Birth order and sex of sibling as determinants of mother-infant interaction.

Mother-infant interaction was assessed on 32 first- and second-born siblings when each was 3 months old. Data were colleted during 2 6-hour naturalistic home observations using a modified time-sampling technique. The sample consisted of 4 equal-size subgroups of same and opposite sex sibling pairs. Results suggested that interaction between a mother and her infant varied depending on the birth order and gender of the infant. Mothers spent significantly less time in social, affectionate, and caretaking interaction (except for feeding activities) with their second borns than they had with their firstborns; this difference was greater if the second born was female. Certain patterns of maternal behaviors appeared to be stable from one sibling to the other. Different types of interaction between the mothers and their younger infants were related to attention-seeking behavior in the firstborn male and female siblings.