Formal models of appraisal: Theory, specification, and computational model

Cognitive appraisal theories (CATs) explain human emotions as a result of the subjective evaluation of events that occur in the environment. Recently, arguments have been put forward that discuss the need for formal descriptions in order to further advance the field of cognitive appraisal theory. Formal descriptions can provide detailed predictions and help to integrate different CATs by providing clear identification of the differences and similarities between theories. A computational model of emotion that is based on a CAT also needs formal descriptions specifying the theory on which it is based. In this paper we propose a formal notation for the declarative semantics of the structure of appraisal. We claim that this formalism facilitates both integration of appraisal theories as well as the design and evaluation of computational models of emotion based on an appraisal theory. To support these claims we show how our formalism can be used in both ways: first we integrate two appraisal theories; second, we use this formal integrated model as basis for a computational model after identifying what declarative information is missing in the formal model. Finally, we embed the computational model in an emotional agent, and show how the formal specification helps to evaluate the computational model.