ABA Therapy
A variable ratio schedule is a reinforcement schedule in which reinforcement follows a changing number of responses around a planned average. For example, under a VR 5 schedule, reinforcement might occur after three responses, then seven, then four, then six. The exact requirement changes, but the average is five responses per reinforcer.
In ABA therapy, variable ratio schedules may be introduced after a desired behavior is already established and no longer requires reinforcement after every correct response. The changing response requirement can support steady responding while making programmed reinforcement less frequent. However, a VR schedule should be introduced according to the learner’s progress, task demands, and response to schedule changes rather than as an automatic next step.
Key Takeaways
- A variable ratio schedule provides reinforcement after a changing number of responses around a planned average.
- Variable ratio schedules commonly produce high, steady response rates with relatively short post-reinforcement pauses, although actual performance varies by learner, task, and reinforcer.
- ABA therapists may use VR schedules after skills become established, while monitoring accuracy, independence, and whether the changing reinforcement requirement is being implemented correctly.
What Is a Variable Ratio Schedule?
A variable ratio schedule, often abbreviated as VR, is an intermittent reinforcement schedule based on the number of responses a learner makes. The number of responses required for reinforcement changes rather than staying the same every time.
For example:
3 responses → reinforcement
7 responses → reinforcement
4 responses → reinforcement
6 responses → reinforcement
If these values are part of a VR 5 arrangement, the average requirement is five responses.
A variable ratio schedule uses changing response requirements while maintaining a planned average. This separates it from a fixed ratio schedule, where the same number of responses is required for every reinforcer.
Variable ratio schedules are one part of the broader reinforcement principles used in Applied Behavior Analysis. Families who want more background on how consequences can strengthen behavior can review Nurturing Nests’ guide to positive reinforcement for autism.
What Does VR 5 Mean?
A VR 5 schedule means reinforcement occurs after an average of five responses, but the exact number required changes from one reinforcement opportunity to another.
It does not mean that every fifth response receives reinforcement. That would be a fixed ratio 5, or FR 5, schedule. It also does not automatically mean that every individual response has a 20% chance of producing reinforcement.
That distinction matters because a variable ratio schedule and a random-ratio schedule are technically different. Under a VR arrangement, the response requirements are varied while maintaining a predetermined average. Under a random-ratio arrangement, each response has a specified probability of producing reinforcement.
For parents, the simplest way to remember it is:
VR 5 = reinforcement requires about five responses on average, but not exactly five every time.
What Are the Main Characteristics of a Variable Ratio Schedule?
Variable ratio schedules have several characteristics that distinguish them from other reinforcement schedules.
Reinforcement Depends on Responses
VR is a ratio schedule, so reinforcement depends on how many qualifying responses occur rather than how much time has passed. If the learner responds more quickly, they may reach the next reinforcement requirement sooner.
The Requirement Changes
The exact number of responses required varies. A learner might complete two responses before one reinforcer, six before another, and four before the next. The sequence is arranged around the target average.
Responding Is Often High and Steady
Variable ratio schedules are commonly associated with relatively high and consistent response rates. Compared with fixed ratio arrangements, VR schedules typically produce steadier responding with less pronounced pausing after reinforcement.
These are general behavior patterns rather than guarantees. Motivation, reinforcer effectiveness, response effort, task difficulty, and learning history can all affect how an individual learner responds.
Variable Ratio vs. Fixed Ratio: What Is the Difference?
Variable ratio and fixed ratio schedules are both based on the number of responses.
The difference is whether the requirement changes.
| Feature | Fixed Ratio | Variable Ratio |
| Based on | Number of responses | Number of responses |
| Requirement | Same each time | Changes around an average |
| Example | FR 5 = exactly 5 responses | VR 5 = average of 5 responses |
| Predictability | Predictable | Less predictable |
| Typical pattern | High responding with possible post-reinforcement pauses | High, relatively steady responding |
Under an FR 3 schedule, reinforcement follows exactly three qualifying responses each time. Under a VR 3 schedule, the requirement could change from one response to four responses to three responses, as long as the sequence maintains an average close to three.
Neither arrangement is universally better. The appropriate schedule depends on the target behavior and learner.
How Is a Variable Ratio Schedule Different From Interval Schedules?
Ratio schedules are based on responses. Interval schedules are based on time.
The four basic intermittent reinforcement schedules are:
| Schedule | Requirement |
| Fixed Ratio (FR) | Fixed number of responses |
| Variable Ratio (VR) | Changing number of responses around an average |
| Fixed Interval (FI) | First qualifying response after a fixed amount of time |
| Variable Interval (VI) | First qualifying response after changing time intervals |
A variable interval schedule may sound similar to a variable ratio schedule because both involve changing requirements.
The difference is:
Variable ratio = changing number of responses.
Variable interval = changing amounts of time.
For example, a VI schedule may make reinforcement available after intervals of three minutes, seven minutes, and five minutes. Once each interval has passed, the next qualifying response can produce reinforcement.
How Are Variable Ratio Schedules Used in ABA Therapy?
Variable ratio schedules may be introduced after a skill has already been established. Early in skill acquisition, a therapist may begin with continuous reinforcement, meaning every correct target response receives the programmed reinforcer.
For example:
Correct response → reinforcement
Correct response → reinforcement
Correct response → reinforcement
Continuous reinforcement is also described as an FR 1 schedule. As the learner becomes more accurate and independent, reinforcement may gradually become less frequent.
A possible progression might look like:
FR 1 → FR 2 → VR 3 → VR 5
This is only an example. There is no universal sequence that every learner should follow.
In classroom ABA settings, continuous reinforcement may be used during early teaching, while intermittent arrangements such as VR may be introduced after skills become established. Accurate implementation also matters. Providing classroom assistants with preplanned variable-ratio schedules helped them stay closer to the intended average response requirement and vary those requirements more accurately.
That finding is about implementing the reinforcement schedule correctly. It does not mean the study demonstrated that VR schedules automatically improved students’ long-term skill maintenance.
When previously learned behaviors need to continue after intensive teaching decreases, reinforcement planning may also connect with maintenance in ABA.
What Is an Example of a Variable Ratio Schedule in ABA?
Imagine a learner has already mastered identifying familiar objects. During early teaching, the therapist may reinforce every correct response.
Later, under a VR 4 schedule, reinforcement might occur after:
- 2 correct responses
- Then 6 correct responses
- Then 3 correct responses
- Then 5 correct responses
The average is four responses.
The learner does not know exactly which response will be followed by the programmed reinforcer, but correct responding continues throughout the activity.
Another example could involve an established classroom behavior. A student who consistently begins assigned work independently might receive planned reinforcement after varying numbers of independent task starts. The purpose is not to confuse the learner. It is to reduce dependence on reinforcement after a predictable number of responses once the behavior is already established.
Therapists can use ABA behavior data sheets to monitor whether accuracy and independence remain stable as reinforcement becomes less frequent.
Why Are Slot Machines Often Used as an Example?
Slot machines are commonly described as examples of variable ratio reinforcement because payouts occur after unpredictable numbers of plays.
Technically, however, modern slot machines generally operate more like random-ratio schedules, where each play has a specified probability of producing a winning outcome. A programmed variable ratio schedule instead varies the number of required responses around a predetermined average. Both arrangements involve unpredictable reinforcement, but they are not programmed in exactly the same way.
This distinction is especially important because ABA therapy is not designed like gambling. Clinical reinforcement plans are developed around meaningful treatment goals, the learner’s needs, available reinforcers, and ongoing behavior data.
The slot-machine example is simply a familiar illustration of how unpredictable reinforcement can contribute to persistent responding.
Does a Variable Ratio Schedule Use Positive Reinforcement?
A variable ratio schedule describes when reinforcement occurs, not whether the reinforcement is positive or negative.
Positive reinforcement occurs when something is added after a behavior, and that consequence increases the future likelihood of the behavior.
Negative reinforcement occurs when something is removed or reduced after a response, and that consequence increases the future likelihood of the behavior. Negative reinforcement is not punishment.
The VR label describes the pattern of response requirements. It does not identify the specific type of reinforcing consequence.
Variable Ratio vs. Progressive Ratio: What Is the Difference?
A progressive ratio schedule is different from a variable ratio schedule. Under VR, the required number of responses changes around a planned average. Under a progressive ratio schedule, the response requirement systematically increases.
For example:
1 response → reinforcement
2 responses → reinforcement
4 responses → reinforcement
8 responses → reinforcement
Progressive ratio procedures can be used to examine how much responding continues as response requirements become increasingly demanding. The highest completed requirement before responding stops is often called a breakpoint.
Progressive ratio schedules increase response requirements across successive reinforcement opportunities.
So:
Variable ratio = requirement varies around an average.
Progressive ratio = requirement systematically increases.
Are Variable Ratio and Concurrent Schedules the Same?
No. A variable ratio schedule describes the reinforcement requirement for a particular response. A concurrent schedule means two or more reinforcement schedules are available at the same time for different response options.
For example, a learner may be able to choose between two activities, each associated with its own reinforcement arrangement.
Concurrent schedules are often discussed with the matching law, which addresses how behavior can be distributed among available choices. Relative reinforcement rates can influence how responses are allocated between concurrently available options.
A variable ratio schedule can be one component of a concurrent arrangement, but the terms do not mean the same thing.
What Are the Benefits and Limitations of Variable Ratio Reinforcement?
A variable ratio schedule may help reduce dependence on reinforcement after every response once a behavior is already established.
Potential benefits include:
- Supporting relatively steady responding
- Making reinforcement less predictable
- Reducing reliance on continuous reinforcement
- Allowing programmed reinforcement to become less frequent
- Helping established behaviors operate under thinner reinforcement conditions
However, VR schedules are not appropriate for every learner or every skill.
A new skill may still require frequent reinforcement. Increasing the average number of responses too quickly can lead to declining performance, especially when a task requires substantial effort or the available reinforcer is not effective.
Variable schedules can also be implemented incorrectly. If the response requirements do not actually average the intended value, the learner is not receiving the schedule that was planned.
The goal should never be unpredictability for its own sake. Reinforcement arrangements should support useful, sustainable behavior.
How Do ABA Therapists Know Whether a VR Schedule Is Working?
ABA therapists monitor performance before and after changing the reinforcement schedule.
They may track:
- Correct responses
- Response frequency
- Independent responding
- Task completion
- Errors
- Reinforcers delivered
- Actual response requirements between reinforcers
Suppose a learner responds accurately under continuous reinforcement but performance drops significantly after moving to VR 5.
The therapist might:
- Lower the average requirement
- Return temporarily to more frequent reinforcement
- Reassess the reinforcer
- Review task difficulty
- Check whether the VR schedule is being implemented correctly
The reinforcement schedule should be adjusted to the learner’s behavior rather than requiring the learner to fit a predetermined schedule.
Families receiving in-home ABA therapy can work with their child’s BCBA to understand when an established behavior may be ready for less frequent reinforcement and how progress will be monitored.
Conclusion
A variable ratio schedule reinforces a changing number of responses around a planned average. This makes it different from fixed ratio schedules, which use the same response requirement each time, and interval schedules, which depend on time. In ABA therapy, VR schedules may be introduced after a skill becomes established to make programmed reinforcement less frequent while supporting steady responding. The schedule should still be planned carefully, implemented accurately, and adjusted according to the learner’s individual performance rather than used as a one-size-fits-all strategy.
At Nurturing Nests Therapy Center, Inc., our Board Certified Behavior Analysts and Behavior Technicians use individualized, data-informed ABA strategies to support communication, learning, daily routines, and independence for children. Contact us. Reinforcement plans are adjusted according to each child’s progress, needs, and everyday environment.
FAQs
What are variable ratio schedules?
Variable ratio schedules are reinforcement schedules in which reinforcement follows a changing number of responses around a predetermined average. For example, a VR 5 schedule averages five responses per reinforcer, but one reinforcer might follow three responses while another follows seven. The exact response requirement changes from one reinforcement opportunity to the next.
What is an example of a variable ratio schedule?
An ABA example of a variable ratio schedule is reinforcing an established skill after changing the number of correct responses. A therapist might reinforce two correct responses, then six, then three, then five. Those values average four responses, creating a VR 4 arrangement.
What is an example of a variable ratio?
An ABA example of a variable ratio schedule is reinforcing an established skill after a changing number of correct responses around a planned average. For example, a VR 5 schedule might reinforce three responses, then seven, then four, then six. Slot machines are another familiar illustration of unpredictable reinforcement, although modern machines typically operate more like random-ratio schedules because each play has a specified probability of producing an outcome.
What are the four schedules of reinforcement?
The four basic intermittent schedules of reinforcement are fixed ratio, variable ratio, fixed interval, and variable interval. Fixed ratio and variable ratio schedules depend on the number of responses, while fixed interval and variable interval schedules depend on time before a qualifying response can receive reinforcement. Fixed schedules use predictable requirements, while variable schedules change around a planned value.
