1Department of Anthropology, The University of Alabama, 2Center for the Prevention of Youth Behavior Problems, The University of Alabama, 3Department of Psychology, The University of Alabama
Saturday 2:30-2:45, Ballroom B
Adrenocortical and autonomic markers (e.g., cortisol, heart rate variability) reflect an evolved, ontogenetically plastic, contextually sensitive state regulation system. Yet temptation remains to treat them simply as stress markers. Except for the early origins literature (e.g., Worthman and Kuzara 2005), evolutionary modeling of individual differences remains thin. Children’s responses evolved to maximize survival across social contexts, including variable caretaker capability and investment (Chisholm 1996, Flinn 2006). To account for individual variation in adaptive flexibility, Boyce and Ellis (2005) suggested reframing “stress reactivity” as “biological sensitivity to context,” (BSC) an individual index of how physical and social contexts evoke changes in physiological state. Since BSC reflects internalization of context, high BSC children experience greater beneficial and detrimental developmental effects of caretaking environment. Yet BSC itself is developmentally plastic, so Boyce and Ellis proposed evolutionary models regarding “optimal” programming of stress responsiveness under varying long-term childhood conditions. We assessed 60 children in a pre-kindergarten U.S. Head Start program for cortisol and autonomic reactivity before and after an intervention designed to improve classroom and home environments. Highly sensitive children (higher HPA reactivity to mild experimental challenges) had poorer behavioral outcomes (p < .01), yet benefited more from the changes in context yielded by the intervention (p < .10). We interpret this within the BSC evolutionary framework. Then, through comparison with & reinterpretation of serial cortisol measures from an earlier field study involving 35 U.S. pre-kindergarten children, we discuss implications for field research of treating variation as indicative of “sensitivity” as well as distress.
Funding: College of Arts & Sciences Academy for Research, Scholarship and Creative Activity (to AG, CB)