lecture 2: classical conditioning. types of learning habituation and sensitization classical...

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