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Psychology with Mr. Duez                                   CH 6: Learning - Operant Conditioning --- Schedules of Reinforcement

Operant conditioning (instrumental conditioning) involves an organism’s learned response in order to obtain a reward.

The response is an action not typically associated with obtaining a particular reward.

B.F. Skinner (Rats/Pigeons) pioneered the study of operant conditioning, although the phenomenon 1st was discovered by Edward L. Thorndike (Cats), who proposed The Law of Effect, which states that a behavior is more likely to recur if reinforced. Skinner ran many operant-conditioning experiments. He often used a specially designed testing apparatus known as a Skinner Box.

Behaviorists use various “Schedules of Reinforcement”: Specific pattern of reinforcers over time. In a continuous reinforcement schedule, every correct response that is emitted results in a reward. This produces rapid learning, but also results in rapid extinction, where extinction is a decrease & eventual disappearance of a response once the behavior is no longer reinforced.

Schedules of reinforcement in which not all responses are reinforced are called partial (or intermittent) reinforcement schedules.

RATIO = After a certain NUMBER of responses.

INTERVAL = After a certain TIME period.

Fixed-Ratio schedule: Reward always occurs after a fixed number of responses.

Produces strong learning, but the learning extinguishes relatively quickly.

Variable-Ratio schedule: Ratio of responses to reinforcement is variable & unpredictable. Reinforcement can come at any time. Takes longer to condition a response; however the learning that occurs is resistant to extinction.

Fixed-Interval schedule: Reinforcement is presented as a function of fixed periods of time, as long as there is at least one response.

Variable-Interval schedule: Reinforcement is presented at differing time intervals, as long as there is at least one response. Variable-interval, like variable-ratio, is more difficult to extinguish than fixed schedules.

Chart demonstrates the different response rate of the 4 simple schedules of reinforcement, each hatch mark designates a reinforcer being given.

When & how often we reinforce a behavior can have a dramatic impact on the strength and rate of the response.

In real-world settings, behaviors are probably not going to be reinforced each and every time they occur. For situations where you are purposely trying to train & reinforce an action, such as in the classroom, in sports or in animal training, you might opt to follow a specific reinforcement schedule.

Some schedules are best suited to certain types of training situations. In some cases, training might call for starting out with one schedule & switching to another once the desired behavior has been taught.

Fixed = Specific                                        

Variable = Unpredictable                                

Ratio = Number #                                        

Interval = Time Period                                

FR: Fixed Ratio = Specified Number # of Responses

FI: Fixed Interval = Specified Number # during Time Period

VR: Variable Ratio = Unpredictable Number # of Responses

VI: Variable Interval = Unpredictable Time Period