Biomedical subjects

Barbara A Spellman

Publications and source records attributed to Barbara A Spellman.

3 recordsLinked to original sources

PubMed2005

Discounting and conditionalization.

When people are asked to judge the strengths of two potential causes of an effect, they often demonstrate discounting--devaluing the strength of a target cause when it is judged in the presence of a strong (relative to a weak) alternative cause. Devaluing the target cause sometimes results from conditionalization--holding alternative causes constant while evaluating the target cause. Yet discounting not attributable to conditionalization also occurs. We sought to dissociate conditionalization and discounting (beyond that accounted for by conditionalization) by having subjects perform either a spatial or a verbal working memory task while learning a causal relation. Conditionalization was disrupted by the verbal task but not the spatial task; however, discounting was disrupted by the spatial task but not the verbal task. Conditionalization and discounting are therefore cognitively dissociable processes in human causal inference.

Association Learning↗

PubMed2005

Nonnormative discounting: there is more to cue interaction effects than controlling for alternative causes.

Several experiments on human causal reasoning have demonstrated "discounting"--that the presence of a strong alternative cause may decrease the perceived efficacy of a moderate target cause. Some, but not all, of these effects have been shown to be attributable to subjects' use of conditional rather than unconditional contingencies (i.e., subjects control for alternative causes). We review experimental results that do not conform to the conditionalizing contingency account of causal judgment. In four experiments, we demonstrate that there is "nonnormative discounting" above what is accounted for by conditionalization, that discounting may depend on the nature of the question put to the subjects, and that discounting can be affected by motivation. We conclude that because nonnormative discounting occurs for summary presentations as well as trial-by-trial presentations of information and because nonnormative discounting depends on motivation, it is not a necessary result of cue competition during the contingency learning process.

Adult↗

PubMed2003

The use of category and similarity information in limiting hypotheses.

Previous studies have shown that adults usually select diverse evidence for generalizing hypotheses. We investigated what kind of evidence people select in another type of inductive task: limiting hypotheses. Whereas generalizing entails extending a property to all members of a category, limiting entails restricting a property to only members of a category. For example, if you know that elephants have property X, which would you test to determine whether only mammals have property X: a hippopotamus, a fox, a crocodile, or a snake? Both category and similarity information are relevant to selecting evidence to generalize or limit a hypothesis. Although 70% of participants chose diverse evidence for generalizing a hypothesis, only 25% chose the analogous evidence for limiting one. However, the percentage of participants choosing the appropriate evidence for limiting increased to 70% when they were given a rule for category membership. These results suggest that hypothesis-limiting behavior is affected by how participants establish category boundaries.

Cognition↗