Sensitivity of the Halstead category test factor scores to brain damage

Recent factor-analytic studies of the Halstead Category Test (HCT) indicate that its seven subtests form three factors including a Counting factor (subtests I and II), a Spatial Positional Reasoning factor (subtests III, IV, and VII), and a Proportional Reasoning factor (subtests V, VI, and VII). The sensitivity and specificity of these factors to heterogeneous forms of brain damage was examined in a large sample of patients and a normal comparison sample. A prorated Impairment Index, which excluded the HCT error score, was used to assign participants with brain damage into mild, moderate, and severe impairment groups. Also, groups with various forms of neuropathology were contrasted. Results indicated that both the Spatial Positional Reasoning and the Proportional Reasoning factors were sensitive to brain damage. However, in all of the brain-damage groups, a greater percentage of errors were made on the Spatial Positional factor, suggesting that of the two it was more difficult for those with brain damage. The sensitivity and specificity of the Spatial Positional factor score for detection of brain damage was comparable to that of the total error score, which has been previously demonstrated to be an excellent indicator of brain damage. Findings provide further support for the validity of the HCT factors, and are consistent with the view that factor scores may be useful in interpreting the HCT.