The implications of limitations in hydrocarbon research for neuropsychological assessment.

As neuropsychologists are involved increasingly in the neuropsychological assessment of individuals reporting both acute and long-term exposure to hydrocarbons, the value of research for providing guidance also increases. Research findings inform neuropsychologists about likely neuropsychological deficits given certain intensity and duration of exposure and about neuropsychological tests most appropriate for detecting hydrocarbon-induced deficits. Although high-dose events are associated with neuropsychological deficits, methodological weaknesses in the existing research impede a consensus on the implications of low-dose exposures in humans. Three flaws inherent in research on low-dose hydrocarbon exposures and their implications for neuropsychological assessment of individuals are discussed: Selection bias in recruitment of research participants, biased recall of research participants, and between-study variation in neuropsychological tests and results. Because they undermine the reliability and validity of existing research, lack of awareness of these weaknesses may interfere with unbiased assessment of individual patients suspected of hydrocarbon-induced neuropsychological deficits. Examples from the social-cognitive psychological literature contribute to understanding how misleading research findings can lead experts to form expectancies that bias assessment of individuals.