The Pennsylvania Infant and Family Development Project, II: The development of reciprocal interaction in the mother-infant dyad.

In order to assess stability and change in mother-infant interaction, 74 mother-infant dyads were observed at home under naturalistic conditions when infants were 1, 3, and 9 months. Both conceptually and empirically guided data-reduction procedures indicated that 4 summary constructs underlie 15 behavioral categories coded: reciprocal interaction, noninvolvement, distress, and basic care. Mean levels of reciprocal interaction remained unchanged over time, with individual differences being stable. Mean levels of noninvolvement increased from 1 to 3 months only, and remained stable across all time periods, while mean levels of distress and basic care declined linearly across the 9-month periods, with individual dyads displaying little stability. A final analysis assessed stability and change in the 9 component variables comprising the reciprocal interaction construct. Significant change was discerned with respect to several of these components, as well as a good deal of instability. These findings led to the conclusion that, in the face of sameness in mother-infant interaction across the first 9 months, there is also much change.