Causal conditional reasoning and strength of association: The disabling condition case

Abstract

Cummins (1995) has shown that reasoning with conditionals involving causal content is affected by the relative number of available alternative and disabling conditions. More recent evidence (Quinn & Markovits, 1998) indicates that, beside the number of stored conditions, the relative strength of association of the alternative conditions with the consequent term is another important factor that affects causal conditional reasoning. In this study we examined the effect of the strength of association for the disabling conditions. We identified causal conditionals for which there exists only one highly associated disabler. With these conditionals we constructed conditional inference problems in which the minor premise was expanded with the negation of a strongly or weakly associated disabler. Results of two experiments indicate that strength of association of stored disabling conditions is affecting reasoning performance: Acceptance of Modus Ponens and Modus Tollens increased when there was no strongly associated disabler available.