Date of Award

Winter 1998

Project Type


Program or Major


Degree Name

Doctor of Philosophy

First Advisor

John Limber


In four experiments, the effects of fixation and suppression processes in problem solving ability were investigated. Previous research has shown that efficient suppression mechanisms are integral to verbal ability (e.g., Gernsbacher & Faust, 1991; Gernsbacher, Varner, & Faust, 1990; Hartman & Hasher, 1991). The present set of experiments demonstrated that such a mechanism is also a component of problem solving ability. The efficiency with which participants were able to suppress inappropriate meanings of ambiguous words was used as a measure of suppression skill. Experiment I established that participants who were able to make use of previously-presented information to solve difficult insight problems were also more efficient at suppressing the inappropriate word meanings. Experiment 3 showed that participants who scored highly on the Remote Associates Test (RAT) were also better able to suppress the inappropriate meanings, in comparison to low RAT solvers.

Experiments 1--4 investigated fixation effects. Experiment 1 demonstrated that fixation to incorrect responses on the insight problems is not easily attenuated when these incorrect responses have been generated by the subject. Experiment 2 showed that this fixation effect is not attenuated even with the inclusion of an incubation period between a first solution trial in which the initial incorrect response is generated and a subsequent trial in which the same problems are again presented, along with clues to solution.

Experiments 3 and 4 showed that fixation can be attenuated when initial incorrect solutions to RAT items are suggested by the experimenter. This is in contrast to Experiments 1 and 2, in which initial incorrect responses were generated by the participants. These attenuation effects were evidenced by increased solution rates to the RATs after an incubation period.

These experiments also investigated the degree to which participants of varying ability levels can benefit from a period of incubation. Previous research has shown mixed results in this regard. The present findings are also inconclusive. Experiment 3 showed that high-ability participants benefited more from the incubation period, while Experiment 4 revealed no differences in the incubation effects for participants of varying problem solving ability.