Computer Simulation of Individual Belief Systems *

In this paper we sketch an attempt at computer simulation of individual belief systems. Although rooted in a series of earlier formulations (Abelson and Rosenberg [1958], 1 Abelson [1959],Rosenberg and Abelson [1960],3 Abelson [1963]'), this complex project has not heretofore been totally outlined in print. We shall begin with several clarifying comments on the nature of our goals and the problems we have faced, thence proceeding further and further into the details of operation of our simulation. By an individual belief system we refer to an interrelated set of affect-laden cognitions concerning some aspects of the psychological world of a single individual. In simulating such a system, our intention is not only to represent its structure of interrelationships, but also some of the processes by which the system maintains itself against the intrusion of new and potentially upsetting information. Our use of the technique of computer simulation is intended to maximizethe explicitness with which we state our assumptions and the vividness with which the consequences of these assumptions are made apparent. The operation of simulated belief systems can be played out on the computer and the details scrutinized in order to refine our level of approximation to real systems. The psychology of belief systems lies athwart the ancient philosophical battleground of whether man is basically "rational" or "irrational." Without claiming to have resolved this honorable controversy, we adopt the useful compromise position current among social psychologists that man is "subjectively rational," i.e., rational within the constraints of his own experience and motivation. This position owes much to Heider's' r' analysis of "naive psychology," and can be found implicitly or explicitly in the work of many "cognitive consistency" theorists (Festinger7 Osgood and Tannenbaum"; Rosenberg and Abelson3 ). To be sure, there is still much room within this compromise position for differences in emphasis as between motivational and cognitive components of the total system. The work of Rokeach and Smith, Bruner, and White'" among others reminds us that individual belief systems areheavily determined by personality needs. Our * The work herein reported was in part supported by Grant MH-