Cardiovascular reactivity and adaptation to recurrent psychological stress: replication and extension.

We analyzed the effects of evaluative observation and baseline duration on cardiovascular reactivity and adaptation to recurrent psychological stress. Cardiovascular reactivity to mental arithmetic stress was assessed in college men and women (N=224) during two pretest tasks, a test task, and a posttest task. Participants were assigned randomly in a 2 x 2 design to manipulations of baseline duration before the test task (4 min vs. 12 min) and evaluative observation during the test task (observed vs. control). Repeated exposure to stress attenuated cardiac but not vascular reactivity. Evaluative observation disrupted cardiac adaptation, resulting in a resurgence of beta-adrenergic cardiac reactivity during the test task. Cardiac adaptation resumed fully during the posttest task. Baseline duration had no effect on reactivity. The results replicate and extend previous work, and support the dual process theory of habituation and sensitization.