Healthy Skepticism Library item: 20236

Warning: This library includes all items relevant to health product marketing that we are aware of regardless of quality. Often we do not agree with all or part of the contents.

Publication type: Journal Article

McKenzie, CRM
Underweighting Alternative and Overconfidence
Organizational Behavior and Human Decision Processes 1997 Aug; 71:(2):141-160
http://psycnet.apa.org/psycinfo/1997-43858-002

Abstract:

Discusses the impact that underweighting the alternative has on overconfidence in a particular hypothesis and other related measures. Consideration of evidence for and against the focal hypothesis while underweighting or ignoring evidence for and against the alternative was emphasized. Computer simulations showed that underweighting the alternative is sufficient for producing overconfidence under quite general conditions. In addition, data from 2 previous empirical studies (C. R. M. McKenzie, 1997, and in press) were reanalyzed. In these simulated medical diagnosis studies, one group of subjects was known to take into account the alternative, and one to underweight it. The pattern of differences between the 2 groups was similar to the pattern found in the computer simulations where weighting of the alternative was manipulated. Furthermore, encouragement to take into account the alternative had no effect on the former group’s behavior, but affected the latter group in a manner predicted by the simulations. Both the simulations and reanalyses provide direct evidence of the effect of underweighting the strength of alternatives on overconfidence.