Abstract: Although previous studies on insight have fully investigated brain activities and neural correlates of “flash of insight”, little knowledge was known on cognitive process of active solution-seeking in problem solving before insight. Studies revealed that we would not obtain a full and deep understanding on insight problem solving and its neural basis, unless given an equal and all-sided study for active solution-seeking before insight and “flash of insight” during hint presentation period. Mental impasse is an important elementary process not only for subsequent incubation and presentation restructuring but also for human problem solving behavior. However, yet to date there were few studies that have examined this issue. Existing studies on FOK in insight tasks solving revealed that people’s metacognition can not accurately monitor sudden insight, but they did not elucidate whether people’s intuition can perceive possible mental impasse subsequently encountered or not. Thus, the present study focused on this problem.
The current study adopted normal three-word Chinese riddles and firstly employed high-density event related potentials (ERPs) to investigate the neural markers of insight during active solutions-seeking period. 13 paid participants were recruited to fulfill a three-character guessing task, and brain electrical activity was recorded. The results showed that, the process of active solutions-seeking of riddles with impasses compared to those without impasses elicited a more positive potential in the time windows of 120~210 ms (P170) and 620~800 ms (terminal LPC). P170 may be associated with the processing that people perceive intuitively mental impasses at the perceptual stage, whereas the terminal LPC may be associated with a conscious reappraisal and reflection of mental impasses. These results imply that mental impasse not only appears at the terminal phase, but also be intuition-sensitive at the perceptual stage. Human brain can perceive whether they would meet subsequent mental impasses or not during problem solving.
The mental ruts hypothesis claims that mental impasses are formed because the repeated exploration of an unsuccessful search path or the search for the same knowledge element adds more and more activation to this path. However, our findings suggest that mental impasses in insight riddle solving task do not result from iterative repetitions of non-effective exploration. If necessary, mental impasses can be formed initially at an early stage, and then be reappraised at a late stage. The finding suggests that human brain can perceive intuitively subsequent mental impasses underlying our complex insight problem solving behaviors at an early stage.

Key words: problem solving, insight, representation restructuring, mental impasse, event-related potentials