Examined whether early differences in stress reactivity were related to self-recognition at 18 months. Found that self-recognition was related to greater cortisol response and less rapid quieting at 6 to 18 months, whereas cortisol and quieting responses of 2- to 4-month-olds did not differentiate self-recognizers and non-self-recognizers,…

Studied individual differences in reactivity in 40 newborns. Measures of reactivity were related during the first two months of extrauterine life. (RJC)

A total of 87 infants 10 months of age received, either directly or indirectly, a positive nonverbal message, a neutral nonverbal message, or no message about a stranger. Infants, especially those with easy temperaments, were friendlier to the stranger when mothers had spoken positively, but only when the message was directly communicated.…

This paper presents research findings on differences in the social and cognitive behavior of first born and only children at 3, 12, and 24 months of age as observed at home and in a free play laboratory setting. The sample consisted of 21 only children (children who did not acquire a sibling for at least the first 48 months of life) and 35 first…