title: Anomalous Evidence, Confidence Change, and Theory Change.
abstract: A novel experimental paradigm that measured theory change and confidence in participants' theories was used in three experiments to test the effects of anomalous evidence. Experiment 1 varied the amount of anomalous evidence to see if "dose size" made incremental changes in confidence toward theory change. Experiment 2 varied whether anomalous evidence was convergent (of multiple types) or replicating (similar finding repeated). Experiment 3 varied whether participants were provided with an alternative theory that explained the anomalous evidence. All experiments showed that participants' confidence changes were commensurate with the amount of anomalous evidence presented, and that larger decreases in confidence predicted theory changes. Convergent evidence and the presentation of an alternative theory led to larger confidence change. Convergent evidence also caused more theory changes. Even when people do not change theories, factors pertinent to the evidence and alternative theories decrease their confidence in their current theory and move them incrementally closer to theory change.
authors.affiliation: Department of Medicine, The University of Chicago.
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Hemmerich
authors.affiliation: Department of Medicine, The University of Chicago.
authors.forename: Kellie
authors.initials: K
authors.lastname: Van Voorhis
authors.affiliation: Department of Psychology, The University of Illinois at Chicago.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Wiley
mesh_terms: D006801:Humans; D007600:Judgment; D008606:Mental Processes
keywords: Anomalous evidence; Conceptual change; Confidence change; Theory change; Theory confidence