Translated from the Portuguese original. Read the original (Português)
A reinforcement schedule is the rule that defines when a response will be reinforced. On a continuous schedule, every correct response is reinforced — great for learning something new. On an intermittent schedule, only some responses are reinforced — which makes the behavior far more resistant to extinction. The four basic schedules combine ratio (counting responses) or interval (measuring time) with fixed or variable, and each combination produces a typical response pattern.
A reinforcement schedule (from the English schedule of reinforcement) is the rule that specifies which responses will be reinforced — how many responses, or after how much time, must occur for the reinforcer to be delivered. Systematically described by Ferster and Skinner (1957), schedules determine not only whether a behavior is maintained, but the pattern and rate at which it occurs.
Continuous or intermittent?
The first major divide is simple: is every response reinforced, or only some? This choice completely changes how the behavior behaves over time. Tap to compare:
Continuous reinforcement
Every occurrence of the response is reinforced (the CRF schedule). It is the best way to teach a new behavior: learning is fast and the link between acting and being reinforced is very clear. In exchange, it has two weaknesses — the person satiates easily (the reinforcer loses value) and, once reinforcement stops, the behavior disappears quickly.
Intermittent reinforcement
Only some responses are reinforced. Learning is a bit slower, but the behavior becomes far more resistant to extinction: since not every correct response was reinforced anyway, the person keeps trying for longer when reinforcement fails. That is why the intermittent schedule is the schedule of maintenance — it keeps alive what has already been learned.
In practice, the well-established rule is “continuous to teach, intermittent to maintain”: you start by reinforcing every correct response and, once the behavior is established, you gradually thin the schedule (so-called thinning) — requiring more responses or more time between one reinforcer and the next.
The four basic schedules
When reinforcement is intermittent, it can depend on how many responses the person makes (ratio) or on how much time has passed (interval). And that criterion can be fixed (always the same) or variable (shifting around an average). Crossing the two dimensions gives us four schedules — each with its own "signature" in the response pattern:
Flip the cards to see how each schedule works and an everyday example:
Why are the patterns different?
Two regularities sum up what research has observed for decades:
- Ratio produces more responses than interval. On ratio schedules, responding faster makes reinforcement arrive faster — so the person speeds up. On interval schedules, hurrying does not help: the time has to pass regardless.
- Variable produces a steadier response than fixed. When the criterion is fixed, a post-reinforcement pause shows up (right after earning reinforcement, there's room to "rest"). When it is variable and unpredictable, it pays to keep responding the whole time — hence the steady pace.
Why is gambling so gripping?Slot machines run on a variable ratio schedule: the next play could be the winning one, and you never know when. This is the schedule that sustains behavior longest and resists extinction the most — which helps explain persistence in gambling, without it being a matter of "lacking willpower."
Be careful when "thinning" the scheduleMoving from continuous to a very lean schedule too fast can make the behavior collapse — this is called ratio strain. The adjustment should be gradual, guided by the data.
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Further reading
- Ferster, C. B. & Skinner, B. F. Schedules of Reinforcement. Appleton-Century-Crofts, 1957.
- Cooper, J. O., Heron, T. E. & Heward, W. L. Applied Behavior Analysis. 3rd ed. Pearson, 2020 (chapter on reinforcement schedules).
- Catania, A. C. Learning. 5th ed. Sloan Publishing, 2013.
- Skinner, B. F. Ciência e Comportamento Humano (1953). Brazilian ed., Martins Fontes.
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