Probability Discounting
Choose between a certain amount of money and a chance at $100 across five winning probabilities. A titration-based, educational adaptation of the probability-discounting procedure (Green & Myerson) that traces your personal discount curve.
Frequently Asked Questions
Have another question? Let us know.
How is this different from delay discounting?
Delay discounting devalues rewards by waiting time; probability discounting devalues rewards by uncertainty. Here a sure smaller amount competes with a chance at a larger one, and the uncertain reward's subjective value falls as the odds against it grow.
What does the h value mean?
For each probability p, h = (V/A − 1) / ((1−p)/p), where V is the reward ($100) and A is your indifference point. It indexes how steeply the reward's subjective value drops as the odds against winning increase: larger h means stronger devaluation of uncertain rewards (risk aversion for gains). Because a single-session estimate is noisy, the median across probabilities — and its log-based geometric version, which is less skewed — are reported together.
How is my indifference point found?
With a 1-up/1-down titration: start at a certain amount of $50; every time you choose the certain amount it goes down, and every time you choose the gamble it goes up, with the step size halving from $25 until it falls below $1. The amount where your choices switch sides brackets your indifference point for that probability.
Is this a validated test?
No. The procedure follows the logic of the probability-discounting paradigm used in behavioral decision research, but this online version is a short educational adaptation with no norms and no diagnostic value. If probability choices matter for a real decision, consult the primary literature or a qualified professional.
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About Probability Discounting
Background
Probability discounting describes how the subjective value of a reward decreases as the probability of receiving it decreases. In the standard procedure (Green & Myerson, 2004), participants choose between a fixed reward available with probability p and a smaller certain amount, and the amount adjusted until the two are subjectively equal. Indifference points typically fall below expected value and are well described by a hyperbolic function of the odds against winning.
Mechanism
Behavioral and neuroeconomic work suggests that evaluating gambles draws on valuation systems that track expected value and on regions that represent probability information. These accounts remain active research areas, and this demo does not measure any neural process.
Research context
In the research literature, probability discounting is studied as a decision-making variable — for example in group-level studies comparing people with and without gambling or substance-use histories, and in work on insurance, investing, and health choices. This page reports only the choices you made in this session; it is not a clinical measure and does not predict any individual behavior.
References
- Rachlin, H., Raineri, A., & Cross, D. (1991). Subjective probability and delay. Journal of the Experimental Analysis of Behavior, 55(2), 233-244. 10.1901/jeab.1991.55-233
- Green, L., & Myerson, J. (2004). A discounting framework for choice with delayed and probabilistic rewards. Psychological Bulletin, 130(5), 769-792. 10.1037/0033-2909.130.5.769
- Richards, J. B., Zhang, L., Mitchell, S. H., & de Wit, H. (1999). Delay or probability discounting in a model of impulsive behavior: Effect of alcohol. Journal of the Experimental Analysis of Behavior, 71(2), 121-143. 10.1901/jeab.1999.71-121
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About This Experiment
This experiment is an educational adaptation for demonstration purposes. It is not a clinical diagnostic tool. Results reflect your performance in this specific session and should not be interpreted as an assessment of your cognitive abilities.
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