Industrial/Organizational Psychology (or I/O Psychology) is the study of the behavior of people in the workplace. It is also known as occupational psychology (the commonest name in the United Kingdom and work psychology (the direct translation of the standard term in German, Arbeitpsychologie).
I/O psychologists use psychological tests and assessments to measure the knowledge, skills, abilities, and other characteristics (KSAOs) of people for a variety of employment-related purposes, such as selection for hiring or promotion, training and development, or measuring employee satisfaction. Historically, the job analysis has been the traditional means by which the essential KSAOs associated with any particular position are identified.
Related information can be found at the Web site of the Society for Industrial and Organizational Psychology.