The right hemisphere maintains solution-related activation for yet-to-be-solved problems.

In five experiments, we examined the time course of hemispheric differences in solution activation for insight-like problems. We propose that solving insight problems requires retrieval of unusual interpretations of problem elements, and that right-hemisphere (RH) coarse semantic coding is more likely than left-hemisphere (LH) fine semantic coding to maintain semantic activation of such interpretations. In four experiments, participants attempted word problems for 7 sec (Experiments 1A and 1B) or 2 sec (Experiments 2A and 2B), and 750 msec later responded to lateralized target words. After 7 sec of solving effort, Experiment 1A participants showed greater solution-related priming (i.e., they named solutions faster than unrelated words) for left visual field-RH (lvf-RH) targets than for right visual field-LH (rvf-LH) targets, and Experiment 1B participants made faster solution decisions on target words presented to the RH, as previously demonstrated following 15 sec of effort. After 2 sec of solving effort in Experiment 2A, women showed symmetric solution-related priming, although men showed a slight lvf-RH advantage in priming; and in Experiment 2B participants made equally quick solution decisions for targets presented to the LH and to the RH. In Experiment 3, participants viewed the problems for 1,250 msec then named lateralized target words; they showed symmetric solution-related priming. These experiments demonstrate solution activation initially in both hemispheres, but maintained solution activation only in the RH.

Right and left hemisphere cooperation for drawing predictive and coherence inferences during normal story comprehension.

In three experiments, healthy young participants listened to stories promoting inferences and named inference-related test words presented to the right visual field-Left Hemisphere (rvf-LH) or to the left visual field-Right Hemisphere (lvf-RH). Participants showed priming for predictive inferences only for target words presented to the lvf-RH; in contrast, they showed priming for coherence inferences only for target words presented to the rvf-LH. These results, plus the fact that patients with RH brain damage have difficulty drawing coherence inferences and do not show inference-related priming, suggest that information capable of supporting predictive inferences is more likely to be initially activated in the RH than the LH, but following coherence breaks these concepts (now coherence inferences) are completed in the LH. These results are consistent with the theory that the RH engages in relatively coarse semantic coding, which aids full comprehension of discourse.

The effect of reportable and unreportable hints on anagram solution and the aha! experience.

Two experiments examine the effects of unreportable hints on anagram solving performance and on solvers' subjective experience of insight. In Experiment 1, after seeing a hint (unrelated, semantically related, or the solution) presented too briefly to identify, participants solved anagrams preceded by the solution fastest and solved anagrams preceded by unrelated hints slowest. Participants' "warmth" ratings for solution hints were more insight-like than those for unrelated hints. In Experiment 2 a hint, or no hint, was presented at one of three different exposure durations (undetectable, unreportable, or reportable). Participants benefited from solution-relevant hints that were either unreportable or reportable, but showed a cost only for unrelated hints that were reportable. Participants' ratings of their insight experiences showed that unreportable solution and semantically related hints produced more insight-like experiences than did unrelated hints. The results suggest that unreportable processing of solution-related information is important for the insight experience.