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Nature Nurture Debate

Nature Nurture Debate

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Nature Nurture Debate

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  1. Nature Nurture Debate It all began with Galton

  2. nature versus nurture debate a classic controversy • No clear conclusion to the dispute • Many hypotheses • Overwhelming evidence has been found in the favour of both hypotheses • Nature argues that: • Hereditary (genetics) is stronger • Nurture argues that: • A person’s environment plays a large role in his mental aptitude.

  3. Historical Background • Before starting to explore the Nature vs. Nurture controversy, it is important to mention the English scientist Francis Galton (1822 –1911), a cousin of Charles Darwin, who initiated this whole debate between hereditarians and environmentalists more than a century ago. • He travelled a great deal particularly in Africa and this would prove to influence his multifaceted career as they "helped to establish Galton's credibility as a serious Victorian man of science" (Bynum, 2002

  4. In 1865, he began to study heredity, partly brought on by reading his cousin, Charles Darwin's publication Origin of Species. Galton soon discovered that his true interest was studying the variations in human ability and intelligence in particular. Specifically, he was convinced that success was due to qualities that are passed down to offspring through heredity. • Interest in the role of heredity led him to introduce the method of twin studies to examine the different contributions of nature and nurture. He also inquired into racial differences and was one of the first to employ questionnaire and survey methods, which he used to investigate mental imagery in different groups.

  5. Galton had observed that the gifted individuals tended to come from families which had other gifted individuals. He went on to analyze biographical dictionaries and encyclopedias, and became convinced that talent in science, the professions, and the arts, ran in families. Galton, influenced by his research and findings, took this observation one step further and argued that it would be "quite practicable to produce a high gifted race of men by judicious marriages during several consecutive generations". (Bynum, 2002)

  6. After World War I: 1920s-1930s • Careful reanalysis of the mass of intelligence test data took place. This new research began to challenge the commonly held view that intelligence was genetically linked to racial differences. Evidence now seemed to support a closer link between social class and intelligence, rather than race and intelligence. This caused a shift of the ‘dominant’ opinion towards the ‘nurture’ camp, and as a result, a great number of psychologists in the 1920s and 1930s changed sides, becoming environmentalists about ‘intelligence’.

  7. 1940s-1990s • The reaction in the favor of environmental factors affecting intelligence faded shortly, and common belief shifted towards the middle. From the early 1940's, it seemed there was a rejection of simplistic nature or nurture views, with more common recognition of their complex interaction. In fact, during the 1960's, the focus of the problem was shifted away from the individual as the cause of the problem, and centered on social determinants. The dominant side was once again the nurture/environmental camp. Efforts were made to stop poor educational achievement through special schooling, and to diminish poor living conditions through welfare, because it was thought that intelligence and mental abilities were almost solely determined by the learning individuals acquire from their environment.It became politically correct to minimize talk and discussion of the role of 'nature' in contributing to any individual differences, let alone intelligence. The evidence of differences in intelligence between socioeconomic groups and racial groups, however, did not go away.

  8. Nature vs. Nurture Debate: Contemporary Ideas • From time to time, there have been inflammatory articles which present and interpret evidence of IQ differences between groups, and today we all come across such articles in science magazines. The most recent, and most major of these publications was Herrnstein and Murray's "The Bell Curve" (1994). This book provided momentum in favour of the 'nature' side, at least in the public's eye, but even more so, it generated massive debate and controversy in psychology, sociology, education, and politics. The work's main thesis is that an individual's intelligence – no less than 40% and no more than 80% of which is inherited genetically from his or her parents – has more effect than socioeconomic background on future life experiences.

  9. In addition to the premise that measured intelligence (IQ) is largely genetically inherited, a second important premise was that IQ is correlated positively with a variety of measures of socioeconomic success in society, such as a prestigious job, high annual income, and high educational attainment; and is inversely correlated with criminality and other measures of social failure. • It was suggested that socioeconomic successes (and failures) are also largely genetically caused. In a nutshell, this work of Herrnstein and Murray supported a somewhat hereditarian explanation of intelligence and definitely influenced many contemporary experts to shift their opinions toward the nature side of the argument. 

  10. Evidence for ‘Nurture’ • We saw earlier that, while not discounting that genetic factors may exist, supporters of the nurture theory believe that our behavioral aspects originate mostly from the environmental factors of our upbringing. Studies on infant and child temperament have revealed the most crucial evidence for the nurture theory. • The nurture camp also took advantage of the nutrition studies, twin studies, and adoption studies for collecting evidence for their hypothesis. In the 1980s, a New Zealand-based political scientist, James Flynn, noticed that IQ was increasing in all countries all the time, at an average rate of about 3 IQ points per decade i.e. the average IQ across the world has risen over 1 standard deviation (i.e. 15 points) since WWII - predominantly due to environmental effects.

  11. • Will give you the graph you need to show the changes according to Flynn • Could this be due to diet? Possibly but IQ scores are still rising just as rapidly in well-nourished western countries. So, it is not exactly the nutrition that causes this increase in IQ.

  12. Could it be schooling? It has been found that interruptions to schooling only have temporary effects on IQ. • One researcher, UlricNeisser suggests that the Flynn effect is due to the way we are being saturated with sophisticated visual images: ads, posters, videogame and TV graphics etc - rather than written messages. He suggests that children experience a much richer visual environment than in the past and that this helps them with visual puzzles of the kind that dominate IQ tests. • There have been posed many such environmentalist hypotheses to explain the Flynn effect; yet, even today, it is still not known what exactly causes the steady increase in IQ as found by James Flynn. • One lesson to be learned from the Flynn example is that when we say environment plays an important in intelligence, in fact we are talking about many different environmental factors, such as nutrition, schooling, parental behaviour…

  13. Those factors, circumstances and attributes have been found to vary to a greater or lesser (but always significant) extent in relation with IQ - note that not all of these relationships increase intelligence, yet they all support the environmental view. This means that although some of those factors negatively affect intelligence, this is still a sign that environment can affect the level of intelligence and mental abilities. It has been found that intelligence can vary with:

  14. Number of years in school • Social group of parental home • Father's profession • Father's economic status • Degree of parental rigidity (negative) • Parental ambition • Mother's education • Average TV viewing (negative) • Average book-reading • Self-confidence according to attitude scale measurement • Age (negative relationship, applies only in adulthood) • Degree of authority in parental home (negative) • Criminality (negative) • Alcoholism (negative) • Mental disease (negative) • Emotional adaptation

  15. "No single environmental factor seems to have a large influence on IQ. Variables widely believed to be important are usually weak....Even though many studies fail to find strong environmental effects....most of the factors studied do influence IQ in the direction predicted by the investigator....environmental effects are multifactorial and largely unrelated to each other." (Bouchard & Segal (1985), p.452) So, it would appear that there are many environmental factors and attitudes each contributing a small fraction to the variance in IQ scores.

  16. American psychologist John Watson, best known for his controversial experiments with a young orphan named Albert, demonstrated that the acquisition of a phobia could be explained by classical conditioning. • 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.

  17. In addition, the amount of nourishment an individual receives has been proven to play a very large part in a person’s mental ability. This is especially true concerning infants and young children. Moreover, the human brain critically needs nutritious food and antitoxins to grow and function properly, particularly in early years of development. A study done in Great Britain in the late 1980s shows that nutrition plays a very large role in a person’s development. Adolescents aged twelve to thirteen were given vitamin and mineral supplements for eight months. These subjects were then administered intelligence tests. Test scores were recorded before the test and after the test. These scores were also compared to other adolescents who were not given the supplements. The scores showed that the students who had taken the supplements scored higher on the tests after taking the supplements (Herrnstein and Murray, 292). This study, thus, proves that nutrition (which is a part of the environment) plays a role in intelligence and mental aptitude.

  18. Adoption studies have also somewhat shown that a person environment plays an important role in his mental ability. For example, a study done with adoptive children raised in the same house had very similar IQs, given that these children were in no way related genetically. The environment that they we raised in provided them with similar abilities for learning and for retaining information (Kagan and Havermann

  19. Genie and the Wolf Boy • Since the 1960s, the idea of nurture has gained an upper hand. Researchers proposed that while genetics did matter, it was the environment that determined whether or not a person was able to reach his or her full potential. This has been seen in studies of neglected infants and of feral children (children who were raised by wild animals). If children do not get care and attention in their early, formative years, whatever innate intelligence they have never gets a chance to develop properly and they remain developmentally backward

  20. On the other hand, in a supportive background, a child will be encouraged to do well and will have more opportunities in which to succeed. It seems that the right environment triggers off the expression of genes that can influence the development of particular traits. • Genes may give a person an advantage when it comes to the development of intelligence; however, a nurturant environment is necessary for that person to utilise that advantage.

  21. Conclusion • "No single environmental factor seems to have a large influence on IQ. Variables widely believed to be important are usually weak....Even though many studies fail to find strong environmental effects....most of the factors studied do influence IQ in the direction predicted by the investigator....environmental effects are multifactorial and largely unrelated to each other." (Bouchard & Segal (1985), p.452) So, it would appear that there are many environmental factors and attitudes each contributing a small fraction to the variance in IQ scores