On a different point Watson believed the stimulus-response theory would eventually lead to a complete understanding of human behaviour (Hayes N 1995, pg 23). In 1911 E.L. Thorndike argued that some responses learned were not just because they were associated with the stimulus-response but were produced from pleasant consequences. (Hayes & Orell 1996,pg19). Stimulus-response is a primitive form of learning which associates a particular response with a particular stimulus, because they have been linked together several times. Ivan Pavlov’s work on conditioned reflexes came together with Watson’s stimulus-response work and became known as classical conditioning (Hayes N 1994, pg 59).
Animals have conditioned reflexes like knee jerking, sneezing, hiccupping and salivation. (Class notes) Pavlov’s salivating dog experiment was the first response he investigated when he discovered classical conditioning. (Hayes ; Orell 1996,pg 15). He showed he could make the dog salivate without the presence of food using a bell. Classical conditioning in a medical setting can also be used to reduce fear and anxiety.
The second type of conditioning is Skinners operant conditioning previously known as the law and effect. Skinner investigated positive and negative reinforced behaviours. For example: The Skinner box – a rat would be placed in a box with only a light, lever and a food delivery chute. When the rat eventually pressed the lever he would be rewarded with food. This resulted in the behaviour of lever pressing being strengthened and reinforced. In other experiments negative reinforcement by pressing the lever was used for a rat to escape or avoid something unpleasant like an electric shock.
There was no food reward; the reward was not getting shocked (Hayes ; Orell, 1996, Pg20). Schedules of reinforcement for strengthening learning were used so learning was not lost and the reinforced behaviour continued. The schedules were continuous, fixed interval, variable interval, fixed ratio and variable ratio. The variable ratio had a high ratio of response and a high resistance to behavioural extinction. (Hayes N 1994,pg65).
Controversial issues expanded on the nature-nurture debate, one of which is the theory of aggression, which is suppose to be instinctive in us all. Other theories consider aggression arise as a result of environmental circumstances. Freud and Lorenz saw aggression as an instinctive drive. One example of this is Lorenz’s tank like human. He saw aggression as a continuous source of energy, which would fill the tank and be released when it overflows. Rose et al; disagreed with aggression being inherited and other studies suggest that aggression arises from a response to frustrating circumstances and also learning by imitation. Individuals that had been exposed to aggressive behaviour in the past will probably be more likely to react aggressively in a frustrating environment. (Hayes & Orrell, 1996 pp39-44).
Interaction between genetic influences and environment are not mutually independent of one another. This is explained in Hebbs example in 1949 with his `Egg` analogy. If genetics in the egg are absent there will be no egg, but if the warm supporting environment was removed the egg will die, there for nature cannot be distinct from nurture (Hayes N 1995, pg 138). There is one distressing story that is happening now in medical circumstances that I feel is important to the nature versus nurture debate. This story has been controversial to the point of tragedy. In 1966 a medical accident happened involving the circumcision of a boys penis.
Bruce Reimer was born a boy in Canada in 1965. He was to have routine surgery, which went horribly wrong. Psychologist John Money took up his case and suggested that Bruce should be raised as a girl. John wanted to prove nurture would over-ride nature in gender identity. Bruce was castrated and called Brenda. Brenda still behaved and felt like a boy even though he did not know he was a boy. The nurturing of Bruce’s parents and environment had little effect in changing his gender identity even though it was thought of as successful. In adult hood he had reconstruction surgery after his parents told him the truth and later married and raised children successfully.
He sadly committed suicide on May 4th 2004. This suggests in this case nurture cannot over ride nature. (T.V Documentary ; Radio Times) There are many debates and examples that give rise to much controversy in the nature verses nurture debate in the development process. In my opinion this is one debate that psychologists will never be able to resolve, as there is strong evidence in certain circumstances, to support each debate, that nature and nurture both influence development.