Schedules of Reinforcement

[Ready for Fall 2026]

Modified: 2026-08-03 11:07s AM CDST

• One of the major discoveries of operant conditioning was that not only do reinforcers have the power to cause responses to be made more often, but that how and when those reinforcers are delivered also affects the pattern of responses.
  • Controlling the how and when of reinforcement is a reinforcement schedule.

• Schedules are of two main types, time-based and response-based.
  • Time-based schedules usually contain the word interval, as in time interval.
  • Response-based schedules usually contain the word ratio, referring to the ratio of responses over time.
• Fixed interval (FI) schedules reinforce any response made after a given interval measured from the preceding reiforcement is reinforced.
  • A given interval is indicated by the addition of a number to the letters FI (minutes, usually).
  • Thus, in FI 15 the first response which occurs fifteen seconds or more after the preceding reinforcement is reinforced.
• Variable interval (VI) schedules reinforce any response made after a variable amount of time.
  • A VI 20 would reinforce after an average of 20 seconds, not every 20 seconds.
• Fixed ratio (FR) schedules deliver a reinforcer based upon a constant number of responses.
  • For example, a FR-10 schedule would deliver a reinforcer every 10th response.
• Variable ratio (VR) schedules are similar to fixed ratio, except that the number of responses required for a reinforcer changes each time.
  • So, a VR-15 schedule would deliver a reinforcer over an average of 15 responses, not on every 15th response.
• Let's examine some everyday examples of reinforcement schedules and their effects.
  • A paycheck is a good example of an FI schedule.
  • Workers get a check once a week, for example, if they show up and work.
  • They do not get rewarded for working harder, or penalized for working less.
• Workers who work by the piece or by the job, piecework, are paid more if they produce more, and are paid less if they produce less.
  • Piecework is an example of an FR schedule.
  • Workers typically work harder on FR schedules than they do on FI schedules.
• Gambling is the classic example of a VR schedule.
  • Part of the allure of gambling is its uncertain payoff.
  • Imagine a slot machine that paid off every 10th time; only the 10th pull would be exciting.
  • A real slot machine, on the other hand, pays off on a random basis, so each pull is exciting.
  • VR schedules maintain behavior at very high rates.
• About the best everyday example of a VI schedule that I can think of is working for a shady character.
  • This person pays you, but you never know when payday is going to be.
    • It could be a week, two weeks, a month.
    • So, you don't work very hard.
  • You would probably jump to another job if the pay were the same but given regularly.