Ainslie George
Department of Veterans Affairs Medical Center, Coatesville, PA 19320, USA.
Behav Brain Sci. 2005 Oct;28(5):635-50; discussion 650-73. doi: 10.1017/S0140525X05000117.
Behavioral science has long been puzzled by the experience of temptation, the resulting impulsiveness, and the variably successful control of this impulsiveness. In conventional theories, a governing faculty like the ego evaluates future choices consistently over time, discounting their value for delay exponentially, that is, by a constant rate; impulses arise when this ego is confronted by a conditioned appetite. Breakdown of Will (Ainslie 2001) presents evidence that contradicts this model. Both people and nonhuman animals spontaneously discount the value of expected events in a curve where value is divided approximately by expected delay, a hyperbolic form that is more bowed than the rational, exponential curve. With hyperbolic discounting, options that pay off quickly will be temporarily preferred to richer but slower-paying alternatives, a phenomenon that, over periods from minutes to days, can account for impulsive behaviors, and over periods of fractional seconds can account for involuntary behaviors. Contradictory reward-getting processes can in effect bargain with each other, and stable preferences can be established by the perception of recurrent choices as test cases (precedents) in recurrent intertemporal prisoner's dilemmas. The resulting motivational pattern resembles traditional descriptions of the will, as well as of compulsive phenomena that can now be seen as side-effects of will: over-concern with precedent, intractable but circumscribed failures of self-control, a motivated ("dynamic") unconscious, and an inability to exploit emotional rewards. Hyperbolic curves also suggest a means of reducing classical conditioning to motivated choice, the last necessary step for modeling many involuntary processes like emotion and appetite as reward-seeking behaviors; such modeling, in turn, provides a rationale for empathic reward and the "construction" of reality.
长期以来,行为科学一直对诱惑体验、由此产生的冲动以及对这种冲动的控制成败不一感到困惑。在传统理论中,像自我这样的主导官能会随着时间的推移持续评估未来的选择,以指数方式降低其延迟价值,也就是说,以恒定速率;当这种自我面对条件性欲望时,冲动就会产生。《意志的崩溃》(安斯利,2001年)提出了与该模型相矛盾的证据。人类和非人类动物都会自发地以一种曲线形式降低预期事件的价值,在这种曲线中,价值大致除以预期延迟,这是一种双曲线形式,比理性的指数曲线更弯曲。采用双曲线贴现时,快速获得回报的选项会暂时比回报更丰厚但延迟更高的选项更受青睐,这种现象在几分钟到几天的时间段内可以解释冲动行为,在几分之一秒的时间段内可以解释非自愿行为。相互矛盾的获取奖励过程实际上可以相互讨价还价,通过将反复出现的选择视为反复出现的跨期囚徒困境中的测试案例(先例),可以建立稳定的偏好。由此产生的动机模式类似于对意志的传统描述,以及现在可以被视为意志副作用的强迫现象:过度关注先例、难以控制但有限的自我控制失败、有动机的(“动态”)无意识以及无法利用情感奖励。双曲线也暗示了一种将经典条件作用简化为有动机选择的方法,这是将许多非自愿过程(如情感和食欲)建模为寻求奖励行为的最后必要步骤;反过来,这种建模为共情奖励和现实的“构建”提供了理论依据。