Rhythms of dialogue in infancy: coordinated timing in development.

Although theories of early social development emphasize the advantage of mother-infant rhythmic coupling and bidirectional coordination, empirical demonstrations remain sparse. We therefore test the hypothesis that vocal rhythm coordination at age 4 months predicts attachment and cognition at age 12 months. Partner and site novelty were studied by recording mother-infant, stranger-infant, and mother-stranger face-to-face interactions in both home and laboratory sites for 88 4-month-old infants, for a total of 410 recordings. An automated dialogic coding scheme, appropriate to the nonperiodic rhythms of our data, implemented a systems concept of every action as jointly produced by both partners. Adult-infant coordination at age 4 months indeed predicted both outcomes at age 12 months, but midrange degree of mother-infant and stranger-infant coordination was optimal for attachment (Strange Situation), whereas high ("tight") stranger-infant coordination in the lab was optimal for cognition (Bayley Scales). Thus, high coordination can index more or less optimal outcomes, as a function of outcome measure, partner, and site. Bidirectional coordination patterns were salient in both attachment and cognition predictions. Comparison of mother-infant and stranger-infant interactions was particularly informative, suggesting the dynamics of infants' early differentiation from mothers. Stranger and infant showed different patterns of vocal rhythm activity level, were more bidirectional, accounted for 8 times more variance in Bayley scores, predicted attachment just as well as mother and infant, and revealed more varied contingency structures and a wider range of attachment outcomes. To explain why vocal timing measures at age 4 months predict outcomes at age 12 months, our dialogue model was construed as containing procedures for regulating the pragmatics of proto-conversation. The timing patterns of the 4-month-olds were seen as procedural or performance knowledge, and as precursors of various kinesic patterns in the outcomes of 12-month-olds. Thus, our work further defines a fundamental dyadic timing matrix--a system that guides the trajectory of relatedness, informing all relational theories of development.

Gender and speech rate in the perception of competence and social attractiveness.

The authors' hypotheses were that (a) listeners regard speakers whose global speech rates they judge to be similar to their own as more competent and more socially attractive than speakers whose rates are different from their own and (b) gender influences those perceptions. Participants were 17 male and 28 female listeners; they judged each of 3 male and 3 female speakers in terms of 10 unipolar adjective scales. The authors used 8 of the scales to derive 2 scores describing the extent to which the listener viewed a speaker as competent and socially attractive. The 2 scores were related by trend analyses (a) to the listeners' perceptions of the speakers' speech rates as compared with their own and (b) to comparisons of the actual speech rates of the speakers and listeners. The authors examined trend components of the data by split-plot multiple regression analyses. In general, the results supported both hypotheses. The participants judged speakers with speech rates similar to their own as more competent and socially attractive than speakers with speech rates slower or faster than their own. However, the ratings of competence were significantly influenced by the gender of the listeners, and those of social attractiveness were influenced by the gender of the listeners and the speakers.

Mathematical models for coordinated interpersonal timing in mother-infant interactions in the first year of life.

Two mathematical models of social contingency are examined in terms of their development over the first year of life. The interactions of 53 mothers and their infants were recorded at 6 weeks, 4 months, and 12 months. The infants' gazes at 6 weeks, the mothers' vocal behavior at 6 weeks, and the vocal behavior of the mother and infant at 4 and 12 months were automatically coded in terms of four states. The conditional dependence model and the response effects model were computed for each interaction at each age, and the coefficients of the models were examined as a function of age. The relative success of the models as estimates of moment-to-moment contingency as well as their variations with age are discussed.

Down's syndrome and infant gaze. Gaze behavior of Down's syndrome and nondelayed infants in interactions with their mothers.

The study reported here compared the gaze behavior of infants with Down syndrome (DS) and nondelayed infants during interactions with their mothers. The subjects were 10 DS infants and 11 nondelayed infants. Five of the DS infants and 6 of the nondelayed infants were 4 months old; the rest were 9 months old. The results support the expectation that infants with DS gazed at their mothers longer than did nondelayed infants during face-to-face play, and also indicate that all the infants visually attended to their mothers less at 9 months than at 4 months of age. It is conjectured that the increased gaze of the infants with DS may well facilitate attachment in the 1st year of life.

Vocal congruence in mother-infant play.

Turn-taking is the fundamental temporal structure of adult dialogue. This structure defines two types of joint silence: intrapersonal pause (silence bounded by the vocalizations of a single speaker) and switching pause (silence bounded by the vocalizations of different speakers). Switching pauses mark the boundaries of the turn exchange. In adult conversation the mean durations of both types of pause are characteristically matched between partners. This matching, termed "vocal congruence," occurs developmentally earlier in the case of switching pauses. We hypothesized and confirmed that mothers and infants match switching pauses but not intrapersonal pauses at 4 months, even though the infants' vocalizations are prelinguistic. Second, since there are known affective correlates of vocal congruence in adult conversation, we hypothesized a similar affective correlate for mother-infant vocal congruence. We found, for the intrapersonal pause only, that the degree of matching within a dyad correlates with infant affective engagement. We conclude, from switching pause congruence, that a turn-taking dialogic structure is being regulated in the mother-infant pair at 4 months in the same way as seen in adult conversation. Thus, both the temporal structure of adult dialogue and its affective correlate are prelinguistic.