Pavlov's Discovery of Conditioning
Autor: Psicologias | Publicado: 2011-08-04T15:24:00-03:00


An Introduction to Classical and Operant Conditioning in Psychology
Conditioning in behavioral psychology  is a theory that the reaction ("response") to an object or event  ("stimulus") by a person or animal can be modified by 'learning', or conditioning. The most well-known form of this is Classical Conditioning (see below), and Skinner built on it to produce Operant Conditioning.


Pavlov's Discovery of Conditioning
This mode of learning was demonstrated by the experiments of Ivan  Pavlov, who decided to research conditioning after discovering during  separate gastric tests that his dog subjects began to salivate not only when meat powder was presented to them, but more significantly, when the person feeding them came into proximity with them. The dogs had been inadvertently trained through classical conditioning to  associate the person feeding them with the food itself, and reacted in a  similar way (salivation) to the feeders. This is known as a stimulus-response (SR), when salivation becomes a responsive action to the stimulus of the person feeding the dogs:

At the start of the experiments:

The Unconditioned/Neutral Stimulus (US/NS) is the person arriving to feed the dogs before the salivation as a result of their presence had began.
The Unconditioned Response (UR) was for the dogs not to salivate.


By the end of the experiments, when the unconditioned stimulus and responses had been conditioned: 

The Conditioned Stimulus (CS) becomes the person arriving to feed the dogs, which stimulates the Conditioned Response:
The Conditioned Response (CR) becomes salivation (normally a reflex action to aid digestion when feeding is going to begin) at the sight of the person.


On disovering this associative learning on the part of the dogs,  Pavlov decided to carry out further research specific to conditioning...


Classical Conditioning

The most famous experiment by the physiologist related to conditioning followed this research. Commonly referred to as "Pavlov's Dogs",  the experiment aimed to condition the dogs to associate the opening of a  doorwith feeding time. By selecting a bell as the Unconditioned  Stimulus instead of the person arriving to feed the dogs, as in his  previous tests, Pavlov was providing a stimulus to which feeding was   unrelated. 

At feeding time, the door was opened and food was then provided.  Initially, salivation was not secreted with the opening of the door, but  over time, the stimulus became conditioned, and when the door was  opened but food was not provided, salivation still occured, suggesting that the door opening had become a Conditioned Stimulus.


Instrumental Learning
An extension of Classical Conditioning was devised by Edward Thorndike (1874-1949), who placed cats in a puzzle box.  The incentive of a fish as food was placed outside of the box, giving  the cats a reason to try to escape from the box. Initially, they had  trouble escaping, and only gained freedom by knocking the latch of the  box. Over time, they learnt that the undoing of the latch would enable  their escape, and so the time spend being trapped in the puzzle box  decreased as their knowledge of how to leave it increased.

Thorndike termed this conditioning the "Law of Effect" in 1911: a positive outcome to a situation resulted in the stamping in  of a particular behavior (in the case of the puzzle box, the opening of  the latch was stamped in). Conversely, if an outcome is undesirable -  had the cats been punished as a result of leaving the box - the action  leaving to it would be stamped out - become less frequent.


Operant Conditioning and Reinforcement
In 1938, B.F. Skinner carried out an experiment with caged rats in an  "operant conditioning chamber" - Skinner's Box - who learnt through Operant Conditioning that if they pressed on a lever, food would be released for them. Under Operant Conditioning, reinforcement plays a key role:


     Reinforcement Type:     Description:     Tendency to Behave in a Particular Manner:   
     Positive Reinforcement     A stimulus is introduced which incentivises a particular behavior. e.g. the reward of a pellet of food in Skinner's Box.     Increases   
     Negative Reinforcement     A desirable incentive is introduced to not behave in a particular way.     Increases   
     Positive Punishment     An undesirable punishment  (e.g. electric shock) is introduced when the subject behaves in a  particular way, discouraging such behavior.     Decreases   
     Negative Reinforcement     Removing the desirable stimulus (e.g. food) to prevent a particular behavior.     Decreases   


The key difference between operant conditioning and classical  conditioning is that the former creates association based on the result  of a subject's behavior and the outcome that it generates as a secondary effect, whereas classical conditioning more primitively concentrates on the behavior itself.


Examples of Conditioning
A dog receiving positive attention after fetching a stick back to its  owner, learns to associate bringing the object back with favorable  attention - positive reinforcement.
A rat in a cage with an electrified floor learns that by pressing a lever, the electrical shock will stop - negative reinforcement.
A cat being shouted at for scratching furniture is discouraged to repeat this - positive punishment.
A child not being allowed to watch television after misbehaving associates bad behavior with an absence of rewards - negative punishment.

Criticisms

Conditioning has numerous practical applications  in everyday training and education. Animal training routinely uses  conditioning, with food treats as a form of positive reinforcement for  good behavior.
Generalisation of Association: A danger,  particularly of the positive punishments described above, is that a  subject may begin to associate an undesirable reinforcement with stimuli  beyond those originally intended. This was demonstrated in Skinner's Little Albert experiment,  in which Albert heard a loud noise on the sight of a white rat.  However, in addition to an aversion to white rats, Albert gained a  phobia of anything that resembled it - including, for example, white  beards.


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