Imitation in infancy: the wealth of the stimulus

Imitation requires the imitator to solve the correspondence problem--to translate visual information from modelled action into matching motor output. It has been widely accepted for some 30 years that the correspondence problem is solved by a specialized, innate cognitive mechanism. This is the conclusion of a poverty of the stimulus argument, realized in the active intermodal matching model of imitation, which assumes that human neonates can imitate a range of body movements. An alternative, wealth of the stimulus argument, embodied in the associative sequence learning model of imitation, proposes that the correspondence problem is solved by sensorimotor learning, and that the experience necessary for this kind of learning is provided by the sociocultural environment during human development. In a detailed and wide-ranging review of research on imitation and imitation-relevant behaviour in infancy and beyond, we find substantially more evidence in favour of the wealth argument than of the poverty argument.     

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.     

Categorization in early infancy and the continuity of development

Arguments and evidence are presented for the conclusion that the young infant's perceptually based categorical representations for natural kinds - animals in this case - are the basis for their mature conceptual counterparts. In addition, it is argued that conceptual development is continuous in nature and without the need for special developmental processes. A consideration of the development of the syllabic, segmental, and featural categories of phonology shows a more complex pattern of change - one marked by both continuities and discontinuities in the representations themselves and the processes that produce them.     

The development of spatial understanding in infancy

This paper examines the development of spatial understanding between 8 and 24 months. In particular, it examines whether young infants code changes in the position of an object or themselves in geographic or egocentric terms. The infants sat in a baby chair which was attached to a circular table in such a way that either the infant could be rotated around the edge of the table or the table-top itself could be rotated. Rotation of infant or table could be performed independently or simultaneously. Infants were shown an object which was then hidden under one of either two or three identical cups sitting on the table. Before the infant was allowed to search for the toy, either the table, the infant, or both were rotated, a procedure which resulted in an invisible displacement of the object in terms of geographical and/or egocentric spatial position. Rotations of 60, 90, 120, and 180° were used. Three groups of infants were tested, one cross-sectional (12–24 months), one longitudinal (12–24 months), and one consisting of a group of infants already known to be accelerated in object concept development (8–20 months). The cross-sectional results indicated that egocentric responding continues well into the second half of the second year of life. Even with fortnightly exposure to the tasks, egocentric responding was still evident in some longitudinal babies as late as 19 months. The results of the accelerated group suggest that acceleration through the sequence of object concept development facilitates development of spatial understanding in a wider sense, that is, in the sense of understanding the interrelation of positions in space. The implications of these results for competing theories of the source of object concept errors are discussed.     

Affect development and its assessment in infancy

Affects are defined as both biobehavioral states and signals of social and intrapsychic communication. Discrete (differentiated) affects can reliably be identified, and their intensities scored, from at least three months of age on. Until recently, no comprehensive quantitative methods have been available for the assessment of discrete affects in clinical settings. Two such methods are reviewed. The clinical application of the Michigan Infant Affect Scales (MIAS) is illustrated. Affects are thought to play a central role in organizing, regulating, and motivating the infant's behaviors and social object relationships. A concept of “affective system” is proposed that integrates the modalities of affect expression and the mechanisms of affect regulation. Within this conceptualization, attachment behaviors are seen as part of the expression and/or regulation of affect states during social interactions.     

Imitation of Self-Stimulation:

Three autistic children participated in single subject, reversal designs to compare the impact of over correction and adult imitation on self-stimulation. In addition to continuous 10-second observations of frequency of self-stimulation during 10 minute sessions, experimenter and observer also rated the child's mood, attention to the experimenter and quality of attention paid. The order of interventions was randomized fro each subject with baseline preceding each intervention. Although each child's response pattern was unique, the data showed systematic changes in rates of self-stimulation across conditions for two of the children with mean levels of self-stimulation declining during the over correction procedure and increasing during imitation. There were parallel changes in mood and attention with all three children appearing “happiest” and most attentive when their self-stimulatory behavior was imitated by the adult. These results raise interesting possibilities for using adult imitation as a vehicle for establishing a reinforcing relationship with the autistic child.     

The development of ordinal numerical knowledge in infancy

A critical question in cognitive science concerns how numerical knowledge develops. One essential component of an adult concept of number is ordinality: the greater than and less than relationships between numbers. Here it is shown in two experiments that 11-month-old infants successfully discriminated, whereas 9-month-old infants failed to discriminate, sequences of numerosities that descended in numerical value from sequences that increased in numerical value. These results suggest that by 11 months of age infants possess the ability to appreciate the greater than and less than relations between numerical values but that this ability develops between 9 and 11 months of age. In an additional experiment 9-month-old infants succeeded at discriminating the ordinal direction of sequences that varied in the size of a single square rather than in number, suggesting that a capacity for non-numerical ordinal judgments may develop before a capacity for ordinal numerical judgments. These data raise many questions about how infants represent number and what happens between 9 and 11 months to support ordinal numerical judgments.     

Imitation and representational development in young children with Down syndrome

Competence in object search and pretend play are argued to reflect young children's representational abilities and appear delayed in children with Down syndrome relative to social and imitative skills. This paper explores the effects on object search and play of this social strength in children with Down syndrome. Three experiments compared performance on traditional tasks with modified tasks designed to assess the role of imitation in object search and pretend play. Children with Down syndrome, relative to typically‐developing children, were able and willing to imitate hiding actions when no object was hidden (Experiment 1). When imitation was prevented in object search, children with Down syndrome searched less effectively than typically‐developing children (Experiment 2). In play, children with Down syndrome expressed more willingness to imitate a counter‐functional action, modelled by the experimenter, despite apparent competence in spontaneous functional play (Experiment 3). These findings indicate that object search and play behaviours of children with Down syndrome rely more heavily on imitation than is the case for typically‐developing children. The implications for the development of children with Down syndrome and models of representational development are discussed.     

Social and cognitive aspects of the development of aggression in infancy

This article addresses theoretical and methodological problems in the study of aggression in infants and toddlers. It is argued that the occurrence of aggressive behavior in very young children must be considered against the background of their developing social competence. As a result, evidence for the infants' capacities to act with specific intentions and the infants' knowledge of the other as a distinctive individual having his own plans and goals are reviewed. Studies of early social interactions in humans are then examined with special emphasis on cognitive development and social cognition. Finally, the problem of dominance in very young children's groups is considered.     

Modelling the stages of the identity theory of object-concept development in infancy

A computational model is presented for the three stages of development of the object concept in infancy identified by Bower and Wishart in their research. The stages are described by sets of PROLOG clauses that interpret object structures representing the perceptual phenomena interpreted by the infants themselves. The infant's changes between developmental stages can be described by differences between the rules modelling each stage. Three experiments are presented and the behaviour of the PROLOG model is described for each stage of development. Motion, rest, and boundedness of objects constitute the theoretical underpinning of the running PROLOG model and are hypothesized as the invariant aspects of perception that explain the behaviour of the infant at each stage of development. A possible explanation for transitions between stages is offered and justified in part by the output of the model, which in turn is used to predict the behavioural outcome of an experiment.     

Pathways from marital aggression to infant emotion regulation: the development of withdrawal in infancy

Associations between marital conflict and infant emotion regulation exist, but explanatory pathways have not been explored. For older children, parental behavior partially mediates this association through a "spillover" process. We test: associations between mothers' and fathers' verbally aggressive marital conflict, infant temperament, and infant withdrawal; mediating effects of negative maternal behavior, and moderating effects of infant temperament, exposure to marital arguments, and contact with father. Eighty mothers, 73 fathers, and their 6-month-old infants participated; parents reported marital aggression prenatally, mothers reported infant exposure to arguments, direct caregiving by father, and infant temperament at 5 months. Negative maternal behavior, infant withdrawal, distress to novelty, activity, and look away were observed at 6 months. Mothers' and fathers' aggressive marital conflict predicted infant withdrawal, interactively with exposure to marital arguments and extent of father caregiving, as did infant temperament and negative maternal behavior. Maternal behavior did not mediate between marital conflict and withdrawal.     

Limb and gender differences in the development of coordination in early infancy

Young infants produce a variety of spontaneous arm and leg movements in the first few months of life. Coordination of leg joints has been extensively investigated, whereas arm joint coordination has mainly been investigated in the sitting position in the context of early reaching and grasping. The current study investigated arm and leg joint coordination of movements produced in the supine position in 10 fullterm infants aged 6, 12 and 18 weeks. Longitudinal comparisons within limbs (intralimb) as well as between limbs (interlimb, ipsilateral and contralateral) were made as well as an exploration of differences in the development for boys and girls. The relationship between the joint angles was examined by measuring pair-wise cross-correlation functions for the angular displacement curves of the leg (hip, knee and ankle) and arm (shoulder, elbow and wrist) joints of both the right and left side. Both the arms and legs were found to follow a similar pattern of intralimb coordination, although the leg joints were more tightly coupled than the arm joints, particularly the proximal with the middle joint. In support of earlier findings, differences in the development of the right and left side were identified. In addition, gender differences in joint coordination were found for both intralimb and interlimb coordination. This contrasts with the view that gender differences in motor development may be primarily a result of environmental influences.     

The development of perceptual grouping biases in infancy: A Japanese-English cross-linguistic study

Perceptual grouping has traditionally been thought to be governed by innate, universal principles. However, recent work has found differences in Japanese and English speakers’ non-linguistic perceptual grouping, implicating language in non-linguistic perceptual processes (Iversen, Patel, & Ohgushi, 2008). Two experiments test Japanese- and English-learning infants of 5–6 and 7–8 months of age to explore the development of grouping preferences. At 5–6 months, neither the Japanese nor the English infants revealed any systematic perceptual biases. However, by 7–8 months, the same age as when linguistic phrasal grouping develops, infants developed non-linguistic grouping preferences consistent with their language’s structure (and the grouping biases found in adulthood). These results reveal an early difference in non-linguistic perception between infants growing up in different language environments. The possibility that infants’ linguistic phrasal grouping is bootstrapped by abstract perceptual principles is discussed.     

At the intersection of social and cognitive development: internal working models of attachment in infancy

Three visual habituation studies using abstract animations tested the claim that infants' attachment behavior in the Strange Situation procedure corresponds to their expectations about caregiver-infant interactions. Three unique patterns of expectations were revealed. Securely attached infants expected infants to seek comfort from caregivers and expected caregivers to provide comfort. Insecure-resistant infants not only expected infants to seek comfort from caregivers but also expected caregivers to withhold comfort. Insecure-avoidant infants expected infants to avoid seeking comfort from caregivers and expected caregivers to withhold comfort. These data support Bowlby's (1958) original claims-that infants form internal working models of attachment that are expressed in infants' own behavior.     

Socio‐emotional development: From infancy to young adulthood

Results from the Uppsala Longitudinal Study (ULS), which started in 1985, are reported in two sections. The first section gives a summary of longitudinal data from infancy to middle childhood (age 9 years; n = 96) concerning predictions of social functioning aspects from the theoretical perspectives of temperament, attachment, and health psychology (social factors). The second section presents the first results emanating from a follow‐up when participants were 21 years old (n = 85). The developmental roots of social anxiety symptoms were studied from the same perspectives as above, although with a special focus on the predictive power of the temperament trait of shyness/inhibition. Results for middle childhood outcomes showed that temperament characteristics were relevant for most outcomes, whereas the contribution of attachment was most convincingly shown in relation to social competence and personality. Social factors were found to have moderating functions, but direct effects were also shown, the most interesting perhaps being positive effects of non‐parental day care. Results from the 21‐year data confirmed the expected predictive relation from shyness/inhibition to symptoms of social anxiety and further showed this relation to be specific; the relation to symptoms of depression did not survive control for social anxiety, although the opposite was true. The broad analysis of predictor associations with social anxiety, showing the relevance of other temperament factors as well as interactive effects, again attested to the need for multi‐faceted models to analyze developmental trajectories.     

The development of anticipatory hand orientation during infancy

The development of infants' prehensile adjustments regarding the orientation of objects was investigated. Five- and nine-month-olds (N = 16 per group) were presented with horizontally and vertically oriented dowels to determine at what point during the reach, hand orientation approximated that of the dowel. Nine-month-olds rotated their hands appropriately, early in the course of the reach, i.e., before tactual contact of the dowel, whereas five-month-olds did so mostly after tactual contact. Analyses of the effects of trials within the experimental session indicated that this age difference was not associated with practice or fatigue effects. The results are discussed in relation to the development of visual control of prehensile behavior.     

Imitation from 12 to 24 months in autism and typical development: a longitudinal Rasch analysis

The development of imitation during the second year of life plays an important role in domains of sociocognitive development such as language and social learning. Deficits in imitation ability in persons with autism spectrum disorder (ASD) from toddlerhood into adulthood have also been repeatedly documented, raising the possibility that early disruptions in imitation contribute to the onset of ASD and the deficits in language and social interaction that define the disorder. This study prospectively examined the development of imitation between 12 and 24 months of age in 154 infants at familial risk for ASD and 78 typically developing infants who were all later assessed at 36 months for ASD or other developmental delays. The study established a developmental measure of imitation ability and examined group differences over time, using an analytic Rasch measurement model. Results revealed a unidimensional latent construct of imitation and verified a reliable sequence of imitation skills that was invariant over time for all outcome groups. Results also showed that all groups displayed similar significant linear increases in imitation ability between 12 and 24 months and that these increases were related to individual growth in both expressive language and ratings of social engagement but not in fine motor development. The group of children who developed ASD by age 3 years exhibited delayed imitation development compared with the low-risk typical outcome group across all time-points, but were indistinguishable from other high-risk infants who showed other cognitive delays not related to ASD.