Overview
This lecture explains the four main schedules of reinforcement—fixed interval, variable interval, fixed ratio, and variable ratio—using real-world examples and highlights their effects on behavior.
Fixed Interval Schedule
- Reinforcement is given after a specified time has passed since the correct response.
- Example: Getting paid every two weeks regardless of how much work is completed.
- Produces a "scalloped" response pattern with low rates that increase as reinforcement time approaches.
Variable Interval Schedule
- Reinforcement occurs after unpredictable time intervals following a correct response.
- Example: Waiting for an elevator, where the wait time varies.
- Results in steady and moderate rates of responding.
Fixed Ratio Schedule
- Reinforcement is provided after a set number of correct responses.
- Example: Being paid for every 100 envelopes stuffed at a job.
- Leads to high rates of response followed by a pause after reinforcement (postreinforcement pause).
Variable Ratio Schedule
- Reinforcement occurs after an unpredictable number of correct responses.
- Example: Slot machines (one-armed bandits) require a random number of lever pulls for a jackpot.
- Generates high and steady rates of responding.
Key Terms & Definitions
- Reinforcement — A consequence that increases the likelihood of a behavior recurring.
- Fixed Interval Schedule — Reinforcement after a set period of time following a response.
- Variable Interval Schedule — Reinforcement after varying time intervals.
- Fixed Ratio Schedule — Reinforcement after a set number of responses.
- Variable Ratio Schedule — Reinforcement after a changing, random number of responses.
- Scalloped Response Pattern — A pattern of responding that increases as the time for reinforcement approaches.
- Postreinforcement Pause — A break in responding after receiving reinforcement.
Action Items / Next Steps
- Review textbook sections on schedules of reinforcement.
- Prepare examples of each reinforcement schedule for class discussion.