Abstract

Delay, probability and social discounting refer to the decrease in the subjective value of a reward as a function of its delay of delivery, probability or social distance, respectively. One question in the area is whether the three types of discounting share the same process or whether they are held by different processes. This question has been investigated by looking at the correlations between the three types of discounting. Moreover, it has been suggested that the method used to obtain the indifference points could modulate the discounting rates. However, the search of a common process underlying the three types of discounting should not be influenced by the method used to obtain the indifference points. Therefore, the purpose of this study was to determine whether the method used to obtain the indifference points contributes to the correlation between the three types of discounting. Forty-four college students responded tasks of delay, probability and social discounting —which used a hypothetical monetary reward— with two different methods: Binary choice and adjusting amount. We found significant correlations between binary-choice and adjusting-amount methods for the three types of discounting. Albeit, a significantly higher delay discounting rate was found with the adjusting-amount method rather than with the binary-choice method, but there were no significant differences between the probability and social discounting rates obtained with both methods. In addition to the previous results, with the binary-choice method it was found that social discounting correlated with delay and probability discounting, but the last two did not correlate between them. In contrast, with the adjusting-amount method, it was only found a correlation between delay and probability discounting. The latter result suggests that the method used to obtain the indifference points contributes to the search of a common process between the three types of discounting. Actually a common decision-making process underlying the three types of discounting could depend on the context in which the choice is made.