lecture 2: classical conditioning. types of learning habituation and sensitization classical...
TRANSCRIPT
Lecture 2: Classical Conditioning
Types of learning
• Habituation and sensitization
• Classical (Pavlovian) conditioning
• Instrumental (Operant) conditioning
• Complex (rule) learning
• Social learning
• Language mediated learning
Pavlovian/Classical Conditioning
Food Salivation
Biological reflex
SalivationFood
Ringing Bell
Salivation
Ringing Bell
Pavlov’s terminology
• Food = Unconditioned stimulus (US) - unconditionally evokes a response
• Salivation = Unconditioned response (UR) - the response evoked by the US
• Bell = Conditioned stimulus (CS) - a stimulus that evokes a response because it has been paired with the US
• Salivation = Conditioned response (CR) - the response evoked by the the CS
Pavlovian Conditioning
USUS(Unconditioned stimulus)
URUR(Unconditioned response)
CSCS(Conditioned stimulus)
CRCR(Conditioned response)
ELICITING STIMULI
CORRESPONDING RESPONSE
Examples of Classical Conditioning
Appetitive:• Eye-blink conditioning• Food preferences• Place preferences
Aversive:• Conditioned fear• Anticipatory nausea • Conditioned taste aversions• Place avoidance
Shock/Startle
USUS(Unconditioned stimulus)
URUR(Unconditioned response)
CSCS(Conditioned stimulus)
CRCR(Conditioned response)
ELICITING STIMULI
CORRESPONDING RESPONSE
Anticipatory Nausea
USUS URUR
CSCS CRCR
John Watson
“Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I'll guarantee to take any one at random and train him to become any type of specialist I might select – doctor, lawyer,
artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents,
penchants, tendencies, abilities, vocations, and race of his ancestors” [Behaviorism
(1930), p. 82]
Conditioned Fear: Little Albert
• This week’s (non-examinable) reading follows up on the Little Albert experiment and some problems with it…of which there are many
• However, main point is the notion that fear, and other emotions, could be conditioned, which there is now good evidence to suggest, e.g. tone+shock=fear in rats
Sexual Fetishes
USUS(Unconditioned stimulus)
URUR(Unconditioned response)
CSCS(Conditioned stimulus)
CRCR(Conditioned response)
ELICITING STIMULI
CORRESPONDING RESPONSE
Conditioned Taste Aversion
USUS(Unconditioned stimulus)
URUR(Unconditioned response)
CSCS(Conditioned stimulus)
CRCR(Conditioned response)
ELICITING STIMULI
CORRESPONDING RESPONSE
2nd Order conditioning
SalivationFood Salivation
Phase 1: 1st order conditioning
2nd Order conditioning
Salivation
Phase 2: Pair CS1 with CS2
Salivation
Phase 3: Test CS2
What Affects Classical Conditioning?
1. Frequency: number of CS-US pairings
2. Intensity:
a) the salience of the CS
b) the salience of the US
3. Contiguity (timing): how far apart the CS and US occur
What Affects Classical Conditioning?
1. Frequency: number of CS-US pairings
2. Intensity:
a) the salience of the CS
b) the salience of the US
3. Contiguity (timing): how far apart the CS and US occur
0
5
10
15
20
25
30
35
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Trials
Str
ength
of
the C
R
CS-US
Acquisition
Note the negatively accelerating form of the CR - the CR gets stronger by smaller amounts each trial until it hits a maximum limit - the asymptote
Asymptotic level of responding
Frequency
NOT EXAMINABLE
What Affects Classical Conditioning?
1. Frequency: number of CS-US pairings
2. Intensity:
a) the salience of the CS
b) the salience of the US
3. Contiguity (timing): how far apart the CS and US occur
0
5
10
15
20
25
30
35
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Trials
Str
ength
of
the C
R
Weaker CS
Acquisition Asymptotic level of responding
Intensity of CS.
NOT EXAMINABLE
What Affects Classical Conditioning?
1. Frequency: number of CS-US pairings
2. Intensity:
a) the salience of the CS
b) the salience of the US
3. Contiguity (timing): how far apart the CS and US occur
0
5
10
15
20
25
30
35
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Trials
Str
ength
of
the C
R
Weaker US
Acquisition
Asymptotic level of responding
Intensity of US.NOT EXAMINABLE
What Affects Classical Conditioning?
1. Frequency: number of CS-US pairings
2. Intensity:
a) the salience of the CS
b) the salience of the US
3. Contiguity (timing): how far apart the CS and US occur
Contiguity
• Refers to time between onset of CS and US
US
US on US off
TimeCS
CS on CS off
ISI
Inter-stimulus interval (ISI) = time between ‘CS on’ and ‘US on’
NOT EXAMINABLE
0102030405060708090
100
CS-US interval (ISI)
CR
(id
eali
sed)
Strength of CR depends on ISI
NOT EXAMINABLE
What Affects Classical Conditioning?
1. Frequency: number of CS-US pairings
2. Intensity:
a) the salience of the CS
b) the salience of the US
3. Contiguity (timing): how far apart the CS and US occur
ANYTHING ELSE???
What Affects Classical Conditioning?
• Is the co-occurrence of the US and CS enough for learning?
Contingency
• Need two pieces of information:– What is the probability that the US follows the
CS?– What is the probability that the US occurs
anyway?
• Learning about the causal, structural and predictive relations between events and stimuli
What Affects Classical Conditioning?
1. Frequency: more CS-US more learning
2. Intensity:
a) more intense CS faster learning
b) more intense US greater amount of learning
3. Contiguity (timing): closer CS and US occur together better learning
4. Contingency: higher contingency better learning
EXAMINABLE
Can We ‘Unlearn’?
• Extinction = repeated CS alone presentations following acquisition resulting in a reduction in the CR
• In other words, reversing the learning process
0
5
10
15
20
25
30
35
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Trials
Str
en
gth
of
the C
R
Acquisition Extinction Spontaneous Recovery
CS alone
CS-USCS alone
What can we use classical
conditioning for?
Advertising
2nd order conditioning
Cure for impotence?
Removing Phobias
Removing Phobias
Extinction