Impulsivity, Impatience, and Risk Taking
Leonard Green and Joel Myerson, Washington University in St. Louis
Leonard Green received his undergraduate degree from the City College of New York and his Ph.D. from the State University of New York at Stony Brook. After completing post-doctoral research, Green ventured west of the Mississippi (although he thought he was still east of the river) where he is now professor of psychology at Washington University in St. Louis. He also serves as director of undergraduate studies for the psychology department.
Green's research concerns choice and decision making in rats, pigeons, and people, with a particular interest in models of self-control, impulsivity, choice and decision making, and basic learning processes. In addition, he is one of the developers of "behavioral economics," a transdisciplinary field that combines the experimental methodology of psychology with the theoretical constructs of economics. He has published over 150 articles and book chapters, is co-author of the book Economic Choice Theory: An Experimental Analysis of Animal Behavior (Cambridge University Press), and editor of Advances in Behavioral Economics, the third volume of which is subtitled Substance Use and Abuse. He has been editor of the Journal of the Experimental Analysis of Behavior, associate editor of the Pavlovian Journal of Biological Science, and consulting editor for Behavior and Philosophy. Green's research has been funded by the National Institutes of Health, National Institute on Aging, and the McDonnell Center for Higher Brain Function. He serves on the executive board of the Society for the Quantitative Analysis of Behavior, and was recently elected a fellow of the Association for Behavior Analysis International and the Association for Psychological Science. He is president of the Society for the Experimental Analysis of Behavior. Len also is on the board of Missouri Families for Effective Autism Treatment. His awards and honors include:
- Council of Students of Arts and Sciences Award, "In Recognition of Outstanding Teaching and University Service"
- Distinguished Faculty Award from Washington University of St. Louis
- Special Recognition for Excellence in Mentoring from the Graduate Student Senate
- ArtSci Council Faculty Award
Abstract: People discount the value of delayed or uncertain outcomes. That is, the subjective values of delayed and uncertain outcomes decrease depending on how delayed or how unlikely they are. How steeply individuals discount is thought to reflect how impulsive they are. From this perspective, steep discounting of delayed outcomes (which fails to maximize long-term welfare) and shallow discounting of probabilistic outcomes (which fails to adequately take risk into account) reflect similar decision-making processes and the same trait of impulsivity. However, several manipulations differentially affect delay and probability discounting, and correlational studies show that how steeply one discounts delayed rewards is relatively independent of how steeply one discounts probabilistic rewards. Thus, calling them both 'impulsivity' may serve only to indicate that they can both cause people real problems. To study such problems, animal models frequently are needed, and indeed, animals' discounting seems similar to human discounting, although there are differences, some more apparent than real. People reportedly discount delayed rewards on a time scale of weeks or months rather than seconds as in animals, but when choices involve real, consumable rewards, people are as impatient as animals. Interestingly, correlational analyses reveal people's discounting of real, consumable rewards on a small time scale and hypothetical money on a large time scale are uncorrelated, suggesting that even within delay discounting, there may be multiple 'impulsivities,' each of which is important for understanding a different aspect of decision-making.