Sanabria Federico, Baker Forest, Rachlin Howard
Department of Psychology, State University of New York, Stony Brook, New York 11794-2500, USA.
Learn Behav. 2003 Nov;31(4):318-31. doi: 10.3758/bf03195994.
Each of four pigeons was exposed to a single random-ratio schedule of reinforcement in which the probability of reinforcement for a peck on either of two keys was 1/25. Reinforcer amounts were determined by an iterated prisoner's dilemma (IPD) matrix in which the "other player" (a computer) played tit-for-tat. One key served as the cooperation (C) key; the other served as the defection (D) key. If a peck was scheduled to be reinforced and the D-key was pecked, the immediate reinforcer of that peck was always higher than it would have been had the C-key been pecked. However, if the C-key was pecked and the following peck was scheduled to be reinforced, reinforcement amount for pecks on either key were higher than they would have been if the previous peck had been on the D-key. Although immediate reinforcement was always higher for D-pecks, the overall reinforcement rate increased linearly with the proportion of C-pecks. C-pecks thus constituted a form of self-control. All the pigeons initially defected with this procedure. However, when feedback signals were introduced that indicated which key had last been pecked, cooperation (relative rate of C-pecks)--hence, self-control--increased for all the pigeons.
四只鸽子中的每一只都被置于一种单一的随机比率强化程序中，在该程序中，啄击两个按键中任意一个获得强化的概率为1/25。强化量由一个重复囚徒困境（IPD）矩阵决定，其中“另一个参与者”（一台计算机）采用针锋相对策略。一个按键用作合作（C）键；另一个用作背叛（D）键。如果一次啄击被安排为获得强化且啄的是D键，那么该啄击的即时强化物总是比啄C键时要高。然而，如果啄的是C键且接下来的啄击被安排为获得强化，那么无论啄哪个键，强化量都比前一次啄D键时要高。尽管对D键啄击的即时强化总是更高，但总体强化率随C键啄击比例的增加而呈线性上升。因此，C键啄击构成了一种自我控制形式。所有鸽子在这个程序开始时都选择背叛。然而，当引入反馈信号以表明最后啄的是哪个键时，所有鸽子的合作（C键啄击的相对比率）——也就是自我控制——都增强了。
