واکنش پذیری آدرنال و شایستگی اجتماعی در کودکان هفت ساله

Abstract We examined temporal changes in salivary cortisol in response to a peer self-presentation task in a group of seven year-olds, some of whom scored high, average, and low on the Harter, 1983Perceived Social Competence Scale. Salivary cortisol was measured pre-task, and 20 and 35 min post-task. We found a significant relation between individual differences in perceived social competence and salivary cortisol reactivity in response to the task. Children who perceived themselves as socially competent exhibited a significantly greater decrease in salivary cortisol from 20 to 35 min following the task compared with children who self-reported a relatively lower degree of social competence. We speculate on the meaning of salivary cortisol changes in childrens socio-emotional development.

1. Introduction Socially competent children, unlike shy children, display a short latency to approach social novelty, appear to be at ease in play groups with unfamiliar peers, and are socially outgoing. Socially competent children also appear to be more successful in regulating the arousal of negative affect during socially evaluative situations compared with shy and socially anxious children. We know, however, comparatively little with regard to how socially competent vs shy children regulate stress during socially evaluative situations. We (Schmidt et al., 1997) recently found that preschoolers who displayed a high proportion of social wariness while interacting with same-age and same-gender peers exhibited high morning salivary cortisol levels. Also, a number of others have linked high cortisol to fear, distress and related constructs in human infants (Gunnar et al., 1989), shyness and inhibition in children (Kagan, et al., 1987; Nachmias et al., 1996), shyness (Bell et al., 1993; Windel, 1994) and agitated depression in adults (Gold et al., 1988a; Gold et al., 1988b), and fearfulness in nonhuman primates (Champoux et al., 1989; Kalin and Shelton, 1989; Levine et al., 1987). The relation between elevated cortisol and fearful and anxious behavioral profiles, however, is not a foregone conclusion. Elevated cortisol has been noted in bold and exuberant children and dominant, rather than submissive, non-human primates (see Gunnar 1994, for a review). The purpose of the present study was to extend our previous research on the relation between cortisol and social development in children (e.g. Schmidt et al., 1997) and to clarify some of the apparent inconsistencies on this relation in the extant literature. We examined temporal changes in salivary cortisol in response to a self-presentation task in a group of seven year-olds, some of whom scored high, average, and low on the Harter, 1983Perceived Social Competence Scale for children. Salivary cortisol was measured pre-task, and 20 and 35 min post-task. We chose to measure cortisol because this stress hormone may provide a window into the origins of emotion regulatory and dysregulatory processes in early school age children during socially evaluative situations. The early school age years are a particularly important period in development as the age point coincides with the childs entry into school and the establishment of peer relationships. We expected that children who scored high on perceived social competence would display a significantly greater decrease in saliva cortisol following the self-presentation task compared with children who scored relatively lower on the self-report social competence measure. In the present paper, we report the relation between individual differences in childrens self-perceptions of social competence and temporal changes in salivary cortisol in response to the task at age seven.

Results Table 1 presents the means (S.D.s) for the salivary cortisol data collected during pre-task (baseline), and 20 and 35 min post-task for the three groups. A separate ANOVA with Group (high, middle, low) as a between-subjects factor was performed on each time point. The dependent measure was mean salivary cortisol level. There were no significant main effects for Group on salivary cortisol for any of the three time points. Table 1. Means and (S.D.s) for salivary cortisol measure collected pre-task (baseline) and 20 and 35 min post self-presentation task by the three social competence groups Social competence group High Middle Low (n = 7) (n = 23) (n = 8) Salivary cortisol (in μg dl−1) Pre task (baseline) 0.10 0.12 0.12 (0.08) (0.06) (0.10) 20 min post-task 0.10 0.07 0.07 (0.09) (0.05) (0.04) 35 min post-task 0.04 0.08 0.09 (0.02) (0.06) (0.07) Table options We next examined whether individual differences in childrens self-perceptions of social competence were related to temporal changes in salivary cortisol in response to the task. We computed three separate delta salivary cortisol change scores in order to index adrenocortical reactivity in response to the task: (1) 35 min post task sample–20 min post task sample; (2) 35 min post task sample–initial sample; and (3) 20 min post task sample–initial sample. An ANOVA was performed with Group (high, middle, low) as a between-subjects factor and Change Score (1, 2, 3) as a within-subjects factor, with repeated measures on the second factor. The dependent measure was salivary cortisol reactivity. The analyses revealed a significant Group×Change Score interaction on salivary cortisol reactivity, F(4, 70) = 2.85, P = 0.03. In order to decompose this interaction, a separate analysis of variance (ANOVA) with Group (high, middle, low) as a between-subjects factor was performed on each of the three salivary cortisol change scores. The analyses revealed a significant main effect for Group only on Change Score 1 (i.e. 35 min post task sample–20 min post task sample), F(2, 35) = 4.54, P = 0.018. Fig. 1 presents the mean differences on this change score for the three groups. Differences between high and low socially competent children and the middle ... Fig. 1. Differences between high and low socially competent children and the middle group on delta salivary cortisol (in μg dl−1) from 20 to 35 min post self-presentation task at age seven (Note that lower values indicate a decrease in salivary cortisol.) Figure options As can be seen in Fig. 1, children in the high socially competent group (M = −0.06, S.D. = 0.07) exhibited a significantly greater decrease in salivary cortisol from 20 to 35 min post-task compared with children in the middle (M = 0.01, S.D. = 0.05), t(28) = 2.65, P = 0.013, and the low (M = 0.02, S.D. = 0.05) groups, t(13) = 2.50, P = 0.027. Because of the small number of children who fell into each of the extreme groups, we ascertained the number of children who exhibited an increase vs a decrease in salivary cortisol from 20 to 35 min post-task by social competence group. As shown in Table 2, all 7 of the children who fell in the high social competence group exhibited a decrease in salivary cortisol 20 to 35 min post task, [Likelihood Ratio χ2(2) = 6.95, P = 0.03]. Table 2. Frequency of children displaying an increase vs decrease in salivary cortisol from 20 to 35 min post self-presentation task by social competence group Social competence group High Middle Low Salivary cortisol Increase 0 9 4 Decrease 7 14 4 χ2(2) = 6.95, P = 0.031. Table options It is also important to note that the three groups did not differ on the behavioral measures collected during baseline and during the self-presentation task.