Psychometrically matched tasks for assessment of hemispheric asymmetries of function.

One of the best methods for studying subtle lateralizing signs of brain dysfunction is the use of psychometrically matched tasks. The current study reports the development and psychometric matching of two pairs of measures of language and visual-spatial functioning. We expanded and modified four existing neuropsychological measures in order to develop tasks with a wide range of item difficulty that could be administered to subjects with impaired attention or extreme fatigue. Using 413 subjects, a Word Finding and a Dot Localization task were matched on their distribution of item difficulty and item-scale correlations. Measures of Similarities and Line Orientation were matched similarly. The psychometric matching for both pairs of tests was cross-validated using an additional 413 subjects. The matched measures of Word Finding and Dot Localization have been used in several studies to date and have proven valuable for identifying subtle lateralized impairment that might otherwise be obscured by psychometric artifacts.