Cortisol Secretion Under Stress: Test of a Stress Reactivity Model in Young Adult Males.

A three-group stress reactivity typology was compared to a five-factor dimensional personality model as predictors of cortisol secretion in two samples of U.S. Navy recruits n 40 and n 53 during military basic training. Initial exposure to basic training was associated with elevated cortisol levels compared to later in training. Individual differences in cortisol were moderately stable over the course of basic training, but neither personality model predicted the stable individual differences reflected in cortisol. In the typological model, stress reactive individuals showed higher cortisol at the end of training. In the dimensional model, agreeableness was associated with higher cortisol in the middle of training, and conscientiousness was associated with lower cortisol at the end of training, so the dimensional model predicted cortisol over a wider range of training conditions. These results are interpreted as consistent with a conditional person-environment fit model of stress. The model postulates that different personality attributes predict cortisol secretion when social stimuli relevant to those attributes are present. The relationships are conditional in that they are present only in a stable social situation.