DETECTING DISSIMULATION - PROFILES OF SIMULATED MALINGERERS, TRAUMATIC BRAIN-INJURY PATIENTS, AND NORMAL CONTROLS ON A REVISED VERSION OF HISCOCK AND HISCOCKS FORCED-CHOICE MEMORY TEST

A computer-administered memory test was given to normal subjects instr ucted to feign brain damage, normal controls, and traumatic brain-inju red (TBI) patients with complaints of memory dysfunction. The test, a revised version of an instrument developed by Hiscock and Hiscock(1989 ), employed forced, two-choice recognition of previously presented fiv e-digit numbers. Two levels of item difficulty and three retention int ervals were used. Control and TBI subjects performed at near ceiling l evel on easy items and items with short retention intervals. Feigning subjects performed worse than TBI and control subjects at all levels o f item difficulty and all retention intervals. Subject groups were max imally distinguishable from one another by performance on difficult it ems and items with the longest retention interval. All TBI patients pe rformed at or above chance level. Only 15% of the feigning subjects pe rformed below chance level on any section of the test. Jack-knifed dis criminant function analysis correctly classified 83% of all subjects i nto their respective groups. Although evaluation of patient performanc e relative to chance probability is useful for indicating the presence of extremely exaggerated memory deficits, criteria derived from sampl e distributions of group scores were superior for evaluation of motiva tion in less obvious cases. The Victoria Revision may be useful for de tecting true memory deficit as well as dissimulation.