The test to be reported on in this paper was designed to evaluate certain assumptions about the effects of cortical brain damage in humans. It is hoped that eventually the degree of differentiation will be accurate enough to justify the use of the instrument as a diagnostic tool. Therefore a control group was used typical of the type of patient population from which the usual differential diagnosis is made.
The test was designed to sample four areas shown by animal and human experiments to be sensitive to organic brain damage. These are visual-motor speed, learning, memory, and flexibility.
Visual-motor speed, as measured by the digit symbol test, is an ability severely affected by factors interfering with intellectual efficiency. Busse, Barnes, Friedman, and Kelty (1956) showed this test to be most severely affected by the aging process. Cohen’s (1957) factor analysis of the WAIS indicates that