Individual Differences in Solution Time in Error‐Free Problem Solving

To investigate individual differences in the basic cognitive component of solution‐time in errorless problem‐solving, 30 subjects were given 21 Thurstone‐type letter‐series items to solve under stressed administration, and mean log speed scores of correct solutions were computed. Three groups of 10 subjects each were constructed on the basis of Maudsley Personality Inventory (MPI) extraversion scores, and their speed scores were compared. These groups were then reconstituted into three groups of 10 subjects each on the basis of MPI neuroticism (N) scores, and the speed scores of these groups were compared. It was found that extraverts were significantly faster than introverts and ambiverts. A curvilinear relationship between neuroticism and solution‐time was suggested, with the mid N subjects performing significantly faster than the combined low N and high N subjects The low N and high N subjects did not differ significantly from each other. The results could not be attributed to differences in age, verbal (vocabulary) intelligence, or sex.