Faking Bad: The Validity of the Lees-Haley FBS

An issue that often arises when discussing the creation of psychological tests is that of malingering — participants who deliberately ‘fake bad’ in order to reap certain benefits from the outcome of their test. Clearly, this is an issue of test validity, as if subjects are able to present themselves in a selective way through the items they endorse, their test results will not be accurate. There are number of reasons participants might use this strategy, often involving deceiving insurance companies for financial gain. Another reason might be to avoid culpability in a court of law — as often seen in Hollywood movies, someone might want to deliberately appear to be insane in order to avoid a lengthy prison sentence. So how might test developers deal with this potential threat to the validity of their tests?

One method that has been developed for the Minnesota Multiphasic Personality Inventory 2 (MMPI-2) is the Lees-Haley Fake Bad Scale. True to its name, this scale purports to assess the validity of physical complaints among test-takers who are seeking compensation for physical injuries. Developed in 1991, the scale consists of 43 items to be incorporated into the MMPI-2, based on the endorsement of items by a sample of participants known to be malingering. The test appears to be a godsend for insurance companies — a sure-fire way to separate the fakers from the truly injured, and with only a few extra items on the personality inventory! Unfortunately, the picture is not as clear as it might seem.

A study in the Archives of Clinical Neuropsychology (Butcher, Arbisi, Atlis, & McNulty, 2003) investigated correlations between the Lees-Haley Fake Bad Scale (FBS) and scores on various subscales of the MMPI-2, with a sample drawn from inpatients at various hospitals, correctional facilities, and chronic pain programs. The results found the highest correlations for scores on the Hypochondriasis, Depression, and Hysteria subscales. Instead of detecting malingerers with a suitable amount of specificity, the FBS appears to be tapping into a measure of general somatic complaints. Many of the statements associated with malingerers by the FBS are those that would actually be endorsed by someone with brain damage, including items concerning attentional difficulties, anxiety, and depression. In fact, the FBS appears to be a pretty good scale for identifying people who have brain damage — which would be great if that was its intended purpose, but it’s not. The authors of the 2003 study concluded that the number of individuals judged by this scale to be malingerers is producing too many false positives, and many people who are actually suffering are being identified as fakers.

While the FBS is a tempting idea, with its promise of separating liars from truth-tellers with only 43 items, the reality is this scale is too good to be true. Incorrectly classifying people who are in a great deal of real distress as malingers has too many negative consequences to justify the use of this scale. While someone might one day devise a valid scale for identifying fakers on the MMPI-2, the Lees-Haley Fake Bad Scale is not an appropriate substitute before that day comes.

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