Sex differences in parent-infant interaction during free play, departure, and separation.

20 18-month-olds were observed with their mothers and 20 with their fathers in laboratory free-play, departure, and separation situations. Parent and infant behaviors were allowed to vary naturally. Although there were no parent sex or infant sex differences in infants' free-play behavior, there were parent sex X infant sex differences in parental free-play behaviors. Parents talked to, sat on the floor more with, and tended to share play more with same-sexed than opposite-sexed infants, and the patterning of free-play behaviors was different for mothers and fathers. During departure, fathers talked to the infants more than mothers. Infants were more distressed in the absence of same-sexed than opposite-sexed parents. There were infant sex X parent sex differences in the relationships between separation distress and parental free-play and departure behaviors. The implications of these findings for understanding differential roles of mothers and fathers, the development of sex differences, and the determinants of separation distress are discussed.