Study Of EEG Mechanism Underlying The Incubation Effect In Divergent Thinking

The present study aimed to explore the effect of different types of interpolated tasks during incubation period on post-incubation divergent creative performance and provide further some evidence for the neural mechanisms underlying incubation effect. In experiment1on behavioral study, we compared the effect of four different interpolated tasks on the creative cognition; in experiment2on brain study, we explore the brain mechanisms underlying incubation effect by the biomarker of the EEG alpha power ERD/ERS, thereby provide the explanation from the view of neuroimaging techniques.The main hypothesis of experiment1is that if the interpolated tasks could elicit remote semantic activation and the formation of remote associations irrespective of their levels of cognitive demand, then they would be associated with stronger incubation effects (i.e., improvements of creative performance after the incubation period compared to the period before). The effects of the four mentioned interpolated tasks on verbal creative problem solving were assessed by means of a delayed-incubation paradigm and the target task was Alternative Uses Task (AUT). Two intervention tasks were administered (Reflecting on the generated ideas [RF]and the Word puzzle task [WP]), which are supposed to elicit remote associative processes but with varying levels of cognitive demands, along with two verbal control tasks (phonemic fluency task[PF] and object characteristics task[OC]). The results showed that only RF and WP tasks, but not the control tasks, were associated with significant incubation effects. The findings suggest that the interpolated tasks that were assumed to elicit remote associative processes can unfold beneficial effects on verbal creative problem solving, regardless of whether the task is cognitively low or high demanding. These findings support the spreading activation hypothesis belonging to unconscious work theory.We adopted the similar paradigm and creative tasks with experiment1in experiment2. Because of the homogeneity of four tasks in experiment land the time limitation of EEG study, we only record the EEG alpha power under the condition of RF and OC tasks. These behavioral results demonstrated that there were significant incubation effects (i.e., improvements of creative performance from stage1to stage2) in the RF, but not in the OC incubation condition. The EEG results demonstrated that the upper alpha synchronization (ERS) during RF incubation period was seen over the prefrontal and parietal cortex in bilateral hemisphere, while the upper alpha desynchronization (ERD) during OC incubation period was seen in a widespread pattern. We also observed that upper alpha increased during the post-incubation creative problem solving under RF condition. Thus we concluded that the upper alpha power was sensitive to creative ideation. Experiment2supported directly the spreading activation hypothesis belonging to unconscious work theory from the biology.The results of the two experiments suggested that different interpolated tasks during incubation period had different effect on post-incubation divergent creative performance. The interpolated tasks that could elicit remote associative processes had positive effect on post-incubation creative thinking task. EEG Alpha power ERS could be regarded as a sign of creative ideation. The unconscious work could account for the results.