Five competing models specifying the factor structure underlying the Wechsler Memory Scale - Third Edition (D. Wechsler, 1997b) primary subtest scores were evaluated in a sample of patients with intractable temporal lobe epilepsy (N = 254). Models specifying separate immediate and delayed constructs resulted in inadmissible parameter estimates and model specification error. There were negligible goodness-of-fit differences between a 3-factor model of working memory, auditory memory, and visual memory and a nested - more parsimonious - 2-factor model of working memory and general memory. The results suggest that specifying a separate visual memory factor provides little advantage for this sample - an unexpected finding in a population with lateralized dysfunction, for which one might have predicted separate auditory and visual memory dimensions.
