2.4 General Psychology: Can you describe the experiments Pavlov did?

2.4 Describe the experiments Pavlov did

Classical conditioning

This is a simple form of learning in which one stimulus comes to bring forth the response usually brought forth by a second stimulus being paired repeatedly with the second stimulus. This type of earning was first studied by a Russian named Ivan Pavlov. Pavlov’s studies which were mainly carried out on dogs, were designed to discover the conditions which should be provided to enable an animal to respond to a neutral stimulus with a response that would otherwise be evoked by a specific natural stimulus for example hungry dogs tend to respond naturally and reflexively to a stimulus such as meat by salivating. Through classical conditioning it is possible to bring this response under the control of a stimulus such as a bell, which does not naturally have the power to evoke salivation and which is virtually a neutral stimulus as gar as the response of salivation goes.

Ivan Pavlov- Psychologist, Pioneer of Operant Conditioning

The set up required to bring this about is as follows:

1. Select a stimulus which naturally evokes a certain response for example meat in the mouth of the dog, elicits salivation that is:

 

Meat powder———————>salivation

(natural stimulus)            (natural response)

2. Select a stimulus which is neutral with respect to the response you want to condition that is a stimulus which does not naturally elicit that response for example:

 

Bell ——————->no salivation

(neutral stimulus)            (no response)

3. Present the neutral stimulus closely followed by the natural stimulus that is,

 

Bell + meat powder————–> salivation

4. Repeat this procedure several times that is,

 

Bell + meat powder———–> salivation (x 5 times)

 

5. Present the neutral stimulus alone to see whether salivation will follow. If salivation follows then conditioning has occurred for example:

 

Bell  ————>   salivation

(conditioned stimulus)          (conditioned response)

 

6. The dog would still salivate at the sound of the bell because it had learnt to associate the bell tone with food.

 

Terminology used in Classical Conditioning

  1. Unconditioned stimulus (UCS): A stimulus that elicits a response naturally from an organism without learning
  2. Unconditioned response (UCR): An unlearned response. It is a response to an unconditioned stimulus
  3. Conditioned stimulus (CS): A previously neutral stimulus that elicits a conditioned response because it has been paired repeatedly with a stimulus that already elicited that response
  4. Conditioned response (CR): A learned response to a previously neutral stimulus. It is a response to a conditioned stimulus

 

The whole procedure used by Pavlov can be summarised as follows:

1. Before conditioning

 

Neutral stimulus————->  no response

(bell)

 

Unconditioned stimulus————->Unconditioned response

UCS                                                              UCR

(food)                                                   (salivation)

 

2. During conditioning

Conditioned    +    Unconditioned—————>Unconditioned

Stimulus                   stimulus                                  response

(bell)                            (food)                                   (salivation)

CS                                    UCS                                         UCR

 

NB: The UCS always follows the CS during conditioning
3. After conditioning

Conditioned stimulus—————–>Conditioned response

CS                                                                  CR

(bell)                                                     (salivation)

 

Another example of classical conditioning is where Watson and Raynor (1920) taught an infant called Albert to react with fear to the sight of a rabbit. The conditioning procedure involved pairing the sight of a white rat or rabbit which previously did not produce a fear response (crying) in Albert, with the occurrence of a loud sound, which naturally elicits a fear response in infants. After a few pairings, presentation of the white rat or rabbit alone was able to produce the same fear response as the loud sound.

1. Before conditioning

White rabbit ——————————–> no fear response

(neutral stimulus)

 

Loud sound————————————>fear response (crying)

UCS                                                       UCR

 

2. During conditioning

White Rabbit + Loud Sound—————–>  Fear Response (x 5 times)

CS                       UCS                                         UCR

NB: The UCS always follows the CS during conditioning

 

3. After conditioning

White Rabbit—————————->  Fear Response

CS                                                               CR

 

The General Characteristics of Classical Conditioning

1. Reinforcement

This is any event, procedure or stimulus which will strengthen the conditioned response. A rein forcer increases the probability of occurrence of a response which it accompanies. In classical conditioning the CS-UCS pairings are the reinforcement.

2. Extinction

This refers to the elimination of the conditioned response as a result of withdrawal of reinforcement. If reinforcement is withheld, that is, if the conditioned stimulus is presented repeatedly alone, the conditioned stimulus loses its power to evoke the conditioned response. This process is called extinction. For example when Pavlov continued ringing the bell alone to evoke the conditioned response, the dogs eventually stopped salivating to the bell as the conditioned response to the bell had suffered extinction.

3. Stimulus Generalisation

This refers to the tendency of an animal to respond to a wide range of stimuli which are similar to that used as the conditioned stimulus. If a stimulus which is similar to the conditioned stimulus is presented instead of the conditioned stimulus the conditioned response may be evoked but to a lesser degree and with a lesser probability. For example, the fear response in the infant Albert was elicited by other furry objects such as white furry coats, or white beards. In other words, the fear generalised to similar objects. The more similar a stimulus is to the conditioned stimulus, the higher the degree of generalisation.

4. Stimulus Discrimination

This refers to the tendency of the animal to confine his responses to the conditioned stimulus rather than respond to any stimulus similar to the conditioned stimulus. If two stimuli are presented to the organism, one of which is always followed by the unconditioned stimulus and the other is never followed by the unconditioned stimulus, the conditioned response will occur only when the reinforced stimulus is presented. In other words responses to the other stimulus suffer extinction. The organism is said to have acquired a discrimination for example, if the white rat is always followed by a loud bang but the white coat is not followed by a loud bang, then a child will only cry when he sees the white rat.

 

Note: Whereas stimulus generalisation tends to occur during the early conditioning trials, stimulus discrimination tends to occur later in conditioning when the animal has had the chance to discover which stimuli are reinforced and which ones are not.

 

5. Spontaneous Recovery

If the experimenter allows the dog that has been conditioned and that has undergone the extinction process to rest for sometime for example a few days then he puts it back in the lab and presents the bell tone (CS) without the food (UCS), the dog starts to salivate again. This is called spontaneous recovery. However if this is continued for some time that is, the conditioned stimulus keeps on being presented without the unconditioned stimulus, the response dies again so the food would be needed to strengthen the association.

 

6. Higher Order Conditioning

First the dog is conditioned to salivate when it hears a given bell tone. Then the experimenter introduces a new element in the situation for example he turns on a light before ringing the bell and presenting the food that is:

 

light ————->    bell —————->  food

 

This is done for some time. The dog therefore learns to salivate when the light is turned on. We therefore have:

CS1    CS2————————————->  CR

 

This is higher order conditioning.

 

Uses of Classical Conditioning

1. Extinction

Extinction involves elimination of a response through the withdrawal of a response through the withdrawal of reinforcement. Extinction can therefore be used by teachers when they want to deal with undesirable behaviour in students. When faced by disruptive behaviour, the teacher should eliminate any reinforcement that maintains the undesirable behaviour. This brings about extinction.

 

For more desirable behaviour, the reinforcement should be given simultaneously. The mistake most teachers make is that they pay attention to children when the children misbehave. This attention is reinforcing and it can actually encourage undesirable behaviour even when the attention consists of orders about things that the child should or should not do. Therefore, what should the teacher do? The teacher should praise the appropriate behaviour and at the same time ignore inappropriate behaviour. This is the most effective method of dealing with disruption in the classroom. In summary for the teacher to use the principle of extinction successfully, he or she should:

  • withhold reinforcement for example if a learner has a habit of reading while saying the punctuation marks and the class laughs, the teacher instructs the class not to laugh and he or she does not say anything to the naughty learner about this bad behaviour
  • reinforce the alternative positive behaviour for example praise the learner on the day he reads without saying the punctuation marks aloud

 

2. Reinforcement

A rein forcer is a stimulus that follows a response and increases the frequency of the response. The teacher therefore should ensure that the environmental conditions are reinforcing. Many human emotions are acquired through classical conditioning therefore positive emotions should be paired with learning experiences and negative emotions should be avoided. The teacher should try as much as possible to avoid associating the school with negative emotions. He or she should avoid situations which give rise to or perpetuate strong emotions in pupils. Strong emotions interfere with effective though processes. The child who is emotionally disturbed cannot be expected to learn efficiently. If a child, for instance, becomes angry or frustrated by an assignment, of if he is humiliated by sarcasm, very little learning will take place until the emotion goes away. It is therefore important for the teacher to avoid arousing such strong emotions in children or try to cool off such strong emotions before engaging the pupils concerned in learning activities.

 

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