[an error occurred while processing this directive]


by Bryan Gibson, Ph.D., David M. Sanbonmatsu, Ph.D.

and Steven S. Posavac, Ph.D.

Gambling has always been a big business. As more states adopt lotteries, permit casino gambling, and as Internet gambling or "gaming" websites proliferate, many people, including young college and university students betting on football and other games, are finding that compulsive or problem gambling is a big issue. But if gambling is, overall, a losing proposition for the gambler, why do so many people do it?

Over the years, psychological researchers have identified several types or erroneous thinking contribute to problem gambling. These include:

  • biased evaluations of past gambling results (explaining away losses and viewing wins as evidence of gambling ability),
  • the illusion of control (overestimating the influence one wields over outcomes and the probability of personal success) and
  • the "gambler's fallacy" (the mistaken belief that over time, chance-determined outcomes will even out).

Researchers from Central Michigan University and the University of Utah have added add another cognitive process to that list:

  • considering only one possible outcome when making decisions (or what they call "selective hypothesis testing").

The researchers conducted a series of three experiments. The conditions for each experiment were:

  1. participants were asked to estimate the probability that a specific National Basketball Association team (one of four) would win the NBA championship and explain how;
  2. participants were also asked to estimate the probability that a specific NBA team beat the point spread in an earlier game;
  3. participants were asked to estimate the probability that an NCAA basketball team (one of four) had won a computer-simulated playoff.
In each experiment, participants were invited to place bets on the team they thought would win, had beaten the point spread or had won.

In each experiment,  when participants focused (as instructed) only on a single team (as opposed to estimating the probability of winning for all four teams), they consistently overestimated the probability of that team winning. These participants were also more likely to place bets and larger bets than those who were not focused on a single team.

This overestimation of probability, the authors say, "could influence gambling decisions in any domain in which the potential gambler may focus on one possible outcome to the exclusion of others. Thus the blackjack player may be particularly interested in the likelihood of receiving a 10 after her or his first two cards sum to 11, the poker player may be particularly interested in the probability of making a straight on her or his next card, and the sports gambler may be particularly interested in the likelihood that the home team may win the league championship."

Interestingly, when other participants were asked to estimate the probability of each of four teams winning a computer-simulated championship, they were less likely to gamble than those who had focused on only one team. In applying the meaning of their research to other gamblers in similar situations, these researchers concluded that, "By encouraging potential gamblers to consider a wide number of potential outcomes, the appeal of any specific outcome is lessened and the likelihood that a bet will be placed is reduced."

Not only might this strategy be useful in the treatment of problem gamblers, the authors suggest it might be useful in preventing gambling problems from developing at all. The researchers in this study noted that training in abstract reasoning skills in high schools schools or college courses "could include a specific component that addresses the necessity of considering numerous potential outcomes when attempting to predict future events. This research suggests that such training could be relatively general in nature and still be readily applied by students to gambling and other risky choice situations."

Reference: "The Effects of Selective Hypothesis Testing on Gambling," by Bryan Gibson, Ph.D., and David M. Sanbonmatsu, Ph.D., and Steven S. Posavac, Ph.D. in the Journal of Experimental Psychology:Applied, Vol. 3 No. 2.


Revised 8/26/08 by Marlene M. Maheu, Ph.D.

The American Psychological Association (APA), in Washington, DC, is the largest scientific and professional organization representing psychology in the United States and is the world's largest association of psychologists. APA's membership includes more than 159,000 researchers, educators, clinicians, consultants and students. Through its divisions in 50 subfields of psychology and affiliations with 58 state, territorial and Canadian provincial associations, APA works to advance psychology as a science, as a profession and as a means of promoting human welfare.


Please help support our SelfhelpMagazine mission
so that we may continue serving you.
Choose your
support amount here: