Information integration theory (IIT) is an approach to the mathematical modeling of judgment developed by Norman Anderson. Although its original application was intended for the measurement of descriptions of personalities, it has since then been used to model many different kinds of judgments and decisions, including medical and health decisions. IIT is a metatheory or framework for studying judgments, along with an associated set of modeling methods. (See Figure 1.)

The IIT model posits four types of constructs associated with the judgmental response to a stimulus. The physical attributes of the stimulus, conventionally denoted by Φi, are the components of a stimulus that are observable by the judge. Each physical attribute is mapped to a psychological scale value, conventionally denoted by Si, through psychophysical functions. The ...