Transcript Ch6_Learning

Learning
Chapter 6
• Learning refers to a relatively durable
change in behavior or knowledge that
is due to experience
• Conditioning involves learning
associations between events that occur
in an organism’s environment
Classical Conditioning
• Pavlov’s conditioning
experiments
–Salivary responses in dogs
–Pairing of stimuli over time
Elements of Classical
Conditioning
• Unconditioned Stimulus (UCS)
• Unconditioned Response
(UCR)
• Conditioned Stimulus (CS)
• Conditioned Response (CR)
• Suzy goes outside to play in her tree house.
A swarm of bees has nested near her tree
house, and she gets stung when she climbs
up to the tree house. This happens three
times in a week. Suzy becomes afraid to go
near the tree and cries violently when her
dad tries to get her to climb up to the tree
house.
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US
UR
CS
CR
bee sting, which causes pain
escape from painful stimulus
tree house
avoidance of tree house
• A couple goes to a movie on their first date
and they have a wonderful time, eventually
getting married. Whenever they see this
movie on the late night show, they get a
tender feeling and think about each other.
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–
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US
UR
CS
CR
feelings for spouse
love
movie
tender feeling, thinking of spouse
• A student survives a plane crash that
occurred because of a thunderstorm.
Now, whenever the student hears
thunder, he gets anxious.
– US plane crash (caused by storm)
– UR fear
– CS thunderstorm
– CR anxiety
Establishing a Classically
Conditioned Response
• Repeated pairings, with close
temporal spacing leads to
establishing a response
Classical Conditioning in
Humans
• Conditioned fear and anxiety
– Phobias traced back to experiences involving
classical conditioning
• Bridge example
– Everyday anxiety responses may also be
products of classical conditioning
• Dentist’s drill example
Classical Conditioning
UCS
(passionate
kiss)
CS
(onion
breath)
CS
(onion
breath)
UCR
(“butterflies”)
UCS
(passionate
Kiss)
CR
(“butterflies”)
UCR
(sexual
arousal)
Classical Conditioning
Strength
of CR
Acquisition
(CS+UCS)
Extinction
(CS alone)
Spontaneous
recovery of
CR
Extinction
(CS alone)
Pause
Nausea Conditioning in
Cancer Patients
UCS
(drug)
UCR
(nausea)
CS
(waiting
room)
UCS
(drug)
UCR
(nausea)
CS
(waiting
room)
CR
(nausea)
Classical Conditioning
Operant Conditioning
Elements of Operant
Conditioning
• Rats in a Skinner box: Speed of correct
response increases over trials
• Law of Effect = Principle of
Reinforcement
• Punishment does not equal
Reinforcement
A Closer Look at
Reinforcement
• Positive and Negative Reinforcement
– Positive reinforces add something
rewarding to the situation
– Negative reinforcers remove an
unpleasant stimulus
• Continuous reinforcement
• Intermittent (partial) reinforcement
Schedules of Reinforcement
• Fixed-Ratio: reinforcer given after a fixed # of
nonreinforced responses
– A student receives a gold star for every 5th correct answer
• Variable-Ratio: reinforcer given after a variable # of
nonreinforced responses
– a slot machine pays out once every ten tries on the average
• Fixed-Interval: reinforcer given for 1st response that
occurs after a fixed time interval has elapsed
– Checking the refrigerator to see if the JELL-O is ready
• Variable-Interval: reinforcer is given for the 1st response
after a variable time interval has elapsed.
– A person refrains from drugs for fear of random drug testing
Schedules of Reinforcement
Number of
responses
1000
Fixed Ratio
Variable Ratio
Fixed Interval
750
Rapid responding
near time for
reinforcement
500
Variable Interval
250
Steady responding
0
10
20
30
40
50
Time (minutes)
60
70
80
• Getting a pay check every other week
– Fixed Interval
• Pop Quizzes
– Variable Interval
• Slot machines at gambling casinos
– Variable Ratio
• A factory worker who is paid on piecework
– Fixed Ratio
• Watching for shooting stars
– Variable Interval
• Buying lottery tickets
– Variable Ratio
• Looking at your watch during a lecture until the end of lecture
– Fixed Interval
• Frequent flyer program: rewards after flying X amount of
miles
– Fixed Ratio
•
1. Provide a word or term that means the same thing as
negative reinforcement:
2. Negative reinforcement…
•
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a. increases behavior.
b. decreases behavior.
c. has no effect on behavior.
3. If you were about to receive a negative reinforcement,
would you look forward to it?
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a. Yes
b. No
4. Would you use positive reinforcement with a child?
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a. Yes
b. No
5. Would you use negative reinforcement with a child?
–
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a. Yes
b. No
A Closer Look at
Punishment
• Decreases the likelihood that ongoing
behavior will recur
• Should be swift, sufficient, certain
• Generally not as effective as skillful
application of reinforcement
• Avoidance training is an alternative
strategy (negative reinforcement)
Behavioral Probability or Rate
Action
Increases
Decreases
Present
Stimulus
Positive
Reinforcement
Positive
Punishment
Remove
Stimulus
Negative
Reinforcement
Negative
Punishment
(Omission, timeout)
Factors Shared by
Classical and Operant
Conditioning
The Importance of
Contingencies
• Contingencies in classical conditioning
– a reliable “if-then” relationship must be
established between the CS and US
• Contingencies in operant conditioning
– Schedules of Reinforcement
• Fixed interval, fixed-ratio, variable-interval,
variable-ratio
New Learning Based on Original
Learning
• Higher-order conditioning
– An earlier CS becomes the US for further
learning
• Secondary reinforcers
– Primary reinforcers: reinforcement rewarding
in and of itself (food, water, warmth, affection)
– Secondary reinforcers: value is learned through
association ($, good grades, attention, flattery,
praise, applause)
Summing Up
• Classical and Operant
Conditioning both involve:
–forming associations between
stimuli and responses
–perceiving contingencies
between one event and another
Summing Up
• Main Difference is in CC the
learner is passive and behavior
is involuntary, whereas in OC,
the learner is active and
behavior involved is voluntary
Biological constraints on learning
• Instinctive drift
– Innate response tendencies interfere with
conditioning processes
– Ex. Raccoons and coins
• Conditioned taste aversion
– Natural selection favors organisms that quickly
learn what not to eat
Learning by Observing
• Social learning theory describes learning by
watching
– We are conditioned indirectly by observing others
– Vicarious learning, reinforcement, punishment
• Must have attention, retention, reproduction, and
motivation for observational learning to be
effective
• Bandura’s study is a classic example-“BoBo
dolls”