Figure and difficulty in syllogistic reasoning

The model theory of syllogistic reasoning assumes that reasoners can devise models of the premises when the middle terms are contiguous. When the arra ngement of the terms is not appropriate, they have to perform additional op erations. Our first experiment shows that the time consumed by these operat ions can be measured in the reading time of the second premise. This effect is not predicted by other theories of syllogistic reasoning. The second ex periment replicates the figural bias in a construction task. Both experimen ts yielded a reliable effect of the number of models on reading time and ac curacy. The number of models and the figure seem to be independent factors that do not interact. An analysis of the invalid conclusions produced by th e participants in Experiment 2 indicates that the invalid conclusions were frequently consistent with any of the initial models.