关键词: tACS, 工作记忆, 精度-数量权衡, 4HZ theta, 心理惯性

Abstract: Previous studies have demonstrated that tACS can enhance cognitive resources, thereby improving working memory (WM) performance. However, some studies have failed to establish tACS as having a definitive advantage in boosting WM. This paper suggests that the timing of stimulation is a crucial variable influencing the regulatory effects of tACS by influencing psychological inertia during the task. Psychological inertia refers to the unconscious, automatic behavior of an individual that is context-dependent. When psychological inertia conflicts with rational decision-making, it may lead the individual to overlook the optimal choice. In Experiment 1, 36 participants were recruited and required to complete a color recall reporting procedure. Active or sham tACS was applied before or after practice to manipulate the total amount of memory resources at the initial stage. We hypothesized that the group receiving tACS stimulation after practice, compared to the group receiving stimulation before practice, would exhibit a resource trade-off strategy between quantity and accuracy similar to the sham stimulation group, due to the influence of mental inertia. The results confirmed this hypothesis. When stimulation was applied before practice, participants were able to remember more items while maintaining accuracy. Conversely, when stimulation was applied after practice, participants improved accuracy while retaining the same number of items. In Experiment 2, 56 participants were recruited and required to complete a color and orientation recall reporting procedure. Experiment 2 investigated whether the regulatory effects of the first task would carry over to the second task by having participants complete two different tasks, with stimulation applied after the practice phase of the first task. The results revealed that, during the first task, participants enhanced accuracy while keeping the number of items unchanged, which is consistent with the group receiving tACS stimulation after practice in Experiment 1. However, in the second task, they increased the number of items remembered while maintaining accuracy, which aligns with the findings in the group receiving stimulation before practice in Experiment 1. This indicates that in new situations, psychological inertia can be disrupted, leading to the formation of new strategies. The regulatory effects of tACS on WM depend on the timing of stimulation. If applied before practice, tACS primarily influences memory quantity; if applied after practice, it mainly affects memory accuracy. Furthermore, regulatory effects established during the first task may be disrupted when encountering a new task. These findings clarify the optimal temporal window for tACS intervention, providing a precise reference for clinical cognitive rehabilitation, such as early intervention in Alzheimer's disease.

Key words: tACS, working memory, accuracy-quantity trade-off, 4 Hz theta, psychological inertia