The detection of malingering (faking bad symptoms for the benefit of personal gain) has always been difficult. A recent article in The Clinical Neuropsychologist investigated faking mental retardation. Here is a description of the article:
… researchers have administered the WAIS-III intelligence test, two tests of psychiatric malingering, and three tests of cognitive malingering to 26 mentally retarded people and 26 non-retarded participants who had no more than 11 years of education.
Half the non-retarded participants were given information about mental retardation and asked to fake being retarded, with a reward of $20 if they managed to do so successfully.
Faking mental retardation wasn’t difficult. According to the WAIS-III, even using special indices designed to detect deliberate poor performance, the scores of the non-retarded fakers were indistinguishable from the genuinely mentally retarded. The same was true for the tests of psychiatric malingering.
However, the three tests of cognitive malingering were moderately successful at distinguishing the fakers from the genuinely mentally retarded (although some of the genuinely retarded were also classified as fakers, showing the tests lacked specificity).
An example of a test of cognitive malingering is the ‘Test of Memory Malingering‘. This requires participants to view 50 pictures and then say which picture in a series of pairs was among those originally viewed. Performance is known to be relatively unaffected by a broad range of neuropsychological impairments which is what makes it a useful measure of malingering.
The researchers concluded: “At present there are almost no other published data on the characteristics of individuals attempting to feign MR, making it difficult to judge how ‘realistic’ the present malingerers were.”
Graue, L.O., Berry, D.T.R., Clark, J.A., Sollman, M.J., Cardi, M., Hopkins, J. & Werline, D. (2007). Identification of feigned mental retardation using the new generation of malingering detection instruments: Preliminary findings. The Clinical Neuropsychologist, 21, 929-942.
Indeed, I was faced with this very dilemma at one point during a forensic administration, but did not find it difficult to ascertain the offender as non-MR. This could be due to the fact that she was not coached. The astute clinician, however, should be able to tell MR from non-MR using a variety of informal and formal assessment methods. An accurate history of employment and education (read: functional ability) would be a good first step, and I wonder if such factors were included in this original study