ABSTRACT
The most common objective of testing is to determine the subject’s current status with respect to a particular domain of functioning (e.g., cognitive, emotional, physical). The test results often are used to aid in clinical decision making or to quantify change from previous levels of functioning due to a disease process or as a result of experimental manipulation. Therefore, obtaining valid and reliable test results are important for making accurate assessments about the subject’s current status and rendering inferences about the effects of a particular condition on the individual. There are many factors that can influence performance. The best way to avoid confounds is by preventing them from the start through proper preparation of the subject for testing, adhering to established standard test administration procedures, and using direct inquiry or observation of factors that can affect performance. This chapter broadly reviews factors that can affect performance, with emphasis on sleep-deprived individuals. Considerations of these factors should be an integral part of interpretation of test scores.
