Fixed-time schedule effects in combination with response-dependent schedules.

We evaluated the effects of fixed-interval (FI), fixed-time (FT), and conjoint (combined) FI FT reinforcement schedules on the responding of 3 adults who had been diagnosed with schizophrenia. Responding on vocational tasks decreased for 2 of 3 participants under FT alone relative to FI alone. Responding under FI FT resulted in response persistence for 2 of 3 participants. Results have implications for the maintenance of desirable behavior, as well as for situations in which FT treatment has been implemented for problem behavior and problem behavior is nevertheless reinforced by caregivers.