Simple schedules such as FR, VR, FI, and VI describe one contingency for one response. A compound schedule combines two or more simple schedules (or a schedule and extinction).
Why it matters
Clients rarely face a single contingency. A student can work or chat; a child's requests are answered at some times and not others; a job task pays off only at the end. Compound schedules name these arrangements and underlie procedures you will use: concurrent schedules help explain why problem behavior persists when the alternative pays off poorly, and signaled multiple schedules help clients learn when reinforcement is and is not available during schedule thinning.
To classify any arrangement, ask three questions:
- Are the schedules in effect at the same time or one after another?
- Is each component signaled by its own stimulus?
- Do the components occur in a fixed order, with the final reinforcer delivered only at the end?
Key ideas
- Concurrent (conc): two or more schedules operate simultaneously and independently, each for a different response alternative. The person "chooses" by how they allocate responding. Concurrent schedules are the standard arrangement for studying choice and the matching law.
- Multiple (mult): two or more schedules for the same response alternate, usually in a random or unpredictable order, and each component has its own discriminative stimulus that is present while that component is in effect. Each component delivers its own reinforcement, or none if it is an extinction component.
- Mixed (mix): the same as a multiple schedule, except that no stimulus signals which component is in effect.
- Chained (chain): two or more schedules occur in a fixed order, each signaled by its own stimulus. Meeting the requirement of one component produces the stimulus for the next, which works as a conditioned reinforcer. The terminal reinforcer arrives only after the last component. The response may be the same or different across components.
- Tandem, a close cousin: like a chained schedule, but the components are not signaled.
Tip
Signals separate the pairs: multiple vs. mixed, and chained vs. tandem. Because each signal is a discriminative stimulus, responding under a multiple schedule usually differs across components, while under a mixed schedule it tends to look alike.
Definitions
- Compound schedule: any arrangement that combines two or more basic schedules of reinforcement, presented at the same time, in alternation, or in sequence.
- Concurrent schedule: two or more independent schedules in effect at the same time for two or more response alternatives.
- Multiple schedule: two or more schedules for one response that alternate, each correlated with its own discriminative stimulus.
- Mixed schedule: two or more alternating schedules for one response with no stimulus correlated with each component.
- Chained schedule: two or more signaled schedules presented in a set order, where completing one component produces the stimulus for the next and the terminal reinforcer follows the final component.
Examples from a session
Four arrangements, four settings
- Concurrent: At home, Marcus, 14, can text friends or work on his homework. Replies from friends arrive on their own unpredictable schedule, and his parent awards a point after every two finished pages. Both options are available at once, so this is a concurrent schedule. A richer homework schedule, such as a point per page, would likely shift more of his time toward homework.
- Multiple: A BCBA is thinning reinforcement for Mia's requests for attention. Mia is 7. When her dad wears a green wristband, every request is answered; when he wears a red one, requests are not answered. The bands switch unpredictably. This is a multiple schedule (mult FR 1 EXT), and Mia soon makes most of her requests during green periods.
- Mixed: Picture the same plan with no wristbands. Answered and unanswered periods still alternate, but nothing signals which is in effect. That is a mixed schedule, and her requests are likely to be spread across both periods.
- Chained: In a lab, a pigeon pecks a red key, and the 20th peck turns the key green (FR 20). While the key is green, the first peck after 1 minute produces food (FI 1-min). The red component always comes first, and food follows only the green one: chain FR 20 FI 1-min. The green key is a discriminative stimulus for pecking in the second component and a conditioned reinforcer for pecking in the first.
Behavior chains you teach with chaining procedures follow the same logic: for Devon, an adult in supported employment, a finished stack of folded towels cues bagging, and only the end of the sequence earns his break.
Common mistakes / exam traps
- Calling two available behaviors a multiple schedule. If two response options, each on its own schedule, are available at once, the arrangement is concurrent. Multiple schedules involve one response and components that take turns.
- Ignoring the signal. Multiple and mixed schedules can have identical component schedules. The only difference is whether a stimulus tells the learner which component is running.
- Treating chain stimuli as "just cues." Each middle stimulus also reinforces the response that produced it.
Exam trap
Multiple vs. chained. Both have signaled components in sequence, so a fixed order alone does not make a chain (the trap: a timer always switches components in the same order). Ask what ends each component. In a chain, meeting one component's requirement produces the next stimulus, and the terminal reinforcer follows only the last component. In a multiple schedule, components usually switch by time and each delivers its own reinforcement.
Exam trap
Ask "same time or one after another?" first. Same time means concurrent. If the components come one after another in a fixed order and reinforcement waits until the end, it is chained (or tandem when unsignaled). If they simply take turns, each with its own reinforcement, ask "is each component signaled?" to separate multiple from mixed.
Quick check
During reading group, Ms. Grant sometimes praises every correct answer Luis gives and at other times praises only every fifth correct answer. The two arrangements alternate across the group, and nothing in the room shows which one is in effect. Which schedule is Luis responding under?