Learning Objective

Explain the four major reinforcement schedules (fixed interval, variable interval, fixed ratio, variable ratio) and predict the typical behavioral patterns and resistance to extinction produced by each.

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Reinforcement Schedules

Reinforcement schedules determine how often a behavior is followed by reinforcement. They strongly influence the rate of responding and resistance to extinction.

There are two major categories: interval schedules (based on time) and ratio schedules (based on number of responses).

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Interval Schedules

Reinforcement depends on the passage of time, not the number of responses.

Fixed Interval (FI)

Reinforcement is delivered after a fixed, predictable amount of time has passed.

Behavior pattern: Slow responding after reinforcement, then accelerates as the interval ends (“scalloped pattern”).

Examples:

• Weekly paycheck
• Holiday-season bonus
• Weekly quiz
• Gift with each weekly purchase

Variable Interval (VI)

Reinforcement is given after unpredictable time intervals.

Behavior pattern: Steady, moderate rate of responding.

Examples:

• Surprise bonus
• Pop quiz
• Waiting for your favorite song on the radio

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Activity

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Ratio Schedules

Reinforcement depends on the number of responses performed.

Fixed Ratio (FR)

Reinforcement is given after a set number of responses.

Behavior pattern: High response rate with a short pause after reinforcement.

Examples:

• Piecemeal work
• Free sandwich after buying 10 sandwiches
• $5,000 bonus after every 5 cars sold

Variable Ratio (VR)

Reinforcement is delivered after a changing and unpredictable number of responses.

Behavior pattern: Very high response rate and maximum resistance to extinction.

Examples:

• Slot machines
• Door-to-door sales
• Unknown/undisclosed sales bonus

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Activity