Task-Specific Impacts of Cognitive Fatigue on Subjective Experience and Psychomotor Performance

Objective To determine how cognitive fatigue (CF) affects subjective experience and reaction time (RT) performance across tasks with different processing demands (simple, go/no-go, choice), and whether these effects depend on the type of fatigue-inducing mental work. Background CF is a psychobiological state of subjective exhaustion from mental effort that can compromise workplace productivity and safety. Although slowed RT is an often-observed consequence of CF, it is unclear how this compares across RT paradigms and fatigue-inducing tasks. Method Using a remotely administered experiment, 402 participants completed a 60-minute CF (Math-Memory, Stroop, Time Load Dual-Back) or control (documentary) intervention. Subjective ratings (mental fatigue, motivation) and RT performance (simple, go/no-go, choice) were assessed pre- and post-intervention. Results Relative to control, all CF tasks increased subjective fatigue ( p < .001), while motivation declined following Dual-Back and Stroop ( p ≤ .030) but not Math-Memory. Simple and choice RT slowed significantly following all CF interventions vs control ( p < .010), with the greatest choice RT slowing after Stroop ( p ≤ .032). Only Stroop produced significant go/no-go RT slowing ( p = .004). Conclusion Subjective fatigue and simple RT were broadly sensitive to CF, indicating general psychomotor slowing. Conversely, motivation and higher-complexity RT measures showed task-specific effects, perhaps reflecting overlap between fatigue-inducing and RT task demands. Application Task type is important when considering RT as a fatigue assessment tool. These findings support multidimensional (subjective and RT) CF assessments and indicate that simple RT may be effective for rapid, broad fatigue monitoring, whereas complex RT metrics may be useful when exploring task-specific executive processing effects.