Clinical Utility of Incomplete Effort WAIS-R Formulas

Abstract

Arithmetic algorithms have been used to differentiate traumatically brain-injured individuals from simulators and patients with diminished motivation. The sensitivity of three algorithms used to detect incomplete effort was evaluated in traumatically brain-injured patients. The patients had been evaluated two or four times over the course of one year following their injury, allowing for assessment of practice effect on the specificity of the formulas. A method derived by discriminant function analysis (Mittenberg et al., 1995) produced the strongest results, both in terms of overall specificity (ranging from 76% to 93%) and its independence from level of cognitive performance. No practice effect was observed. The use of a method based on a discriminant function appears to minimize false positives in individuals with traumatic brain injuries.

Key Words:

• Psychological assessment
• malingering
• traumatic brain injury