Final answer:
In multiple reinforcement schedules, there is a signal indicating changes in the schedule, enabling discrimination of the schedule in effect. Mixed schedules lack this signal, resulting in more unpredictable response patterns from the subject.
Step-by-step explanation:
The difference between multiple and mixed reinforcement schedules is that in multiple schedules there is a signal that the schedule has changed. These types of schedules are a part of partial reinforcement strategies, where not every desired behavior is reinforced. A multiple schedule of reinforcement involves two or more basic schedules that occur in an alternating, usually random sequence, where each schedule is signaled by a different stimulus. The key aspect of multiple schedules is that these stimuli allow the organism to discriminate which particular schedule is in effect.
In contrast, a mixed schedule, also involving two or more basic schedules of reinforcement (like the multiple schedule), differs in that there is no discriminative stimulus, or signal, to indicate when one schedule has ended and another has begun. This lack of signal can significantly affect the response patterns as the subject tries to figure out which schedule is in effect.
As an example, with a multiple variable interval schedule, a signal might indicate to the subject that a reinforcement will be available following the first response after a variable amount of time has passed, while during a mixed variable interval schedule, the subject has no such signal and must respond more unpredictably.