Mother-Infant Face-to-Face Interaction: Influence is Bidirectional and Unrelated to Periodic Cycles in Either Partner's Behavior

During mother-infant face-to-face interactions, bidirectional influence could be achieved through either the entraining of periodic cycles in the behavior of each partner or through the stochastic organization of behaviors. To determine whether and how bidirectional influence occurs, we used both timeand frequency-domain techniques to study the interactions of 54 mother-infant pairs, 18 each at 3, 6, and 9 months of age. Behavioral descriptors for each mother and infant were scaled to reflect levels of affective involvement during each second oftbe interaction. Periodic cycles were found in infants' expressive behavior only at 3 months and not in mothers' behavior. Nonperiodic cycles, which were found in some mothers' and infants' behavior at each age, were more common. At no age was the occurrence of cycles in mothers' or infants' behavior related to the achievement of bidirectional influence. Similar proportions of mothers and infants were responsive to momentto-moment changes in the other's behavior, except at 6 months when the proportion of mothers was higher. Bidirectional influence was brought about by the stochastic organization of behaviors rather than through the mutual entraining of periodic cycles.