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Classical Conditioning

Relaunched: 17 January 2016

Classical Conditioning, the first school of  Behaviourism is learning by association – ie: associating one thing with another. The formula is shown in the graphic below.

Graphic copyright © tutor2u

NS = Neutral Stimulus
The neutral stimulus on it own  is one that does not normally trigger any notable response.

UCS = Unconditioned Stimulus     UCR = Unconditioned Response
The unconditioned stimulus (eg: smell of food) produces an unconditioned response (eg: dog salivating). An unconditioned response is essentially an unlearned innate reflex. It is triggered  consistently and automatically by the occurrence of one kind of stimulus. Once such a response is triggered, it is not normally altered for its duration by subsequent events. Experience does little to alter the time course or pattern of the response.

When the unconditioned stimulus is paired with the neutral stimulus (eg: sound of door opening) at the same time (‘spontaneous conditioning’) as or immediately before (‘forward conditioning’) the unconditioned stimulus (eg: smell of food), the pairing produces the unconditioned response (salivation). Usually it takes repeated multiple pairings for the association to be made.

 CS = Conditioned Stimulus     CR = Conditioned Response
The conditioned stimulus (what was the neutral stimulus) will now produce the conditioned response (what was the unconditioned response).

The conditioned response is thought to be labile  – ie: it is not permanently established as a  response. Often the CR will last not much longer than the exposure to the conditioned stimulus.)

The concept of Classical Conditioning originated from the work of Ivan Petrovich Pavlov (1902). Pavlov was investigating how much dogs salivated – the salivary reflex – when they smelled food. Pavlov exposed part of the salivary gland in a a dog’s cheek and then attached a capsule to the cheek to measure salivary flow.

Graphic copyright © 2001 Psychology Press Ltd

Pavlov realised that they started salivating when they heard a researcher open the door to bring them food. He then tried having the researcher open the door without food and the dogs still salivated. They had learned to associate the sound of the door opening with food. Pavlov called this ‘psychic secretion’

Pavlov devoted much of the rest of his career trying different sounds and sights (such as bells/buzzers and  flashing lights) and varying time intervals to test the strengths and effects of associations.

He found that usually it took repeated pairings of the UCS and the NS for the NS to become a CS.

Pavlov found that repeated presentation of the conditioned stimulus without it being paired  with the unconditioned stimulus would lead to the conditioned response becoming weaker (as  measured by the amount of saliva the dog  produced). Eventually the conditioned response would become extinct.

Eg: if a dog trained to salivate at the sound of a bell was repeatedly exposed to the bell sound  without the presence of the smell of food, eventually the dog would stop salivating. Ie: the conditioned response had become extinct. However, Pavlov found that spontaneous recovery of a supposedly ‘extinct’ behaviour can occur for no apparent reason. The behaviour may not have been unlearned. It  may just have become dormant.

For instance, Pavlov found that a dog taken out  of the experiment and then brought back later, might salivate spontaneously at the ringing of  the bell. Pavlov also found that it was much easier to retrain a dog in which the CR had become  ‘extinct’ using the original NS-UCS pairings.

Pavlov described an extinct CR as ‘inhibited’.

Stimulus Generalisation
When using  bells for the neutral-to-conditioned stimulus, Pavlov found that, if he varied the bell pitch and tone from those of the conditioned stimulus, the dogs would still salivate. This is when the conditioned response is generalised to similar stimuli to the conditioned stimulus. As Wayne Weiten (2002, p172) puts it: “Stimulus generalisation occurs when an organism  that has learnt a response to a specific stimulus  responds in the same way to new stimuli that are similar to the original stimulus.”

Pavlov found that the dogs would salivate at any stimulus that closely resembled a CS – eg:  dogs  conditioned to salivate at the sight of a circle would also salivate at an oval.

It makes sense, that, if we are bitten by an adder, for example, we  learn to avoid similar-looking snakes in case we get bitten again.

Stimulus Discrimination
This is where there is no response to a stimulus that is dissimilar to the specific conditioned stimulus.

Pavlov found that, if he presented repeatedly  two tones – one paired with food, the other not –  the dog, after being trained to salivate at the first  tone, would salivate at the second. Ie:  generalisation is taking place. However, after a while, the dog stopped  salivating at all to the second tone. Ie: it had  learned to discriminate between the two tones.

The role of expectation
In conditioning, is there a prediction – an expectation of the UCS/CR?

Although the idea of ‘expectation’  – a schema – is a mental concept foreign to Behaviourists, Leon Kamin (1969) demonstrated the critical role  expectation plays in Classical Conditioning.

Kamin trained one group of rats to fear light paired with electric shock. This group and  another, untrained group were then exposed to a light/tone combination followed by electric shock. The second group responded with fear to the tone alone but the first group did not. Kamin  came up with the notion that the first group  blocked the tone-predicting-shock effect because they had already become fearful  due to the association of shock with the light. Robert Rescorla & Allen Wagner (1972)  put forward the idea that conditioning  depends on there being a discrepancy  between the expected reinforcement and the obtained reinforcement. For Kamin’s first  group of rats, the light fully predicted what  would follow – ie: the shock. The addition of  the tone added no discrepancy between the expected and the obtained reinforcement  and, therefore, had no conditioning effect.

Thus, there is a cognitive element to the way Classical Conditioning works – what ever the dogma of the Behaviourists!

Why is it easier to become conditioned to some things – eg: developing phobias – than others?

John Garcia, Frank Ervin & Robert Koelling  (1966) found that rats needed only one trial with  a toxic drink that made them ill to have learned  to avoid that drink in  the future. Rats normally have a strong preference for  sweet-tasting food. Garcia, Ervin & Koelling gave some of  their rats saccharin-flavoured water, followed  by  a drug that caused intestinal illness several  hours later. The rats needed to be  sick only once to avoid drinking the water again.

Garcia et al’s findings were so unique at the  time that they had trouble getting them published and accepted!

In a later study J0hn Garcia, Kenneth Rusiniak & Lynda Brett (1997) fed coyotes and wolves mutton wrapped in raw sheep hide and laced with (toxic) lithium chloride. The (hungry) animals were then allowed to  approach live sheep. The coyotes sniffed  their prey and turned away, some of them  retching. The wolves initially charged the  sheep. When their mouths closed on the  sheep’s flanks, they immediately released their quarry. During the next half hour, the  sheep became increasingly dominant and  the wolves withdrew like submissive pups.

In the natural world, learning to avoid food  that would make you ill would be a critical  lesson to learn.

Martin E P Seligman (1971) put forward the  concept of preparedness – the tendency for  members of a certain species to be biologically  predisposed to acquire certain conditioned  responses to stimuli which might be significant  in their environment. Stimuli which are less  likely to be encountered in their environment would be harder to create a conditioned  response to. Eg: rats learned to associate saccharin- flavoured water with illness produced by X-rays but they did not learn to associate the light and  sound of the X-ray machine with the illness.

Seligman’s concept, like Kamin’s, is predicated on there being a cognitive element in the way Classical Conditioning works.

Classical Conditioning affects modern behaviour
The effect of conditioning on attitude formation was demonstrated by Michael Olson & Russell Fazio (2001). Female participants, told that they were taking part in an experiment about ‘video surveillance’, were shown hundreds of paired words and images. Some of the pairings included ’Pokemon’ cartoon characters (NS) paired with either an emotionally ‘negative’ or ‘positive’ word or image (UCS). (Positive words included ‘excellent’ or ‘awesome’ and positive images included puppies and hot fudge sundae. Negative words included ‘terrible’ and ‘awful’ and the images included a man with a knife and a cockroach.) Each target pairing was repeated 20 times during the presentation. Afterwards the participants were asked how they felt about the Pokemon images. Those which had been paired with a positive UCS were rated more positively than those paired with a negative UCS.

Classical conditioning may affect sexual preferences too. Todd Kippin & James Pfaus (2001) conditioned rats to ejaculate to the smell of only either lemon or almond. Prior to the conditioning, these males had been allowed to mate with females smelling of either lemon or almond and had shown no preference for either smell. However, after conditioning, the males showed a distinct preference for mating with females with the smell they had been taught to associate with ejaculation.

With regard to humans becoming conditioned, Matt Jarvis, Julia Russell & Dawn Collis (2008) cite an entry in The People’s ‘Dr Vernon Coleman’s Casebook’ (14/10/00) in which a lady wrote in saying that she and her boyfriend had made love to Barry White CDs every night for 2 months. At the end of the ‘experiment’, it didn’t matter where either of them was…if they heard any of those songs, they would become sexually aroused!

John Watson, the founder of Behaviourism as a psychological discipline, was able to fashion an entire (and lucrative) second career from applying the principles of Classical Conditioning to advertising.


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