Objective: To test in a laboratory setting the hypothesis that the most problematic daily outcomes should be particular to individuals displaying higher cortisol reactivity and deficits in executive functioning as assessed in a task-switching paradigm.
Methods: Thirty-eight volunteers completed a comprehensive assessment protocol. Individual differences in cortisol reactivity were quantified in an initial laboratory session involving a social stress speech task. Subsequently, individual differences in task-switching costs in a cognitive paradigm were assessed in a second session. Participants then reported on four problematic outcomes—error reactivity; worry; core aspects of negative emotionality; and aggression behavior frequency—for 15 consecutive days.
Results: Levels of cortisol reactivity did not predict task-switching costs. Instead, and as hypothesized, individual differences in cortisol reactivity and task-switching costs interacted to predict the problematic daily outcomes. The highest levels of such problematic outcomes were particular to high cortisol reactors also exhibiting greater task-switching costs.
Conclusions: The findings support the dual vulnerability model proposed and are discussed from temperamental, health risk, and daily outcome perspectives. These findings indicate that cortisol is a risk factor, particularly when combined with deficiencies in task-switching.
MLM = multilevel modeling; RT = reaction time.