The human bind is truly a marvel and with it humanity has managed incredible feasts in so short a history it is staggering. Even so, the mind is flawed. Psychologists have shown time and again that we can fail-constantly and predictably-at even simple and common tasks, such as tracking changes in a visual scene. As software development races forward, and the need for human software testers continues, these cognitive biases must be considered and compensated for during the software testing process. This thesis examines a number of these biases and their applicability to software testing, it proposes the integration of aspects of psychology into the software testing process, and shows experimentally that the human software tester can very easily be tricked and manipulated in simple ways.