Factor analysis of verbal and nonverbal clinical memory tests

This study represents an attempt to evaluate the construct validity of various verbal and nonverbal clinical memory tests. Marker variables for verbal, visual-perceptual-motor and attention-concentration abilities were employed in order to demonstrate the relative independence of these abilities from the memory measures. Subjects were 119 individuals (aged 16-74) from a combined sample of brain damaged and non-neurologic medical controls. Principal components analyses with orthogonal varimax rotations produced four factors in both Immediate and Delayed analyses: nonverbal memory and visual-perceptual-motor skills, verbal learning and memory, general verbal abilities, and attention-concentration. The inclusion of additional nonverbal memory measures helped to create a modality specific nonverbal factor but did not produce a pure nonverbal memory factor. The Wechsler Memory Quotient had modest loadings on three of the four factors.