Transcript Learning - North Ridgeville City Schools

LEARNING
Chapter 5
CLASSICAL CONDITIONING:
LEARNING THROUGH
ASSOCIATION
Chapter 5 Section 1
Introduction
• Do your muscles tighten at the sound
of a dentist’s drill?
• Do you suddenly begin to salivate
when passing your favorite
restaurant?
• You weren’t born with these
responses- you learned them.
Introduction
• Learning- a relatively permanent
change in behavior acquired through
experience.
• To understand learning, we need to
consider the work of the Russian
physiologist Ivan Pavlov (1849-1936).
• Pavlov discovered the form of learning
we call classical conditioning.
Introduction
• Classical conditioning is the process of learning
by which a previously neutral stimulus comes to
elicit a response identical or similar to one that
was originally elicited by another stimulus as the
result of the pairing or association of the two
stimuli.
• Ex. Pavlov rang a bell and then presented his
dogs with food. Over time, when the dogs heard
the bell, they salivated, knowing they would be
fed.
Introduction
• Because of past experiences, we are
conditioned to react in certain ways
based on those experiences.
• Although classical conditioning is a
relatively simple form of learning, it
plays an important role in our lives.
Principles of Classical Conditioning
• Pavlov performed many experiments
in classical conditioning.
• He placed food on a dog’s tongue to
create natural salivation.
• This reflexive behavior is known as
unconditioned response (UR)- an
unlearned response to a stimulus.
Principles of Classical Conditioning
• In this instance the unconditioned
stimulus (US), the stimulus that elicits
an unconditioned response, is the dog
food.
Principles of Classical Conditioning
Principles of Classical Conditioning
• In the 2nd trial, there is the introduction of a
neutral stimulus (NS), a stimulus that before
conditioning does not produce a particular
response.
• The NS may elicit other reactions (dog’s ears
turning up), but it does not salivate due to the
buzzer or bell.
• However, repeated pairings of the NS and the
unconditioned stimulus (US), the dog acquires a
learned response: salivation at the tone or buzzer
alone.
Principles of Classical Conditioning
• Salivation to the sound of a tone or buzzer
alone is an example of a conditioned
response (CR)- an acquired or learned
response to a conditioned stimulus.
• A previously neutral stimulus becomes a
conditioned stimulus (CS)- a previously
neutral stimulus that comes to elicit a
conditioned response after it has been
paired with an unconditioned stimulus.
Principles of Classical Conditioning
• Pavlov observed that the strength of
the conditioned response (amount of
saliva) increased with the number of
pairings of the CS and US.
Principles of Classical Conditioning
Principles of Classical Conditioning
Extinction and Spontaneous Recovery
• Pavlov also noticed that the
conditioned response would gradually
weaken over time when he repeatedly
presented the tone in absence of the
US (food).
• Extinction- The gradual weakening
and eventual disappearance of a
conditioned response.
Extinction and Spontaneous Recovery
• The extinguished response is not forgotten or
lost to memory, it may return spontaneously at
a later time when the animal is again exposed
to the conditioned stimulus
• Spontaneous recovery- The spontaneous
return of a conditioned response following
extinction.
• The recovered response will once again
extinguish as the CS occurs in the absence of
the US.
Extinction and Spontaneous Recovery
• Pavlov discovered that when the CS and
US are paired again after extinction, the
response is likely to be learned more
quickly than in original conditioning.
• In many cases, the animal needs only one
or two pairings.
• Reconditioning- the process of relearning a
conditioned response following extinction.
Stimulus Regeneration and Stimulus
Discrimination
• Pavlov
also found that once the dogs were
conditioned to salivate at the sound of a
tone would also salivate (although less so)
at the sound of a related stimuli (such as a
different pitch).
• This is known as stimulus generalizationthe tendency for stimuli that are similar to
the conditioned stimulus to elicit a
conditioned response.
Stimulus Regeneration and Stimulus
Discrimination
• Stimulus generalization has survival value
because it allows us to respond to a range
of stimuli that are similar to an original
threatening stimulus
• Ex. Bitten by a large dog when you were
young and now you tense up when you see
a large dog coming. Not all dogs are
dangerous, but stimulus generalization
prepares us just in case.
Stimulus Regeneration and Stimulus
Discrimination
• Stimulus generalization can also help
explain feelings of déjà vu.
• The feeling of familiarity in novel situations
may involve a process of conditioning in
which responses are evoked by
generalization stimuli in these new
environments that resemble conditioned
stimuli encountered before.
Stimulus Regeneration and Stimulus
Discrimination
• Stimulus discrimination- the ability to differentiate
among related stimuli, represents the opposite
side of the coin to stimulus generalization.
• Ex. If an animal is being tested and is given a
shock after hearing a certain tone, the animal will
become afraid after it hears the tone (cowers or
urinates). Even if the tone is heard and no shock
is given, the animal will become scared, but if a
different tone is played (similar to the fear
inducing one) the animal will remain calm.
Stimulus Regeneration and Stimulus
Discrimination
• Stimulus discrimination in daily life allows
us to differentiate between threatening and
nonthreatening stimuli.
• Ex. Through repeated non-eventful
encounters with the Labrador who lives
next door, we understand that we may only
need to react with fear to unfamiliar large
dogs.
Stimulus Regeneration and Stimulus
Discrimination
Conditioned Stimulus
A large white dog
Conditioned Response
Child displays fear
Stimulus Generalization
The child cringes when a small,
white dog appears
Stimulus Discrimination
The child shows no
Fear of a small, brown dog
Stimulus Characteristics That Strengthen
Conditioned Responses
• Psychologists have identified several key
factors relating to the timing and intensity of
stimuli that serve to strengthen conditioned
responses:
• Frequency pairings- The more often the CS is
paired with the US, the stronger and more
reliable the CR will be.
• Timing- The strongest CRs occur when the CS
is presented first and remains present
throughout the administration of the US
Stimulus Characteristics That Strengthen
Conditioned Responses
• Intensity of US- A stronger US will typically
lead to faster conditioning than a weaker
one.
• Ex. A puff of air (US) may be delivered after
a tone. The puff will produce a blink (UR).
After a few pairings, you will blink (CR)
once you hear the tone (CS) alone. A
stronger air puff will lead to faster
conditioning.
A Cognitive Perspective on Classical
Conditioning
• Psychologist Robert Rescola argued that
conditioning depends on a cognitive factor- the
informational value of a conditioned stimulus as a
reliable signal for predicting the occurrence of the
US.
• Humans and animals actively seek information
that helps them make predictions about important
events in their environments.
• Ex. If an animal catches a scent known to be
associated with a predator, it can respond quicker
and leave the situation.
Why It Matters
• Classical conditioning helps us explain
such diverse behaviors as phobias,
drug cravings, and taste aversions.
• In 1919, John B. Watson discovered
that fear response could be acquired
through classical conditioning.
Classical Conditioning of Fear Response
• http://www.youtube.com/watch?v=Xt0ucxOrPQE&safety_
mode=true&safe=active&persist_safety_mode=1
• Before Conditioning- Child shows no fear of
white rat.
• During Conditioning- White rat (CS) is
paired with loud sound (US) that naturally
evokes fear response.
Classical Conditioning of Fear Response
• After Conditioning- Child shows fear
(CR) of white rate alone (CS).
• Stimulus Generalization- Child shows
fear reaction (CR) to related stimulus.
• Findings have helped explain phobias
and the development of therapy
known as behavior therapy
(OCD/phobias).
Classical Conditions of Positive Emotions
• Classical Conditioning can also be used for
positive feelings.
• Hearing a sound may evoke past
experiences associated with pleasant
emotions.
• Feelings of nostalgia may be brought up by
something as simple as catching a whiff of
a familiar perfume or cologne.
Classical Conditioning of Drug Cravings
• Drugs cravings may be elicited by cues in the
environment that were associated with
previous drug use.
• Ex. A former alcoholic may experience strong
cravings when they pass a bar or meet up with
former friends whom they’ve drank with.
• Cravings may represent conditioned
responses that continue to be elicited long
after the physiological signs of withdrawal
have passed.
Classical Conditioning of Drug Cravings
• Studies have shown that people with
alcoholism salivate more at the sight
and odor of alcohol than nonalcoholic
subjects.
• Drug counselors encourage
recovering alcoholics and drug addicts
to avoid cues associated with their
former drug use patterns.
Classical Conditioning to Taste Aversion
• Psychologist John Garcia was the first to
demonstrate experimentally the role of classical
conditioning in the acquisition of taste aversions.
• Garcia noticed that lab rats developed an
aversion, or “conditioned nausea” to flavored
water when it was coupled with nauseaproducing radiation.
• The radiation is the US; the nausea it produces is
the UR; the flavored water is the CS; and the
aversion (nausea) the CS elicits on its own is the
CR.
Classical Conditioning to Taste Aversion
• What Garcia also found is that the US (nausea
inducing stimulus) could be presented hours
after the CS (food taste) and still have the
same result.
• What does this mean? Prior to this, it was
thought that the US had to immediately follow
or precede the CS to give the intended results.
• This explains why we may shy away from
foods that we’ve eaten prior to getting sick
(either from food poisoning or other reasons).
Classical Conditioning to Taste Aversion
• Taste aversion has practical uses for survival
as well.
• Ex. Our ancestors lived without refrigeration or
preservatives. When they ran across rancid
smells and the ensuing tastes sickened them,
they knew not to eat foods that smell like that
in the future.
• Ex. Injecting sheep carcasses with poison so
that coyotes would stop attacking live sheep.
OPERANT CONDITIONING:
LEARNING THROUGH
CONSEQUENCES
Chapter 5 Section 2
http://www.youtube.com/watch?v=DUa_F2OJT0k&safety_mode=tr
ue&safe=active&persist_safety_mode=1
http://www.youtube.com/watch?v=tMMNkxxXVKI&safety_mode=tru
e&safe=active&persist_safety_mode=1
Introduction
• Whereas classical conditioning explores
learning that results from association
between stimuli before a response occurs,
operant conditioning explores learning that
results from the association of a response
with its consequences.
• Responses are acquired and strengthened
by the effects they produce in the
environment.
Thorndike and the Law of Effect
• Edward Thorndike (1874-1947)
constructed a device called a “puzzle
box”- a cage in which an animal
(usually a cat) had to perform a simple
act (pulling a looped string or pushing
a pedal) in order to make its escape
and reach a food dish placed within its
view just outside the cage.
Thorndike and the Law of Effect
• The animal would first engage in seemingly
random behaviors until accidentally
performing the response that released the
door.
• Thorndike argued that the animals did not
employ any reasoning, insight, or any other
form of higher intelligence.
• He said it was through trial and error that they
chanced upon their successful behavior.
Thorndike and the Law of Effect
• Successful responses were then “stamped in”
by the pleasure they produced and became
more likely to be repeated in the future.
• Based on his observations, Thorndike
proposed the Law of Effect- responses that
have satisfying effects are more likely to recur
(reward), while those that have unpleasant
effects are less likely to recur (punishment).
• http://www.youtube.com/watch?v=fanm--
WyQJo&safety_mode=true&safe=active&persist_safety_mode=1
B.F. Skinner and Operant Conditioning
• http://www.youtube.com/watch?v=SUwCgFSb6Nk&safety_mode=true&safe=
active&persist_safety_mode=1
• Though Thorndike laid the foundation for
learning through consequences, it was B.F.
Skinner (1904-1990) who developed a
more formal model of this type of learning,
which he called operant conditioning.
• Skinner was the most famous psychologist
of his time, but he was also the most
controversial.
B.F. Skinner and Operant Conditioning
• Skinner believed in radical behaviorism,
which says that behavior, whether animal
or human, is completely determined by
environmental and genetic influences.
• Free will, according to Skinner, is but an
illusion.
• Skinner was different from Pavlov in that he
wanted to understand how new behaviors
were learned.
B.F. Skinner and Operant Conditioning
• Skinner developed the Skinner box, which was a
cage that contains a food-release mechanism the
animal activates when it responds in a certain
way- ex. Pressing a lever or pushing a button.
• http://www.youtube.com/watch?v=I_ctJqjlrHA&safety_mode=true&safe=activ
e&persist_safety_mode=1
• Operant conditioning is also called instrumental
learning since the behavior is instrumental in
bringing about rewarding consequences.
• These behaviors have a reinforcer- a stimulus or
event that increases the likelihood that the
behavior it follows will be repeated.
B.F. Skinner and Operant Conditioning
• Skinner observed that the longer the
reinforcement is delayed, the weaker its
effects will be.
• Skinner also showed how operant conditioning
can explain some forms of superstitious
behavior.
• Ex. A baseball player who hits a homerun after
a long slump and then wears the same pair of
socks he had on at the time for good luck in
the rest of his games.
Positive and Negative Reinforcement
• Positive reinforcement- A response is strengthened by the
introduction of a stimulus after the response occurs.
• Ex. You are more likely to continue to study if you see
your efforts rewarded in the form of good grades. If you
study and fail, you are less likely to continue to study.
• Negative reinforcement- A response is strengthened when
it leads to the removal of an “aversive” (unpleasant or
painful) stimulus.
• Ex. A parent picks up a crying baby to comfort it is
negatively reinforced when the baby stops crying because
the aversive stimulus (crying) is being taken away.
Positive and Negative Reinforcement
• The difference between the two is that
in the positive reinforcement,
behaviors are strengthened when they
are followed by the introduction of a
stimulus, whereas in negative
reinforcement, behaviors are
strengthened when they lead to the
removal of a stimulus.
Positive and Negative Reinforcement
• Negative reinforcement can have undesired
effects in some situations.
• Ex. A child throws a tantrum in a store because he/she
wants a certain toy. The child may have learned that
throwing a tantrum will get the results he/she desires. In
operant learning terms, when the tantrum gets results, the
child is positively reinforced (because the parent “gives
in”), while the parent is negatively reinforced for
complying with the child’s demands because the tantrum
stops. Because it is handled this way, tantrums will occur
more frequently.
Primary and Secondary Reinforcers
• Primary reinforcers- Rewards that satisfy
basic biological needs and drives.
• Ex. Food, water, sleep, relief from pain or loud noise, oxygen, sexual
stimulation, and novel visual stimuli.
• Secondary reinforcers- Reinforcement
through a learning process by which they
become associated with primary
reinforcers.
• Ex. Money is a secondary reinforcer because it acquires
reinforcement value because we learn it can be exchanged for more
basic reinforcers (food, clothing, etc.)
Primary and Secondary Reinforcers
• Other types of secondary reinforcers
include good grades, awards, and
praise.
• Much of our daily behavior is
influenced by secondary reinforcers in
the form of expressions of approval
from others.
Discriminative Stimulus
• Discriminative stimulus- A cue that signals that
reinforcement is available if the subject makes a particular
response.
• Ex. When is it better to ask someone for a favor, when
someone appears to be down in the dumps or when
someone is smiling? We know the answer because we
know that facial cues serve as discriminative stimuli that
signal times when requests will likely be positively
received.
• Ex. A green traffic light is discriminative stimulus in that it
signals that driving through an intersection is likely to be
safe.
Shaping
• Shaping- The process of learning that
involves the reinforcement of
increasingly closer approximations of
the desired response.
• Ex. The experimenter may reinforce
the rat when it moves to the part of the
cage that contains the bar.
Shaping
• Then reinforcement only occurs when
the rat moves closer to the bar until it
actually presses the bar.
• Ex. Think of how we solve multi-step
math problems.
Schedules of Reinforcement
• One of Skinner’s major contributions
was showing how schedules of
reinforcement- predetermined plans
for timing the delivery of
reinforcement- influence learning.
• Schedule of Continuous
Reinforcement- Reinforcement follows
each instance of operant response.
Schedules of Reinforcement
• Most rapid way of learning, but is the
quickest way to extinction when
reinforcement is withheld.
• Ex. Every time the rat presses the
lever, it gets food.
Schedules of Reinforcement
• Schedule of Partial Reinforcement-
Only a portion of responses are
reinforced.
• Response takes longer to fade out
because absence of reinforcement is
unlikely to be noticed.
Schedules of Reinforcement
• 2 types of partial reinforcement:
• Ratio schedules- reinforcement is based on
the number of responses
• Interval schedules- reinforcement based on
the timing of responses
• For each, reinforcement can be
administered on either fixed or variable
basis.
Fixed-Ratio (FR) Schedule
• Reinforcement is given after a certain
number of responses.
• FR schedules produce a constant, high
level of response, with a slight dip in
responses occurring after each
reinforcement.
• Ex. The faster people work, the more items
they produce and the more money they
earn, but quality may suffer.
• www.betabunny.com/behaviorism/FRS.htm
Variable Ratio (VR) Schedule
• Reinforcement is given at varying
times throughout the schedule.
• Produces high, steady rates of
response.
• Ex. If VR is 20, reinforcement is given
after an average of every 20
responses.
Variable Ratio (VR) Schedule
• Ex. Gambling on slot machines may
win (reinforcement) may occur after
different numbers of tries.
• www.betabunny.com/behaviorism/VRS.htm
Fixed-Interval (FI) Schedule
• Reinforcement is given only for a
correct response made after a fixed
amount of time has elapsed since the
last reinforcement.
• Produces a “scalloped” pattern in
which the rate of response typically
dips just after reinforcement and then
increases as the end of the interval
approaches.
Fixed-Interval (FI) Schedule
• Ex. Workers who receive monthly
performance reviews may show more
productive behaviors in the days
leading up to their evaluations than
immediately afterward (cops and
speeding tickets at end of the month).
• http://www.betabunny.com/behaviorism/FIS.htm
Variable-Interval (VI) Schedules
• Reinforcement is given after a specific
amount of time has elapsed.
• Produces a slow but steady rate of
response and tends to be more
resistant to extinction than on a FI
schedule.
Variable-Interval (VI) Schedules
• Ex. If the VI is 60, reinforcement is
given after an average of 60 seconds
has elapsed (could be as short as 1
sec. or as long as 120 sec.).
• Ex. Teachers use surprise “pop”
quizzes to encourage regular study
habits.
Escape Learning and Avoidance Learning
• Escape learning- Learning behaviors that
allow an organism to escape from an aversive
stimulus.
• Ex. We escape from heat of a summer day by
turning on a fan or air conditioning.
• Avoidance Learning- The organism learns
to perform a response that avoids an
aversive stimulus.
• Ex. We open an umbrella before stepping
outside into rain to avoid the unpleasantness
of being drenched.
Punishment
• Skinner observed that behaviors that are not
reinforced or that are punished are less likely
to be repeated.
• Punishment is the flip side to reinforcement.
• Punishment is different than negative
reinforcement in that punishment is the
introduction of an aversive stimulus or
negative consequence (e.g. a timeout) after a
behavior that occurs weakens or suppresses
the behavior.
Punishment
• Negative reinforcement is the removal of an
aversive stimulus (a baby’s crying) after a
behavior occurs strengthens the behavior
(picking up the baby).
• Psychologists and pediatricians encourage
parents not to rely on punishment, but they
recommend reinforcing desirable behaviors.
• Punishment is more effective when combined
with positive reinforcement for desirable
alternative behaviors.
Behavior Modification: Putting Learning
Principles into Practice
• Behavior modification (B-mod): The
systematic application of learning principles to
strengthen adaptive behavior and weaken
maladaptive behavior.
• Skinner and his colleagues used the first
token economy program in a mental hospital.
• Token Economy- tokens were earned for
performing desired behaviors can be
exchanged for positive reinforcers (extra
privileges).
Programmed Instruction
• Programmed Instruction- A learning method
in which complex material is broke down
into a series of small steps that learners
master at their own pace.
• Over the years, this has given way to
computer-assisted instruction, in which a
computer guides students through an
inventory of increasingly more challenging
questions.