Determinants of Operant Behaviour in Humans: Some Differences from Animals

Abstract

The performance of human subjects was investigated on fixed-interval (FI) schedules of reinforcement where responses meeting the schedule requirement produced points, later exchanged for money. For one group (the conventional FI condition) presses on a single response-panel were reinforced according to an FI schedule. For another group the procedure was the same as in the conventional FI condition, except that each response also illuminated a digital clock for 0.5 s. A third group responded on two panels; presses on one panel produced reinforcement on an FI schedule, and presses on the second panel illuminated the digital clock for 0.5 s. Responding in the conventional FI condition varied considerably both within and between subjects and different response measures showed no systematic relationship with FI value. For subjects in the other two groups, the pattern of responding on the clock-illuminating panel was scalloped, showing a pause after reinforcement followed by an accelerated response rate; the post-reinforcement pause was an increasing function, and running rate (calculated after excluding the post-reinforcement pause) was a decreasing function, of the value of the FI schedule. The data were compared with results of animal studies on FI schedules and some of the factors which affect performance on these schedules were analysed.