Relative use of necessity and sufficiency information in causal judgments about natural categories.

Participants in 4 studies placed less emphasis on necessity information (instances when the event occurred but the target factor was absent) than sufficiency information (instances when the target factor was present but the event did not occur) when the target factor corresponded to a natural kind category (e.g., race or species) in comparison with an artificial category (e.g., preferences or facial features) or an artifactual category (e.g., product type). Results were not due to differences in familiarity, prior causal beliefs, or ease of imagining the class of instances, but instead derived from less willingness to search for alternative explanations when the target explanation was based on a natural kind category in comparison with artificial or artifactual categories.