Date of Award


Degree Type


Degree Name

Doctor of Philosophy


The temporal relations of expressive behaviours in early mother-infant interactions were investigated for evidence of infant social competence. Competence was operationalized as an overall increase in expressive behaviour with age, selective display of expressive behaviour while attending to mothers, and onset of expressive behaviours contingent upon those of mothers. Parallel analyses were conducted of maternal behaviours to investigate the behaviour of the senior and presumably "competent" partner. 25 mother-infant dyads were studied longitudinally when the infants were 8, 12, 16, and 20 weeks of age and 32 dyads cross-sectionally at the latter 3 ages (N's = 10, 12, and 10, respectively). All dyads were videotaped while engaged in face-to-face play interactions. Elements of expressive behaviour were independently coded for each interactant. Infants displayed more positive behaviours (smiles, eyebrow raises) with increasing age and when attending, relative to not attending, to their mothers (smiles, vocalizations). Mothers displayed more positive behaviours (smiles, eyebrow raises, vocalizations) to their attentive than inattentive infants. There were no effects of infant age on maternal behaviours nor infant sex on either partner's behaviours.;Infant expression onsets were associated with preceding expression onsets of mothers and vice-versa. These results were found when expressions were defined as smiles and a constellation of positive behaviours including smiles. This evidence of infant and maternal contingent behaviours was further explored with measures of responsiveness and dependency. Infant smiles were dependent upon and not responsive to maternal smiles and maternal smiles were responsive to and not dependent upon infant smiles. Infant expressions were responsive to and mother expressions were dependent upon those of their partners and both indices increased across ages. These patterns suggested that the two behavioural assays had very different functions. Infants were responsive to general rather than specific like-expressions and mothers showed the opposite pattern. Inferences were drawn as to how the consequences of this behavioural patterning may be perceived by each interactant and contribute to early cognitive and social development.



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