Four experiments investigated uncertainty about a premise in a deductive argument as a function of the expertise of the speaker and of the conversational context. The procedure mimicked everyday reasoning in that participants were not told that the premises were to be treated as certain. The results showed that the perceived likelihood of a conclusion was greater when the major or the minor premise was uttered by an expert rather than a novice (Experiment 1). The results also showed that uncertainty (...) about the conclusion was higher when the major premise was uttered by a novice and an alternative premise by an expert, compared to when the major premise was uttered by an expert and the alternative by a novice (Experiment 2). Similarly, the believability of a conclusion was considerably lower when the minor premise was uttered by a novice and denied by an expert, as opposed to when an expert uttered the minor premise and a novice denied it (Experiment 3). Experiment 4 showed that the nature of the uncertainty induced by a denial of the minor premise depended on whether or not the context was a conversation. These results pose difficult problems for current theories of reasoning, as current theories are based on the results of experiments in which the premises are treated as certain. Our discussion of the results emphasises the importance of pragmatics in reasoning, namely, the role of general knowledge about the world in assessing the probability of a premise uttered by an expert or a novice and the role of interpretations of the premise based on pragmatic inferences in revising these initial probabilities. (shrink)

Natural myside bias is the tendency to evaluate propositions from within one's own perspective when given no instructions or cues (such as within-participants conditions) to avoid doing so. We defined the participant's perspective as their previously existing status on four variables: their sex, whether they smoked, their alcohol consumption, and the strength of their religious beliefs. Participants then evaluated a contentious but ultimately factual proposition relevant to each of these demographic factors. Myside bias is defined between-participants as the mean difference (...) in the evaluation of the proposition between groups with differing prior status on the variable. Whether an individual difference variable (such as cognitive ability) is related to the magnitude of the myside bias is indicated by whether the individual difference variable interacts with the between-participants status variable. In two experiments involving a total of over 1400 university students ( n = 1484) and eight different comparisons, we found very little evidence that participants of higher cognitive ability displayed less natural myside bias. The degree of myside bias was also relatively independent of individual differences in thinking dispositions. We speculate that ideas from memetic theory and dual-process theory might help to explain why natural myside bias is quite dissociated from individual difference variables. (shrink)

In this study, we examine the belief bias effect in syllogistic reasoning under both standard presentation and in a condition where participants are required to respond within 10 seconds. As predicted, the requirement for rapid responding increased the amount of belief bias observed on the task and reduced the number of logically correct decisions, both effects being substantial and statistically significant. These findings were predicted by the dual-process account of reasoning, which posits that fast heuristic processes, responsible for belief bias, (...) compete with slower analytic processes that can lead to correct logical decisions. Requiring rapid responding thus differentially inhibits the operation of analytic reasoning processes, leading to the results observed. (shrink)

In this paper, I show that the question of how dual process theories of reasoning and judgement account for conflict between System 1 (heuristic) and System 2 (analytic) processes needs to be explicated and addressed in future research work. I demonstrate that a simple additive probability model that describes such conflict can be mapped on to three different cognitive models. The pre-emptive conflict resolution model assumes that a decision is made at the outset as to whether a heuristic or analytic (...) process will control the response. The parallel-competitive model assumes that each system operates in parallel to deliver a putative response, resulting sometimes in conflict that then needs to be resolved. Finally, the default-interventionist model involves the cueing of default responses by the heuristic system that may or may not be altered by subsequent intervention of the analytic system. A second, independent issue also emerges from this discussion. The superior performance of higher-ability participants on reasoning tasks may be due to the fact that they engage in more analytic reasoning ( quantity hypothesis ) or alternatively to the fact that the analytic reasoning they apply is more effective ( quality hypothesis ). (shrink)

College-student subjects made notes about the morality of early abortion, as if they were preparing for a class discussion. Analysis of the quality of their arguments suggests that a distinction can be made between arguments based on well-supported warrants and those based on warrants that are easily criticised. The subjects also evaluated notes made by other, hypothetical, students preparing for the same discussion. Most subjects evaluated the set of arguments as better when the arguments were all on one side than (...) when both sides were presented, even when the hypothetical student was on the opposite side of the issue from the evaluator. Subjects who favoured one-sidedness also tended to make one-sided arguments themselves. The results suggest that ?myside bias? is partly caused by beliefs about what makes thinking good. (shrink)