Abstract: Prosocial behavior refers to voluntary actions intended to benefit others or society. Although substantial research has examined the economic and moral costs associated with prosocial behavior, the impact of effort cost has received relatively little scholarly attention. Effort cost encompasses the cognitive and motivational resources that an individual allocates toward attainment of a goal, typically characterized as burdensome and aversive. The manifestation of prosocial behavior frequently depends on an individual's willingness to invest effort for the benefit of others, encompassing both the pursuit of rewards and the mitigation of potential losses. The effort-cost-reward model posits that both social and non-social motivations play a significant role in shaping an individual's decision to invest effort in a task. Non-social motivations include elements such as rewards, punishments, risks, and perceived efficacy. Meanwhile, social motivations, which encompass the intended beneficiaries of the decision and social cues, significantly affect the decision-making process. This study investigates the impact of effort cost on prosocial decision-making behaviors and the related neural activity in contexts involving gains (e.g., helping others in achieving positive outcomes) and losses (e.g., helping others avoid negative outcomes). This study used event-related potentials (ERPs) to investigate the influence of gain-loss contexts and effort costs on prosocial decision making. It includes a comparative analysis of the decision-making processes when individuals make decision on behalf of themselves versus others.
The study utilizes a 2 (context: gain, loss) × 2 (decision beneficiaries: self, others) within-subjects experimental design with 40 participants (M_age = 19.63 years, SD = 2.1 years). Participants were required to engage in two different conditions: making decisions for themselves and making decisions on behalf of others. In the decision-making phase, participants were presented with two lottery options. One option required high effort, characterized by a greater number of key presses, and offered either a higher probability of monetary gain or a lower probability of monetary loss. The other option required low effort, was reflected by fewer key presses, and was associated with a lower probability of gain or a higher probability of loss. In the subsequent effort phase, participants were required to press keys a specified number of times to unlock a virtual lock, with successful unlocking signifying that the selected lottery outcome had been secured. In the feedback phase, participants received information about the actual outcomes of the chosen lottery, indicating whether they had won or lost.
The behavioral results revealed that participants were more likely to exert high effort when the benefits were personally advantageous. In decision-making scenarios on behalf of others, participants showed a higher willingness to invest significant effort in gain contexts rather than loss contexts. Furthermore, under high effort cost conditions, participants displayed significantly slower response times. The ERP results indicated that high effort costs were associated with significantly larger effort-P3 amplitudes compared to low effort costs. In gain contexts, RewP amplitudes were significantly larger than in loss contexts. When participants made decisions autonomously, feedback-P3 amplitudes were significantly higher under low effort cost conditions compared to high effort cost conditions. Moreover, in loss contexts, low effort costs elicited larger feedback-P3 amplitudes than high effort costs.
This research provides novel insights into the mechanisms by which gain-loss contexts and effort costs jointly influence behavior and neural responses in prosocial decision making, applicable to both self-directed and other-directed actions. The results advance our comprehension of the effort cost-reward model by incorporating both social and non-social motivational elements. The findings of this study bear significant implications for the development of effective social policies and interventions aimed at promoting prosocial behavior. By elucidating the interaction between effort, context, and social motivations, this research highlights the complexity of human decision making and offers a nuanced understanding of how individuals navigate the balance between personal and social considerations in prosocial actions.

Key words: prosocial decision-making, effort cost, gain-loss context, event-related potentials

摘要： 采用事件相关电位技术探讨得失情境和努力成本对亲社会决策的影响,并比较个体在为自己和为他人决策时的差异。行为结果表明,个体更愿为自身利益付出高努力;为他人决策时,人们在收益情境下更倾向于付出高努力,且高努力成本导致努力行为的反应速度减慢。神经层面上,高努力成本诱发的努力-P3波幅显著大于低努力成本;收益情境下的反馈相关正成分波幅显著高于损失情境;为自己决策时,低努力成本的反馈-P3波幅显著高于高努力成本;损失情境下,低努力成本同样诱发了更大的反馈-P3波幅。综上,收益情境有助于亲社会决策,而高努力成本增加认知负荷,促使个体更倾向于自利决策。研究结果深化了对社会决策中努力-收益权衡机制的理解。

关键词: 亲社会决策, 努力成本, 得失情境, 事件相关电位