Cortisol levels and time-discounting of monetary gain in humans

This study was conducted to examine the relationship between cortisol levels and preference to a small immediate over a larger delayed monetary reward. The degree of preference to a small immediate reward (a time-discounting rate) was investigated with an economic decision-making task in which each subject made an inter-temporal choice between (a) 10 000 yen available immediately and (b) an equal or larger amount of money after a delay of one year. The time-discounting rate was defined as [the required minimal amount of the delayed monetary gain for (b) to be preferred]-10 000/10 000. Low cortisol levels were shown to associate with a large time-discounting rate, indicating that subjects with low cortisol levels may be impulsive in inter-temporal choice.