blinking Bird Brains: A Timing Specific Deficit in Auditory Learning in Quail Hatchlings

Contingency perception is critical during infancy, providing the basis for the continuous learning (and re‐learning) of the relation between the developing body, self‐produced actions, and the environment. Nevertheless, relatively few studies have systematically examined the spatiotemporal parameters that optimize learning during development. Here, we present a series of experiments exploring a novel timing‐specific deficit in auditory learning in an animal model, the bobwhite quail (Colinus virginianus). In this paradigm, chicks vocalize to hear playback of an unfamiliar maternal call and are later tested for their filial preference for that call over a novel maternal call. Rather than a simple, hyperbolic decline in learning with increased delay between chick vocalization and playback, we found a window—450–900 msec after chicks ceased vocalizing—in which chicks appeared to have difficulty learning and forming a preference for the maternal call. This deficit nonetheless occurred only when the spatial location of call playback switched semi‐randomly during training, suggesting an attentional explanation for this deficit. Our findings indicate that optimization of the temporal parameters in operant paradigms with infants can be complex, particularly if tasks requiring the switching of attention between spatial locations. Our findings may thus be instructive for other developmental research with infants employing operant components.     

A Cross‐National Investigation of the Relationship Between Infant Walking and Language Development

The acquisition of walking has recently been linked with infant language development (Walle & Campos, 2014). If this relation reflects the consequence of an epigenetic event, then it should be present regardless of when the infant typically begins to walk, the infant's culture, and the infant's native language. This study sought to replicate the previously reported link between walking and language development in American infants and investigate whether this relation exists cross‐nationally in typically developing Chinese infants exposed to Mandarin. Urban Chinese infants not only provide a distinct linguistic and cultural population in which to study this relation but also typically begin walking approximately 6 weeks later than American infants. Our results demonstrated that (1) walking infants in both the American and Chinese samples had greater receptive and productive vocabularies than same‐aged crawling infants, (2) differences between crawling and walking infants were proportionally similar in each sample, and (3) the walking‐language relation was present for both noun and non‐noun vocabularies. These findings provide further support of a relation between infant walking onset and language development, independent of age. Avenues for future research of the processes involved in this relation, as well as additional populations of interest to investigate, are discussed.     

Exploring Infant Gesture and Joint Attention as Related Constructs and as Predictors of Later Language

In infancy, use of gesture and the ability to engage in joint attention with others both predict later language development. Conceptually, gesture and joint attention abilities may reflect a similar underlying social‐communicative skill. However, these abilities are often studied separately. Despite the fact that gesture is often used in episodes of joint attention, little is known about the degree to which measures of gesture use and joint attention ability are associated with one another or how they similarly, or differentially, predict children's language abilities. Participants in this study were 53 infants. At 12 months, multiple measures of infants’ gesture use were gleaned from a free–play interaction with a parent. Infants’ responding to and initiating joint attention were measured via the Early Social‐Communicative Scales (Mundy et al., 2003). Infants’ expressive and receptive language was measured at 24 months with the Mullen Scales of Early Learning (Mullen, 1995). A factor analysis including gesture and joint attention measures indicated that at 12 months, joint attention, particularly responding to joint attention, reflects a similar underlying construct with infant gesture use, yet they uniquely predict later language ability.     

Premature infant behavior: an ethological study in a special care nursery.

The Social and Sensory Environment Studies of very low birthweight infants have quantified the amount and quality of social interaction with staff and parents and described the sound environment in an incubator. The present study concerns preterm infant behavior and reactions to these stimuli with particular reference to approach and withdrawal and vocalization. Among the findings are that while intermittent vocalization increases, infant cry decreases over the first three weeks in the incubator. Approach activities take place with some consistency whereas withdrawal differs from child to child. The ethnographic focus on interactive components of the intensive care experience documents the process of intersubjective development for the purpose of locating and isolating points of vulnerability in language and cognitive skills of infants born at very low birthweight.     

Attention during Visual Preference Tasks: Relation to Caregiving and Face Recognition

This research examined how caregiver experience (female primary caregiver or distributed caregiving with mom and dad) influenced 10‐, 14‐, and 16‐month‐olds’ visual preferences and attention toward internal facial features of female–male face pairs, and how these behaviors related to novelty preferences in a face recognition task and speed and accuracy on a visual search task. In the visual preference task, infants visually preferred male faces, regardless of caregiver experience. Despite similarities in visual preferences, infants’ attention toward females and males’ internal facial features was related for infants with distributed caregiving only. Infants’ performance across face processing tasks most often correlated for those with female primary caregivers. Results further our understanding of how infants with female primary caregivers display specialized processing of female faces, and how infants with distributed caregiving show similarities in their attention to female and male facial features.     

Infants’ response to a mobile phone modified still‐face paradigm: Links to maternal behaviors and beliefs regarding technoference

Interruptions to parent–child interactions due to technology, or “technoference,” have been correlated with a host of negative child developmental outcomes. Yet, the influence of technoference on parent–infant interactions and infant behaviors has received less attention and more experimental work is warranted. For this study, parent–infant dyads (n = 227) completed a modified still‐face paradigm (SFP) using a mobile phone during the still‐face phase. Infant responses were coded for positive and negative affect, object and parent orientation, self‐comforting, and escape behaviors during the task. Results showed a robust still‐face effect, with infants displaying increased negative affect, decreased positive affect, increased self‐comforting, object orientation, and escape behaviors during the “still‐face” or phone distracted phase of the paradigm and frequently failing to return to baseline during the reunion phase. Older infants (older than 9 months) likewise demonstrated higher levels of negative affect across all three phases of the paradigm relative to younger infants (less than 9 months). Parent reports of technoference behavior were related to increased object orientation for younger infants. Parental technoference behaviors were also linked to more escape behaviors for younger infants and decreased object orientation in older infants during the still‐face portion of the SFP. Higher levels of technoference also appear to attenuate the negative emotional response of infants during still face. Results are discussed in relation to infants’ increasing exposure to digital technology in the context of early relationships.     

Let Me Go: The Influences of Crawling Experience and Temperament on the Development of Anger Expression

Infants’ emerging ability to move independently by crawling is associated with changes in multiple domains, including an increase in expressions of anger in situations that block infants’ goals, but it is unknown whether increased anger is specifically because of experience with being able to move autonomously or simply related to age. To examine the influence of locomotion on developmental change in anger, infants’ (N = 20) anger expressions during an arm restraint procedure were observed longitudinally at a precrawling baseline assessment and 2 and 6 weeks after the onset of crawling. Infant age at each crawling stage was unrelated to the frequency of anger expressed in response to arm restraint. At 6 weeks postcrawling onset, infants whose mothers rated them as temperamentally higher in distress to limitations, compared with those rated lower, showed a greater increase in the frequency of anger expressed during the arm restraint relative to earlier assessments and took longer to reduce the frequency of anger expressed when no longer restrained. Findings suggest that experience with autonomous crawling has an effect on anger expression, independent of age, and that a temperamental tendency to become distressed by limitations may exacerbate the effect of crawling on anger expression.     

Crawling Predicts Infants’ Understanding of Agents’ Navigation of Obstacles

We investigated whether crawling versus noncrawling infants interpret an agent's movements around an obstacle as goal‐directed. Infants (6–9 months) were habituated to a self‐propelled circle jumping over an obstacle to reach a goal. When the obstacle was removed, infants who crawled (n = 13) showed longer looking time to the familiar but now nonrational jumping path versus a novel but rational straight‐line path. Noncrawlers (n = 17) did not discriminate. Looking preference was independent of age and speed of habituation. These findings support the claim that infants’ processing of agency emerges early and applies to all agents, but stress the role of experience in the development of action interpretation.