Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Multi-conditional problems can be used to corripare the mental model theory and mental rule theories of deductive reasoriing. The two theories make coiitrasting predictions about performance. The mental model theory relates the difficulty of a problem with the number of models the reasoner has to construct, whereas inentul rule theories explain this difficultyin terms of the number and complexity of the rues of inference to be applied. Experiment 1 tested the fivo theories using multiconditional problems and measured both accuracy and latency. The results supported the mental model theory, but there was a ceiling effect for accuracy and some unexpected time measurements. In experiment 2 the ceiling effect disappeared, and the mental rnodel theory was again corroborated. The paper discusses when reasoners are likely to construct mental models, the limitations of the human cognitive system and its strategic nature.

The concept of global primacy in the processing of visual information holds that the higher level elements (global features) are perceived first, before lower level elements (local features). However, this sequence of precedence has been influenced by a nurnber of variables such as colour,form, or components of the stimulus. This paper studies the effect of these variables on global precedence applied to the perception of hierarchical stimuli: geornetrical figures made up of geometrical elements. Two main results were found: first, there were two interactions between the factors "geornetrical figure" and "peripheral geornetrical elements" and between"geornetrical figure" and "central geometrical elements" both for reaction times and for the proportion of correct answers. This suggests the clse of global strategies in the recognition of visual images. Second there was an interaction between the factors "peripheral geometrical elements" and "stimulatory contrast" for reaction times, suggesting that the contrast existing between the elements of the visual images acts to delay global primacy due to the "figure-background" effect of the Gestalt grouping.

This article analyzes the leading theoretical approaches to Bayesian reasoning in the literature, and its main sources of empirical support. Many errors in probability estimates are attributed to people's inability to think in statistical tems when faced with information about a single event. Specifically, in situations where the normative model is Bayes's theorem, the well-known base rate neglect is analyzed both from rhe heuristic and biases approach, of Tversky and Kahneman, and from the frequentist hypothesis defended by Gigerenzer, Cosmides et al. The discrepancy between intuitions and formal mathenlatical reasoning is also analyzed through the studies with the three prisoners problem. Finally, we present the mental rnodel theoly of extensional probabilistic reasoning(Johnsorl-Laid et al., 1999) which explains how naive individuals can infer posterior probabilities without relying on Bayes 's theorern.