1) A multiple schedule is two or more basic schedules (CRF, FR, FI, VI, VR) presented sequentially in which each link ends with primary reinforcement (or in some cases extinction) and the component schedules are signaled by discriminative stimuli. In other words, a multiple schedule is the same as a chain schedule, but each link produces primary reinforcement.

2) A multiple schedule is a combination of several schedules of reinforcement, each of which is accompanied by a characteristic stimulus. For example, in the presence of a red light, key pecking is reinforced on a fixed-ratio schedule and in the presence of a green light, key pecking is reinforced on a fixed-interval schedule.

3) Reinforcement is programmed by two or more schedules alternating, usually at random, each schedule being accompanied by an appropriate stimulus as long as the schedule is in force. Differs from mixed schedule simply in the presence of controlling stimuli. (E.g., mult FI 5 FR 100 represents a schedule under which reinforcement sometimes occurs after an interval of 5 minutes and sometimes after 1 00 responses, the possibilities occurring either at random or according to some program in any determined proportion when an appropriate stimulus accompanies each schedule.)