Delay-discounting probabilistic rewards: Rates decrease as amounts increase.

Area of Science:

• Behavioral Economics
• Decision Science
• Psychology

Background:

• Delay discounting describes the tendency to devalue rewards as they are delayed.
• Previous research often used hypothetical rewards, potentially limiting real-world applicability.
• Understanding factors influencing delay discounting is crucial for economic and behavioral modeling.

Purpose of the Study:

• To investigate the relationship between delay-discounting rate and monetary reward size.
• To examine whether reward size influences the rate at which individuals discount future rewards.
• To identify potential gender differences in delay-discounting behavior with real rewards.

Main Methods:

• 621 subjects made choices between immediate and larger, delayed monetary rewards.
• Rewards were actual, with participants entered into a lottery to receive their chosen reward.
• A novel parameter estimation procedure quantified discounting rates for small, medium, and large reward sizes.

Main Results:

• The delay-discounting rate was found to be a decreasing function of the delayed reward size (p < .0001).
• This relationship held true regardless of whether hyperbolic or exponential discounting models were applied.
• A significant gender difference emerged, with males exhibiting higher average discounting rates than females (p = .005).

Conclusions:

• Monetary reward size significantly influences delay-discounting, with larger rewards being discounted less steeply.
• The findings challenge the assumption of independence between discounting rate and reward magnitude.
• Gender is a significant factor in delay discounting, with males showing a greater preference for immediate rewards.