Detection of incomplete effort on the Wechsler Adult Intelligence Scale-Revised: a cross-validation

This study determined whether the Vocabulary-Digit Span difference score and discriminant function based on subtests of the Wechsler Adult Intelligence Scale-Revised (WAIS-R) developed by Mittenberg et al. (1995) could differentiate patients with moderate and severe traumatic brain injuries (n = 50) from persons with financially compensable mild head injuries who were giving incomplete effort (n = 50). Employing modified cutoff scores, the discriminant function and Vocabulary-Digit Span difference score accurately classified 90% and 79% of the cases, respectively. Persons with traumatic brain injuries may produce WAIS-R subtest patterns that can be differentiated from individuals showing incomplete effort. These WAIS-R algorithms appear useful in making that distinction.