This paper reported on observation made of early face-to-face interaction of infants with their mothers and with a stranger during the Baltimore study.

Infants' face-to-face interactions with mother and with a stranger were videotaped across several session between ages 6 to 15 weeks, totalling 732 episodes. Results from this were compared with mother-infant attachment assessed using the Strange Situation Procedure at 12 months (all infants were classified as either anxious or secure).

Across the 6-15 week period, individual differences in maternal behaviour were found to be stable. Infant behaviours, however, did not show stability over this period. As a control, infant state prior to interaction episodes was coded and showed no relationship with attachment classification.

Mothers of infants who were assessed as anxious at 12 months, were more likely to intitiate early face-to-face interactions with a silent and impassive face, more likely to behave abruptly or in a routine manner, and were least likely to respond to their baby's attempts to initiate interaction. Episodes of face-to-face contact were of shorter duration. Mothers of infants who were assessed as secure at 12 months were more playful and lively, tended to encourage further interaction and engaged in episodes that had longer duration. They were more contingently playful, and generally showed higher levels of sensitivity to the type of interaction saught by the infant.

Infants later judged to be anxious showed no difference in behaviour between mother and stranger except that they were more likely to cry or fuss when interacting with the mother. Infants later judged to be secure showed a similar level of response to anxious infants when interacting with a stranger but were significantly more responsive and active when in interaction with their mothers.

Overall, the key variable appeared to be the sensitivity and flexibility of the interaction between mother and infant, rather than any specific behavioural trait displayed by mother or infant. The authors concluded that early behavioural differences when with familiar and unfamiliar figures resulted from the degree of sensitivity and responsiveness shown by individual adults, and emphasises the way that infants adapt to early conditions, particularly to the adults with whom they regularly interact.