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.
From the Psychology Department, North Dakota State University, Fargo, North Dakota.
Address correspondence and reprint request to Michael D. Robinson, Department of Psychology, North Dakota State University, Dept. 2765, PO Box 6050, Fargo, ND 58108-6050. E-mail: Michael.D.Robinson@ndsu.edu
Received for publication July 7, 2010; revision received November 21, 2010.
This study was supported, in part, by Grant BCS 0843982 from the National Science Foundation (M.D.R.) and by a Graduate Research Fellowship from North Dakota State University (S.O.).