Early and late processes in syllogistic reasoning: evidence from eye-movements

An eye-movement monitoring experiment was carried out to examine the effects of the difficulty of the problem (simple versus complex problems) and the type of figure (figure 1 or figure 4) on the time course of processing categorical syllogisms. The results showed that the course of influence for these two factors is different. We found early processing effects for the figure but not for the difficulty of the syllogism and later processing effects for both the figure and the difficulty. These results lend support to the Model Theory (Johnson-Laird, P. N., Byrne, R. M. J. (1991). Deduction. Hillsdale, New Jersey: LEA.) as opposed to other theories of reasoning (Chater, N., Oaksford, M. (1999). The probability heuristics model of syllogistic reasoning. Cognitive Psychology, 38, 191-258; Rips, L. J. (1994). The psychology of proof. Cambridge, MA: MIT Press; Rips, L. J. (1994). The psychology of proof. Cambridge, MA: MIT Press).     

Priming effect in affirmative complex conditional connectives

We report the results of an experiment that examined the mental representations underlying the comprehension of complex conditional connectives (such as “A, on condition that B”) and the conditional if (such as “A, if B”). The mental representations during the comprehension stage were analysed using a “priming methodology”. The experiment showed that participants read the possibility “A and not-B” faster when it was primed by “A, if B” than when it was primed by “A, on condition that B”. The finding suggests that people understand the sentence “A, on condition that B” as biconditional; other possibilities (“A and B”, “not-A and B”, “not-A and not-B”) were primed equally by both connectives. We discuss the implications of this for current theories of reasoning.