Behavioral and neural evidence of incentive bias for immediate rewards relative to preference-matched delayed rewards.
Behavioral and neural evidence of incentive bias for immediate rewards relative to preference-matched delayed rewards.
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DOI：
10.1523/jneurosci.4261-09.2009
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发表时间：
2009-11-25
期刊：
影响因子：
--
通讯作者：
Monterosso JR
中科院分区：
文献类型：
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作者：
Luo S;Ainslie G;Giragosian L;Monterosso JR
几种自我控制理论（包括跨期讨价还价和自我信号）暗示，跨期决策可能比与决策背景之外的奖励相关的激励所预测的更有远见。我们使用行为和功能性神经影像学来检验这一假设。首先，受试者对延迟四个月的金额和当天可用的较小金额表示偏好。这使我们能够为每个参与者建立个性化的“无差异对”--即时和延迟的金额都是同样受欢迎的。参与者随后进行了一项反应时间fMRI任务，为他们提供了不同的机会来赢得组成无差异对的每一个奖励。解剖区域的利益分析以及全脑分析表明，更大的反应招募的即时奖励（相对于偏好匹配的延迟奖励），在以前涉及的区域敏感的激励价值使用相同的任务（包括双边壳核，双边前额叶和中脑）。在即时奖励试验中，相对于延迟奖励试验，目标的RT也更快（p <0.01），即时与延迟奖励试验之间RT的个体差异与优先响应即时奖励的集群中MR信号的方差相关（r = 0.33，p <0.05）。这些研究结果表明，与即时与偏好匹配的延迟奖励相关的激励差异。这种差异可能标志着自我控制过程的贡献，这些过程在决策过程中被招募，但在个人预期奖励时却不存在。
Several theories of self-control (including intertemporal bargaining and self-signaling) imply that intertemporal decisions can be more farsighted than would be predicted by the incentive associated with rewards outside a decision context. We examined this hypothesis using behavior and functional neuroimaging. First, subjects expressed preferences between amounts of money delayed by four months and smaller amounts available that day. This allowed us to establish “indifference pairs” individualized to each participant -- immediate and delayed amounts that were equally preferred. Participants subsequently performed a reaction time fMRI task that provided them with distinct opportunities to win each of the rewards that comprised the indifference pairs. Anatomical Region of Interest analysis as well as whole-brain analysis indicated greater response recruited by the immediate rewards (relative to the preference matched delayed rewards) in regions previously implicated as sensitive to incentive value using the same task (including bilateral putamen, bilateral anterior insula and midbrain). RT to the target was also faster during the immediate relative to delayed reward trials (p < .01), and individual differences in RT between immediate versus delayed reward trials correlated with variance in MR signal in those clusters that responded preferentially to immediate rewards (r = .33, p < .05). These findings indicate a discrepancy in incentive associated with the immediate versus the preference-matched delayed rewards. This discrepancy may mark the contribution of self-control processes that are recruited during decision-making, but that are absent when rewards are individually anticipated.