The theory of mental models postulates that conditionals of the sort, if A then C, have a “core” meaning referring to three possibilities: A and C, not-A and C, and not-A and not-C. The meaning of a conditional's clauses and general knowledge can modulate this meaning, blocking certain possibilities or adding relations between the clauses. Four experiments investigated such interpretations in factual and deontic domains. In Experiment 1, the participants constructed instances of what was possible and what was impossible according to various conditionals. The results corroborated the general predictions of the model theory and also the occurrence of modulation. The resulting interpretations governed the conclusions that participants accepted in Experiment 2, which also yielded the predicted effects of a time limit on responding. In Experiment 3, the participants drew the predicted conclusions for themselves. In Experiment 4, modulation led to predicted temporal relations between A and C. We relate these results to current theories of conditionals.

The theory of mental models postulates that meaning and knowledge can modulate the interpretation of conditionals. The theory's computer implementation implied that certain conditionals should be true or false without the need for evidence. Three experiments corroborated this prediction. In Experiment 1, nearly 500 participants evaluated 24 conditionals as true or false, and they justified their judgments by completing sentences of the form, It is impossible that A and ___ appropriately. In Experiment 2, participants evaluated 16 conditionals and provided their own justifications, which tended to be explanations rather than logical justifications. In Experiment 3, the participants also evaluated as possible or impossible each of the four cases in the partitions of 16 conditionals: A and C, A and not-C, not-A and C, not-A and not-C. These evaluations corroborated the model theory. We consider the implications of these results for theories of reasoning based on logic, probabilistic logic, and suppositions.

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The purpose of the studies reported in this paper was to evaluate the function of counterfactual thinking (CT) in depression. In Experiment 1, depressed and non-depressed participants were asked to imagine themselves as the protagonist of a hypothetical situation, and to think counterfactually about three different scenarios. The results showed that there was a similar CT style (in terms of direction, structure and focus of mutation) for the depressed and the nondepressed groups. It was also found that the perceived preparation for a future similar situation increased after CT and, contrary to our hypotheses, this effect was observed in both groups. In Experiment 2, a real-life situation was used (a course examination) in which participants experienced a negative outcome (a poor score on the test). Again, it was observed that depressed and non-depressed participants showed the same CT style, but non-depressed participants were more likely to use CT spontaneously. In addition, the second study showed further differences between the two groups: depressed participants not only showed a lack of cognitive benefi ts from thinking counterfactually (i.e., after CT they do not feel more prepared for future similar events, nor able to avoid a similar bad outcome, in contrast to the non-depressed participants), but also show a lack of behavioural changes (both intentions to change and actual changes over the subsequent week). In conclusion, these results provide evidence about the function of CT both in depressed and in non-depressed thinking, and highlight both the similarities and differences for these two groups.

a b s t r a c tThe mental model theory postulates that the meanings of assertions, and knowledge about their context can modulate the logical meaning of sentential connectives, such as ''if'' and ''or''. One known effect of modulation is to block the representation of possibilities to which a proposition refers. But, modulation should also add relational information, such as temporal order, to models of possibilities. Three experiments tested this prediction. Experiment 1 showed that individuals spontaneously matched the tense of their conclusions (in Portuguese) to embody implied, but unexpressed, temporal relations in conditional premises. Experiment 2 demonstrated the same phenomenon in inferences from disjunctions. Experiment 3 showed that the number of such implicit relations in inferences from conditionals affects both accuracy and the speed of reasoning. These results support the modulation hypothesis.