A new performance-curve method for the detection of simulated cognitive impairment

• Published in: British journal of clinical psychology Vol. 37; no. 3; pp. 327 - 339
• Main Authors: Wogar, Mary A., van den Broek, M. D., Bradshaw, C. M., Szabadi, E.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.09.1998; British Psychological Society
• Subjects: Adolescent; Adult; Biological and medical sciences; Brain Injuries - complications; Clinical psychology; Cognition; Cognition Disorders - diagnosis; Cognition Disorders - etiology; Cognitive dissonance; Cognitive impairment; Detection; Female; Humans; Individual performance; Injuries; Male; Malingering - diagnosis; Measures; Medical sciences; Psychology. Psychoanalysis. Psychiatry; Psychometrics. Diagnostic aid systems; Psychopathology. Psychiatry; Quantitative analysis; Simulation; Techniques and methods; Intellectual deterioration; Human; Simulation; Reaction time; Diagnosis; Method; Quantitative analysis
• ISSN: 0144-6657; 2044-8260
• DOI: 10.1111/j.2044-8260.1998.tb01389.x

Objectives. To evaluate a new performance‐curve method for detecting simulated cognitive impairment. Design. The method was based on quantitative analysis of choice reaction times in a series of eight matching‐to‐sample tasks of graded complexity, in which participants were required to identify which of two comparison stimuli was identical to a simultaneously presented sample stimulus. The stimuli consisted of arrays of letters, the number of letters ranging from 1 to 10 in the eight tasks. Methods. Mean reaction times of a standardization group of 20 healthy young adults were used to construct regression equations to describe the behaviour of three test groups: 20 healthy individuals instructed to perform to the best of their ability (non‐simulators), 20 healthy individuals instructed to simulate cognitive impairment incurred as a result of a head injury (simulators), and 25 patients with a history of closed head injury (patients). Results. There was a linear relationship between individual participants' latencies and the mean latencies of the standardization sample; the patient group showed steeper slopes, and the simulators higher intercepts, than the non‐simulator group. A univariate measure of performance, based on the proportionate increase in latency corresponding to a standard increase in the standardization group's latency was able to identify 14/20 simulators while misclassifying 2/20 non‐simulators and 2/25 patients. Other measures, including the number of errors made in the choice reaction time task and in recognition memory tasks, and a performance‐curve measure based on Raven's Standard Progressive Matrices, were less successful in identifying simulators. Conclusions. This new performance‐curve method may prove to be a useful addition to tests currently used to diagnose simulated cognitive impairment in clinical and medicolegal settings.