Reported fatigue, difficulty, and cardiovascular response to a memory challenge.

Female undergraduates were presented the opportunity to earn a small chance of winning a modest prize by memorizing in 2 min two or six nonsense trigrams (meaningless series of three letters, such as AED). Analysis of cardiovascular measures taken during the work period indicated that systolic blood pressure responses first rose and then fell with self-reported fatigue in the two trigram condition. By contrast, the responses declined with self-reported fatigue in the six trigram condition, starting relatively high and ending low. Whereas systolic blood pressure responses were stronger for Six Trigram participants where fatigue was low, they tended to be stronger for Two Trigram participants where fatigue was moderate and were weak for both trigram groups where fatigue was high. Response patterns for diastolic blood pressure and, especially, mean arterial blood pressure, were similar. The blood pressure findings conceptually replicate and extend previous fatigue study results and provide further support for a recent conceptual analysis of fatigue influence on effort and associated cardiovascular responses.