The world is complex, and yet people are able to make some sense out of it. This paper offers an information-processing model to describe this aspect of perception and cognition. The model assumes that a person receives information which is less than perfect in terms of its completeness, its accuracy, and its reliability. The model provides a dynamic description of how a person evaluates this kind of information about a case, how he selects one of his pre-existing patterns (called schemata) with which to interpret the case, and how he uses the interpretation to modify and extend his beliefs about the case. It also describes how this process allows the person to make the internal adjustments which will serve as feedback for the interpretation of future information. A wide variety of evidence from experimental and social psychology is cited to support the decisions which went into constructing the separate parts of the schema theory, and further evidence is cited supporting the theory's system-level predictions. Since the schema theory allows for (but does not assume) the optimization of its parameters, it is also used as a framework for a normative analysis of the selection of schemata. Finally, a few illustrations from international relations and especially foreign-policy formation show that this model of how people make sense out of a complex world can be directly relevant to the study of important political processes.
