Concurrent validity of the Test of Nonverbal Intelligence in Parkinson's disease patients.

The Test of Nonverbal Intelligence (TONI-2; L. Brown, R. J. Sherbenou, & S. Johnsen, 1990) and Raven's Colored Progressive Matrices (RCPM; J. C. Raven, 1965) are defined as language-free measures of cognitive ability. The purpose of the present study was to investigate the relation between the RCPM and the TONI-2 for samples of patients with Parkinson's disease (n = 75) and controls (n = 47). A regression equation was computed to evaluate the relation of the RCPM scores to the TONI-2 quotient. Regression equation results indicate that there is a significant overlapping linear variance between the two measures in both patients and controls.