Long-Term Cognitive Tasks Impair the Ability of Resource Allocation in Working Memory: A Study of Time-Frequency Analysis and Event-Related Potentials

Long-term cognitive tasks can lead to mental fatigue, which can increase the risk of accidents. P300, theta (4-7 Hz), and alpha (8-13 Hz) power are related to cognitive functions. In this paper, we selected long-term cognitive tasks to induce mental fatigue. Sternberg-WM paradigm was performed before and after fatigue, and EEG data was collected and analyzed. P300 amplitude had no significant difference in the normal state, but significantly reduced with increasing of the workload in parietal region in the fatigue state. This indicated that mental fatigue reduced the allocatable cognitive resources in the high workload. P300 latency had no significant difference between the normal and fatigue state, indicating that mental fatigue had no significant effect on the speed of cognitive resource allocation. Theta power increased significantly with increasing of the workload only in the normal state, indicating that the high workload required more top-down attention resource input to promote memory retrieval. Mental fatigue weakened attention resource input. Alpha power significantly decreased with increasing of the workload only in the fatigue state, indicating that mental fatigue reduced the energy of suppressing irrelevant information interference in the high workload. Long-term cognitive tasks can impair the allocation of cognitive resources, reduce cognitive ability, and lead to behavioral errors in the high workload. P300 can be used as a biomarker for monitoring mental fatigue in the high workload, besides, theta and alpha rhythms can be used as potential targets for neural oscillations regulation.