Keith E Rice - Classical Conditioning

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.

NS = Neutral Stimulus

The neutral stimulus will be one that does not normally trigger the reflex itself.

? = no effect

The unconditioned stimulus is paired with a neutral stimulus (eg: sound of door opening) at the time or immediately before the unconditioned stimulus (eg: smell of food produces the unconditioned response (salivation).

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 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.)

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 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.

Extinction

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).

Eg: if a dog trained to salivate at the sound of a bell was repeatedly exposed to the bell sound without food accompanying it.

Eventually extinction took place - ie: the conditioned response ceased altogether

However, Pavlov found that spontaneous recovery of a supposedly ‘extinct’ behaviour can occur. 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

This is when the conditioned response is generalised to similar stimuli to the conditioned 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.

"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." - Wayne Weiten in 'Psychology: Themes & Variations' (p172, 5th edition, Wadsworth, London, 2002).

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' 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.

‘Preparedness’

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 et al 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 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 Seligman (1970) 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.

(See Fear of Animals: what is prepared for more on preparedness.)

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 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 (2000) 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!