Classical Conditioning

Psychology Cavern

CS + UCS - UCR/CR

As we all know, when you present food to a dog, it will inevitably lead to the dog drooling. But what happens when you associate the food with something else?
In experiments performed by Ivan Pavlov, a bell was rung before food was presented to a dog, so that the dog would associate the two together. After many trials of the bell and food together, it was found that a dog would salivate at the sound of a bell alone, without the presentation of food. Subsequent research has found that the dog uses the bell as an indicator of the onset of food presentation.
Although this may be hard for many to appreciate, the same sort of learning may be applied to human beings successfully. Specific elements of the conditioning process may be clicked upon in the representation above, to find out more.

The Unconditional Stimulus (UCS)

'Classical' conditioning, as termed by Pavlov, invloves three central components. Firstly there must be a stimuli that naturally produces a reflexive response (eg., food being placed in front of a dog, which leads to salivation). This is termed the 'Unconditional Stimulus' (UCS). The word 'unconditional' indicates that there are no specific conditions upon which the association depends. That is, in the dogs case, that drooling occurs simply by placing food in front of it to smell and see. This stimulus must be able to elicit the 'Unconditional Response' naturally, ie., without training.

The Unconditional Response (UCR)

The term 'Unconditional Response' refers to the response that will ensue, when the individual is stimulated by the 'Unconditional Stimulus'. In the dogs case, the UCR is the drooling - which is inevitable once it knows the food is there for it to eat. The UCR must be a reflexive behaviour of some sort, for example, a knee jerk reflex, eye blink etc. Once the UCR is conditioned completely in a process known as 'acquisition', it becomes known as the the 'Conditional Response' (CR). The change in terminology indicatates that there are specific conditions now placed upon the reflexive behaviour, which allow a 'Conditional Stimulus' (see below) to elicit the same behaviour.

The Conditional Stimulus (CS)

Once a stimulus-response pattern is found, for example, that putting food in front of a dog makes it drool, the conditioning process allows us to associate a nuetral stimulus to the 'Unconditional Stimulus'. In Pavlovs' experiments, a bell-sound was used. This second stimulus must not elicit reflexive behaviours of its own (hence the name nuetral).
Through the pairing of this stimulus, termed the 'Conditional Stimulus'(CS), to the UCS, the process of acquisition takes effect. Over subsequent pairings, the CS becomes a good indicator that the UCS is about to occur, and thus the animal (or human) will reflexively perform the UCR. Once the behaviour is readily learned, the UCR becomes the 'Conditional Response'(CR), meaning that the response now may be elicited by the CR.

The Conditioning Process

Stage 1 - UCS - UCR (a 'stimulus-reflex' relationship)
Stage 2 - CS + UCS - UCR ('acquisition' phase)
Stage 3 - CS - CR (conditioning process complete)

For example..

1 - food - salivation (food stimuli cause the dog to drool)
2 - bell + food - salivation (bell is being associated to the food stimuli)
3 - bell - salivation (the sound of the bell alone makes the dog salivate)

Or..

1 - spider bite - increased pulse, fear (a spider bite causes the body to go into panic state)
2 - see a spider + spider bite - increased pulse, fear (a spider is seen before it bites you)
3 - see a spider - increased pulse, fear (the sight of a spider alone elicits panic and fear)

NB - Although this is a simplified method of explaining classical conditioning it may give you a basic idea of the processes involved in associative learning. It also demonstrates the simple nature of human beings, despite the concept that we are completely logical. It is entirely possible for example, that the 'Conditional Stimulus' could be a piece of toast in the spider example.
On the other hand never oversestimate the power of associative conditioning, as this would be an undersestimate of the complexity of human learning.