Classical conditioning is one of the well known systems that the behavourists have developed over the years. A question that has been addressed is whether there are any biological constraints to classical conditioning. This means , does a subjects biological makeup have an effect on the traditional propositions of classical conditioning.
An idea that has been put forward is that human beings have innate phobias which cause them to learn differently when exposed to CS and US associations. Support of this view is by Ohman, Dimberg and Ost (1985) , who have come to the conclusion that human beings have a innate predisposition to gain fears of things which have been a danger to our ancestors , such as spiders and snakes. A study conducted by McNally (1987) , involved skin conductance responses as a conditioned response. One group's CS were pictures of a spider , while the US was a shock. The group were then presented pictures of snakes followed by no shocks. This procedure allowed the participants to develop a conditional discrmination because the spiders where followed by a shock but the snakes were not. In the Second group the roles of spiders and snakes had been swapped. Furthermore, in one control groups , shocks were administrated after viewing pictures of flowers , but not after viewing mushrooms and again the roles were reversed for the next control group. Usually, a study like this generates results that participants exibit a consistant SCR to the CS followed by the shock , whilst the CS not followed by a shock does not cause a SCR. McNally found that , discrimination learning is just as effective with mushrooms and flowers as it is with snakes and spiders. This finding weakens the biological prepardeness hypothesis , however some studies have found that extiction was much slower in the groups conditioned to snakes and spiders (Ohman , Dimberg &Ost , 1985 ; Schell , Dawson & Marinkovic 1991). Further support of biological prepardness is , when told verbal instructions such as ' you will recieve no more shocks' , fear responses were harder to shrug off for groups exposed to snakes and spiders than to groups who were shown mushrooms and flowers (Huddahl & Ohman 1977). This shows that our evolutionary and biological foundations , effect the processes of classical conditioning.
There seems to be more stimuli that contain a biologically prepared response. For example , humans have a predisposition to be afraid of angry faces. The reason for this is due to the consquences our ancestors have faced after seeing an angry or intimidating face. Support of this view is by Dimberg & Ohman (1983) . These researchers conducted a study similiar to the snakes and spiders conditional discrimination experiment. The only difference was , one group saw an aggressive face followed by a shock and the other group observed a neutral or happy face followed by a shock. The findings were that participants exibited a stronger SCR if they saw an angry face rather than a neutral or happy face. These findings contribute to the proposition that classical conditioning contains biological constraints. However ,Packer, Clark , Bond & Siddle (1991) , replicated the study involving conditional discrimination using angry faces and happy faces. Their findings were the complete opposite to (Packer et.al) , which has raised some thoughts to whether a null hypothesis should have been accepted instead of accepting that the results were due to biological prepardness.
In classical conditioning , the principle of continguity is a important principle of association. We can see that if the CS and US are seperated by even a few seconds like in trace conditioning , the rate of learning decreases. Support of this is by Kimble (1961) who claimed , "At the present time it seems unlikely that learning can take place at all with delays of more then a few seconds" . Therefore, the principle of…