Two experiments presented 36 preschool children with videotapes of their own and unknown mothers interacting with strange and familiar people. The children were able to guess correctly whether their own mother was interacting with a friend or a stranger, but were unsuccessful with unknown mothers. (Author/JMB)

In a second follow-up study of sibling interaction, 24 pairs of same-sex siblings and 24 pairs of mixed-sex siblings were observed in their homes 18 months after the first follow-up and 3 years after the initial observations. The patterning of interaction was similar to that observed earlier. (Author/DR)

Thirty-six pairs of mixed-sex siblings were observed for two 1-hour periods in their homes. The younger siblings averaged 20 months of age and the interval between siblings was either large or small. Results are compared with a previous study of same-sex sibling interaction. (Author/RH)