Kendall S B
Psychology Dept., University of Western Ontario, London, Ontario Canada, N6A 5C2.
Behav Processes. 1985 May;10(4):399-413. doi: 10.1016/0376-6357(85)90040-3.
In Experiment I four pigeons were trained in a concurrent chains procedure with fixed-ratio schedules (FR1) in the initial components and fixed-time schedules in the terminal components. Pecking one of the keys when both keys were white initiated a fixed time schedule on that key. A peck to the left key produced three stripes on the key. At the termination of the fixed-time component food always occurred. Pecking the other key produced either a circle or a triangle. If a circle appeared, reinforcement occurred. If a triangle appeared a brief timeout was given. Initially the stripes appeared on the left key and the circle and triangle on the left. This was reversed during the course of the experiment. In addition, sessions were conducted in which both circle and triangle sometimes preceded reinforcement and sometimes timeout. For most birds under most conditions there was a preference for the key that produced the circle and triangle. When these were uncorrelated with reinforcement and time out three of the birds preferred the key producing 100% reinforcement. In Experiment II three factors were varied and VI 20 sec schedules were used in the initial links instead of FR1. The results showed that pigeons preferred the 50% condition more 1) the greater the duration of the terminal links, 2) the smaller the value on the initial link VI schedules and 3) the less the probability of food in the terminal link with stripes on the key.
在实验一中，四只鸽子接受了并发链程序训练，初始成分采用固定比率时间表（FR1），终端成分采用固定时间时间表。当两个按键都为白色时啄其中一个按键，会在该按键上启动一个固定时间时间表。啄左边的按键会在按键上产生三条条纹。在固定时间成分结束时总会出现食物。啄另一个按键会产生一个圆形或一个三角形。如果出现圆形，就会得到强化。如果出现三角形，则会给予短暂的超时。最初，条纹出现在左边的按键上，圆形和三角形出现在右边。在实验过程中这一情况发生了逆转。此外，还进行了一些实验环节，其中圆形和三角形有时先于强化出现，有时先于超时出现。在大多数情况下，大多数鸟类更喜欢产生圆形和三角形的按键。当这些与强化和超时不相关时，三只鸟更喜欢产生100%强化的按键。在实验二中，改变了三个因素，初始环节采用了VI 20秒时间表，而不是FR1。结果表明，鸽子更倾向于50%的情况，具体如下：1）终端环节的持续时间越长；2）初始环节VI时间表的值越小；3）按键上有条纹的终端环节中食物出现的概率越低。
