He believed in the unitary nature of intelligence but subscribed to the idea that intellect can be best measured through interdependent, qualitatively different abilities. Historical, the picture arrangement subsets of the Wechsler scales have been characterized repeatedly as being nonverbal and verbal measure of social competence.
He held the belief that intelligence is unified but acknowledged that intellectual capacity could be assessed through a combination of distinct, qualitative skills. Historically, the picture-based subtests within the Wechsler scales have been categorized as measuring both nonverbal and verbal aspects of social competence.