Schaal D W, Branch M N
University of Florida.
J Exp Anal Behav. 1990 Jan;53(1):103-21. doi: 10.1901/jeab.1990.53-103.
Two experiments with pigeons examined the relation of the duration of a signal for delay ("delay signal") to rates of key pecking. The first employed a multiple schedule comprised of two components with equal variable-interval 60-s schedules of 27-s delayed food reinforcement. In one component, a short (0.5-s) delay signal, presented immediately following the key peck that began the delay, was increased in duration across phases; in the second component the delay signal initially was equal to the length of the programmed delay (27 s) and was decreased across phases. Response rates prior to delays were an increasing function of delay-signal duration. As the delay signal was decreased in duration, response rates were generally higher than those obtained under identical delay-signal durations as the signal was increased in duration. In Experiment 2 a single variable-interval 60-s schedule of 27-s delayed reinforcement was used. Delay-signal durations were again increased gradually across phases. As in Experiment 1, response rates increased as the delay-signal duration was increased. Following the phase during which the signal lasted the entire delay, shorter delay-signal-duration conditions were introduced abruptly, rather than gradually as in Experiment 1, to determine whether the gradual shortening of the delay signal accounted for the differences observed in response rates under identical delay-signal conditions in Experiment 1. Response rates obtained during the second exposures to the conditions with shorter signals were higher than those observed under identical conditions as the signal duration was increased, as in Experiment 1. In both experiments, rates and patterns of responding during delays varied greatly across subjects and were not systematically related to delay-signal durations. The effects of the delay signal may be related to the signal's role as a discriminative stimulus for adventitiously reinforced intradelay behavior, or the delay signal may have served as a conditioned reinforcer by virtue of the temporal relation between it and presentation of food.
两项以鸽子为对象的实验研究了延迟信号（“延迟信号”）的持续时间与啄键速率之间的关系。第一个实验采用了一种复合式程序表，由两个成分组成，每个成分都有相等的可变间隔60秒程序表，食物强化延迟27秒。在一个成分中，紧跟开始延迟的啄键之后呈现的短延迟信号（0.5秒）在各阶段中持续时间增加；在第二个成分中，延迟信号最初等于程序设定的延迟长度（27秒），并在各阶段中逐渐缩短。延迟前的反应速率是延迟信号持续时间的递增函数。随着延迟信号持续时间的缩短，反应速率通常高于在延迟信号持续时间增加时相同延迟信号持续时间条件下获得的反应速率。在实验2中，使用了单一的可变间隔60秒程序表，食物强化延迟27秒。延迟信号持续时间同样在各阶段中逐渐增加。与实验1一样，随着延迟信号持续时间的增加，反应速率也增加。在信号持续整个延迟的阶段之后，不像实验1那样逐渐引入较短延迟信号持续时间的条件，而是突然引入，以确定延迟信号的逐渐缩短是否解释了实验1中在相同延迟信号条件下观察到的反应速率差异。与实验1一样，在第二次暴露于较短信号条件期间获得的反应速率高于在信号持续时间增加时相同条件下观察到的反应速率。在两个实验中，延迟期间的反应速率和模式在不同个体间差异很大，并且与延迟信号持续时间没有系统的关联。延迟信号的作用可能与其作为偶然强化的延迟内行为的辨别性刺激的作用有关，或者延迟信号可能凭借其与食物呈现之间的时间关系而起到了条件强化物的作用。
