Creativity is a rare trait. This is presumably because it requires the simultaneous presence of a number of traits (e.g., intelligence, perseverance, unconventionality, the ability to think in a particular manner). None of these traits is especially rare. What is quite uncommon is to find them all present in the same person. One imagines that all of these traits have biological bases. In this chapter, I shall focus upon the type of thought involved in creative insight. First, I describe the nature of this type of thought; then I present arguments as to why it must be based upon specific physiological states; finally, I review evidence that it is in fact so based.

A creative idea is one that is both original and appropriate for the situation in which it occurs. It would seem that creative productions always consist of novel combinations of pre-existing mental elements. As Poincareé (1913) noted, “To create consists of making new combinations of associative elements which are useful” (p. 286). Creative ideas, he further remarked, “reveal to us unsuspected kinships between other facts well known but wrongly believed to be strangers to one another” (p. 115).

To create, then, involves the realization of an analogy between previously unassociated mental elements. On the verbal level, creativity involves production of novel statements of the form “A is like B” or statements involving novel modifiers for A. Hugo's image, “I climbed the bitter stairs” is more creative than, say, “I climbed the steep stairs.”