Social-evaluative threat, cognitive load, and the cortisol and cardiovascular stress response.

BACKGROUND: Current evidence suggests that exposure to social-evaluative threat (SET) can elicit a physiological stress response, especially cortisol, which is an important regulatory hormone. However, an alternative explanation of these findings is that social-evaluative laboratory tasks are more difficult, or confer greater cognitive load, than non-evaluative tasks. Thus, the current experiment tested whether social-evaluative threat, rather than cognitive load, is truly an "active ingredient" in eliciting a cortisol response to stressors.

METHODS: Healthy undergraduate students (N = 142, 65% female) were randomly assigned to one of four speech-stressor conditions in a fully-crossed two (social-evaluative threat [SET] manipulation: non-SET versus SET) by two (cognitive load manipulation: low versus high) stressor manipulation. Social-evaluative threat was manipulated by the presence (SET) or absence (non-SET) of two evaluators, while cognitive load was manipulated by the presence (LOAD) or absence (non-LOAD) of a tone-counting task during the speech stressor. Salivary cortisol and cardiovascular measures were taken before, during, and after the speech stressor.

RESULTS: Compared to the non-SET condition, SET condition led to greater cortisol and cardiovascular responses to the speech stressor. There were no main or additive effects of cognitive load on cortisol and cardiovascular responses to the speech stressor.

CONCLUSIONS: These findings suggest that social-evaluative threat is a central aspect of stressors that elicits a cortisol response; however we found no evidence that increased difficulty, or cognitive load, contributed to greater cardiovascular or cortisol responses to stressors.