Cardiovascular responses to mental fatigue in a sequential task paradigm

This study investigated mental fatigue within a sequential task paradigm using cardiovascular measures and predictions derived from Motivational Intensity Theory. Forty-two undergraduate students were assigned to either a fatigue group (n = 21) or a control group (n = 21). The fatigue group completed a difficult task, while the control group watched a documentary, before both groups performed the same difficult subsequent task. Subjective fatigue, performance, and cardiovascular responses were assessed. Participants in the fatigue group reported significantly higher levels of subjective fatigue and lower effort intensity during the subsequent task compared to the control group, as evidenced by reduced PEP and HR reactivity. Despite these differences, performance on the subsequent task did not differ between groups. These findings suggest that a prior difficult task can increase the perceived difficulty of subsequent tasks. When the subsequent task is also difficult, the effort required may be viewed as no longer worthwhile, leading to reduced effort investment. Cardiovascular measures and theory-driven approaches, such as Motivational Intensity Theory, provide valuable insights for understanding mental fatigue and should be employed rather than relying exclusively on performance-based data.