Ho M Y, Mobini S, Chiang T J, Bradshaw C M, Szabadi E
Psychopharmacology Section, Division of Psychiatry, University of Nottingham, B Floor, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK.
Psychopharmacology (Berl). 1999 Oct;146(4):362-72. doi: 10.1007/pl00005482.
Impulsive choice refers to the selection of small immediate gains in preference to larger delayed gains, or the selection of large delayed penalties in preference to smaller immediate penalties. Current theoretical interpretations of impulsive choice are reviewed, and a synthesis of these ideas, the "multiplicative hyperbolic model of choice", is presented. The model assumes that the value of a positive reinforcer increases as a hyperbolic function of its size, and decreases as a hyperbolic function of its delay and the odds against its occurrence. Each hyperbolic function contains a single discounting parameter which quantifies the organism's sensitivity to the variable in question. The hyperbolic discounting functions combine multiplicatively to determine the overall value of the reinforcer. Equivalent functions are postulated to govern the (negative) value of aversive events, the net value of an outcome reflecting the algebraic sum of the positive and negative values. The model gives rise to a quantitative methodology for studying impulsive choice, based on a family of linear indifference (null) equations, which describe performance under conditions of indifference, when the values of the reinforcers are assumed to be equal. This methodology may be used to identify individual differences in sensitivity to the magnitude, delay and probability of reinforcement. The methodology is also suitable for the quantitative evaluation of the effects of some pharmacological interventions on discounting parameters. Recent psychopharmacological studies of impulsive choice are reviewed, and the utility of indifference equations for extending this work, and developing a quantitative psychopharmacology of impulsive choice is discussed.
冲动选择是指优先选择小的即时收益而非大的延迟收益，或者优先选择大的延迟惩罚而非小的即时惩罚。本文回顾了当前对冲动选择的理论解释，并提出了这些观点的综合，即“选择的乘性双曲线模型”。该模型假设，正强化物的价值作为其大小的双曲线函数而增加，并作为其延迟和发生概率的双曲线函数而降低。每个双曲线函数都包含一个单一的折扣参数，该参数量化了生物体对相关变量的敏感性。双曲线折扣函数相乘组合以确定强化物的总体价值。假定等效函数用于控制厌恶事件的（负）价值，结果的净值反映正价值和负价值的代数和。该模型基于一族线性无差异（零）方程产生了一种研究冲动选择的定量方法，这些方程描述了在无差异条件下的表现，即假设强化物的价值相等时的表现。这种方法可用于识别个体在对强化的大小、延迟和概率的敏感性方面的差异。该方法也适用于对某些药物干预对折扣参数影响的定量评估。本文回顾了最近关于冲动选择的精神药理学研究，并讨论了无差异方程在扩展这项工作以及发展冲动选择的定量精神药理学方面的效用。
