Download Learning

Learning
 Learning
“relatively permanent change in an
organism’s behavior due to experience”
HOWEVER: what most psych texts call
“Learning” the rest of us call
“motivation”
“Learning” = learning what is
rewarding and what isn’t.
Association
We learn by association
Our minds naturally connect events
that occur in sequence
Aristotle 2000 years ago
John Locke and David Hume 200 yrs
ago
Associative Learning
learning that two events occur together
two stimuli
a response and its consequences
Association
Event 1
Event 2
Learning to
associate
two events
Sea snail associates splash with a tail shock
Seal learns to expect a snack for its showy antics
Classical or Pavlovian
Conditioning
Classical Conditioning
organism comes to associate two stimuli
begins with a reflex (note that humans
don’t have many of these)
a neutral stimulus is paired (associated) with
a stimulus that evokes the reflex
neutral stimulus eventually comes to evoke
the reflex
Classical or Pavlovian
Conditioning
Ivan Pavlov
1849-1936
Russian physician/ neurophysiologist
Nobel Prize in 1904
studied digestive secretions
Maybe you’ve heard of “Pavlov’s dogs”…
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 or Pavlovian
Conditioning
Unconditioned Stimulus (UCS)
effective stimulus that unconditionallyautomatically and naturally- triggers a
response
Unconditioned Response (UCR)
unlearned, naturally occurring automatic
response to the unconditioned stimulus
salivation when food is in the mouth
Classical or Pavlovian
Conditioning
Conditioned Stimulus (CS)
previously 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
Dr Fred’s handy guide to
classical conditioning
1 – remember that humans salivate to the
smell of food just like dogs (reflex!)
2 – freshly baked donuts smell great
3 – so….
Dr Fred’s handy guide to
classical conditioning
Modern
Classical
Conditioning
Classical or Pavlovian
Conditioning
Spontaneous Recovery
reappearance, after a rest period, of an
extinguished CR
Generalization
tendency for a stimuli similar to CS to evoke
similar responses
Interstimulus interval
Time between the CS and the UCS
Optimal usually .5-5 seconds but Garcia effect!
Classical or Pavlovian
Conditioning
Blocking
 Prior learning hinders later learning
 e.g., dog learned to salivate to bell, now use a light – ineffective!
 Latent inhibition
 early exposure to a neutral stimulus without a
UCS slows later learning of a CS-UCS association
for that stimulus
Prepared learning
Some responses easier to learn - evolutionary
predisposition to that response
Operant Conditioning
(aka “Behaviorism”)
Operant Conditioning
type of learning in which behavior is
strengthened if followed by reinforcement or
diminished if followed by punishment
Law of Effect
Thorndike’s principle that behaviors followed
by favorable consequences become more
likely and behaviors followed by unfavorable
consequences become less likely
Behaviorism
John B. Watson
viewed psychology as objective
science
generally agreed-upon consensus
today
recommended study of behavior
without reference to unobservable
mental processes
not universally accepted by all
schools of thought today
Behaviorism
B.F. Skinner (1904-1990)
elaborated Thorndike’s Law of
Effect
developed behavioral technology:
The “Skinner Box”…
Operant Chamber
Skinner Box
soundproof
chamber with a
bar or key that an
animal presses or
pecks to release a
food or water
reward
contains a device
to record
responses
Operant Conditioning
= another form of associative
learning
We learn to
associate a
behavior and its
consequence
Hot stove =
pain
Some terms in both classical and
operant conditioning
Acquisition
the initial stage of learning, during which a
response is established and gradually
strengthened
in classical conditioning, the phase in which a
stimulus comes to evoke a conditioned
response
in operant conditioning, the strengthening of
a reinforced response
Some terms in both classical and
operant conditioning
Discrimination
in classical conditioning, the ability to
distinguish between a CS and other stimuli
that do not signal and UCS
in operant conditioning, responding
differently to stimuli that signal a behavior
will be reinforced or will not be reinforced
Some terms in both classical and
operant conditioning
Extinction
diminishing of a CR
in classical conditioning, when a
UCS does not follow a CS
in operant conditioning, when a
response is no longer reinforced
Operant Conditioning
Positive reinforcement
Negative reinforcement
BOTH are rewards
Both escape learning and avoidance
learning can occur with negative rein.
 Positive punishment
 Negative punishment
BOTH are punishments
Operant Conditioning
Shaping
conditioning procedure in which
reinforcers guide behavior toward closer
approximations of a desired goal
Successive Approximations
reward behaviors that increasingly
resemble desired behavior
Chaining
Stringing together sets of previously
shaped behaviors
Principles of
Reinforcement
Primary Reinforcer
innately reinforcing stimulus
satisfies a biological need
Secondary Reinforcer
conditioned reinforcer
learned through association with
primary reinforcer
Mechanisms of
Reinforcement
Drive reduction (homeostasis)
 Association (secondary reinforcers)
 Behavioral Approach System (BAS)
Distinct neural pathway for reward (left PFC)
Dopamine
Behavioral Inhibition System (BIS)
Distinct neural pathway for anxiety (right PFC)
Norepinephrine
Fight or Flight system (FFS) – sympathetic NS
Schedules of
Reinforcement
Continuous Reinforcement
reinforcing the desired response each time it
occurs
learning occurs rapidly
extinction occurs rapidly
Partial Reinforcement
reinforcing a response only part of the time
results in slower acquisition
greater resistance to extinction
Schedules of
Reinforcement
Fixed Ratio (FR)
reinforces a response only after a
specified number of responses
faster you respond the more rewards you
get
different ratios
very high rate of responding
like piecework pay
Schedules of
Reinforcement
Variable Ratio (VR)
reinforces a response after an
unpredictable number of responses
very hard to extinguish because of
unpredictability
And just in case you think this stuff
only applies to rats…
Skinner boxes for humans
Another form of variable
ratio reinforcement
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
Schedules of
Reinforcement
Variable Interval (VI)
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
Punishment
aversive event that decreases
the behavior that it follows
powerful controller of unwanted
behavior
Problems with
Punishment
Punished behavior is not forgotten, it's
suppressed- behavior returns when
punishment is no longer imminent
Causes increased aggression- shows that
aggression is a way to cope with problemsExplains why aggressive delinquents and
abusive parents come from abusive homes
Regression to the mean - fools the punisher
More Problems with
Punishment
Creates fear that can generalize to desirable
behaviors, e.g. fear of school, learned
helplessness, depression
Does not necessarily guide toward desired
behavior- reinforcement tells you what to do-punishment tells you what not to doCombination of punishment and reward can be
more effective than punishment alone
Using punishment
wisely
The “hot stove” rule:
Punishment should be:
Immediate
Consistent
Impersonal
Cognitive Learning
(aka
Cognitive-social learning)
Cognition
thinking; information processing
input - processing/storage - output
Cognition = information processing and
storage (memory)
includes judgment, motivation, emotions,
etc.
Cognitive Learning
Cognitive Map
mental representation of the layout of one’s
environment
example- after exploring a maze, rats act as
if they have learned a cognitive map of it
Latent Learning
learning that occurs, but is not apparent until
there is an incentive to demonstrate it
Social Learning
Observational Learning
learning by observing and imitating others
{opportunity to practice!}
Modeling
process of observing and imitating behavior
Vicarious reinforcement (conditioning)
observing another’s consequences
Tutelage and mentoring
Cognitive Learning (aka
Cognitive-social learning)
More on this in chapter 7…