Proceedings of the Annual Meeting of the Cognitive Science Society

The Theory of Explanatory Coherence, or TEC, (Ranney & Thagard, 1988; Thagard. 1989, 1992) and ECHO, a connectionist implementation of TEC, attempt to model human reasoning about evidence and hypotheses. The ECH O model is based on the simultaneous satisfaction of multiple constraints. This yields predicted activations ("believabilities") for propositions, which are based on the propositions' evidential status, their explanatory relationships, and their contradictory relationships. While ECH O has been demonstrated to usefully model human reasoning, it does not model processing limitations on the maintenance of coherence. WanderECHO is a variation on the ECH O model that attempts to simulate attentional and memorial limitations with a stochastic updating algorithm that is based on a traveling focus of attention. Several variants of the WanderECHO simulation were applied to Schank and Ranney's (1991) data, and were found to generally simulate subjects' mean believability ratings better than standard ECHO.