People’s metacognitions, both before and during problem solving, may be of importance in motivating and guiding problem-solving
behavior. These metacognitions could also be diagnostic for distinguishing among different classes of problems, each perhaps
controlled by different cognitive processes. In the present experiments, intuitions on classic insight problems were compared
with those on noninsight and algebra problems. The findings were as follows: (1) subjective feeling of knowing predicted performance
on algebra problems but not on insight problems; (2) subjects’ expectations of performance greatly exceeded their actual performance,
especially on insight problems; (3) normative predictions provided a better estimate of individual performance than did subjects’
own predictions, especially on the insight problems; and, most importantly, (4) the patterns-of-warmth ratings, which reflect
subjects’ feelings of approaching solution, differed for insight and noninsight problems. Algebra problems and noninsight
problems showed a more incremental pattern over the course of solving than did insight problems. In general, then, the data
indicated that noninsight problems were open to accurate predictions of performance, whereas insight problems were opaque
to such predictions. Also, the phenomenology of insight-problem solution was characterized by a sudden, unforeseen flash of
illumination. We propose that the difference in phenomenology accompanying insight and noninsight problem solving, as empirically
demonstrated here, be used to define insight.