Propositional reasoning and working memory: the role of prior training and pragmatic content.

Working memory involvement in propositional reasoning was explored after different kinds of training. The training conditions aimed to reduce the impact of non-analytic heuristics and to enhance analytic inference processes according to mental logic theories, the mental model theory, and the theory of pragmatic reasoning schemata. Following an initial training phase, secondary task interference was investigated using concurrent spatial tapping (Experiment 1), random number generation (Experiment 2), and articulatory suppression (Experiment 3). A training condition practicing the construction and use of mental models via a truth table task increased the disruption of reasoning performance by random number generation and articulatory suppression, whereas the other training conditions did not affect susceptibility to secondary task interference. The results corroborate implications of the mental model theory of reasoning.

On belief bias in syllogistic reasoning.

A multinomial model is used to disentangle the respective contributions of reasoning processes and response bias in conclusion-acceptance data that exhibit belief bias. A model-based meta-analysis of 22 studies reveals that such data are structurally too sparse to allow discrimination of different accounts of belief bias. Four experiments are conducted to obtain richer data, allowing deeper tests through the use of the multinomial model. None of the current accounts of belief bias is consistent with the complex pattern of results. A new theory of belief bias is proposed that assumes that most reasoners construct only one mental model representing the premises as well as the conclusion or, in the case of an unbelievable conclusion, its logical negation. New predictions derived from the theory are confirmed in 4 additional studies.

Training propositional reasoning.

Two experiments compared the effects of four training conditions on propositional reasoning. A syntactic training demonstrated formal derivations, in an abstract semantic training the standard truth-table definitions of logical connectives were explained, and a domain-specific semantic training provided thematic contexts for the premises of the reasoning task. In a control training, an inductive reasoning task was practised. In line with the account by mental models, both kinds of semantic training were significantly more effective than the control and the syntactic training, whereas there were no significant differences between the control and the syntactic training, nor between the two kinds of semantic training. Experiment 2 replicated this pattern of effects using a different set of syntactic and domain-specific training conditions.