Mazur J E, Snyderman M, Coe D
J Exp Psychol Anim Behav Process. 1985 Oct;11(4):565-75.
An adjusting procedure was used to measure pigeons' preferences among alternatives that differed in the duration of a delay before reinforcement and of an intertrial interval (ITI) after reinforcement. In most conditions, a peck at a red key led to a fixed delay, followed by reinforcement, a fixed ITI, and then the beginning of the next trial. A peck at a green key led to an adjustable delay, reinforcement, and then the next trial began without an ITI. The purpose of the adjusting delay was to estimate an indifference point, or a delay that made a subject approximately indifferent between the two alternatives. As the ITI for the red key increased from 0 s to 60 s, the green-key delay at the indifference point increased systematically but only slightly. The fact that there was some increase showed that pigeons' choices were controlled by more than simply the delay to the next reinforcer. One interpretation of these results is that besides delay of reinforcement, rate of reinforcement also influenced choice. However, an analysis that ignored reinforcement rate, but considered the delays between a choice response and the reinforcers on subsequent trials, was able to account for most of the obtained increases in green-key delays. It was concluded that in this type of discrete-trial situation, rate of reinforcement exerts little control over choice behavior, and perhaps none at all.
采用一种调整程序来测量鸽子在不同强化前延迟时间和强化后试间间隔（ITI）的选项之间的偏好。在大多数情况下，啄红色按键会导致固定延迟，随后是强化、固定的ITI，然后是下一次试验的开始。啄绿色按键会导致可调整的延迟、强化，然后下一次试验开始，没有ITI。调整延迟的目的是估计一个无差异点，即一个使受试者在两个选项之间大致无差异的延迟。随着红色按键的ITI从0秒增加到60秒，无差异点处绿色按键的延迟系统性增加，但增加幅度很小。存在一些增加这一事实表明，鸽子的选择不仅仅受限于到下一次强化物的延迟。对这些结果的一种解释是，除了强化延迟外，强化率也影响选择。然而，一种忽略强化率，但考虑选择反应与后续试验中的强化物之间延迟的分析，能够解释所获得的绿色按键延迟增加的大部分情况。得出的结论是，在这种类型的离散试验情境中，强化率对选择行为的控制作用很小，甚至可能根本没有控制作用。
