Effects of reward magnitude, alcohol and cigarette use on social discounting in Japan and United States college students

Social discounting occurs when participants share more of a reward with individuals with whom they are close to, relative to those more distant individuals. Previous social discounting studies have shown consistent effects of drug use and reward magnitude on sharing. However, previous cross-cultural social discounting studies have not incorporated reward magnitude or drug use as factors that may influence discounting. The current experiment randomized 569 American and Japanese university students into either a standard ($150; ¥15,500) or large ($1,500; ¥155,000) magnitude condition where participants made choices about allocating hypothetical rewards to individuals at varying social distances. Participants also self-reported cigarette and alcohol use. There was no social discounting difference between American and Japanese participants at the standard reward magnitude. However, American participants shared more than Japanese participants at the large reward magnitude, replicating a previous study. Only Japanese participants showed a magnitude effect. Including age, gender, or cigarette and alcohol use as covariates did not change the main findings. However, similar to previous social discounting studies, cigarette use was a significant predictor for social discounting. Cross-cultural social discounting differences between American and Japanese participants were accounted for by reward magnitude.