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Date of Award


Document Type


Degree Name

Doctor of Philosophy in Applied Cognitive Science and Human Factors (PhD)

College, School or Department Name

Department of Cognitive and Learning Sciences

First Advisor

Edward T. Cokely


Rocio Garcia-Retamero


The current research investigated the effect of decision aids used in educational brochures that present diagnostic testing statistics in two experiments conducted with a large general sample of United States citizens. In these samples, a decision aid increased overall understanding of diagnostic testing statistics and, in particular, understanding of the positive predictive value of the at-home human immunodeficiency virus (HIV) test. In addition, this research found that a measure of risk literacy using two validated measures of numeracy was predictive of understanding, trust in diagnostic tests and healthcare professionals, information satisfaction, and decision making. The current research is the first step in a series of studies that will investigate ways of increasing people’s understanding of diagnostic test statistics so they can effectively use the data to make decisions regarding their healthcare. In line with the Centers for Disease Control and Prevention (CDC) recommendation that individuals find out their HIV status, home testing kits have been released for general public use. The home test allows for private, affordable testing; however, misinterpreting positive test results may lead to negative outcomes (e.g., depression, divorce, and health consequences). Additionally, positive test results are more likely to be false positives for low-risk than for high-risk individuals. If every person in the United States followed the CDC’s recommendation to test their HIV status and used a home HIV test, more than 250,000 citizens would receive a false positive result. Given this large number of false positive test results, it is important to identify the factors that guide people in making good decisions following a positive test result. This research also discusses a cognitive theory that attempts to identify the critical factors that predict accurate interpretation of diagnostic test results.