Variable-Ratio Schedules Characteristics

Table of Contents
View All
Table of Contents

In operant conditioning, a variable-ratio schedule is a schedule of reinforcement where a response is reinforced after an unpredictable number of responses. This schedule creates a steady, high rate of responding. Gambling and lottery games are good examples of a reward based on a variable ratio schedule.

Schedules of reinforcement play a central role in the operant conditioning process. The frequency with which a behavior is reinforced can help determine how quickly a response is learned as well as how strong the response might be. Each schedule of reinforcement has its own unique set of characteristics.

How a variable ratio schedule works
Illustration by Brianna Gilmartin, Verywell


There are three common, well-known factors:

  • Leads to a high, steady response rate
  • Results in only a brief pause after reinforcement
  • Rewards are provided after an unpredictable number of responses

When identifying different schedules of reinforcement, it can be very helpful to start by looking at the name of the individual schedule itself. In the case of variable-ratio schedules, the term variable indicates that reinforcement is delivered after an unpredictable number of responses. Ratio suggests that the reinforcement is given after a set number of responses. So together, the term means that reinforcement is delivered after a varied number of responses.

It might also be helpful to contrast the variable-ratio schedule of reinforcement with the fixed-ratio schedule of reinforcement. In a fixed-ratio schedule, reinforcement is provided after a set number of responses.

So, for example, in a variable-ratio schedule with a VR 5 schedule, an animal might receive a reward for every five response, on average. This means that sometimes the reward can come after three responses, sometimes after seven responses, sometimes after five responses, and so on. The reinforcement schedule will average out to be rewarded for every five response, but the actual delivery schedule will remain completely unpredictable.

In a fixed-ratio schedule, on the other hand, the reinforcement schedule might be set at a FR 5. This would mean that for every five responses, a reward is presented. Where the variable-ratio schedule is unpredictable, the fixed-ratio schedule is set at a fixed rate.

Variable-Ratio Schedule
  • Reinforcement provided after varying set of responses

  • Delivery schedule unpredictable

  • Examples include slot machines, door-to-door sales, video games

Fixed-Ratio Schedule
  • Reinforcement provided after a set number of responses

  • Delivery schedule predictable

  • Examples include production line work, grade card rewards, sales commissions


  • Slot machines: Players have no way of knowing how many times they have to play before they win. All they know is that eventually, a play will win. This is why slot machines are so effective, and players are often reluctant to quit. There is always the possibility that the next coin they put in will be the winning one.
  • Sales bonuses: Call centers often offer random bonuses to employees. Workers never know how many calls they need to make to receive the bonus, but they know that they increase their chances the more calls or sales they make.
  • Door-to-door sales: The salesperson travels from house to house, but never knows when they are going to find an interested buyer. It could be the next house, or it might take multiple stops to find a new customer.
  • Video games: In some games, players collect tokens or other items in order to receive a reward or reach the next level. The player may not know how many tokens they need in order to receive a reward or even what that reward will be.
Was this page helpful?
3 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. James RJE, O'Malley C, Tunney RJ. Understanding the psychology of mobile gambling: A behavioural synthesisBr J Psychol. 2017;108(3):608‐625. doi:10.1111/bjop.12226

  2. Comparative Cognition Library University of Iowa. Schedule of reinforcement.

  3. Killeen PR, Posadas-Sanchez D, Johansen EB, Thrailkill EA. Progressive ratio schedules of reinforcement [published correction appears in J Exp Psychol Anim Behav Process. 2009 Apr;35(2):152]J Exp Psychol Anim Behav Process. 2009;35(1):35‐50. doi:10.1037/a0012497