A further study of choice and percentage reinforcement

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.