This study examined the effects of emotion on the long-term acquisition of a procedural skill over a five-day period. Two tasks were employed: a word association task (WAT) and a visual discrimination task (VDT). Over the initial four days of the study participants went through a mood induction procedure (MIP) then subsequently completed both tasks. Both tasks showed a reduction in reaction time consistent with the power law of learning. No significant change in reaction time between day four and day five (one week later) was noted suggesting the change in reaction time was robust. These data further suggest that emotion modifies the rate at which the VDT is acquired.

The role of probabilistic reasoning in moral decision making has seen relatively little research, despite having potentially profound consequences for our models of moral cognition. To rectify this, two experiments were undertaken in which participants were presented with moral dilemmas with additional information designed to anchor judgements about how likely the dilemma’s outcomes were. It was found that these anchoring values significantly altered how permissible the dilemmas were found when they were presented both explicitly and implicitly. This was the case even for dilemmas typically seen as eliciting deontological judgements. Implications of this finding for cognitive models of moral decision making are discussed.

The inference of or-introduction, p, therefore p or q, is fundamental in classical logic and probability theory. Yet traditional research in the psychology of reasoning found that people did not endorse this inference as highly as other one- premise valid inferences. A radical response to this finding is to claim that or-introduction is in fact invalid. This response is found in the recent revision of mental model theory (MMT). We argue that this revision of the theory leads to a number of logical problems and counterintuitive consequences for valid inferences, and present an experiment extending recent studies showing that people readily accept or-introduction under probabilistic instructions. We argue for a pragmatic explanation of why the inference is sometimes considered odd. The inference is not odd when people reason from their degrees of belief.

In a major theoretical paper, Gigerenzer and Goldstein (1996a) argue that classical rationality should be rejected as a norm of good reasoning, and that this thesis undermines both rational models of human thought and the alternative heuristics-and-biases program. They illustrate their argument by proposing that a specific cognitive estimation problem may be carried out by the "Take the Best" algorithm, which is "fast and frugal," but not rational. We argue: (1) that "fast and frugal" cognitive algorithms may approximate rational norms, and only in this way can their success be explained; and (2) that new computer simulations, and considerations of speed and generality, suggest that other algorithms are at least as psychologically plausible as Take the Best.

The centering inference - p & q, therefore if p then q - is important in reasoning research because it is logically valid for some accounts of conditionals (e. g. the material and the probability conditionals), but not for others (e. g. the inferential conditional, according to which a conditional is true if and only if there is an inferential connection between p and q). We tested participants' acceptance of centering compared to valid and invalid inferences not containing conditionals, varying the presence of an inferential connection and of a common topic of discourse between p and q. Participants' acceptance of centering was more similar to valid inferences than to invalid inferences, and there was no reliable effect of a connection between p and q. Acceptance rates were higher when there was a common topic of discourse, independently of the type of inference. The findings support the probability conditional account.

In this paper, we explore the Principle of Charity. This is an epistemic assumption that people should not judge people to be irrational unless they have an empirically justified account of what they are doing when they violate normative standards. Through two studies, we provide evidence in support of the principle. Study 1 suggests people believe others will arrive at the same conclusions they would themselves given the same information. Study 2 suggests that people assume others may differ in the subjective degrees of belief but that they broadly use the same (Bayesian) updating mechanism when evaluating information about other people. We believe this paper provides the first empirical test of this principle.