Fixed-interval and fixed-ratio reinforcement schedules with human subjects.

Operant laboratory studies were conducted as part of the regular activities of a psychiatric research ward. This report includes only some early data obtained from the ward staff, not the patients. A multiple schedule having alternating fixed-ratio and fixed-interval components permitted observations of acquisition and maintenance of behavior at low schedule values, transition to and final performance at greater schedule values, and behavioral changes after a limited-hold contingency was added to the fixed-interval. Prior to the added limited-hold, subjects used watches to time the interval, and usually responded only once before obtaining each fixed-interval reinforcement. Short limited-hold values eliminated clock watching and increased fixed-interval responding. Subjects communicated freely with each other, and it was clear that their performances were controlled both by the contingencies and by instructions. Just as clearly, the instructions themselves were controlled by the contingencies. It was concluded that the kinds of verbal control that were responsible for "nonstandard" fixed-interval performances did not require the postulation of any new behavioral principles.