Is Mary Y subject to suicidal (or homicidal) impulses she may not be able to overcome if left to her own devices?
Is Joe Z gifted (or suffering from severe mental retardation)?
Is Tom P honest and trustworthy (or motivated for sales work)?
Is Jane Q capable of doing college-level work (or flying an airplane)?
Should John X receive the treatment (medication, psychotherapy, etc.) that is recommended for the disorder in question?
Should Mary Y continue to be hospitalized (or incarcerated )?
Should Joe Z be admitted to a special education program for gifted (or mentally retarded) individuals?
Should Tom P be hired for work as a cashier (or salesperson)?
Should Jane Q be admitted into college (or granted an airplane pilot's license)?
Will John X profit (a little, a lot, or not at all) from the recommended treatment?
Will Mary Y attempt to kill herself (or someone else) if left at liberty?
Will Joe Z benefit (a little, a lot, or not at all) from a special education program?
Will Tom P be a conscientious cashier (or a successful salesperson), or will he steal money (or make few sales)?
Will Jane Q be able to finish college with a grade-point average high enough to graduate (or be able to fly a plane without causing accidents)?
Form B. See Chapter 7 for further explanation of the terminology used to designate incorrect decisions (e.g., false positive and false negative decisions).
Additional validation evidence for the WIST includes studies done in Mexico and Spain with Spanish translations of the instrument. These studies show some support for the WIST's ability to detect the thought impairment associated with schizophrenia, albeit with different rates of efficiency and different cutoff scores.
The hit rate obtained when the WIST cutoff scores are used to discriminate S from NS subjects is fairly typical for tests of this kind. Because of the relatively high error rates that the WIST cutoff scores can yield, they should never be used as the sole vehicle for establishing a diagnosis of schizophrenia, any more than any other single indicator should. However, depending on the setting and context of testing, the WIST may prove useful as part of a screening battery or as one index of change in the symptomatology of patients diagnosed with schizophrenia.
• Because of the less-than-perfect nature of all diagnostic indicators, psychologists engaged in clinical assessment—as well as diagnosticians in other fields—should never rely on a single indicator
• Psychological test results, as well as medical test results and those in many other fields, are not expected to achieve 100% accuracy.
Although the discriminations made with the use of WIST cutoff scores are far from perfect, they may still be useful in investigating the possibility that a person suffers from thought impairment. For a review of the WIST, see Flanagan (1992).
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