Infants' responses to mothers' imitative behaviors

Several investigators have suggested that young infants' smiles and vocalizations following their mothers' imitative behaviors might reflect infant recognition that the mother's behavior is imitative or at least contingent. This study investigated whether infants smile and vocalize more frequently subsequent to maternal imitative than non-imitative behavior during both spontaneous and imitative face-to-face interactions. Fourteen 3 1/2-month-old infants and their mothers were videotaped in these two face-to-face interaction situations. The infants vocalized more frequently during the imitative situation and infant vocalizations plus simultaneous smiling, and vocalizations occurred more often following maternal imitative than non-imitative behavior. Although these data suggest that infant vocalizations and simultaneous smiles and vocalizations may reflect the infants' recognition of maternal imitative behavior, they do not establish definitively that it is the imitation per se vs. the contingency aspect that is recognized by the infant.     

Imitation in language development: If,when, and why

In order to explore the function of imitation for first language learning, imitative and spontaneous utterances were compared in the naturalistic speech of six children in the course of their development from single-word utterances (when mean length of utterance was essentially 1.0) to the emergence of grammar (when mean length of utterance approached 2.0). The relative extent of imitation, and lexical and grammatical variation in imitative and spontaneous speech were determined. There were inter-subject differences in the extent of imitation, but each child was consistent in the tendency to imitate or not to imitate across time. For those children who imitated, there were both lexical and grammatical differences in imitative and spontaneous speech, and a developmental shift from imitative to spontaneous use of particular words and semantic-syntactic relations between words. The results are discussed as evidence of an active processing of model utterances relative to the contexts in which they occur for information for language learning.     

Infant-adult vocal interaction dynamics depend on infant vocal type,child-directedness of adult speech,and timeframe

This study explored the temporal contingencies between infant and adult vocalizations as a function of the type of infant vocalization, whether adult caregivers’ vocalizations were infant-directed or other-directed, and the timescale of analysis. We analyzed excerpts taken from day-long home audio recordings that were collected from nineteen 12- to 13-month-old American infants and their caregivers using the LENA system. Three 5-minute sections having high child vocalization rates were identified within each recording and coded by trained researchers. Infant and adult vocalizations were sequenced and defined as contingent if they occurred within 1 s, 2 s, or 5 s of each other. When using 1 s or 2 s definitions of temporal adjacency, infant vocalizations generally predicted subsequent infant-directed adult vocalizations. A reflexive vocalization (i.e. a cry or a laugh) was the strongest predictor. Likewise, within 1–2 s timeframes, infant-directed adult speech generally predicted infant vocalizations with reflexive vocalizations being particularly predictive. Infant vocalizations predicted fewer subsequent other-directed adult vocalizations and were less likely following other-directed adult vocalizations when considering up to 5 s lags. This suggests an understudied communicative role for infants of non-infant-directed adult speech. These results demonstrate the importance of timescale in studying infant-adult interactions, support the communicative significance of reflexive infant vocalizations and other-directed adult speech in addition to more commonly studied vocalization types, and highlight the challenges of determining direction(s) of influence when using only two-event sequences.     

USING TIME DELAY TO PROMOTE SPONTANEOUS SPEECH IN AN AUTISTIC CHILD

One of the frequently observed deficits in autistic children is their lack of spontaneous speech. We used a multiple baseline across behaviors to investigate the effectiveness of a time delay procedure for inducing spontaneous speech in a 10-year-old male autistic child during play. We first taught the child to imitate the experimenter's verbal prompts that described the child's motor response. Once the child reached criteria on imitation, we implemented baseline wherein an immediate verbal prompt for speech was provided after each of the child's motor responses. Intervention consisted of a gradual delay in the presentation of the verbal prompts. The time delay effectively increased the child's spontaneous speech on trained items; some generalization to untrained items also occurred, but only within the same behavioral class of car play. Generalization was also observed across settings. Spontaneous speech remained at high levels during the 4-month maintenance for the behavior of car play but decreased for a second behavior. Decreases in the child's response latencies suggest that spontaneous speech may be an anticipatory verbal response.     

Imitative behavior

This article reviews the results of experimental studies on imitative behavior reported by various investigators, and then discusses the possible brain mechanisms responsible for this behavior. It was found that human infants in their first hours of life were already capable of spontaneous imitation of simple motor acts demonstrated by an adult, without previous training or reward; these observations suggest that imitative behavior is an innate process that can be considered anunconditional reflex of imitation. It was also found that satiated animals resumed eating when they saw their companions eating. In the latter case, the imitative reflex triggered the previously acquired feeding behavior. Similar mechanisms could be responsible for the phenomenon of eating more in the presence of companions than in their absence, as well as that of preferring the food chosen by companions. When followed by a reward, the imitative act can be learned—that is, transformed into aninstrumental conditional response; learning by imitation of simple motor acts was observed in animals, and that of complex motor acts was observed in children who had already achieved a certain developmental stage. In animals, learning complex motor tasks was facilitated by previous observation of a companion performing this task. In this case, the presence of the observer during the session could lead to habituation of the experimental situation and production of associations between this situation and stimuli or emotions related to the reward or punishment, and might result in more efficient learning later. The imitative behavior can be inhibited by stimuli producing responses antagonistic to the act of imitation.     

Vocal imitation between mothers and infants

The aim of the present mixed cross-sectional and longitudinal study was to observe and describe some aspects of vocal imitation in natural mother-infant interaction. Specifically, maternal imitation of infant utterances was observed in relation to the imitative modeling, mirrored equivalence, and social guided learning models of infant speech development. Nine mother-infant dyads were audio-video recorded. Infants were recruited at different ages between 6 and 11 months and followed for 3 months, providing a quasi-longitudinal series of data from 6 through 14 months of age. It was observed that maternal imitation was more frequent than infant imitation even though vocal imitation was a rare maternal response. Importantly, mothers used a range of contingent and noncontingent vocal responses in interaction with their infants. Mothers responded to three-quarters of their infant's vocalizations, including speech-like and less mature vocalization types. The infants’ phonetic repertoire expanded with age. Overall, the findings are most consistent with the social guided learning approach. Infants rarely imitated their mothers, suggests a creative self-motivated learning mechanism that requires further investigation.     

Neonatal imitation in chimpanzees (<Emphasis Type="Italic">Pan troglodytes</Emphasis>) tested with two paradigms

Primate species differ in their imitative performance, perhaps reflecting differences in imitative capacity. The developmentally earliest form of imitation in humans, neonatal imitation, occurs in early interactions with social partners, and may be a more accurate index of innate capacity than imitation of actions on objects, which requires more cognitive ability. This study assessed imitative capacity in five neonatal chimpanzees, within a narrow age range (7–15 days of age), by testing responses to facial and vocal actions with two different test paradigms (structured and communicative). Imitation of mouth opening was found in both paradigms. In the communicative paradigm, significant agreement was found between infant actions and demonstrations. Additionally, chimpanzees matched the sequence of three actions of the TC model, but only on the second demonstration. Newborn chimpanzees matched more modeled actions in the communicative test than in the structured paradigm. These performances of chimpanzees, at birth, are in agreement with the literature, supporting a conclusion that imitative capacity is not unique to the human species. Developmental histories must be more fully considered in the cross-species study of imitation, as there is a greater degree of innate imitative capacity than previously known. Socialization practices interact with innate and developing competencies to determine the outcome of imitation tests later in life.     

THE DEVELOPMENT AND GENERALIZATION OF DELAYED IMITATION1

An individual's behavior can be identified as imitative if it temporally follows the behavior of another individual and if its topography is controlled by the demonstrated behavior [Baer, Peterson, and Sherman (Journal of the Experimental Analysis of Behavior, 1967, 10 , 405–416)]. This definition takes into account both temporal and topographical characteristics of the behavior in question. More recent research in the area of imitation has interpreted the temporal component of the above definition differentially by limiting imitation to those topographically similar responses occurring within 3, 5, or 10 sec after a model's demonstration. Yet, Gewirtz and Stingle (Psychological Review, 1968, 75 , 375–397) pointed out that much of the imitation seen in young children is not of this immediate nature, but instead occurs sometime after a model's response. They further suggest that this type of imitative behavior can be characterized as a response class and is susceptible to development and modification as a function of consequences delivered to subjects contingent on this type of delayed responding. Four retarded children, three initially imitative and one nonimitative, were individually trained to imitate a number of motor responses in an immediate and a delayed fashion. Immediate imitation was defined as a response similar to a model's demonstration occurring within 5 sec after the model's demonstration; delayed imitation was defined as a response similar to a model's demonstration occurring more than 5 sec, but not more than 25 sec, after the model's demonstration. A reversal (ABAB) design was employed to examine the experimental development of a generalized delayed imitative repertoire. Untrained probe responses were demonstrated to subjects systematically through the ongoing training. Generalized immediate and delayed imitation were observed in each subject; this generalization was restricted to the type of imitation currently undergoing training. This development of a generalized imitation repertoire was observed in each subject. That is, these subjects imitated some responses that had never been specifically trained. More importantly, a training package consisting of prompting, fading, and consequences for delayed imitation functioned to develop generalized delayed imitation. These data exemplify a special case of generalization that was a function of the most recent training history of immediate or delayed imitation. The reversal design demonstrated that imitations of nontrained models were either delayed or immediate, depending upon which form of imitation was currently receiving training. Therefore, for each form of imitation trained, delayed or immediate, a corresponding response class was demonstrated. These data relate to data reported by Garcia, Baer, and Firestone (Journal of Applied Behavior Analysis, 1971, 4 , 101–112). The association lies in the proposition that there are identifiable boundaries of generalized imitation and that these boundaries are functionally related to previous training histories.     

The You-I event: on the genesis of self-awareness

I present empirical evidence suggesting that an infant first becomes aware of herself as the focal center of a caregiver's attending. Yet that does not account for her awareness of herself as agent. To address this question, I bring in research on neonatal imitation, as well as studies demonstrating the existence of a neural system in which parts of the same brain areas are activated when observing another's action and when executing a similar one. Applying these findings, I consider gestural exchanges between infant and caregiver, such as reciprocal smiles and imitative vocalizations. Lacking self-awareness at first, the infant is unaware of her own agency. By returning her unwitting gesture, the caregiver singles out for her—thanks to neural matching—the gesture's kinesthesis. Moreover, the caregiver's smile, imitative vocalization, or other gesture is the form that focusing takes. The kinesthesis of the infant's gesture, in being singled out, is experienced by the infant as what the caregiver is focusing on. It is experienced as being within the focal center. In this way, the infant becomes aware of herself as a bodily entity acting toward the caregiver. Exchanges that involve matching are at first essential, I argue, in making the infant present to herself in action. Matching will cease to be necessary, but self-awareness continues to depend fundamentally on others until the acquisition of language, when the child becomes capable of talking to herself as if she were the caregiver.     

Fourteen‐Month‐Olds' Imitation of Differently Aged Models

Studies comparing adult and peer imitation are rare and have to date provided mixed results. The aim of the present study was to investigate 14‐month‐olds' imitation of different actions (novel versus familiar) performed by televised models of different age groups (peers, older children or adults). In two experiments, we investigated infants' imitative performance when observing a novel action (Experiment 1) and familiar actions (Experiment 2). The results showed that the likelihood of imitating a novel action increased as the age of the model increased. The opposite was true for familiar actions where infants imitated the peer more frequently than either the older child or the adult model. These findings are discussed in relation to infants' ability to take into account a model's characteristics such as age when imitating actions. Copyright © 2011 John Wiley & Sons, Ltd.     

Children's recognition of emotions from vocal cues

Emotional cues contain important information about the intentions and feelings of others. Despite a wealth of research into children's understanding of facial signals of emotions, little research has investigated the developmental trajectory of interpreting affective cues in the voice. In this study, 48 children ranging between 5 and 10 years were tested using forced‐choice tasks with non‐verbal vocalizations and emotionally inflected speech expressing different positive, neutral and negative states. Children as young as 5 years were proficient in interpreting a range of emotional cues from vocal signals. Consistent with previous work, performance was found to improve with age. Furthermore, the two tasks, examining recognition of non‐verbal vocalizations and emotionally inflected speech, respectively, were sensitive to individual differences, with high correspondence of performance across the tasks. From this demonstration of children's ability to recognize emotions from vocal stimuli, we also conclude that this auditory emotion recognition task is suitable for a wide age range of children, providing a novel, empirical way to investigate children's affect recognition skills.     

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.     

The effects of differential reinforcement on generalized imitation

The present study examines the transfer of imitative learning to other nonimitative performance conditions and compares imitative and nonimitative performance under contingencies of differential reinforcement for S⁰ behavior, differential reinforcement for nonimitative behavior, and extinction. Many authors have suggested that a child's continued imitative performance of rewarded S^D and unrewarded S^Δ behavior is a function of subtle social cues or experimental demand present in most generalized imitation procedures. The two experiments presented here support that conclusion but also provide evidence that conclusions drawn from such generalized imitation studies were generally accurate. Even though a child's trial-by-trial imitative performance appeared to be a function of procedural artifacts, the child's later performance in the role of a model indicated that a functionally interdependent generalized response class of imitative behavior had been learned while the child imitated. As such, these experiments generally supported Baer's secondary reinforcement hypothesis for imitative performance and suggest that future research employ nonimitative tasks such as reversed imitation as a measure of imitative learning.     

Reciprocal Imitation Following Adult Imitation by Children with Autism

This study examined the effects of adult imitation and adult playfulness on the imitation, social attention and initiation of new behaviours by non‐verbal preschoolers with autism. Videotapes taken from a previous study were recoded for the adult's imitation and playful behaviour and the children's imitation, social attention (looking at the adult's actions) and initiation of new behaviours. In the original study, twenty non‐verbal, 4‐ to 6‐year‐old children with autism were randomly assigned to an imitation or a contingent responsivity group. Both groups of children engaged in an intervention phase (during which the adult imitated the children or contingently responded to them) and a subsequent spontaneous play phase (during which the adult interacted spontaneously with the children). ANOVA for the current study revealed that the imitation group children versus the contingent responsivity group children spent a greater percent time showing social attention and initiating new behaviours during the intervention phase and showing social attention and imitating the adult's behaviours during the subsequent spontaneous play phase. A correlation analysis yielded significant correlations between the percent time the adult imitated the child during the intervention phase and the percent time the child showed social attention during the same intervention phase and imitating the adult during the subsequent spontaneous play phase. Adult imitation and playfulness during the spontaneous play phase were also correlated with the children's social attention during that phase. Copyright © 2013 John Wiley & Sons, Ltd.     

Infant twins’ social interactions with caregivers and same-age siblings

The study of twin behavior offers the opportunity to study differential patterns of social and communicative interactions in a context where the adult partner and same-age peer are equally familiar. We investigated the development of social engagement, communicative gestures, and imitation in 7- to 25-month-old twins. Twin dyads (N = 20 pairs) participated in 10-min, semi-structured play sessions, with the mother seated in a chair completing paperwork for half the session, and on the floor with her children for the other half. Overall, twins engaged more with their mothers than with their siblings: they showed objects and imitated speech and object use more frequently when interacting with their mothers than with their siblings. When the mother was otherwise engaged, the twins played with toys separately, observed each other's toy play, or were unengaged. These results demonstrate that adult scaffolding of social interactions supports increased communicative bids even in a context where both familiar peers and adults are available as communicative partners.     

Melodies in caregivers' speech: A species-specific guidance towards language

The author reports on a series of integrated studies on melodic contours in infant-directed (ID) speech. ID melodies in speech are taken as an instructive example of intuitive parenting in order to review current evidence on its forms, functions and determinants. The forms and functions of melodic prototypes are compared in terms of universal properties and individual and/or cultural variability across samples of German, Chinese and American mothers, and German mothers and fathers with their 2- and 3-month-old infants. Microanalyses of interactional contexts show that forms and functions of ID melodies are intimately related to typical dimensions of intuitive caregiving–arousing/soothing, turnyielding/turn-closing, approving/disapproving. The communicative functions of ID melodies as both categorical and graded signals are discussed with respect to the current knowledge on infant responses to ID speech and on early speech perception. According to a comprehensive longitudinal study of ID speech in relation to stages of infant vocalization, ID speech results from fine-tuned adjustments in various prosodic and linguistic features to developmental changes in infants' perceptual and vocal competence. ID melodies evidently have the potential to draw infant attention to caregivers' speech, to regulate arousal and affect in infants, to provide models for imitation, to guide infants in practising communicative subroutines and to mediate linguistic information. Current evidence suggests that the melodies in caregivers' speech provide a species-specific guidance towards language acquisition.     

Is language acquired through imitation?

The role of imitation in language acquisition is examined, including data from the psycholinguistic, operant, and social learning areas. From the psycholinguistic data, four empirical statements have been extracted: (1) there is no evidence that spontaneous imitations of adult speech influence grammatical development, (2) imitation of speech does not appear to occur with frequency beyond age 3 years, (3) speech and hence imitation are not necessary for the comprehension of linguistic structures, and (4) most utterances of a child are novel and therefore could not have been exactly modeled. The first and second propositions are seen to be based on a too restrictive definition of imitation-immediate and exact copying. Selective imitation-a functional relationship involving similarity of a particular form or function of the model's responses-is proposed as an alternative, thus leaving the validity of statements (1) and (2) in question. Concerning assertion (4), certain data from the operant literature are presented as evidence of the compatibility of novel responding and modeling, imitation, and reinforcement. Finally, it is proposed that statement (3) suggests a mechanism by which selective imitation can be understood. A three-stage process is proposed in which comprehension of a grammatical form sets the stage for selective imitation of that structure, which leads in turn to spontaneous production. Thus imitation is a process by which new syntactic structures can be first introduced into the productive mode.     

Individual differences in social, cognitive, and morphological aspects of infant pointing

Little is known about the origins of the pointing gesture. We sought to gain insight into its emergence by investigating individual differences in the pointing of 12-month-old infants in two ways. First, we looked at differences in the communicative and interactional uses of pointing and asked how different hand shapes relate to point frequency, accompanying vocalizations, and mothers’ pointing. Second, we looked at differences in social-cognitive skills of point comprehension and imitation and tested whether these were related to infants’ own pointing. Infants’ and mothers’ spontaneous pointing correlated with one another, as did infants’ point production and comprehension. In particular, infants’ index-finger pointing had a profile different from simple whole-hand pointing. It was more frequent, it was more often accompanied by vocalizations, and it correlated more strongly with comprehension of pointing (especially to occluded referents). We conclude that whole-hand and index-finger pointing differ qualitatively and suggest that it is index-finger pointing that first embodies infants’ understanding of communicative intentions.     

INCREASING SPONTANEOUS VERBAL RESPONDING IN AUTUSTIC CHILDREN USING A TIME DELAY PROCEDURE

One oft-cited problem with teaching speech skills to autistic children isthe failure of the speech to be spontaneous. That is, the children's speech often remains underthe control of the verbal behavior of others rather than underthe control of other nonverbal referents inthe environment. We investigatedthe effectiveness of a time delay procedure to increasethe spontaneous speech of seven autistic children. Initially, the experimenter presented a desired object (e.g., cookie) and immediately modeledthe appropriate response “I want (cookie).” Gradually, asthe child imitatedthe vocalization, the experimenter increasedthe time between presentation of the object andthe modeled vocalization in an attempt to transfer stimulus control of the child's vocalization fromthe experimenter's model tothe object. Results indicated that allthe children learned to request items spontaneously and generalized this behavior across settings, people, situations, and to objects which had not been taught. These results are discussed in relation tothe literature on spontaneous speech, prompting, and generalization.     

Social feedback to infants' babbling facilitates rapid phonological learning

Infants' prelinguistic vocalizations are rarely considered relevant for communicative development. As a result, there are few studies of mechanisms underlying developmental changes in prelinguistic vocal production. Here we report the first evidence that caregivers' speech to babbling infants provides crucial, real-time guidance to the development of prelinguistic vocalizations. Mothers of 9.5-month-old infants were instructed to provide models of vocal production timed to be either contingent or noncontingent on their infants' babbling. Infants given contingent feedback rapidly restructured their babbling, incorporating phonological patterns from caregivers' speech, but infants given noncontingent feedback did not. The new vocalizations of the infants in the contingent condition shared phonological form but not phonetic content with their mothers' speech. Thus, prelinguistic infants learned new vocal forms by discovering phonological patterns in their mothers' contingent speech and then generalizing from these patterns.