Abstract: | This study used an ultimatum game to test the hypothesis that older individuals make more selfish offers when bargaining for highly attractive rewards, regardless of the impacts of others' responses on reward size. Both older and younger individuals separately participated in the experiment and made offers as allocators. The effects of four factors (age, certainty of the allocators' own reward depending on the recipient's response, the recipient's response, and type of rewards to be shared) on participants' offers and expectations of recipients' replies were observed. Older participants demanded higher shares for themselves than younger participants, even under the low certainty condition in the highly attractive reward scenario. Particularly in this scenario, older participants increased their portions immediately after receiving rejections. Moreover, they consistently expected the recipients to accept their offers regardless of the proposed distribution amount or bargaining conditions. It was implied that the high attractiveness of the rewards made it difficult for older individuals to predict the recipient's view of their proposals and thus contributed to them making selfish proposals. |