Week 2: Lecture 3.1
Biological basis of behaviour
Lecture 3.1: Pavlovian (classical) conditioning: the basics
Content of part 1:
- Pavlov
- Quick recap of the basics
- Basic parameters of conditioning
- Reading for the week
Pavlov’s Basic Conditioning Paradigm:
1. Start with an unconditioned stimulus (in this case meat powder).
2. This produces an unconditioned response of salivation
3. We then take a neutral stimulus which will then be our conditioned stimulus later (in
this case a tone)
4. This neutral stimulus, as of right now, does not produce any salivation
5. Now the conditioning takes place: the tone is presented and followed shortly
afterwards by meat powder
6. The pairing of the meat powder and the tone is the conditioning
7. The response to the tone (which is now a conditioned stimulus) is tested
8. The tone has been conditioned and now produces salivation, which we call the
conditioned response
Explanation:
- We think that the repeated pairings in step 5 causes the representation of the tone
to be associated with the representation of the meat powder.
- The representation of the tone can associatively activate the representation of the
powder, which leads to the same response as if meat powder were actually
presented
- This is the principle of Stimulus Substitution. The CS comes to act as if it were the US
(but typically to a weaker extent).
In what conditions does Pavlovian conditioning work?
, Week 2: Lecture 3.1
- It works in all vertebrate species that have been tested and in at least some
invertebrates- very general
- It works for any conditioned stimulus an animal can detect
- It works with spinal reflexes (e.g: in brain damaged patients)
- In humans (using paradigms such as eye-blink, GSR and knee jerk)
Common Pavlovian procedures
• Eye blink to an air puff in humans (CS=>airpuff)- tone is reliably followed by a puff of
air to the eye and it makes someone blink.
• Electrodermal conditioning in humans (CS=>shock)- a visural or auditory
conditioned stimulus (originally neutral) is followed by a shock that makes your skin
conductance increase to the conditioned stimulus
• Key pecking in pigeons (“autoshaping”) – a keylight being illuminated (the
conditioned stimulus) is reliability followed by delivery of food (grain, which is an
unconditioned stimulus) which will cause the pigeon to peck at the key - this is
another example of stimulus substitution, as the illuminated keylight is associated
with the food, and so comes to stand for the food, and so it pecks at the keylight as it
would the food.
• Taste aversion in rats (flavour plus illness) – we have come across this in lecture 2.2
• Conditioned suppression (of lever pressing) in rats- we have come across this in
lecture 2.1
Quick reminder: Conditioned suppression
- In this procedure the rat (typically) is trained to press a lever for food pellets.
- After responding is established, the lever is withdrawn and the pairing of CS (e.g.
light, tone) and US (normally a shock) takes place.
- Then testing of the conditioning is performed with the lever back in the chamber.
- We play the CS (tone) sometimes and record the responses before the CS and during
the CS
- The rate of responding during the CS (=RCS) and just before the CS (=Rpre-CS) is
RCS
recorded, and a suppression ratio is calculated = .
( RCS + Rpre−CS)
- This measure has the property that for good conditioning it will approach 0, and for
weak or no conditioning it will approach 0.5.
- If the tone is played and the animal freezes as it is afraid of the tone (as they had
received socks), then the ratio is 0, and so they have a high suppression, and so have
been conditioned well.
Some basic parameters and effects
1. Stimulus generalisation
2. Extinction
3. Timing
4. Responding
Stimulus generalisation
Biological basis of behaviour
Lecture 3.1: Pavlovian (classical) conditioning: the basics
Content of part 1:
- Pavlov
- Quick recap of the basics
- Basic parameters of conditioning
- Reading for the week
Pavlov’s Basic Conditioning Paradigm:
1. Start with an unconditioned stimulus (in this case meat powder).
2. This produces an unconditioned response of salivation
3. We then take a neutral stimulus which will then be our conditioned stimulus later (in
this case a tone)
4. This neutral stimulus, as of right now, does not produce any salivation
5. Now the conditioning takes place: the tone is presented and followed shortly
afterwards by meat powder
6. The pairing of the meat powder and the tone is the conditioning
7. The response to the tone (which is now a conditioned stimulus) is tested
8. The tone has been conditioned and now produces salivation, which we call the
conditioned response
Explanation:
- We think that the repeated pairings in step 5 causes the representation of the tone
to be associated with the representation of the meat powder.
- The representation of the tone can associatively activate the representation of the
powder, which leads to the same response as if meat powder were actually
presented
- This is the principle of Stimulus Substitution. The CS comes to act as if it were the US
(but typically to a weaker extent).
In what conditions does Pavlovian conditioning work?
, Week 2: Lecture 3.1
- It works in all vertebrate species that have been tested and in at least some
invertebrates- very general
- It works for any conditioned stimulus an animal can detect
- It works with spinal reflexes (e.g: in brain damaged patients)
- In humans (using paradigms such as eye-blink, GSR and knee jerk)
Common Pavlovian procedures
• Eye blink to an air puff in humans (CS=>airpuff)- tone is reliably followed by a puff of
air to the eye and it makes someone blink.
• Electrodermal conditioning in humans (CS=>shock)- a visural or auditory
conditioned stimulus (originally neutral) is followed by a shock that makes your skin
conductance increase to the conditioned stimulus
• Key pecking in pigeons (“autoshaping”) – a keylight being illuminated (the
conditioned stimulus) is reliability followed by delivery of food (grain, which is an
unconditioned stimulus) which will cause the pigeon to peck at the key - this is
another example of stimulus substitution, as the illuminated keylight is associated
with the food, and so comes to stand for the food, and so it pecks at the keylight as it
would the food.
• Taste aversion in rats (flavour plus illness) – we have come across this in lecture 2.2
• Conditioned suppression (of lever pressing) in rats- we have come across this in
lecture 2.1
Quick reminder: Conditioned suppression
- In this procedure the rat (typically) is trained to press a lever for food pellets.
- After responding is established, the lever is withdrawn and the pairing of CS (e.g.
light, tone) and US (normally a shock) takes place.
- Then testing of the conditioning is performed with the lever back in the chamber.
- We play the CS (tone) sometimes and record the responses before the CS and during
the CS
- The rate of responding during the CS (=RCS) and just before the CS (=Rpre-CS) is
RCS
recorded, and a suppression ratio is calculated = .
( RCS + Rpre−CS)
- This measure has the property that for good conditioning it will approach 0, and for
weak or no conditioning it will approach 0.5.
- If the tone is played and the animal freezes as it is afraid of the tone (as they had
received socks), then the ratio is 0, and so they have a high suppression, and so have
been conditioned well.
Some basic parameters and effects
1. Stimulus generalisation
2. Extinction
3. Timing
4. Responding
Stimulus generalisation
