Evaluating creative ideas: Insights from erps and changes in the upper alpha bank

Thus far, electrophysiological research on creativity has employed production tasks and measured changes in the alpha band in time windows lasting several seconds, while participants produced creative ideas. These studies had, however, limited temporal resolution, which made it difficult to identify specific cognitive processes underlying creative thinking. In the current study, we employed a modified version of the alternate uses task, in which participants evaluated word pairs representing the common, creative, and impossible uses of objects according to how (im)possible and (un)common they seemed. In the even-related potential (ERP) analysis, a graded effect was found, with impossible uses evoking the largest, common the lowest, and creative intermediate N400 amplitudes. Moreover, greater power in the upper alpha band was observed in the creative than common condition in the time window between 400–1000ms. Interestingly, this effect was absent in the lower alpha band, which differs from previous reports in which an increase in both the upper and lower alpha bands was found. The graded N400 effect can be interpreted as reflecting increased activity in semantic memory needed to evaluate the creative word pairs. The difference in the upper alpha band might index increased semantic processing demands and larger inhibition of task-irrelevant information on creative than common trials. Since task demands remain comparable on all trials, these findings seem directly related to cognitive processes involved in evaluating creative ideas.