How do fixed-ratio and variable-ratio reinforcement schedules differ?

In operant conditioning, reinforcement schedules determine how often an animal receives a reward for a specific behavior. Both fixed-ratio and variable-ratio schedules are types of intermittent reinforcement, meaning they reward some responses but not others.1

The primary difference lies in the predictability of the reinforcement:

• Fixed-ratio schedule: Reinforcement is provided only after a set, predetermined number of correct responses have been performed.1
• Variable-ratio schedule: Reinforcement is provided after a changing or unpredictable number of correct responses.1

While both methods are used to shape animal behavior, intermittent reinforcement schedules generally produce more robust results than continuous reinforcement. Specifically, behaviors learned through intermittent schedules are significantly more resistant to extinction, meaning they are much more difficult for an animal to unlearn or discard.1