Proceedings of the Annual Meeting of the Cognitive Science Society

In the present paper we deal with several violations of normative rules in probability judgement: the inverse-base-rate and the conjunction fallacy, among others. To reproduce these failures, a sample of subjects was asked to judge the probability of several items according to what they had learnt in a previous learning task on medical diagnosis. Attempts are made to explain the results within the connectionist framework. W e based our approach in a simple network, designed by Gluck and Bower (1988), which updates its weights using the L MS rule.