Cunningham W R, Clayton V, Overton W
J Gerontol. 1975 Jan;30(1):53-5. doi: 10.1093/geronj/30.1.53.
The theory of fluid and crystallized intelligence predicts that the relationship between these two abilities will decline systematically across the age span after young adulthood. In order to test this hypothesis in an elderly sample, the Raven Progressive Martices and the WAIS vocabulary subtest were administered to a sample of individuals (N=40), ranging in age from 60 to 79, and also, for purposes of comparison, to a sample of young adults (N=35). It was found that the correlation was significantly lower in the elderly sample (.386) than in the young adult sample (.672).
