Learning

Learning
relatively
permanent change in
behavior due to experience
 Associative
learning
 two
Learning
that two events occur together
stimuli (classical conditioning)
 a response and its consequences (operant
conditioning)
Classical /Pavlovian Conditioning
Two related events:
Stimulus 1
Lightning
Stimulus 2
Thunder
Result after repetition
Stimulus
We see
lightning
Response
We wince
anticipating
thunder

We learn to
associate two
stimuli
Operant Conditioning

Response: Pushing
vending machine button
Consequence:Receiving
a candy bar
We learn to
associate a
response and
its consequence
Learning

Behaviorism
John
B. Watson
Psychology…
 should
be an objective science
 should study behavior without
reference to mental processes
Classical/Pavlovian Conditioning
 Ivan
Pavlov
1849-1936
Russian
physician/
neurophysiologist
Nobel Prize (1904)
studied digestive secretions
Classical/Pavlovian Conditioning

Classical Conditioning
 organism
comes to associate two stimuli
lightning and thunder
 tone and food

 begins
with a reflex
 a neutral stimulus is paired with a stimulus
that evokes the reflex
 neutral stimulus eventually comes to evoke
the reflex
Classical/Pavlovian Conditioning
 Pavlov’s
device
for recording
salivation
Classical/Pavlovian Conditioning

Unconditioned Stimulus (UCS)
 stimulus
that unconditionally triggers a
response
natural & automatic
 food


Unconditioned Response (UCR)
 unlearned,
naturally occurring response to the
unconditioned stimulus


salivation when food is in the mouth
Unconditioned = Unlearned
Classical/Pavlovian Conditioning

Conditioned Stimulus (CS)
 originally
neutral stimulus that, after
association with an unconditioned stimulus,
comes to trigger a conditioned response

Conditioned Response (CR)
 learned
response to a previously neutral
conditioned stimulus

Conditioned = learned
Pavlov’s Classic Experiment
Before Conditioning
UCS (food
in mouth)
UCR
(salivation)
During Conditioning
Neutral
stimulus
(tone)
No
salivation
After Conditioning
UCS (food
in mouth)
Neutral
stimulus
(tone)
UCR
(salivation)
CS
(tone)
CR (salivation)
Classical/Pavlovian Conditioning

Acquisition
 the
initial stage of classical conditioning
 a response is established and gradually
strengthened
 associating a neutral stimulus with an
unconditioned stimulus so that the neutral
stimulus starts to evoke a conditioned
response
Classical/Pavlovian Conditioning
 Extinction
diminishing
of a conditioned
response
when an unconditioned stimulus
does not follow a conditioned
stimulus
example: if tone is repeatedly
sounded without food, dogs will
salivate less and less
Classical/Pavlovian Conditioning
Strong
Acquisition
(CS+UCS)
Extinction
(CS alone)
Spontaneous
recovery of
CR
Strength
of CR
Extinction
(CS alone)
Weak
Pause
Time
Classical/Pavlovian Conditioning

Spontaneous recovery
 reappearance,
after a rest period, of an
extinguished conditioned response

Generalization
 tendency
to respond to stimuli that are
similar to the conditioned stimulus
Generalization
Drops of saliva
in 30 seconds
60
50
40
30
20
10
0
Pelvis
Hind
paw
Thigh
Shoulder
Trunk
Front
paw
Foreleg
Part of body stimulated
Classical/Pavlovian Conditioning
 Discrimination
learned ability to distinguish between
a conditioned stimulus and other
irrelevant stimuli


dogs learned to respond to a specific tone and
not to other tones
Nausea Conditioning among
Cancer Patients
UCS
(drug)
UCR
(nausea)
CS
(waiting
room)
UCS
(drug)
UCR
(nausea)
CS
(waiting
room)
CR
(nausea)
Little Albert’s Fear
Conditioning
UCS
(loud noise)
UCR
(fear)
CS
(rat)
UCS
(loud noise)
CS
(rat)
Stimulus similar
to rat (such as
rabbit)
CR
(fear)
Conditioned fear
(generalization)
UCR
(fear)
Operant Conditioning

Operant Conditioning
 type
of learning in which organisms associate
their own actions with consequences
 behavior is strengthened if followed by
reinforcement
 diminished if followed by punishment

Law of Effect
 Thorndike’s
principle that rewarded behavior
is likely to recur
Classical vs. Operant Conditioning

Operant Behavior
 complex or voluntary behaviors

push button, perform complex task
 operates

(acts) on environment
 produces consequences
Respondent Behavior (Classical Conditioning)
 occurs as an automatic response to
some stimulus (salivating in response to
meat and a tone)
Operant Conditioning
 B.F.
Skinner (19041990)
elaborated
Thorndike’s Law of
Effect
developed behavioral
technology
Operant Conditioning

Operant Chamber
(“Skinner Box”)
 bar
pressed by
animal to obtain
food/water
reinforcement
 device attached to
record rate of
pressing
Operant Conditioning

Shaping
 Reinforcers
(e.g., food) gradually guide
actions toward a desired behavior

http://www.youtube.com/watch?v=mm5FGrQEyBY
Operant Conditioning

Reinforcer
 any
event that strengthens the behavior it
follows

Positive reinforcement
 strengthens
a response by presenting a
pleasurable stimulus

Negative reinforcement
 strengthens
a response by removing
something unpleasant
Principles of Reinforcement

Primary Reinforcer
 innate
 satisfies

a biological need (e.g., food)
Secondary Reinforcer
 conditioned
(learned)
 money; good grades

Immediate and Delayed Reinforcers
 Delayed
gratification (think back to the kids &
marshmallows video!)
Schedules of Reinforcement

Continuous Reinforcement
 reinforcing
the desired response each time it
occurs
 extinction occurs rapidly

Partial (Intermittent) Reinforcement
 reinforcing
a response only part of the time
 results in slower acquisition
 greater resistance to extinction
 gambling; occasionally giving in to tantrums
Schedules of Reinforcement
 Fixed
Ratio (FR)
 schedule
that reinforces a response only
after a specified number of responses
 the faster you respond, the more rewards
you get
 different ratios
 very high rate of responding
 like piecework pay
 example: free sub after buying 10
Schedules of Reinforcement
 Variable
Ratio (VR)
reinforces
a response after an
unpredictable number of responses
slot machines; fly fishing
very hard to extinguish because of
unpredictability
Schedules of Reinforcement
 Fixed
Interval (FI)
reinforces
a response only after a
specified time has elapsed
response occurs more frequently as
the anticipated time for reward
draws near
checking cookies in oven
Schedules of Reinforcement
 Variable
Interval (VI)
schedule
that reinforces a response at
unpredictable time intervals
produces slow, steady responding
like pop quiz
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
Punishment
 aversive
event that decreases
the behavior that it follows
Problems with Punishment

Punished behavior is not forgotten, it's
suppressed
 May
just learn discrimination (behavior not okay in
one setting, but still does it elsewhere)

Causes increased aggression
 shows
that aggression is a way to cope with
problems
Problems with Punishment




Creates fear
Does not necessarily guide toward desired
behavior
Punishment often just teaches how to avoid the
punishment
Most psychologists favor emphasis on
reinforcement
 Notice
what the individual is doing right and affirm
them for it
Operant vs Classical Conditioning
Comparison of Classical and Operant Conditioning
Classical Conditioning
Operant Conditioning
The response
Involuntary, automatic
“Voluntary,” operates on environment
Acquisition
Associating events; CS announces
UCS.
Associating response with a consequence (reinforcer or punisher).
Extinction
CR decreases when CS is repeatedly
presented alone.
Responding decreases when reinforcement stops.
Cognitive
processes
Subjects develop expectation that
CS signals the arrival of UCS
Subjects develop expectation that a
response will be reinforced or punished;
they also exhibit latent learning, without
reinforcement.
Biological
Natural predispositions constrain
predispositions stimuli and responses can easily be
associated.
Organisms best learn behavior similar to
their natural behaviors; unnatural behaviors instinctively drift back toward
natural ones.
Observational Learning

Observational Learning
 learning
by observing and imitating the
behavior of others

Modeling
 process

of observing and imitating behavior
Prosocial Behavior
 positive,
constructive, helpful behavior
 opposite of antisocial behavior
Observational Learning

Albert Bandura
 pioneer
researcher of
observational learning
 Bobo Doll Study
 http://www.youtube.co
m/watch?v=vdh7Mngn
tnI
Negative Observational Learning




antisocial effects
TV – powerful source of observational
learning
Link between viewing violence and
aggressive behavior
Desensitization – become increasingly
indifferent to violence after prolonged
exposure