Attitude Polarization

23 Pages Posted: 6 Aug 2009

See all articles by Alexander Zimper

Alexander Zimper

University of Pretoria; Kiel Institute for the World Economy

Alexander Ludwig

Max Planck Society for the Advancement of the Sciences - Munich Center for the Economics of Aging (MEA); Goethe University Frankfurt

Date Written: November 7, 2007

Abstract

Psychological evidence suggests that people's learning behavior is often prone to a 'myside bias' or 'irrational belief persistence' in contrast to learning behavior exclusively based on objective data. In the context of Bayesian learning such a bias may result in diverging posterior beliefs and attitude polarization even if agents receive identical information. Such patterns cannot be explained by the standard model of rational Bayesian learning that implies convergent beliefs. As our key contribution, we therefore develop formal models of Bayesian learning with psychological bias as alternatives to rational Bayesian learning. We derive conditions under which beliefs may diverge in the learning process and thus conform with the psychological evidence. Key to our approach is the assumption of ambiguous beliefs that are formalized as non-additive probability measures arising in Choquet expected utility theory. As a speciffc feature of our approach, our models of Bayesian learning with psychological bias reduce to rational Bayesian learning in the absence of ambiguity.

Keywords: Non-additive Probability Measures, Choquet Expected Utility Theory, Bayesian Learning, Bounded Rationality

JEL Classification: C79, D83

Suggested Citation

Zimper, Alexander and Ludwig, Alexander, Attitude Polarization (November 7, 2007). MEA Discussion Paper No. 155-07, Available at SSRN: https://ssrn.com/abstract=1444896 or http://dx.doi.org/10.2139/ssrn.1444896

Alexander Zimper

University of Pretoria ( email )

South Africa

Kiel Institute for the World Economy ( email )

P.O. Box 4309
Kiel, Schleswig-Hosltein D-24100
Germany

Alexander Ludwig (Contact Author)

Max Planck Society for the Advancement of the Sciences - Munich Center for the Economics of Aging (MEA) ( email )

Amalienstrasse 33
Munich, 80799
Germany

Goethe University Frankfurt ( email )

Grüneburgplatz 1
Frankfurt am Main, 60323
Germany