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High School Psychology
Homeschool Pro
Independent Study
Classical Conditioning
Unit 4 – Learning
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We experience more than one type of learning
Image of student studying in classroom – conscious type of learning
Unconscious, reflexive learning is vital to survival of a species
o Ex. A child only needs to touch a hot stove once to learn to avoid glowing red
elements to prevent pain and injury
Case Study: Treating headaches caused from bad weather
- Her head began to throb at mere sight of cloud
The two types of unconscious learning
Classical conditioning
- Allows us to associate two related events
Instrumental conditioning
- Allows us to associate actions and
consequences
Classical Conditioning
Unit 2
Pavlov’s groundwork on classical conditioning
- Foundation for classical conditioning done by
Ivan Pavlov: Russian Physiologist (1890 –
1900s)
- Classical Conditioning also called Pavlovian
conditioning to honor his contributions
- Observation: dogs would begin to salivate
even before any food reached their mouth.
- It was as if an early step in the process of
digestion was triggered even before the food stimulus arrived
- Focused his latter part of career investigating this phenomenon
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Pavlov’s famous conditioning experiment
- Sound of metronome signaled to a dog
that food was about to be delivered
- Prior to training metronome had no effect
- Following training, a dog would begin
salivating in response to the sound of the
metronome alone
- New behaviours was called conditional
reflex, so called because it was conditional
upon training
Contingencies: When one stimulus reliably
predicts the presentation of another
- The presentation of one stimulus reliably
leads to the presentation of another
- Ex. Flash of lightening before crash of
thunder
- Ex. Eating strawberry leads to allergic
reaction
- When an organism learns the association
between a signal and an event, we say that
a contingent relationship has formed
between the two stimuli
A Contingency is formed when the CS reliably predict the US
Classical Conditioning
- Learning of a contingency between a particular
signal and a later event that are paired in time
and/or space
- When a contingent relationship is learned, organism
can respond to signal before event occurs
- Conditional response is prepatory in nature and can
promote survival
- Salivating in anticipation before food – efficient
digestion
- Avoiding strawberries – prevents strong allergic reactions
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Salivating when seeing food is an example of classical
conditioning (LEMON)
Remember example
- Contingency between sight of lemon and act of
citric acid meeting mouth (neutralize and
digest)
Learning contingencies can be critical for avoiding
predators
- An antelope may overcome this problem by
learning to flee to a variety of cues that may
signal an impending attack
- Cues may include sounds smells and sight
associated with predators
- Learning this contingent relationship is critical
to the antelope’s chances for survival
Unit 3
Components of Classical Conditioning
The Unconditional Stimulus (US)
- Any stimulus or event
- Occurs naturally, prior to learning
- Unconditionally and Automatically triggers a
response in the absence of any learning
- Ex. Food placed in dogs’ mouth or lemon in
humans’ mouth
o Naturally trigger a response without
any training being necessary
The Unconditional Response (UR)
- Response that occurs after the unconditioned stimulus
- Occurs naturally, prior to any learning
- Specific response that unconditional stimulus triggers
- When US occurs UR always follows without the need for any training
o Biologically programmed reflex
o Ex. Food elicits UR of salivation in dogs
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o Ex. Lemon juice elicits similar UR in humans
The Conditional Stimulus
Conditional Stimulus (CS)
- Paired with the unconditioned stimulus to produce a learned contingency
- Previously neutral stimulus becomes associated with an unconditional stimulus to
eventually triggers its own response
- Pavlov paired CS of sound of metronome with US of placing food in dogs’ mouth
- Sight and smell of lemon (CS) paired with lemon juice (US) being placed in mouth
The CS occurs before the US
- Can take several trials in which stimuli are paired before CS can elicit own response –
when organism learn of contingent relationship
Conditioned Response (CR)
- The response that occurs once the
contingency between the CS and the US has
been learned
- With pairing of CS to US the CS begins to elicit
a conditional response
- Very similar to unconditional response
- Ex. Sound of metronome will eventually
elicit conditional response of salivation
o Just as food presentation
- Presenting lemon visual can cause salivatory response in a human observer
Contingencies are acquired mostly during earlier trials
Acquisition
- The process by which a
contingency between a CS and
US is learned
- Pavlov characterized acquisition
as a negatively accelerating
curve
- Contingencies are learned
slowly
o Many trials before US
and CS are effectively
paired
o Most learning happens
during early trials
o With each additional trial – some learning, but never as much as in the beginning
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Some contingencies can be acquired in a Single
Trial
- Rats have special learning mechanisms
for food selection to survive
- Rats generally avoid unfamiliar food (risk
of poisoning) – Dietary neophobia
- Therefore, pinpoint source of illness
- Rats learn contingency between food and
sickness in one trial
Modelling taste aversion using classical
conditioning
- Consuming poison makes rat sick
eliciting strong aversion response
- Sickness that rat feels is paired with
novel taste of food
o Contingency can be learnt in
one trial
- Now taste of novel food elicits
aversion response before actual
sickness
- POWERFUL SURVIVAL MECHANISM
Leaning is specialized for specific adaptations
Unit 4
Extinction
How long does a contingency last?
- As long as the conditional stimulus continues to be a reliable cue for the unconditional
stimulus, the contingency will be maintained
- If the conditions change such that the conditional stimulus is no longer a reliable cue,
the conditional response will eventually fade.
Extinction leads to “forgetting” a contingency
- Extinction is the loss of the CR when the CS
no longer predicts the US
- Presenting CS alone, over many trials without
the US with which its usually paired
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At first CS will elicit conditional response, but over trials RESOPONSE will become weaker
CR fades, contingency is “forgotten”
Does extinction cause unlearning, or inhibition of CS?
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If contingency is simply
unlearned, we would expect
that following extinction,
retraining between the
conditional and
unconditional stimuli would
lead to acquisition of the
conditional response at
about the same rate as the
original training
If extinction leads to new
learning – suggests that
there exists two learned
processes that sit side by side: original learned response to the CS and a new inhibitory
learned response to the CS
If this was the case, we would expect that retraining between the conditional and
unconditional stimuli would occur at a faster rate compared to the original training
Spontaneous Recovery suggests that
Extinction leads to learning an
inhibitory response
Spontaneous Recovery
- The sudden recovery of a
conditional response following
a rest period after extinction
- Suggests that extinction
involves a new inhibitory
learned response
- Extinction procedure in which
the conditional stimulus is
presented repeatedly in the
absence of the unconditional stimulus, the CR gradually fades
o Following rest period, if CS presented once more, it once again elicits a CR
o Suggests that original learned association between the CS and US is not
unlearned
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o Extinction seems to promote a learned inhibitory response that competes with
original learned contingency
EXAMPLE
- Due to classical conditioning, Michelle has developed a fear response (the CR) to the
formerly neutral stimulus of dogs (CS)
o Fear of dog (CR)
o A dog (CS)
o Fear of being bitten (US)
o Bitten pain (UR)
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CS, fear – can reoccur spontaneously when the CS (a dog) is presented. The US (being
bitten) is not required
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Michelle may find that her fear response spontaneously recovers long after the
supposed extinction, even without the US (being bitten).
Unit 5
Generalization and Discrimination
Classical conditioning in the real-world foes beyond simple contingencies
- Variable stimulus
- Ex. During war people developed a conditional fear response to the whistling sound
made by the falling bombs
- This was the case even though the particular whistling sound was different from one
bomb to another depending on the distance, type, and weather conditions
Similar types of stimuli can elicit the same
conditional response
Stimulus Generalization
- The process by which stimuli similar to the
CS will also elicit a CR
- Contingency for one specific CS can work
for others
- Ex. As a child bitten by a type
of dog
- As adult sight of any dog will
elicit the same fear response
An experimental example of Stimulus
Generalization
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Experimentally tested using 500Hz tone (CS) causes Shock (US)
As training proceeds, the presentation of the 500Hz tone alone will lead to a conditional
fear response
How to test for Stimulus Generalization
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Test by presenting various tones
and measuring the fear response
We observe a normal distribution
called a generalization gradient
As expected, strongest
conditional response is elicited by
original 500Hz training tone
Stimuli similar to the original tone
(say 475 or 25Hz) also elicit fear
response at similar levels
As you test with a higher or lower
frequency, less and less fear is
elicited
The Generalization Gradient exists for any
kind of conditional stimuli
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Conditioned fear of dogs
Strongest fear response is elicited by
image of black Doberman, the type of
dog that originally bit you as a child;
some fear response is still elicited by
images of other types of dogs;
progressively less fear is elicited as the
image of the type of dog become
more different from the original
Doberman
Stimulus generalization adds flexibility and efficiency to classical conditioning
If a stimulus is potentially harmful, you will not require separate conditioning
experiences to learn that relationship
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How does Extinction affect a generalized
Stimulus?
Example of being bitten by a dog as a child
- To eliminate (fear) conditional
response learnt, undergo extinction
o Repeatedly showing dog pic
and calming down
- Expose several test stimuli along
generalization gradient – should flatten
- Decrease in response to stimuli
Using Extinction to cause Stimulus
Discrimination
- Stimulus Discrimination is the
opposite to Stimulus Generalization
- Restricts the range of CS that can
elicit a response
- Can eliminate fear of 600 Hz tones,
while maintaining her fear of 500
HZ tones by repeatedly presenting a
600 Hz tone in the absence of the
electric shock
- The conditional fear response to
the 600Hz tone will diminish
- Fear response elicited by the rest remains intact
How to create the most precise
Stimulus Discrimination
- Alternate between trials
where 600Hz tone stimulus
presented in absence of
electric shock and trials where
the 500Hz tine is still paired
with shock
- Achieve precise discrimination
and fear response will be
pinpointed to 500Hz tone
The variables in Stimulus
Discrimination
CS+: Predicts the presence of an
unconditional stimulus
(500Hz tone) (Paired with US)
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CS -: Predicts absence of unconditional stimulus
(600 Hz tone)
If presented at same time –
intermediate fear response
Generalization provides efficiency
and flexibility
Discrimination refines learning
process
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Together allow organisms to
build complex responses that
allow adaptive interactions with the environment
How can Classical Conditioning explain phobias?
Phobia: exaggerated/intense and persistent fear
of certain situations, activities things or people
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Sometimes CS not even needed to
create CR
Disturbing story of snake bite/plane
crash may elicit fear response when
thinking about flying or walking through
forest
Two therapies for treating phobias
Implosive therapy:
- An individual is encouraged to confront CS
that evokes the anxiety
- CS presented in absence of US
- May lead to extinction of CR
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But also, traumatic (germophobic – sit in dirt)
Systematic desensitization:
- Gradual exposure to feared stimulus
- Extinguish stimuli at far end of curve
working towards middle
- More accessible to patients
- Germophobic sitting in paper confetti
(relax, prevent anxiety) gradually move
towards dirt in palms
Example
A dog is trained to learn that when a red-light flash, they will receive a shock. A blue light is also
used, but no shock allows. Over time, the dog beings to flinch at the sight of a red light, bit not
at the sight of a blue shock
CS+ : a red light
CS - : a blue light
CR : flinching (due to expectation)
US : a shock
UR : flinching (due to pain)
Unit 6
Homeostasis and Compensatory Responses
Classical Conditioning can regulate physiology
- Body actively working to keep core temperature, glucose and ion levels and numerous
other processes within strict parameters through a process called homeostasis
Homeostasis: more efficient through classical conditioning
- Physiological conditioning within body
Compensatory responses:
- Process which counteracts a challenge to homeostasis
- (ex. Release of insulin after drinking beverages)
Release of insulin to regulates glucose levels and maintain homeostasis
- Release of insulin an example of compensatory response – a process which counteracts
a challenge to homeostasis
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Modelling Compensatory Responses with
classical conditioning
- Ingestion of sugar initially raises
blood glucose levels (US)
- Rise in blood sugar elicits insulin
release to counter (UR)
- On each trial, pairing flavour of
beverage with spike in blood
glucose levels
- Thus, taste of cola acts as CS,
predicts spike, and cues a CR of
insulin
Compensatory Response are not always
beneficial
- Man gives up cola for sugar free cola
- Familiar sweet taste, release insulin
(CR) even without actual sugar
- Decrease in blood sugar level,
increase hunger (gain weight)
Compensatory Response lead to increases
drug tolerance in familiar environments
- Morphine – decrease respiration
and sensitivity
- Chemical changes (drug
administration) are also signaled by
cues
- The various natural occurring effects
of drugs – unconditional stimulus
(US)
- Body responds with compensatory
mechanisms (countering drug effects)
- US of morphine effects; UR of increases respiration and pain sensitivity
- Over many trials, CS in environment paired with drug effects and contingency learned
- CS: cues from drug taking locations paraphernalia used to administer drug
- Once contingency established, display of cues will trigger CR – compensatory responses
in body to tackle drug effects
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Morphine addict shows an empty syringe (not drug) will experience discomfort, pain of
drug. Effect)
Drug withdrawal responses =drug prepatory responses
Conclusion
The importance of Classical Conditioning
- Dynamic complex process
- Critical for physiological and behavioural regulation
Understanding,
Help us deal with side effects and homeostatic balance