Timeout and concurrent fixed-ratio schedules with human subjects.

Human subjects given choices among 10 different pairs of concurrent fixed-ratio schedules preferred the smaller ratio. After a preference had been determined, timeout of increasing duration followed the completion of the preferred schedule. The larger the fixed-ratio difference, the longer the timeout necessary to produce the shift to the previously nonpreferred ratio. Responses by two of three subjects were unaffected by changes from response-dependent to response-independent pay.