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Operant Conditioning I
Priscilla the Fastidious Pig
• http://www.youtube.com/watch?v=y6tpXC2mwlQ
Thorndike and Law of Effect
• Rewarded behavior is likely to occur
B. F. Skinner
“Operant conditioning shapes behavior as a sculptor shapes a lump of clay”
It’s all a matter of consequences
Operant Conditioning
• Learning where responses come to be controlled by their consequences
– Classical conditioning = regulating reflexive, involuntary responses
– Operant conditioning = voluntary responses
Skinner = Pigeons
• http://www.youtube.com/watch?v=vGazyH6fQQ4
What the what!? How did he do that?
• http://www.youtube.com/watch?v=TtfQlkGwE2U
• Shaping and reinforcement– Shaping – operant technique, reward for
closer and closer approximation of desired response
Skinner says…• Organisms tend to repeat
responses that are followed by favorable consequences
– Understood best through idea of reinforcement – response is strengthened because it leads to rewarding consequences
– Defined AFTER THE FACT
Response: Go to Chipotle for a meal
Rewarding stimulus presented: Most delicious meal you will ever have… ever
Tendency to patronize Chipotle increases
Response: Tell jokes Rewarding stimulus presented: Friends laugh
Tendency to tell jokes increases
REINFORCEMENT IN OPERANT CONDITIONING
Primary vs. Secondary Reinforcers
Generalization vs. Discrimination
• Which is which?
1) Kids only ask parents for sweets when they know the parents are in a good mood.
2) A cat runs into the kitchen whenever a can opener is being utilized
Basic Processes in Classical and Operant Conditioning
VS.
Operant Conditioning II
Fixed-ratio schedule
• A rat is reinforced for every tenth lever press
• A salesperson receives a bonus for every fourth gym membership sold
Variable-ratio schedule
• A slot machine in a casino pays off once every six tries on the average. – The number of winning responses between
payoffs varies greatly from one time to the next.
Fixed-interval schedule
• A man washing his clothes periodically check to see whether each load is finished– The reward (clean clothes) is available only
after a fixed time interval– The man who checks his laundry before it is
completed in the cycle does not receive reinforcement of clean clothes… because they’re not done yet
Variable-interval schedule
• Person wants to win a radio contest, so calls the station and gets a busy signal– Getting through to the DJ is the reinforcer
• A rat is reinforced for the first lever press after a 1 minute interval, but the following intervals are 3 min, 2 min, and 4 min (average of 2 min)
Conclusion:
• Faster responding leads to reinforcement sooner when ratio is in effect
• Variable schedules tend to generate steadier response rates– Greater resistance to extinction
Operant Conditioning II
Positive vs. Negative Reinforcement
• Study hint – THEY BOTH HAVE THE WORD REINFORCEMENT IN IT – so it has to REINFORCE the behavior either way
• Positive reinforcement: response is strengthened because it is followed by the presentation of a rewarding stimulus
– Ex: good grades, tasty meals, paychecks, scholarship, promotions, nice clothes, attention, flattery
• Negative Reinforcement: occurs when a response is strengthened because it is followed by the removal of an aversive stimulus– ex: you rush home in winter to get out of the
cold, you clean a house to get rid of a mess, you give in to an argument to avoid an unpleasant situation
REINFORCEMENT IS REINFORCEMENT
• Both positive and negative reinforcement involve a favorable outcome that
STRENGTHENS a response tendency
Positive vs. Negative Reinforcement in a Skinner Box
+
-
Behavior Consequence
Response: Press lever
Response: Press lever
Rewarding stimulus presented: food delivered
Aversive Stimulus removed: shock turned off
Tendency to press lever increases
Tendency to press lever increases
Negative reinforcement applications1. Escape learning: organism acquires a
response that decreases or ends some aversive stimulation– Ex: you leave a party where you were getting
picked on by peers
2. Avoidance learning: organism acquires a response that prevents some aversive stimulation from occurring– Ex: you quit going to parties because of your
concern about being picked on
How does avoidance learning present an example of how classical conditioning and operant conditioning work together to regulate behavior?
Ex: Rat, shuttle box, shock
Punishment: Consequences that weaken responses
• Punishment: occurs when event following a response weakens the tendency to make that response
– Super easy to mix-up– How is this different from negative
reinforcement?
Punishment examples:
1) If you wear a new outfit and your classmates make fun of it, your behavior will have been punished and your tendency to wear the same clothing will probably decline.
2) If you have a bad meal and a restaurant, your response will have been punished, and you will be less likely to go to the restaurant again.