Michelle de Haan

Temperament, social competence, and adrenocortical activity in preschoolers

The relations among temperament, social competence, and levels of a stress-sensitive hormone (salivary cortisol) were examined in two studies of preschoolers children (Study 1, N = 29; Study 2, N = 46). In both studies, we sampled cortisol daily for the initial weeks of school year (Group Formation period) and for several weeks later in the year (Familiar Group period). For each child, we examined two measures of cortisol activity (separately for each period) based on the distribution of cortisol levels across days: (a) median cortisol (50th percentile) and (b) cortisol reactivity (the difference between the 75th and 50th percentile). Median cortisol was modestly stable across periods, but cortisol reactivity was not. Children who showed high cortisol reactivity (75th minus 50th percentile > or = 0.10 micrograms/dl) during the Group Formation period but low-to-normal cortisol reactivity during the Familiar Group period were outgoing, competent, and well liked by their peers. In contrast, children who changed from low/normal to high cortisol reactivity and those who maintained high cortisol reactivity from the Group Formation to Familiar Group period were affectively negative and solitary. Children who showed high median cortisol during the Familiar Group period or over both periods scored lower on a measure of attentional and inhibitory control. Together, these results suggest that relations among temperament, social competence, and neuroendocrine reactivity reflect both individual and contextual differences.

Familiar and novel contexts yield different associations between cortisol and behavior among 2‐year‐old children

We examined 10:30 a.m. salivary cortisol levels in twenty-four 2-year-old children at home, and then at several points during transition into preschool: Week 1, Weeks 6-9, and the 1st week following a month-long holiday break. Cortisol levels did not increase when the children first started school as compared to either home or later school levels. Cortisol levels were correlated across similar, but not across dissimilar, psychosocial contexts. Home levels were correlated wit more shy, anxious, internalizing behavior while the response to starting school was correlated with more assertive, angry, and aggressive behavior. Behavior was assessed using parent temperament reports, teacher reports, and observational measures. We conclude that HPA activity as indexed by salivary cortisol measures is differentially associated with behavior in familiar and novel contexts. Consistent with our prior work, shy/anxious behavior is not significantly associated with elevations in cortisol when young children enter new social situations.

Hemispheric differences in brain activity related to the recognition of emotional expressions by 5‐year‐old children

Event‐related potentials were recorded while 5‐year‐olds (N= 44) watched slides of a woman posing happy, angry, and fearful expressions. In 1 session, children were instructed to press a button whenever they saw the happy face, and in another, they were instructed to respond to the fearful face. Four event‐related potential components (N170, P280, N400, and P700) differed in amplitude, latency, or both at right compared to left hemisphere recording sites, and hemispheric differences were present at both anterior (F3, F4) and posterior (T5, T6) recording sites. Hemispheric differences in the amplitude of the P700 were influenced by the task instructions: The P700 was larger at the right posterior than the left posterior recording site for nontarget, but not for target, faces. In contrast, hemispheric differences in the components preceding the P700 were not affected by task instructions. These results suggest that hemispheric differences in brain activity related to recognition of expressions are modulated...