Human species as a whole are a product of evolution and that individual differences are due to each person’s unique genetic code.
Characteristics and differences that are not observable at birth, but which emerge later in life, are regarded as the product of maturation. That is to say we all have an inner “biological clock” which switches on (or off) types of behavior in a pre programmed way. [The classic example of the way this affects our physical development are the bodily changes that occur in early adolescence at puberty.]
At birth the human mind is a blank slate and that this is gradually “filled” as a result of experience.
Psychological characteristics and behavioral differences that emerge through infancy and childhood are the result of learning. It is how you are brought up (nurture) that governs the psychologically significant aspects of child development and the concept of maturation applies only to the biological. So, when an infant forms an attachment it is responding to the love and attention it has received, language comes from imitating the speech of others and cognitive development depends on the degree of stimulation in the environment and, more broadly, on the civilization within which the child is reared.
Galton (a relative of Charles Darwin) was convinced that intellectual ability was largely inherited and that the tendency for “genius” to run in families was the outcome of a natural superiority. A modern proponent is the American psychologist Arthur Jenson. Finding that the average I.Q. scores of black Americans were significantly lower than whites he went on to argue that genetic factors were mainly responsible – even going so far as to suggest that intelligence is 80% inherited.
Theses demonstrate natural inequalities between social groups.
For many environmentalists part of the difference in the I.Q. scores of different ethnic groups is due to inbuilt biases in the methods of testing. More fundamentally they believe that differences in intellectual ability are a product of social inequalities in access to material resources and opportunities. To put it simply children brought up in the ghetto tend to score lower on tests because they are denied the same life chances as more privileged members of society.
Scientists are on the verge of discovering (or have already discovered) the gene for criminality, for alcoholism or the “gay gene”.
Certain things are inborn, or that they simply occur naturally regardless of environmental influences. People who take the position that all or most behaviors and characteristics are the result of inheritance are known as nativists.
Other thinkers believed in what is known as tabula rasa, which suggests that the mind begins as a blank slate. According to this notion, everything that we are and all of our knowledge is determined by our experience. People who take the position that all or most behaviors and characteristics are the result of learning are known as empiricists.
Nativist theory
Language Acquisition Device
According to this theory, all children are born with an instinctive mental capacity that allows them to both learn and produce language.
How a person behaves can be tied to influence such as parenting styles and learned experiences. For example, a child might learn through observation and reinforcement to say 'please' and 'thank you.' Another child might learn to behave aggressively by observing older children engage in violent behavior on the playground.
Empiricist theory
Social learning theory
According to theory, people learn by observing the behavior of others.
A study looking at peer pressure recognizes that "nurture" is also important in people's potential for addiction.
Traits
such as eye color and hair color are determined by specific genes encoded in
each human cell. The Nature Theory takes things a step further to say
intelligence, personality, aggression, and sexual orientation are also encoded
in an individual's DNA.
- The search for "behavioral" genes is the source of constant debate. Many fear that genetic arguments might be used to excuse criminal acts or justify divorce.
- The most debated issue pertaining to the nature theory is the exsistence of a "gay gene," pointing to a genetic component to sexual orientation.
Our
behavioral aspects originate only from the environmental factors of our
upbringing. Studies on infant and child temperament have revealed the most
crucial evidence for nurture theories.
- American psychologist John B. Watson, after observing children in the field, was interested in finding support for his notion that the reaction of children, whenever they heard loud noises, was prompted by fear. Furthermore, he reasoned that this fear was innate or due to an unconditioned response. He felt that following the principles of classical conditioning, he could condition a child to fear another distinctive stimulus which normally would not be feared by a child.The aim of Watson and Rayner was to condition phobias into an motionally stable childThis experiment led to the following progression of results:
- Introduction of a loud sound (unconditioned stimulus) resulted in fear (unconditioned response), a natural response.
- Introduction of a rat (neutral stimulus) paired with the loud sound (unconditioned stimulus) resulted in fear (unconditioned response).
- Successive introductions of a rat (conditioned stimulus) resulted in fear (conditioned response).
·
Harvard
psychologist B. F. Skinner's early experiments produced pigeons that could
dance, do figure eights, and play tennis. Today known as the father of
behavioral science, he eventually went on to prove that human
behavior could be conditioned in much the same way as animals.
- A study in New Scientist suggests that sense of humor is a learned trait, influenced by family and cultural environment, and not genetically determined.
- If environment didn't play a part in determining an individual's traits and behaviors, then identical twins should, theoretically, be exactly the same in all respects, even if reared apart. But a number of studies show that they are never exactly alike, even though they are remarkably similar in most respects.
The Nurture Assumption: Why Children Turn Out the Way They Do is a book written by Judith Rich Harris.
In this book, she challenges the idea that the personality of adults is determined chiefly by the way they were raised by their parents. She looks at studies which claim to show the influence of the parental environment and claims that most fail to control for genetic influences. For example, if aggressive parents are more likely to have aggressive children, this is not necessarily evidence of parental example. It may also be that aggressiveness has been passed down through the genes. Indeed, many adopted children show little correlation with the personality of their adoptive parents, and significant correlation with the natural parents who had no part in their upbringing.
The role of genetics in personality has long been accepted in psychological research. However, even identical twins, who share the same genes, are not exactly alike, so inheritance is not the only determinant of personality. Psychologists have tended to assume that the non-genetic factor is the parental environment, the "nurture". Adoptive siblings are as unalike in personality as non-related children.
Harris' most innovative idea was to look outside the family and to point at the peer group as an important shaper of the child's psyche. For example, children of immigrants learn the language of their home country with ease and speak with the accent of their peers rather than their parents.
Nature vs nurture in personality traits
Identical twins reared apart are far more similar in personality than randomly selected pairs of people. Likewise, identical twins are more similar than fraternal twins. Also, biological siblings are more similar in personality than adoptive siblings. Each observation suggests that personality is heritable to a certain extent.The Nurture Theory: Environment
Those that support nurture feel that children are like a clean slate and the experiences they have in life and people who influence them determine what is written upon the slate.
Abusers: Evidence from numerous studies supports that children who have been abused are more likely to become abusers themselves
Conditioning: Scientists, such as John Watson and B.F. Skinner have completed numerous experiments in which they proved that environment greatly impacts a person. In 1920 Watson took an orphan, Albert, who was afraid of nothing except loud noise. He then conditioned him by hitting a hammer on a piece of steel every time he saw a rat. Soon every time Albert saw the rat he was terrified, his fear also transferred to other hairy objects. Proving that environment was stronger than genetics.
Humor: A study in New Scientist suggests that humor is a learned trait. The study was conducted with 127 pairs of twins who rated how funny they thought a variety of Far Side Cartoons were. “Surprisingly, the identical twins shared no more common responses to the jokes than did the fraternal twins during the study.“ Family upbringing had a greater contribution of the reaction of the twins than did genetics.
Twins: Environment must play a factor in determining traits. Because if not twins, whose DNA is exactly the same, would be exactly the same, even if they were raised apart. Studies show that twins are similar in many aspects but not exactly the same.
The Nature Theory: Genetics
Criminal Behavior: Some scientists support the nature theory as additional evidence indicates that some people are more inclined to commit criminal acts. “In Iowa, the first adoption study was conducted that looked at the genetics of criminal behavior. The researchers found that as compared to the control group, the adopted individuals, which were born to incarcerated female offenders, had a higher rate of criminal convictions as adults. (Tehrani & Mednick, 2000).
Divorce: A study done at Boston University compared marriage and divorce rates in identical and non-identical male twins. They found that “identical twins, who share the same genes, were more likely to follow the same patterns of divorce than non-identical twins, who only share about half their genes.” They believe that this suggests that genetics greatly influences the possibility of divorce.
Twins: Numerous researchers have studied the personalities of twins, both those raised together and those raised apart. If genetics didn’t play a part twins raised together would be exactly the same, and they aren’t. Likewise twins raised apart would be completely different. Researchers have found that even though they were raised apart they are very similar in many aspects of their personalities. Supporting the idea that genetics plays a role in determining personality and behavior.