When good evidence goes bad: the weak evidence effect in judgment and decision-making.

An indispensable principle of rational thought is that positive evidence should increase belief. In this paper, we demonstrate that people routinely violate this principle when predicting an outcome from a weak cause. In Experiment 1 participants given weak positive evidence judged outcomes of public policy initiatives to be less likely than participants given no evidence, even though the evidence was separately judged to be supportive.

Asymmetries in predictive and diagnostic reasoning.

In this article, we address the apparent discrepancy between causal Bayes net theories of cognition, which posit that judgments of uncertainty are generated from causal beliefs in a way that respects the norms of probability, and evidence that probability judgments based on causal beliefs are systematically in error. One purported source of bias is the ease of reasoning forward from cause to effect (predictive reasoning) versus backward from effect to cause (diagnostic reasoning). Using causal Bayes nets, we developed a normative formulation of how predictive and diagnostic probability judgments should vary with the strength of alternative causes, causal power, and prior probability.

Two systems of reasoning: architecture and relation to emotion.

Distinguishing cognitive systems that support intuition and deliberation has proven necessary to explain how people reason,1, 2 decide,3 categorize,4 form attitudes,5 make confidence6 and moral7 judgments, and prioritize goals.8 Both behavioral and neuroimaging evidence show that the evidence supports similar distinctions in each field. Deliberative processing enlists working memory, and intuitive processing depends more directly on long-term memory retrieval.

Neglect of alternative causes in predictive but not diagnostic reasoning.

People are renowned for their failure to consider alternative hypotheses. We compare neglect of alternative causes when people make predictive versus diagnostic probability judgments. One study with medical professionals reasoning about psychopathology and two with undergraduates reasoning about goals and actions or about causal transmission yielded the same results: neglect of alternative causes when reasoning from cause to effect but not when reasoning from effect to cause.