All ETDs from UAB

Advisory Committee Chair

Rex A Wright

Advisory Committee Members

Elizabeth Griffith

Sylvie Mrug

David Schwebel

Diane Tucker

Document Type


Date of Award


Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences


Wright's integrative analysis suggests that effort can be measured via cardiovascular (CV) response. In addition, the analysis breaks with tradition in suggesting that effort varies not with benefit alone, but also with the difficulty of the behavioral challenge at hand. Recent research has focused upon the effects of fatigue on effort related CV response, assuming that fatigue negatively affects perceived ability. Results have supported interactional predictions. Specifically, they have indicated higher levels of CV response among high- as compared to low fatigue participants when tasks were possible and worthwhile and the reverse response pattern when tasks were excessively difficult (given the incentive) or impossible. One implication is that high fatigue individuals may strive harder than low fatigue individuals in meeting challenges perceived as possible and worthwhile. If they do so chronically, this could yield chronically elevated CV responses and increased risk for negative health outcomes such as hypertension and heart disease. The purpose of the present study was to extend the preceding fatigue research by (1) studying participants with low and high levels of naturally occurring fatigue, and (2) doing so across multiple task difficulty levels, including an extreme difficulty condition. Each participant calculated mentally the sum of increasingly difficult series of audible numbers and was offered a modest monetary reward for each correct sum total. Analysis of CV responses measured during the task periods indicated that for Low Fatigue participants, a quadratic trend for SBP, DBP, and HR responsiveness was present, with responses rising with difficulty up to a point and then declining. CV response was low for High Fatigue participants, regardless of difficulty, and especially low in the impossible task condition. Results were interpreted to suggest that fatigue in High Fatigue participants was so high that it discouraged engagement even when difficulty was low. Wright's integrative fatigue analysis implies that a different cardiovascular response pattern might have been observed for High Fatigue participants had a more powerful performance incentive been provided. This work has practical implications not only for health, but also for performance outcomes in social, educational, and occupational settings.