تمارض و غیرمشارکتی در ارزیابی روانشناختی و روانپزشکی: شیوع و اثرات آن در یک نمونه آلمانی از مدعیان

Effort has repeatedly been shown to have a pervasive effect on performance in psychological tests. The current study evaluates to what degree performance on various psychological tests is affected by lack of effort as compared with brain injury. Psychological and medical data from a sample of 233 patients referred from Workers' Compensation Boards or from claimants in personal injury litigation were retrospectively analyzed. Each patient underwent a battery of psychological tests and a medical examination. Measures of effort were derived from the Word Memory Test (WMT) and the Medical Symptom Validity Test (MSVT). Insuficient effort was shown by 44.6% of the patients. The frequency of patients failing the effort tests was independent of age, sex, referral source, and leading complaint. Effort accounted for up to 35% of the variance of performance in the domains of cognitive speed, memory and intelligence. After controlling for effort, there was no significant effect that could be attributed to substantial brain injury. The findings confirm that there is a general and strong effect of effort on psychological test results, which dwarfs the impact of substantial brain injury. Effort testing should become a standard procedure in psychological testing.

Psychological tests are routinely assumed to yield objective and standardized measures of an individual's mental abilities. However, it has long been recognized that test results may be completely invalidated if the patient is not cooperating. Standard psychological tests require good effort to yield valid results. The reason for this is that the reference values that are used to classify a given individual's performance as normal, suboptimal or superior are derived from normative samples composed of persons who perform to the best of their ability. In normative samples, effort is not formally assessed, but subjects participate voluntarily and are often compensated by payment. Thus, they have an interest in performing well and acting in compliance with test instructions. Moreover, they gain no advantage by showing mediocre effort. These assumptions apply neither to clinical settings nor to forensic cases, especially when compensation for some injury is at stake. Thus, in practice, test scores may fall well below published norms, not because of cognitive impairment, but due to lacking cooperation. Uncooperativeness may have many sources: mere lack of interest in taking the test, leading to careless or random responding, fatigue, general distrust of psychological tests, or malevolent intentions such as fraud. Ideally, a test for cooperativeness would allow us to distinguish between a mere lack of interest and deliberate attempts to manipulate the test.