Appendix.

Analyses using two mental fatigue related items from VAS-F as the measure for self-report/perceived fatigability.

1. Correlation between objective and perceived mental fatigability:
We examined the correlation between objective and perceived mental fatigability using GEE adjusting for age, sex, and education. Self-report fatigue was significantly and positively related to RT (B = 0.333, SE = 0.109, p = .002) over the course of fatigability manipulation task.
2. Predictors of perceived mental fatigability (control for age, sex, and education):
Psychological factor	Session	Factor	Factor × session
Subjective chronic fatigue	0.05, p = .83	3.53, p = .067	0.01, p = .91
Executive control	0.46, p = .50	0.56, p = .46	4.75, p = .035
Depressive symptom	0.04, p = .85	2.27, p = .14	0.41, p = .53
Physiological factor
Vascular risk = 1 (vascular risk > 1 as reference)	0.004, p = .95	0.09, p = .91	0.75, p = .48
Sleepiness	0.18, p = .67	4.03, p = .051	0.32, p = .57
Taking anti-inflammation (not taking anti-inflammation as reference)	0.08, p = .79	0.32, p = .58	0.17, p = .69
Taking beta-blocker (not taking beta-blocker as reference)	0.02, p = .89	1.14, p = .29	0.31, p = .58
Situational factor
History of mental activities	0.01, p = .94	0.09, p = .76	1.29, p = .26