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GENERAL PSYCHOLOGY
Lecture 6
LEARNING
Visiting Assistant PROFESSOR YEE-SAN TEOH
Department of Psychology
National Taiwan University
Unless noted, the course materials are licensed
under Creative Commons AttributionNonCommercial-ShareAlike 2.5 Taiwan (CC
BY-NC-SA 3.0)
LEARNING
Habituation
Classical Conditioning
Operant Conditioning
Habituation
• The decline in an organism’s response to a stimulus once
the stimulus has become familiar.
• Important function – Helps us ignore old news to allow us
to pay attention to unfamiliar stimuli that may signal
danger or an unexpected opportunity.
• Ignore inputs that are already familiar & unimportant and
focus on the novel inputs.
Dishabituation
• Increase in organism’s response to a familiar stimulus
caused by a change in the stimulus.
• Important function – calls attention to newly arriving
information, which may signal danger or an unexpected
opportunity.
CLASSICAL CONDITIONING
Pavlov’s Dogs
wikipedia:
ИльяГо(грохотайло)
History
• Pavlov was studying digestive physiology by studying the
secretion of saliva in dogs.
• Found that salivation could be triggered by formerly
neutral stimuli, like the sight of a food dish.
2 types of responses & 2 types of stimuli
UR
• Unconditioned
Response
US
• Unconditioned Stimulus
CR
• Conditioned Response
CS
• Conditioned Stimulus
Unconditioned Response (UR)
• Biologically determined reflex.
• Triggered by a certain stimulus independent of
learning.
• E.g. Salivation occurs reflexively when food is
placed in the mouth.
• Salivation = UR
• Food in mouth = US
Unconditioned Stimulus (US)
• Trigger for Unconditioned Response.
• E.g. Food in mouth is the trigger for the dog to
salivate
Unconditioned
Linkage between the US & UR is
biological, nor learned.
Conditioned Response
• Response triggered by some initially neutral stimulus (CS)
as a result of pairings between that CS and an
unconditioned stimulus (US).
• The CR is typically not identical to the UR, although it is
often similar to it.
• E.g. If food in dog’s mouth (US) is paired with the sound
of a bell (CS), the dog will salivate (UR), with repeated
pairings, soon the dog will salivate (CR) to the sound of a
bell (CS).
• The CR will be less intense than the UR.
Conditioned Stimulus
• Initially neutral, that comes to elicit a new response to
being associated with the unconditioned stimulus (US)
through repeated pairings.
• E.g. If a neural stimulus, like the sound of a bell (CS) is
paired with a US, like food placed in the mouth, the CS
will be associated with the US, and the dog will salivate at
the CS.
Conditioned
Linkage between the CS & CR is learned
through conditioning
(associating the CS with the US)
Acquisition of Conditioned Responses
Learning is Gradual
The strength of the CR slowly grows as the animal
experiences more and more pairings of the the CS
& US.
Second-Order Conditioning
• A neutral stimulus is paired with some already established
CS and through repeated pairings, the new CS begins to
elicit the CR.
Learn to associate Bell + Food (1st order)
Learn to associate Light + Bell (2nd order)
Light becomes signal for bell which is
associated with food
Characteristics of Classical Conditioning
Extinction
Generalization
Discrimination
Contingency
Extinction
• Weakening of the CS to elicit the CR, due to unreinforced
presentations of the CS.
• Undo previously learned CR, so that the response will no
longer be produced.
• CR will eventually disappear if the CS is presented
several times by itself, without the US.
• Extinction does not mean forgotten.
• Mere passage of time is not enough to undo
conditioning.
• Animal learns that the association between the
CS and UR is no longer active.
• But………
• If we pair the US with the CS again, we can
recondition the animal.
• Reconditioning occurs much more quickly,
because the animal retains some memory of the
CS.
• When animal remembers that the CS used to
signal the US and produces the CR in anticipation
that the CS might signal the US again =
spontaneous recovery
Example of Extinction & Spontaneous
Recovery
Treating Anxiety Disorders Using Exposure Therapy
•Person is exposed to a specific stimulus or situation (CS)
that has been a source of anxiety (e.g. heights, elevators)
•But person is kept safe and comfortable so there is no
fearful US associated with the CS.
•Repeated pairings (CS without US) = extinction of the CR
(feelings of anxiety).
•However, if after some time the person is suddenly
exposed to the CS, the CR might follow.
Stimulus Generalization
• Animals respond to a range of new stimuli, provided that
these stimuli are sufficiently similar to the original CS.
• E.g If a light (CS) has been conditioned to elicit salivation
(CR), the dog may salivate even if the light is slightly
brighter or slightly dimmer than the original CS.
• However, the greater the distance between the new
stimulus and the original CS (e.g. very loud bell and very
soft bell), the weaker the CR will be.
Discrimination
• Process of learning to respond to certain stimuli that are
reinforced, and not to others that unreinforced.
• Example:
Red light (CS) is paired with the blast of a horn (US) which
produces a startled response (UR).
Red light alone (CS) produces startled response (CR).
Alternate trials of red light plus horn and orange light and
no horn = animal learns to discriminate the colors and will
only startle to red light.
CS as a Signal
• The rate at which conditioning develops depends on how
the CS and the US are related to each other in time.
Rate of Presentation
Effectiveness of Pairing
US Before CS
Not Effective
CS & US Simultaneously
Less Effective
US shown few sec after CS
Effectiveness Declines Sharply
US presented 0.5 Sec after CS
OPTIMUM
• CS warns (signals) the organism that the US is coming so
it can prepare itself.
• If the CS and US are presented too far apart, the
organism might not connect the CS with the US.
• IF CS & US occur simultaneously, or if US comes before
CS – CS cannot signal that the US is coming (it’s already
happened)
Contingency
Contingency
•Contingent relationship exists when one stimulus (CS)
reliably occurs when another stimulus (US) is about to
appear.
•First stimulus can be used to accurately predict the arrival
of the US.
Contiguity
•When stimuli occur close together in time.
•Appears that the CR is acquired only when the CS predicts
what is going to follow.
Surprise & Expectations
• If an animal is in a situation in which the CS is followed by
the US 90% of the time, the animal will end up with strong
expectations for what’s going to happen next whenever it
happens.
• Animals have a set of expectations based on experience.
Relationship between the CR & UR
• CR and UR are not the same.
• Animal reacts differently to CS than the US.
• CS tells animal to get ready so the CR is the adjustment
the animal makes in preparation for the US.
• Example: Bell (CS) signals food (US) so mouth is
moistened (CR) in anticipation – the food (US) then
produces more saliva.
EXAMPLE OF CLASSICAL
CONDITIONING
Body’s Responses to Drugs
Conditioning & Compensatory Responses
• Drug tolerance
o Decrease in the response to a drug, usually resulting from
continued use.
• Drug dependence & cravings
o Inability to function without the drug.
o Overwhelming desire for yet another dose.
o Cravings accompanied by increased sensitivity to pain.
o Depression.
o Overproduction of fluid in person’s mouth & mucus
membrane.
Homeostasis – Stable environment that exists
inside our bodies.
• US = Heroin
• UR = Body’s natural response to the drug.
• CS = Stimuli that signal the drug is about to arrive (sight
of needle, thought about drug)
• CR = Opposite of the UR – since body’s mechanisms of
homeostasis want to cancel out the effects of the drug.
Body’s Compensatory Response
• Internally produced response.
• Body seeks to reduce the effects of some external
influence by producing a reaction opposite in its
characteristics to those of the external influence.
Example:
• CS causes body to produce an increase in pain sensitivity
in response to decrease in pain sensitivity caused by
heroin = cancels out heroin’s reaction & produces drug
tolerance & homeostasis.
• No compensatory response when exposed to drug for the
first time.
• After repeated exposures to the drug, learning occurs,
and the compensatory response occurs.
• Person preserves homeostasis but also gets drug
tolerance effects.
Drug cravings
• When a compensatory response occurs because the
body is anticipating the arrival of the drug, but no drug is
actually available…
• Person will experience the compensatory response on its
own – depression, pain sensitivity – drug cravings.
OPERANT CONDITIONING
Skinner
Thorndike & the Law of Effect
Edward Thorndike’s photo
courtesy of Science Photo
Library
Cats in a Puzzle Box
• Problem for cat to
solve.
• How to open door
and escape from box
to get reward.
• Cats learnt solution
gradually, with no
sudden improvement.
Law of Effect
• The tendency of a stimulus to evoke a response
is
i. Strengthened if the response is followed by
reward.
ii.Weakened if the response is not followed by
reward.
• If an animal makes a response and reward
follows shortly, the response is more likely to be
performed again.
Skinner & Operant Behavior
• Operants = Instrumental response defined by the effect it
has (the way it operates) on the environment.
i. Operant followed by a positive consequence is more likely
to be repeated in the future.
ii.Operant followed by a negative consequence is less likely
to be repeated in the future.
Behavior can be changed by providing or removing
rewards and punishments.
Classical Conditioning
Operant Conditioning
Builds on a response (UR)
that is automatically
triggered reflexively by a
stimulus (US)
Involves behaviors that are
voluntary.
Learning the association
between two stimuli (US &
CS)
Learning the association
between response and
stimulus (the operant and a
reward)
Learning trials typically
involve presentation of CS
followed by a US
Learning trials typically
involve a response followed
by a reward or reinforcer.
Reinforcers
• Presentation of something good or the termination or
prevention of something bad.
• Increases likelihood of the response occurring again.
Examples
• Receiving something good
gold stars, praise, etc.)
• Termination or prevention of
something bad (avoiding being
terminating loud noise)
(candy,
grounded,
A Reinforcer can generally be
determined only after a trial:
If a response is repeated to gain the
reward…the stimulus is a reinforcer.
Discrimination
• Discriminative stimuli = external stimuli that signal a
particular relationship between a response and the
reinforcer.
• Positive discriminative stimulus (S+)
• Negative discriminative stimulus (S-)
Example:
• Green light = S+ when it signals to a bird that it will get
food if it hops on a lever.
• Red light = S- which indicates that action will not lead to
reward.
Generalization – same as CC
• Animals respond to a range of new stimuli, provided that
these stimuli are sufficiently similar to the original
discriminative stimulus S+.
• However, the bigger the difference between the new
stimulus and the original S+ (e.g. very bright light and very
dim light), the weaker the response will be.
Contingency – Same as CC
• There needs to be some predictive relationship.
• Response needs to be predictive of the reward,
so that the probability of getting the reward after
the response is greater than the probability of
getting the reward without the response.
• Predictability helps give animal control.
LEARNED
HELPLESSNESS
A Contingency Breakdown
What is learned helplessness?
• Condition created by exposure
to inescapable, aversive events.
• Impairs or prevents learning in
subsequent situations in which
escape or avoidance is possible.
• If there is no contingency
between acts and outcomes –
no point in trying.
Seligman’s Dog Study
• Two groups of dogs received same amount
of electric shocks.
• 1 group given control – could turn off shock by pressing a
panel.
• 1 group had no control.
• Dogs with control in 1st task learned to escape & avoid
shocks in next task.
• Dogs with no control in 1st task did not try to escape in next
task.
BEHAVIORAL CONTRAST &
MOTIVATION
Behavioral Contrast
• Organism seems to evaluate a reward relative to other
rewards that are available or that have been available
recently.
• Example: A teen is not likely to be willing to sweep the
floors for $100 if he received $200 the last time he swept
the floors.
Motivation according to type of reward
INTRINSIC
• Reward serves some internal
need.
• Engage in activity because of
the pleasure of the activity.
EXTRINSIC
• Reward serves some external
need.
• Under control of experimenter.
Schedules of Reinforcement
• Rules about how often and under what conditions a
response will be reinforced.
• Ratio Schedule – person/animal is rewarded for producing
a certain number of responses.
• Interval Schedule – Person/animal is rewarded for
producing a response after a certain period of time has
passed.
LATENT LEARNING
LEARNING THAT TAKES PLACE WITHOUT
ANY CORRESPONDING CHANGE IN
BEHAVIOR….
Tolman’s Rats
• Had rats exploring a maze without a reward for 10 days.
• No change in behavior.
• On 11th day, gave food as a reward for getting to the end
of the maze.
• The rats ran to the end virtually without error.
• Knowledge of maze acquired but not used until a
reward was given to motivate the rats.
OBSERVATIONAL
LEARNING
Observational Learning
• Process through which we watch how others
behave and learn from their example.
• This type of learning is found in many species.
Mirror Neurons
• Located in frontal lobe, near
motor cortex
• Fire whenever an animal performs an action, and
whenever the animal observes someone else
performing the same action.
Bandura’s Classic Bobo Doll Study
(1969,1977)
• Children who had observed an
adult behaving aggressively with
a Bobo doll were more likely to
behave aggressively with the
Bobo doll…
• Compared with children who
viewed an adult who did not
behave aggressively with the
Bobo doll.
AP Psychology Learning
Neural Basis for learning
Where?
• Brain circuits underlying fear conditioning are centered in
the amygdala.
• Brain circuits underlying eyeblink conditioning are
centered in the cerebellum.
• Conditioning with a long delay between the CS and the
US typically involves the hippocampus.
Neural Plasticity
• Capacity for neurons to change the way they
function as a consequence of experience.
• Involves changes at the synapse – how neurons
communicate with each other.
Presynaptic Facilitation
• Some neurons, after learning, end up sending a
stronger signal than they did before.
• May release more neurotransmitter than they did
before learning.
Postsynaptic Changes
Long-term Potentiation (LTP)
•Postsynaptic neuron becomes more sensitive (potentiated)
to the signal received from the presynaptic neuron, which
lasts for days or weeks (long-term).
Formation of New Synapses
• Learning can lead to the creation of entirely new
connections among neurons – new synapses.
• Changes take place mostly on the dendrites – new
dendritic spines.
Consciousness
Two Aspects of Consciousness
Level of alertness or sensitivity
•Distinction between being dimly aware of something and
being highly alert.
•Corresponds to brain sites: thalamus or reticular activating
system.
•Alertness is disrupted with damage to system that controls
overall arousal and cycling of sleep & wakefulness.
Content of Consciousness
•May be thinking about the past, present, or future.
•Various contents of consciousness require different brain
sites.
•In dreaming, we are conscious of a richly detailed content,
but our level of sensitivity to the environment is low.
DRUG-INDUCED CHANGES IN
CONSCIOUSNESS
Depressants, Stimulants, Marijuana, Hallucinogens
Depressants
• Drugs that decrease activity in the nervous
system.
• Alcohol, sleeping pills, drugs used to treat anxiety.
Effects of alcohol
• At low doses: Produces feelings of pleasure & well-being.
• But also depresses activity in the neural circuits that
controls our impulses.
• Narrowing of attention.
• Thinking tied to here and now, little attention to possible
consequences of one’s actions.
• Effects derived from actual impact on brain and people’s
expectations: When participants ‘believed’ that they had
consumed alcohol, they behaved with less inhibition.
Effects of Sleeping Pills, Anti-Anxiety Drugs
• Can produce physical & psychological dependence.
- Withdrawal symptoms after prolonged use quite likely –
enhanced anxiety, insomnia.
• Can produce drug tolerance.
- When person becomes less sensitive to the drug, higher
& higher doses are needed to achieve the same effects.
- Risks of high doses causing cognitive impairment or even
coma.
Stimulants
• Drugs that stimulate the nervous system and broadly
•
•
•
•
•
increase the level of bodily arousal.
Can raise blood pressure, increase heart & breathing rate.
Increase overall alertness, boost energy.
Decrease the need for sleep.
Can lead to psychological & physical dependence with
withdrawal symptoms.
Caffeine, cocaine, amphetamines (incl MDMA/ecstasy),
Ritalin.
Effects of Cocaine
• Temporary rush of excitement and euphoria.
• Following arousal, person comes crashing down, feels
fatigue, depression.
• Risk of dependence.
• Feelings of paranoia.
• Risk of cardiac arrest, respiratory problems.
Copyrights
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Work
License
Author/Source
Wikipedia: unknown
http://commons.wikimedia.org/wiki/File:Ivan_Pavlov_LIFE.
jpg
2012/04/11 visited
Wikipedia: ИльяГо(грохотайло)
http://en.wikipedia.org/wiki/File:MonumentIPAVLOV.jpg
2012/04/11 visited
National Taiwan University
YEE-SAN TEOH
This photo is from Science Photo Library
http://www.sciencephoto.com/media/228950/enlarge
and used in accordance with its terms of use
http://www.sciencephoto.com/terms.html for educational
purpose only.
36
Wikipedia: Jacob Sussman
http://en.wikipedia.org/wiki/File:Puzzle_box.jpg
2012/04/11 visited
56
AP Psychology Learning
https://laurensaplearning.wikispaces.com/Bandura
2012/04/11 visited