Cognitive control of invalid predominant ideas in insight-like problem solving.

Predominant ordinary ideas are insufficient for solving insight-like problems; they interfere with subordinate original ideas and can produce a mental impasse. However, how people monitor and control invalid predominant ideas remains largely unknown. In the current study, participants were asked to solve a sequence of several similar practice problems that had the same solution to strengthen a predominant idea; the participants were then presented with an insight-like test problem that could not be solved by the predominant idea. The results showed that if the test problem was similar to the practice problems in which the predominant idea could typically be applied, it elicited greater late sustained potential (LSP) over the whole brain but no conflict-related N2 or N400 components, which suggests that the participants did not experience cognitive conflict and continued to verify the predominant but currently invalid idea. When the test problem differed from the practice problems, the items that participants reported trying to solve elicited greater N2-N400 and LSP over the whole brain, which suggests that the participants experienced cognitive conflict and exerted more reactive control over the invalid predominant idea; in contrast, the items that participants reported thinking about how to solve did not evoke greater conflict-related N2-N400 components and evoked even lower LSP, which likely indicates an ineffective state. These findings demonstrate three kinds of cognitive control toward invalid predominant ideas in situations where they are typically and not typically applied and provide empirical evidence of a mental impasse in insight-like problem-solving behaviors.