Impact of hierarchical processing levels on division of labor: neural electrophysiological evidence from a joint rule shifting

Objectives Although previous studies have revealed the behavioral and neural mechanisms underlying cognitive control, the neural electrophysiological process in joint task switching has rarely been discussed. Moreover, the hierarchy process remains unclear. Therefore, the present study aimed to explore the neural mechanism of a target when two actors use division of labor between action selections in a joint hierarchical rule-shifting situation. Methods The present study employed a joint hierarchical rule shifting paradigm, and each participant was responsible for the selection of one type of action (left key and right key). The cue was the letter ‘R’ with three features, which indicated the hierarchical rule of the current trial. The target was an Arabic numeral (1–9, except 5). Participants made a magnitude judgement or a parity judgment based on the high and low hierarchical features of cues. Results The P2 component was smaller in the high-shift condition than in the repeat condition; however, the high-shift condition elicited a larger N2 amplitude than the low-shift and repeat conditions. We believe that the current P2 is related to selective attention to the hierarchical features of rules, and N2 is related to conflict control. In addition, the high-shift condition had the largest P3 amplitude, which indicates that this condition has the largest extent of update and leads to the most unstable association between rule and stimuli. Conclusions The study demonstrated that participants had dynamic brain responses to target stimuli in the joint rule-shifting situation. In other words, participants first confirmed the actor of the current target and then processed the target stimuli themselves.