Is the Halstead Category Test a multidimensional instrument?

Factor structure of the Halstead Category Test was evaluated in patients with schizophrenia, heterogeneous forms of brain damage, and patient controls using confirmatory factor analysis. Analyses were performed including and excluding subtests 1 and 2. In the first analysis, a three-factor model was optimal, with subtests 1 and 2 loading on one factor (Counting), 3, 4, and 7 loading on a second factor (Spatial Positional Reasoning), and subtests 5 and 6 loading on a third factor (Proportional Reasoning). Excluding subtests 1 and 2, a two-factor solution was optimal consisting of the Spatial Positional (subtests 3 and 4) and Proportional Reasoning (subtests 5 and 6) factors, with subtest 7 loading on both factors. Optimal factor structures for the three groups were identical. Correlations between factor scores were similar among groups. Factor scores also correlated significantly (p <.01 ) with all of the other cognitive measures. It was concluded that the Category Test is a multidimensional procedure with factors associated in a general way with other cognitive abilities.