Activation and metacognition of inaccessible stored information: potential bases for incubation effects in problem solving.

Two experiments were conducted with a hybrid procedure that involved a battery of indirect criterion tests designed to study the activation and metacognition of inaccessible stored information. In each experiment, subjects first attempted to recall some rare target words in response to a series of definitions meant to cue retrieval from long-term semantic memory. For the words that could not be recalled initially, the subjects rated their feelings of knowing. They then performed a lexical-decision task in which the target words and other control words were presented. Reaction times were measured as a function of the feeling-of-knowing ratings and the length of the interval between the initial exposure to the definitions and the subsequent lexical decisions. Faster decisions occurred for the target words than for the controls, especially when strong feelings of knowing had been expressed about the targets. Similar facilitation was obtained in a subsequent old-new recognition task. It appears that unsuccessful attempts to retrieve inaccessible stored information prime the later recognition of the information through a process of spreading activation. Such activation may sensitize people to future occurrences of stimulus inputs needed for insightful solutions of semantically rich problems.