Herrstein and Murray estimate the relationship between IQ and occupation to be between.2 and.6 (i. e. that IQ explains between 4% and 36% of the variations in occupation). These correlations are slightly higher for skilled, professional jobs, and slightly lower for jobs that require less skill. Whilst this might be useful in describing groups, it means there is questionable value in administering an IQ test to an individual in an attempt to help determine their occupational options. It may be a useful approach, however, to help select the best 100 employees from a 1000 applicants (Howe,1997, p.97).
Comments on the scope & quality of intelligence research: All this research uses psychometric, quantitative tests of intelligence, which we know from previous lectures corresponds somewhat (but not entirely) with our conceptions of what intelligence is.
Multiple intelligences or subcomponents of intelligence are barely considered in much of this research. Neither are alternative measures of intelligence, such as speed of processing, evoked potentials, or practical intelligence, etc. Future research on brain-behaviour connections will probably help to more accurately isolate the functions of 'intelligence' (Weinberg, 1989). In addition, as we come to understand and develop more effective environmental interventions to maximise individuals' IQs, this will possibly expand the relative important of the 'nurture' component. Nevertheless, there remains the spectre of eugenics - those who would argue for selective breeding on the basis of intellectual ability. This issue is likely to rear its head again in the future and with new genetic technologies could appear in a more dynamic form. The role of “interaction": An under researched area, while the nature vs. nurture debate has raged, is the contribution of interactions between genetics and environment on IQ variance. In the over focus on nature vs. nurture issues, the attempts to estimate the relative contribution rests on the somewhat naive notion that there is a constant, true value. In reality, "gene expression is environment dependent" and it impossible to obtain pure estimates of genetic vs. environmental contribution - one could not exist without the other. The environment a child experiences is partly a consequence of the child’s genes as well as external factors. To some extent a person seeks out and creates his or her environment. If she is of a mechanical bent she practices mechanical skills; if a bookworm, she seeks out books. Thus genes may create an appetite rather than an aptitude. Remember that the high heritability of shortsightedness is accounted for not just by the heritability of a gene for short sightedness but also by the heritability of literate habits. Thus, a future area for research which blends those in the nature camps with those in the nurture camps would be examine which environmental components allow people to optimally realise their genetic potentials for a variety of areas of cognitive performance (e. g. see Feldman, 1986).
What have we learnt about intelligence:
So, what can we say about nature vs. nurture as causal determinants of intelligence? A conservative, seemly safe position is that: "In the field of intelligence, there are three facts about the transmission of intelligence that virtually everyone seems to accept:
1. Both heredity and environment contribute to intelligence. 2. Heredity and environment interact in various ways. 3. Extremely poor as well as highly enriched environments can interfere with the realization of a person's intelligence, regardless of the person's heredity” (Sternberg & Grigorenko, 1997, p. xi). 4. Although most would accept a causal role of genetics, the exact genetic link and how it operates is very far from being understood - another point that most psychologists would agree on. It is certainly not a single gene, but a complex combination of smaller genetic markers. 5. But likewise, it is difficult to pin-down single, identifiable elements of the environment, which directly influence IQ scores. So what have we learned about intelligence: that it’s difficult to define but that there is SOMETHING we call intelligence that appears to relate to ability to reason abstractly, to learn and to adapt. That we can measure some part of it, although poorly; that it’s partially caused by genetics, partially be environment; that the real causes are the complex, not well understood interplay between genetics and environment; that it is somewhat though not greatly modifiable; that sometimes what we learn from tests is used inappropriately but that IQ tests can be useful in helping children attain their potential.
"Measures of intelligence have reliable statistical relationships with important social phenomena, but they are a limited tool for deciding what to make of any given individual. Repeat it we must, for one of the problems of writing about intelligence is how to remind readers often enough how little an IQ score tells you about whether the human being next to you is someone whom you will admire or cherish." Herrnstein and Murray (1994, p. 21)
"Mother Nature has plainly not entrusted the determination of our intellectual capacities to the blind fate of a gene or genes; she gave us parents, learning, language, culture and education to program ourselves with." (Ridley, 1999, p. 77) THE CONTROVERSY OF NATURE AND NURTURE
Are we the way we are because of our genes? How much of our personality and characteristics are because of the way we were brought up, and our experiences, and how much is because of the way we were wired when we were born? The argument of nature, our genetics, and nurture, our upbringing, has been going on for years, and scientists are still struggling to find out why we are whom we are. If you asked 100 randomly selected genetic scientists their view on the controversy of nature vs. nurture, you would get 100 entirely different answers, and almost every one would make perfect sense with the evidence that supports it. As Kenneth Rothman said, "It is easy to show that 100 percent of any disease is environmentally caused, and 100 percent is inherited as well." Thus, it is a heated debate that has been going on for decades, one that may never stop. (N vs. N; an Unnecessary Debate) In February 1999, we completed the Human Genome project. Since then, scientists have been looking for new clues in our DNA, trying to find hints of certain genes and what they mean, and what that means for human society. Most scientists base their conclusions about nature and nurture by studying identical twins that were separated at birth. These twin sets tell us many things about nature vs. nurture. We can compare how they acted in different environments, see how many things they did that were surprisingly alike, how they score on IQ tests, if they answer many of the questions the same way, and how similar their health records are. (Farber, 4) One living example of the idea that your genes say much about who you are the Lewis and Springer Twins. When they were born, they were both adopted into different families. They first met when they were forty years old, and they then found that the similarities between them were extraordinary. Both were named Jim, both got dogs and named them "Toy," they had the same hobbies, jobs, handwriting, weight, appearance, and test results. Because of this, and other similar cases, some scientists believe that genes are the dominant force in creating who we are. (Farber, 33) Some scientists however, think that our genes have very little to do with the specific things that we do. Scientists started thinking this more when we first finished the human genome and discovered that we only had 30,000 genes. Until we finished the genome, we thought there could be genes for nearly all of our characteristics, but when we learned we only had 30,000 genes we decided that was not enough genes to have that many different genetic characteristics. (Clark, 102) One of the main questions that has been asked is, "Does Genetics influence intelligence?" Could social Darwinism, the belief that some people are farther along in evolution than others and thus have social advantages, be alive in our society today? Some scientists say yes, while others say no way.
Francis Galton says, "Men who are gifted with high abilities... easily rise through all the obstacles caused by inferiority of social rank." He believes that genetics has a great deal to do with intelligence. He argues that social advantages are not enough to make an average man great; however, social inferiorities are not enough to make a smart man "average."(Roleff, 25)
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