School psychologists' diagnoses of learning disabilities: A study of illusory correlation

We examined whether school psychologists based diagnoses of learning disabilities on irrelevant data. Nationally certified school psychologists received case study material containing both relevant and irrelevant information for diagnosing a learning disability. The psychologists indicated (a) the probability that the client was learning-disabled, (b) their confidence in the diagnosis, and (c) their decision-making strategy. They tended to base diagnostic decisions on false beliefs, which we discuss in respect to prior research on illusory correlation.