Classical conditioning describes a process where a stimulus becomes associated with, and is used to predict, the occurrence of an important event which subsequently leads to an increase in response behavior (Malim and Birch, 1998).
This can be contrasted with habituation, which involves disassociating a stimulus with a particular event and a decrease in response behavior (Gleitman, 1992).
Perhaps the best example to demonstrate the principles involved in classical conditioning learning are the experiments carried out by Ivan Pavlov.
Acquisition
Pavlov noticed that when he presented his dogs with food, this unconditioned stimulus (UCS) elicited an automatic unconditioned response (UCR) in the form of salivation.
When a bell was rung at the same time as the food was presented, over time with repeated pairings, this conditioned stimulus (CS), which the dogs had now learned to associate with food, was able to cause salivation, a conditioned response (CR), in the absence of food.
Conditioned responses are more likely to occur when there is a strong UCS. Wagner, Siegal, Thomas and Ellison (1964) for example, found that the rate of salivation in dogs increased when they were presented with larger quantities of food.
The delay between the presentation of the CS and the UCS can also affect CR acquisition. In Pavlov’s experiments, conditioning occurred most rapidly when the CS was presented 0.5 seconds before the UCS (Martin, Carlson and Buskist, 2007), and least rapidly, or not at all, when the CS-UCS interval was less than 0.2 seconds or greater than two seconds (Baron, 2000).
Extinction
In order to maintain a CR, the CS must be paired with the UCS. Trapold and Spence (1960) for example, found that presenting a tone (CS) without a puff of air (UCS) after conditioning eye blinks to occur in response to the tone (CR), eventually lead to the extinction of the CR.
However, as Pavlov discovered, an extinct CR may not actually permanently disappear. Dogs which were taught not to salivate in response to the sound of a bell, because it had been presented many times without food, were found to start salivating again once they were placed back into Pavlov’s conditioning chamber and a bell was rung.
This spontaneous recovery seems to suggest that rather than deleting what has been learned, extinction causes an inhibition of the CR when the CS occurs repeatedly in the absence of the UCS (Gross, 2009).
Stimulus Generalization And Discrimination
Stimulus generalization occurs when something closely resembling a CS causes the CR. For example, Pavlov found that once a dog had been conditioned to salivate at the sound of a bell, it could also be made to salivate when similar sounding bells were rung.
One possible reason for why stimulus generalization may occur is that the learning which occurred with the CS is transferred onto other similar stimuli (Domjan, Grau and Krause, 2009). The conditioned phobia of “Little Albert” provides a vivid example in support of this claim (Watson and Rayner, 1920).
However, research carried out by Campolattaro, Schnitker and Freeman (2008) in stimulus discrimination training has shown that even though transference may occur initially, once the ability to discriminate between two stimuli has been learned, a generalized CR can largely be eliminated.
This seems to suggest that in addition to transference, generalization may also occur as a result of not being able to differentiate stimuli and thus discriminate amongst them.
References
Baron, R.A. (2000). Psychology (5th edition). Boston, MA: Allyn & Bacon.
Campolattaro, M.M., Schnitker, K.M., & Freeman, J.H. (2008). Changes in inhibition during differential eyeblink conditioning with increased training. Learning & Behavior 36, 159-165.
Domjan, M., Grau, J.W., & Krause, M.A. (2009). The Principles of Learning and Behavior (6th edition). Wadsworth Publishing Company.
Gleitman, H. (1992). Basic Psychology (3rd edition). W. W. Norton & Company Inc.
Gross, R. (2009). Psychology The Science Of Mind And Behaviour (5th edition). Hodder Education.
Malim, T., & Birch, A. (1998). Introductory Psychology. Palgrave Macmillan.
Martin, G.N., Carlson, N.R., & Buskist, W. (2007). Psychology (3rd Edition). Pearson Education Limited.
Trapold, M.A., & Spence, K.W. (1960). Performance changes in eyelid conditioning as related to the motivational and reinforcing properties of the UCS. Journal of Experimental Psychology 59, 209-213.
Wagner, A.R., Siegal, S., Thomas, E., & Ellison, G.D. (1964) Reinforcement history and the extinction of a conditioned salivary response. Journal of Comparative and Physiological Psychology 58, 354-358.
Watson, J.B., & Rayner, R. (1920). Conditioned emotional reactions. Journal of Experimental Psychology 3, 1-14.
Reviewed – 28th March 2016