The second theory for increased IQ scores is improvement in cognitive stimulation. This includes parents that are better educated, availability of television and the internet, and improvements in education (Lynn, 1990). Improved cognitive stimulation appears to be the logical explanation for increased IQ scores, as each generation is exposed to far more information than the previous generation. However previous research have indicated that even infants only a few months of age, with no chance to be influenced by external cognitive stimulation, have demonstrated signs of accelerated cognitive development, therefore suggesting that cognitive stimulation is not the only influence on increased IQ (Lynn, 1990).
The third plausible theory for increased IQ scores is genetics. Eugenics, a theory for rising IQ scores, is the study and practice of selective breeding applied to humans, with the aim of improving the species. It has been hypothesised people with higher IQ’s have more children and passes on their intelligence gene. However, research has demonstrated a negative correlation between people with high intelligence levels and fertility, ruling out the theory of eugenics (Lynn, 1990).
It is possible that all, none or a mixture of these theories could explain why IQ scores are rising on an average of 3 points a decade. Research indicates that the IQ scores must be influenced by some external factor, due to the increase of such an impossible amount in such a short space of time.
While it is not certain what affects intelligence levels, psychologists are confident that they are able to measure a persons IQ. The most popular tests that are used include the RPM, the Stanford-Binet, and the WAIS (Hiscock, 2007). Each test has been shown to successfully measure a person’s g (general intelligence). Although each test assesses an individuals IQ, not all test scores have risen equally over time. The most dramatic gain is on the RPM, with an IQ score gaining on average 0.6 IQ points per year between 1930 and 1990 (Hiscock, 2007). Scores on the WAIS and Stanford-Binet IQ tests have also risen, but are not as dramatic as the rates from the RPM tests. Flynn concluded that the WAIS and Stanford-Binet IQ tests continued to rise at the rate of 0.3 points a year, 0.3 points less than the RPM (Hiscock, 2007).
A plausible explanation for the differences between the RPM and the Stanford-Binet/WAIS tests may be that each test assesses different forms of intelligence. The RPM is said to measure fluid intelligence (the ability to solve novel problems), the WAIS scale measures both fluid intelligence and crystallized intelligence (domain-specific knowledge over time), and the Stanford- Binet measures mostly learned information or crystallized intelligence (Hiscock, 2007). There is a consistent finding that fluid intelligence shows an increase twice as large as that observed for tests of learned information or crystallized intelligence. This increase represents the enhancement of people’s ability to solve certain kinds of problems rather than their acquisition of information.
Flynn’s previous research has indicated that IQ scores have been rising from 1930 and 1990 in developed countries, but no recent research has indicated that these trends are still continuing. In fact, various experiments have shown that the Flynn effect is no longer present in the current century. Teasdale and Owen (2008) investigated whether or not the Flynn effect was still present in Denmark. They presented 23,598 males with the RPM and compared test results from similar experiments in 1988 and 1998 to 2004. The study revealed that between 1988 and 2004, Danish test scores has declined by 1.5 IQ points. Denmark, a highly developed country, may be the first of the nations to suggest that there is no longer a Flynn effect in developed countries.
While Denmark revealed no signs of the Flynn effect in the new century, Estonia, a developing country, reveal improved IQ scores from 1934 to 2002 by almost 1 standard deviation (SD) on some IQ tests (Must, Must & Raudik, 2002). In 1934, 6000 school children completed the U.S National Intelligence Test. In 1998, and then again in 2002, the same test was administered and test results showed that although the increase was not as significant as it has been in the developed countries, Estonia’s IQ scores had increased. Therefore, it is possible that due to the nourished life style of the developed nations, they have reached their full potential of IQ. In addition, underdeveloped nations IQ levels are still rising and may continue to rise as their living standards improves. Further research is required to investigate whether the Flynn effect is still continuing into the new century, in both developed and developing countries, in order to make appropriate conclusions.
Even if the Flynn effect is no longer in effect, there is still strong evidence that IQ scores have risen over the past 100 years. If this is true, it would suggest that we are smarter than we were 100 years ago. However, Flynn commented that the jump in IQ scores seems too large to be possible, and that people aren’t getting more intelligent, but better at completing IQ tests (Lynn, 1990). He concludes that people are improving on abstract problem solving, not increasing intelligence levels, arguing that if intelligence had really risen by 1 SD over the last century there would be far more intelligent youth and a higher amount of intellectual achievements would have increased far more than it has occurred (Lynn, 1990). Rogers (1999) questioned the validity of Flynn’s results, and suggested that perhaps Flynn misinterpreted his results, or used inappropriate measures to gain his data, as no longitudinal data were used, only cross sectional data. He also suggested that Flynn inferred the existence of the increase in IQ through a logical argument applied to a certain type of data, and not on the data itself.
However, although the Flynn effect has some criticisms or concerns of validity, the majority of research suggests that people’s intelligence levels have indeed risen in the past 100 years, and that we are more intelligent that we once were. It is still unclear as to why the Flynn effect occurs, but it is highly likely that a combination of nutrition, genetics and cognitive stimulation are contributing to the increase in IQ levels. The evidence suggests that in the new century, the Flynn effect has come to a standstill in developed nations due to the high standards of living, but developing nations IQ scores are still rising and will continue to rise as their living standards advance. There needs to be further research as to whether or not the Flynn effect is continuing into the new century for both developed and developing nations. This could help to estimate future IQ levels and could help develop education programs that would lead to increased intelligence levels. Furthermore, due to evidence indicating higher increases in fluid intelligence than crystallized intelligence, further study delineating the types of intelligence and the cause for their increases would help to suggest whether the population is becoming more intelligent or more adaptable to their changing environment. Intelligence is a highly debated topic because so many aspects of it are so unclear and undefined. Further research needs to be conducted to asses the various aspects of intelligence, how they are influenced and future intelligence levels.
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Lynn, R. (1990). The role of nutrition in the secular increases in intelligence.
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