In this paper we investigate the locus of believability effects in syllogistic reasoning. We identify three points in the reasoning process at which such effects could occur: the initial interpretation of premises, the examination of alternative representations of them (in all of which any valid conclusion must be true), and the “filtering” of putative conclusions. The effect of beliefs at the first of these loci is well established. In this paper we report three experiments that examine whether beliefs have an (...) effect at the other two loci. In experiments 1 and 2 subjects drew their own conclusions from syllogisms that suggested believable or unbelievable ones. In the third experiment they evaluated conclusions that were presented to them. The data show that beliefs both affect the examination of alternative models and act as a filter on putative conclusions. We conclude by showing how some types of problem and some problem contents make the existence of alternative models more obvious than others. (shrink)

K. C. Klauer, J. Musch, and B. Naumer (2000) presented a general multinomial model of belief bias effects in syllogistic reasoning. They claimed to map a particular mental model account of belief bias (J. V. Oakhill, P. N. Johnson-Laird, & A. Garnham, 1989) onto this model and to show empirically that it is incorrect. The authors argue that this mental model account does not map onto the multinomial model and that it can account for the data presented by Klauer et (...) al. (Experiments 1–4). The authors further argue that additional data Klauer et al. presented in support of a new model of their own (Experiments 5– 8) are explained by this mental model account. The mental model account is, therefore, refuted neither by Klauer et al.’s theoretical analysis nor by any of the results they presented. Furthermore, the account can accommodate more recent findings on belief bias in a more satisfactory way than can alternative models that have been proposed. (shrink)