Discrepancy between predicted and obtained WAIS-R IQ scores discriminates between traumatic brain injury and insufficient effort.
This study examines how well the discrepancy between predicted and obtained Wechsler Adult Intelligence Scale--Revised (WAIS-R) scores discriminate between insufficient effort (IE) and traumatic brain injury (TBI). The 27 IE patients performed significantly more poorly on the WAIS-R than the 48 moderate-severe TBI patients. Premorbid IQs were calculated with formulae that use demographics (Barona Index) or demographics and WAIS-R performance (Best-3 and the Oklahoma Premorbid Intelligence Estimation). Predictions were similar on the Barona, but IE patients' predicted IQs were lower than TBIs for measures with a performance component. IE patients demonstrated a greater discrepancy score (i.e., predicted IQ--obtained IQ) than TBIs; variable levels of sensitivity and specificity were obtained when discriminate functions were developed on these scores. The potential advantage of using discrepancy scores versus performance-based measures to detect insufficient effort is discussed.
Demakis
G J
GJ
Department of Psychology, Elmhurst College, 190 Prospect Avenue, Elmhurst, Illinois 60126, USA. georged@elmhurst.edu
Sweet
J J
JJ
Sawyer
T P
TP
Moulthrop
M
M
Nies
K
K
Clingerman
S
S
D000328:Adult; D001930:Brain Injuries / Q000175:diagnosis* / Q000523:psychology*; D003937:Diagnosis, Differential; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007360:Intelligence; D008297:Male; D008306:Malingering / Q000175:diagnosis* / Q000523:psychology; D008875:Middle Aged; D011237:Predictive Value of Tests; D011594:Psychometrics; D012680:Sensitivity and Specificity; D014888:Wechsler Scales / Q000592:standards*