Signalled and unsignalled free-operant avoidance in the pigeon

Pigeons were trained to depress a lever to avoid electric shock under free-operant avoidance schedules without a warning signal, or with a warning signal that could be terminated only by a response. Most birds in the signalled avoidance procedure terminated more than 50% of the warning signals before shock. In the unsignalled avoidance procedure, several birds formed a temporal discrimination and received relatively few shocks; other birds responded only in post-shock bursts, and received many more shocks.     

M.T.S.: An adaptable microcomputer-based testing system

An Apple II + computer-based human testing system is described. The system, which was developed using the Pascal language, provides library units of low-level procedures to rapidly access a clock, collect responses, control video output, control a touch-sensitive monitor, and display high-resolution graphics. Built-in hardware and software checks provide a high degree of system reliability. Use of easily altered text files for control of trials within a task and inclusion of and ordering of tasks within a session allows the system to be readily adapted.     

Transfer of control of the pigeon's key peck from food reinforcement to avoidance of shock

Eight pigeons were initially trained to peck a white key for food under a variable-interval 1-min schedule of reinforcement. Then, a shock-avoidance schedule was initiated and food was no longer available in the experimental situation. Under the avoidance schedule, each peck on the key postponed shock for 40 sec. A warning signal, consisting of tone and red houselights, was presented after 30 sec without a response. If no response occurred, a shock was delivered 10 sec after warning-signal onset. Shocks were delivered every 10 sec in the presence of the warning signal until a response was made. The warning signal was terminated only by a response. Key pecking of all eight pigeons came under control of the avoidance schedule and responding continued throughout the 20-day avoidance training period.     

Drugs and punished responding II: d-amphetamine-induced increases in punished responding

The effects of d-amphetamine on punished responding were studied in two experiments. In Experiment I, pigeons responded under a multiple fixed-ratio 30 response fixed-interval 5-min schedule of food presentation with 60-sec limited holds in both components. Each response was punished with electric shock, the intensity of which was varied systematically. In Experiment II, another group of pigeons responded under a multiple fixed-interval 5-min fixed-interval 5-min schedule of food presentation with 40-sec limited holds. Each response was punished with shock during one component, and every thirtieth response was punished in the other component. d-Amphetamine increased overall rates of punished responding only rarely under any of the punishment conditions; however, response rates within the fixed-interval when rates were low were increased by d-amphetamine when the shock intensity was low (Experiment I), or when responses produced shock intermittently (Experiment II). The data suggest that the effects of d-amphetamine on punished responding depend on the control rate of responding, the punishment intensity, the punishment frequency, and the schedule of food presentation.     

Using an Apple II microcomputer for real-time control in a behavioral laboratory

This report describes the hardware and software developed to implement an Apple II (48 KB) as a real-time control device for operant experiments. The hardware has a straightforward design, so that it is readily understandable and can be built by individuals with only minimal experience in the use of integrated circuits and other electronic components. The software routines listed below represent an approach to controlling and handling the data generated by an operant experiment. Using these routines, we are able to record each response and experimental event, the time of the occurrence, and the conditions at that time.