‘Does pure water boil, when it’s heated to 100°C?’: The Associative Strength of Disabling Conditions in Conditional Reasoning

Reasoning with conditionals involving causal content is known to be affected by retrieval of alternative and disabling conditions. Recent evidence indicates that besides the number of stored conditions, the relative strength of association of the alternative conditions with the consequent term is another important factor that affects the retrieval process. 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 indicate that strength of association of the disabling conditions is affecting reasoning performance: Acceptance of Modus Tollens increased when there was no strongly associated disabler available.