Watson was the first psychologist to apply the principles of classical conditioning to human behaviour, he set-up an experiment using an 11 month old baby, where he associated the sight of a white rat with the sound of a hammer striking a steel bar just out of sight behind the baby’s head. As you can imagine Watson was successful in inducing a phobia of rats in the young boy. This is considered to be one of the most ethically dubious psychology experiments ever conducted.
Operant conditioning is where a response is learnt not simply because it’s associated with a particular stimulus, but because it produces pleasant consequences. It deals with voluntary actions rather than just reflexes. In 1911 Thorndike named this the Law of Effect.
Skinner was the psychologist most responsible for developing this theory. He created the Skinner box, which contained a light, a lever and a food delivery chute. In the box he would place a rat or pigeon and when they stood on the lever a pellet of food would be delivered, effectively rewarding the animal for its actions and positively reinforcing the behaviour so it was more likely to happen again. In the same way, rats who had to press the lever to avoid an electric shock, still had pleasant consequences, but through negative reinforcement.
Behaviour which has been learned through negative reinforcement does not die out quickly, even when it is no longer being reinforced. Behaviour which has been learned through positive reinforcement is not so resistant. How quickly it dies out depends on which of the four main kinds of reinforcement schedule were being used when the behaviour was being learned, though a psychologist may use a combination of them when studying a specific form of learning.
The four main reinforcement schedules are: Fixed-ratio reinforcement, where the animal receives reinforcement according to how many correct responses they have made and so the more responses the higher the reward, but this way of learning is not very resistant to extinction; Variable-ratio reinforcement, where the animal is reinforced according to the number of correct responses they have made, but the required number is subject to change, this way of learning is more resistant to extinction than Fixed-ratio; Fixed-interval reinforcement, where a certain period of time needs to pass between reinforcements, this way of learning is also not very resistant to extinction; and Variable-interval reinforcement, where the time which has to pass between reinforcements changes each time, an animal trained according to this schedule produces a steady response rate which is highly resistant to extinction.
When presented with this evidence it is, I think, impossible to side completely with either the nativists or the behaviourists. That is where the interactionists come in, they believe that nativism and behaviourism aren’t mutually exclusive. Both Freud and Piaget were interactionists, they believed that the environment must not only be benign, that is not harmful in any way, but particular environmental input is often necessary for a characteristic or ability to develop. They believe experience is as important as maturation. A good example of this is language, we all possess the skills to learn any language, but tend to learn the language of the community in which we grow up.
In 1953 Tinbergen, an interactionist, conducted a study of sticklebacks. He showed that a sign stimulus in the environment, the flash of red on another male’s belly, triggered their attack ritual – an inherited behaviour, triggered by an environmental stimulus. Hebb’s (1949) example of the link between genetic influences and the environment was that of a developing egg – without the genetic component there is no egg, but without the supporting environment, the warmth, the egg dies. There are several areas of behaviour where the nature-nurture debate is particularly predominant, I will now look at a couple of these controversies.
One area of particular interest is intelligence. The first issue is the definition of intelligence. Some see intelligence as related to adaptation to the environment, the qualitative aspects. But most definitions relate to the quantitative aspects of intelligence, the measurement of intelligence using psychometric tests, in order to compare ‘how much’ of it different people possess. In 1911 Binet developed what is generally accepted as the first intelligence test, with the aim of identifying children who needed extra academic help. He did this by developing a range of questions and establishing how old a child should be when it could first answer them, children who took the test could then be compared to what was considered to be ‘the norm’.
As with all areas of the nature nurture debate there are some extreme views. One such view is that of Galton, a nativist. In 1884 he “wrote a paper on ‘hereditary genius’, in which he showed that eminent people in society tended to be related, and that genius seemed to run in families. He argued that this showed that intelligence must be inherited” (Hayes and Orrell 1998, P.31). Behaviourists would argue this view by pointing out that something that runs in families does not necessarily happen because it is genetic, as families also provide a certain environment, and this can also have a substantial influence on intelligence. An example of this is Skeels (1966) study of “a group of children removed from orphanages into more stimulating environments. Most of those raised by foster mothers showed significant improvements in their IQ, whereas those raised in the orphanage had dropped out of high school, or were still institutionalised or not self-supporting”.
Gender identity is another area of the nature nurture debate. One argument is that girls and boys learn to behave differently through being treated differently and by observing others and imitating what they see to be sex-appropriate behaviour. For example, boys are given cars and guns to play with, their rooms decorated in blue with an emphasis on more boisterous play and assertive behaviour, whereas girls are given dolls and wear pink dresses with an emphasis on nurturtant behaviour.
The opposing argument is that males and females are biologically programmed for certain activities associated with gender roles. A very famous, but sad, supporting example is that of David Reimer. As a result of an accident during circumcision, one of a pair of identical twins lost his penis. At 22 months he was surgically castrated, oestrogen was given and a vaginal canal constructed. He was subsequently raised as a girl named Joan.
Aged 4, Joan preferred dresses to trousers, took pride in her appearance and was cleaner than her brother. Psychologists Money and Erhardt (1972) used these findings to support the view that gender identity is inherited. In reality Joan suffered years of bullying and was an extremely unhappy adolescent. Just before her 16th birthday Joan decided to stop living as a girl and underwent sex change surgery just before his 16th birthday. He made several attempts on his life before having a second operation on his penis aged 21. He did meet and fall in love with a single mother of three children, but his unhappy childhood continued to haunt him until he committed suicide in 2004, he was in his late thirties. (Gross 2005, P.626)
In conclusion, and after taking into account all the evidence I don’t think it is possible to say that any aspect of human development happens purely because of biological or environmental influences. I would have to agree with the interactionists and say that human traits are determined by both nature and nurture, though I’m sure the debate over the relative contributions of each will continue until the end of time.