Fixed ratio
A fixed ratio (FR) schedule delivers reinforcement after a set number of responses, such as after every 5th response on an FR 5 schedule.
On a fixed ratio schedule, the number of responses required for each reinforcer stays the same. FR 1 is continuous reinforcement; FR 3 means every third response is reinforced; FR 10 means every tenth. In sessions, FR schedules often appear in token systems ("one token every 3 correct responses") and in work tasks ("break after completing 5 items").
FR schedules typically produce a high rate of responding, followed by a pause after each reinforcer (a post-reinforcement pause) before responding starts again. The pause tends to be longer when the ratio is larger. This pattern is sometimes described as "break and run". If the ratio is raised too quickly, responding may break down; this is called ratio strain.
FR schedules are easy for an RBT to implement and count. The RBT tracks responses carefully, delivers the reinforcer exactly when the required number is reached, and does not add extra reinforcers in between unless the plan calls for it. Any change to the ratio, including thinning, is decided by the supervisor.
Example and non-example
| Example | On an FR 4 schedule, an RBT gives a client a token after each fourth correctly sorted item: after items 4, 8, 12 and so on. |
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| Non-example | Giving a token after an average of 4 sorted items, sometimes after 2, sometimes after 6, is a variable ratio schedule. |
Don't confuse it with
| Variable ratio | Fixed ratio uses the same number of responses each time; variable ratio uses a number that changes around an average. |
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| Fixed interval | Fixed ratio is based on the number of responses; fixed interval is based on time passing before a response is reinforced. |
Test yourself
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Question 1In a vocational program, an adult client sorts mail. As the plan directs, the RBT gives a token after every 4 pieces sorted correctly. Which schedule is this?
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A: Fixed ratio 4. The token is delivered after a set, unchanging number of responses (4), which is a fixed ratio schedule.
- B: A variable ratio 4 would deliver tokens after a changing number of responses that averages 4.
- C: A fixed interval schedule depends on time passing, not on the number of responses.
- D: Continuous reinforcement would deliver a token after every correct response.
Task C.1 · 40-hour curriculum section A
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Question 2What is the main difference between ratio and interval schedules of reinforcement?
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B: Ratio schedules depend on the number of responses; interval schedules depend on time passing.. On a ratio schedule, reinforcement is delivered after a number of responses. On an interval schedule, reinforcement is delivered for the first response after an amount of time has passed.
- A: Both kinds of schedules can be used at different stages of teaching; neither is limited to maintenance.
- C: Any type of reinforcer can be delivered on either kind of schedule.
- D: Both ratio and interval schedules can be fixed or variable.
Task C.1 · 40-hour curriculum section A
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Question 3The plan says: "When the client reaches mastery on FR 1, move to FR 2." The client reached the criterion in the last session. What should the RBT do in today's session?
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D: Reinforce every second correct response, as the plan states.. The supervisor has already written the next step and the criterion for it. The RBT implements the plan as written, which means moving to FR 2 (reinforcing every second correct response).
- A: Skipping steps changes the plan and can cause responding to break down.
- B: The plan sets the criterion for the change; the RBT does not wait for the client to signal it.
- C: Mastery leads to schedule thinning in this plan, not to stopping reinforcement altogether.
Task C.1 · 40-hour curriculum section A
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On the RBT exam
This term belongs to task C.1 Positive and negative reinforcement in content area C, Behavior Acquisition, which is 19 of the 75 scored questions.