Reasoners revise their beliefs in the premises when an inference they have made is contradicted. We describe the results of an experiment that shows that the belief they revise depends on the inference they have made. They revise

One of the most debated questions in psychology and cognitive science is the nature and the functioning of the mental processes involved in deductive reasoning. However, all existing theories refer to a specific deductive domain, like syllogistic, propositional or relational reasoning. Our goal is to unify the main types of deductive reasoning into a single set of basic procedures. In particular, we bring together the microtheories developed from a mental models perspective in a single theory, for which we provide a formal foundation. We validate the theory through a computational model (UNICORE) which allows fine-grained predictions of subjects ’ performance in different reasoning domains. The performance of the model is tested against the performance of experimental subjects—as reported in the relevant literature—in the three areas of syllogistic, relational and propositional reasoning. The computational model proves to be a satisfactory artificial subject, reproducing both correct and erroneous performance of the human subjects. Moreover, we introduce a developmental trend in the program, in order to simulate the performance of subjects of different ages, ranging from children (3–6) to adolescents (8–12) to adults (>21). The simulation model performs similarly to the subjects of different ages.

In this study, we describe the influences of qualitative changes to the reasoning problem on the reasoning process. The first manipulation is the quality of the test context: A rule is learned in a certain context and contradicted in another. The belief in the rule is then measured in the learning context, the contradictory context, and a new context. The second manipulation is the quality of contradiction: The contradictory rule can neutralize or inverse the learned rule. Both qualitative changes influence the belief revision process.

This article tests human inference rationality when dealing with default rules. To study human rationality, psychologists currently use classical models of logic or probability theory as normative models for evaluating human ability to reason rationally. Our position is that this approach is convincing, but only manages to capture a specific case of inferential ability with little regard to conditions of everyday reasoning. We propose that the most general case to be considered is inference with imperfect knowledge -- in the present case restricted to uncertain knowledge -- and that a natural framework for testing the rationality of plausible reasoning is System P. This system provides rational postulates for nonmonotonic inference.

Individuals often revise their belief in conditional relations when faced with contradictory evidence. However, individuals ’ beliefs about the reliability of particular sources may influence their acceptance of such evidence. In three experiments, we examined effects of source credibility on belief revision. Participants were presented with a description of a mechanical system comprised of conditional relations with either uniform or randomly alternating components. Next, participants received a contradictory observation from a reliable, unreliable, or neutral source. When evidence came from an unreliable source, participants often failed to revise the conditional belief, regardless of the design of the system.

The dominant cognitive model that accounts for the persistence of delusional beliefs in schizophrenia postulates that patients suffer from a general deficit in belief revision. It is generally assumed that this deficit is a consequence of impaired reasoning skills. However, the possibility that such inflexibility affects the entire system of a patient’s beliefs has rarely been empirically tested. Using delusion-neutral material in a well-documented advice-taking task, the present study reports that patients with schizophrenia: 1) revise their beliefs, 2) take into account socially provided information to do so, 3) are not overconfident about their judgments, and 4) show less egocentric advice-discounting than controls. This study thus shows that delusional patients ’ difficulty in revising beliefs is more selective than had been previously assumed. The specificities of