ABSTRACT
Throughout this book the point is made that in psychological evaluations of various types, a determination of the validity of the data is essential. While reliability refers to the consistency of test scores, validity is the extent to which tests assess what they were designed to measure. In the situation of a neuropsychological evaluation, the validity of neuropsychological tests is compromised whenever variables other than the cognitive function and/or brain ability under investigation influence test performance. In neuropsychological assessment, the goal typically is to determine the best possible performance of the examinee’s brain-based functions. For that neuropsychological assessment to be valid, it must accurately reflect the cognitive abilities and/or brain function presumed to be assessed by the tests administered. Thus, in neuropsychological assessment, test validity is compromised when performance is anything less than the client is capable of achieving under optimal testing conditions.
