The study of dyadic interaction plays a major role in infancy research. To advance conceptually-informed measurement of dyadic interaction and integration across studies, we examined factor structure of individual parents’ and infants’ measures and dyadic measures from face-to-face interactions in two samples of 6-mo-old infants and their parents: mothers from a demographically heterogeneous sample (N = 164) and mothers and fathers (N = 156) from a Caucasian middle-class sample. Results suggested: a) individual and dyadic measures, and parents’ and infants’ behaviors contribute independent information, b) measures of both valence and process are needed, c) there are context-general and context-specific qualities, and d) structure of dyadic interaction is more similar among mother-infant dyads from independent samples than between mother- and father-infant dyads within the same sample. Future research should use multiple measures incorporating valence, temporal processes, contextual influences, and behaviors of individual partners along with dyadic measures to adequately assess the quality of dyadic interaction.

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.

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