My research interests lie in the area of human judgment and decision making. More specifically, I am interested in the role of emotion and motivation in social, medical, legal, moral, and political judgments. Currently, my research is focused in two primary areas.

First, I am interested in "motivated reasoning," or how the desire to reach a particular conclusion biases the processing of information related to that conclusion. My work in this area has examined the role such biases play in how people respond to threatening medical information and my more recent work focuses on motivated biases in moral and political judgments.

Second, I have a long standing interest in a variety of psychological issues involved in end-of-life medical decision making such as how people decide that living in a particular health state would be a "fate worse than death", how decisions about life-sustaining medical treatments change over time and across changes in health status, and the biases physicians and family members show when trying to predict their patients/loved ones' wishes regarding the use of life-sustaining medical treatments. This work has implications for policy and law encouraging people to complete advance directives (i.e., "living wills").

Primary Interests:

Applied Social Psychology
Health Psychology
Judgment and Decision Making
Law and Public Policy
Motivation, Goal Setting
Person Perception
Political Psychology
Prejudice and Stereotyping
Social Cognition

Applied Social Psychology
Health Psychology
Judgment and Decision Making
Law and Public Policy
Motivation, Goal Setting

Person Perception
Political Psychology
Prejudice and Stereotyping
Social Cognition

Journal Articles:

Ditto, P. H. (2006). What would Terri want? On the psychological challenges of surrogate decision making. Death Studies, 30, 135-148.
Ditto, P. H., Danks, J. H., Smucker, W. D., Bookwala, J., Coppola, K. M., Dresser, R., Fagerlin, A., Gready, R. M., Houts, R., Lockhart, L. K., & Zyzanski, S. (2001). Advance directives as acts of communication: A randomized controlled trial. Archives of Internal Medicine, 161, 421-430.
Ditto, P. H., Druley, J. A., Moore, K. A., Danks, J. H., & Smucker, W. D. (1996). Fates worse than death: The role of valued life activities in health state evaluations. Health Psychology, 15, 332-343.
Ditto, P. H., & Hawkins, N. A. (2005). Cancer decision making near the end of life. Health Psychology, 24, S63-S70.
Ditto, P. H., Jacobson, J. A., Smucker, W. D., Danks, J. H., & Fagerlin, A. (2006). Context changes choices: A prospective study of the effects of hospitalization on life-sustaining treatment preferences. Medical Decision Making.
Ditto, P. H., & Lopez, D. F. (1992). Motivated skepticism: Use of differential decision criteria for preferred and nonpreferred conclusions. Journal of Personality and Social Psychology, 63, 568-584.
Ditto, P. H., Munro, G. D., Apanovich, A. M., Scepansky, J. A., & Lockhart, L. K. (2003). Spontaneous skepticism: The interplay of motivation and expectation in responses to favorable and unfavorable medical diagnoses. Personality and Social Psychology Bulletin, 29, 1120-1132.
Ditto, P. H., Pizarro, D. A., Epstein, E. B., Jacobson, J. A., & MacDonald, T. K. (2006). Visceral influences on risk taking behavior. Journal of Behavioral Decision Making, 19, 99-113.
Ditto, P. H., Scepansky, J. A., Munro, G. D., Apanovitch, A. M., & Lockhart, L. K. (1998). Motivated sensitivity to preference-inconsistent information. Journal of Personality and Social Psychology, 75, 53-69.
Ditto, P. H., Smucker, W. D., Danks, J. H., Jacobson, J. A., Houts, R. M., Fagerlin, A., Coppola, K. M., & Gready, R. M. (2003). The stability of older adults’ preferences for life-sustaining medical treatment. Health Psychology, 22, 605-615.
Fagerlin, A., Ditto, P. H., Danks, J. H., Houts, R., & Smucker. W. D. (2001). Projection in surrogate decisions about life-sustaining medical treatment. Health Psychology, 20, 166-175.
Munro, G. D., & Ditto, P. H. (1997). Biased assimilation, attitude polarization, and affect in the processing of stereotype-relevant scientific information. Personality and Social Psychology Bulletin, 23, 636-653.

Courses Taught:

Error and Bias in Social Judgment
Psychology and Social Behavior
Psychology Fundamentals
Social Animal: An Introduction to Social Psychology
Social Psychology

Error and Bias in Social Judgment
Psychology and Social Behavior
Psychology Fundamentals

Social Animal: An Introduction to Social Psychology
Social Psychology

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Peter H. Ditto
Department of Psychology and Social Behavior
4209 Social and Behavioral Sciences Gateway
University of California
Irvine, CA 92697-7085
United States

Phone: (949) 824-1844
Fax: (949) 824-3002