Zeigarnik effect in Insight problem solving: Hemi-spheric difference in brain activities following problem solving and during hint presentation

Abstract

People tend to exhibit enhanced memory performance for the unfinished tasks relative to the finished ones, which known as the Zeigarnik effect. Consistently, the impasse state in insightful problem solving were believevd to play an important role in maintaining the problem in one’s mind and in catching the critical clue to overcome the main obstacles. More importantly, through hemi-visual field presentation technology, studies on insight found the keynotes for the unsolved puzzle could be more efficient in catalyzing a breakthrough when presented to the left-visual field (i.e., the right hemisphere) than to the right-visual field, especially when there was a temporal delay between the disappearance of the puzzle and the presentation of keynotes. This observation implied that the right hemisphere, relative to the left one, might play a more important role in keeping the information of the unsolved problem online and might be more ready in processing the related clue for that problem. In order to testify this hypothesis, we compared the Event-Related Potentials (ERPs) between the solved and unsolved insightful chunk decomposition problems during (a) the moment when the subjects pressed a key to indicate whether or not they could solve the problem by themselves before seeing any external hint, and (b) the moment when subjects were given the hint. The ERPs results showed that, during the moment of subjects’ confirmation of their successful or unsuccessful problem solving, the unsolved problems were accompanied with a more positive P150 over the right frontal cortex, whereas the solved ones exhibited a more positive P150 over the left side. Consistently, during the moment of hints presentation, the hints to the unsolved problems also elicited a more positive P2 over the right hemisphere, whereas the the hints to the solved problems elicited a more positive P2 over the left side. These results confirmed the hypothesis that, after the failure in insight problem solving, the right hemisphere might be more positive in preserving the unsolved problem in mind and be more responsive to the external hint for problem solving.