Two or more basic schedules of reinforcement are presented in an alternating, sometimes random, fashion for one or more behaviors. Multiple and Mixed schedules are the same schedules with one exception. An SD is correlated with the schedules in multiple schedules, while no SD is present in Mixed Schedules.
Multiple Schedule Example: While in a classroom, a teacher puts a blue sticky note on the board (SD signaling the schedule) when an FR schedule is available, and then puts a red sticky note (SD) when a VR schedule is available. A multiple schedule would be identical except no sticky notes would be used.