Frontal lobe functioning in man: the riddle revisited.

Forty-eight patients, each with a single frontal lobe lesion, were tested with a battery of 10 of the most widely used neuropsychological tests, comprising five traditional "frontal" tests and five others, for which that claim is not generally made. All correlations among the tests in the group were positive and significant. Moreover, the average correlation between each frontal test and the other tests in the frontal group was found to be higher than the average correlation of the same frontal test with the tests in the other group. A factor analysis of the scores on the five frontal tests yielded a single factor accounting for 53% of the variance. A factor analysis on the entire battery of tests (frontal plus nonfrontal) also yielded a strong general factor; although this accounted for a smaller portion (43%) of the shared variance, and one test (Verbal Span) failed to show a substantial loading on the factor. Neither the results of the present study nor the findings of other researchers argue for the abandonment of the concept of "executive" functioning, mediated by the functioning of the frontal lobes, in favor of a variant of fractionation.