Estimated, using 'mental tests', impairment of intellect. The 'theory of two factors' has been outlined as an explanation of intelligence. The tests used included 2 tests of memorizing and 3 motor tests on speed of successive innervations, perceptual activity, and co-ordination. 68 patients and two groups of normals were tested. The results appear incompatible with the current view of dementia, and mental injury appears to be of diffused character or to constitute a lowering of the whole intellectual level, and dependent on the entire cortex rather than a specific substratum. The sole theory capable of accounting for these and other results seems to be the theory of two factors. With regard to practical diagnosis, the method of mental tests appeared to be capable of accurately determining general level of intellectual power. (PsycINFO Database Record (c) 2006 APA, all rights reserved)