Dispositional Optimism and Cardiovascular Reactivity to Mental Stress – Does Task Difficulty Matter?

Research examining the relation between dispositional optimism and the magnitude of cardiovascular reactivity (CVR) to stress has produced mixed findings, with some studies finding that optimism was associated with increased CVR, some with decreased CVR, and some with no association with CVR. The purpose of the present study was to examine whether task difficulty accounted for these mixed findings and moderated the association between optimism and CVR. Seventy-four young adults classified as having high optimism and 78 young adults classified as having low optimism based on the Life Orientation Test-Revised were randomized to complete either an easy or difficult Raven’s Matrices task. Blood pressure (BP), heart rate (HR), and HR variability were measured during a pre-task rest period followed by the task period. Participants also completed ratings of positive and negative affect experienced while completing the task, as well as measures of task appraisals. Results revealed that high optimism participants exhibited greater diastolic blood pressure reactivity (DBP) to both the easy and difficult stress tasks compared to low optimism counterparts. Low optimism participants randomized to the difficult task condition exhibited a significant reduction in standard deviation of normal-to-normal (SDNN) intervals in comparison to those assigned to the easy task condition, a differential task response not detected among the high optimism sample. Analysis of affective responses to the tasks showed that high optimism participants reported experiencing more positive affect than low optimism participants, but no group differences were observed for negative affect. No differences between high and low optimism samples were observed on task performance, and significant DBP and SDNN findings remained when controlling for task performance. Task difficulty only moderated the relation between optimism and SDNN response to stress but not HR or BP responses, demonstrating the importance of assessing a broad range of physiological parameters when exploring relations between psychological constructs like optimism and autonomic responses to stress.