There has been a rise in IQ score for the world populationovertime. This effect was known as the Flynn Effect, named after James R. Flynnwho has been well known in recording the effects and getting public’s attentionto its implication.
The Flynn Effect has started as early as the time IQ testsemerged. Studies has been trying to record the IQ scores differences and it hasbeen shown that there were around 3 points increases every decade (Flynn, 2009;Trahan et al., 2014). One way of testing this effect is to compare the scores ofthe same participant but using different versions of the same test. And itshows that the same participant scores higher on the older version of the test.This causes the norms of IQ tests needed to be updated periodically, so that ascore of 100 is the median of the distribution. Like the Wechsler IntelligenceScale for Children which was originally invented in 1949, its norm has beenupdated in 1974, 1991, 2003 and more recently 2014. They achieve this bystandardising scores that comes from participants of the standardizationsample.
Because of this standardisation, this means that the people a centuryago would have an average IQ of 70 if they are scored against the modern norms.And in reverse, if we use the norms 100 years ago against scores of peoplenowadays, they would score on average 130. The Flynn Effect not only shows the phenomenon of a risingIQ scores in population, it also provided the evidence of supporting the theorythat intelligence is not only a genetically inherited, fixed variable. It canalso be affected by the environment. There are 2 main explanations proposed byscientist to explain the causes of the Flynn Effect, we can refine them intotwo major categories, Cognitive stimulation and Nutrition. Cognitivestimulation includes change in duration and type of schooling received,test-taking sophistication, child rearing practice and change in culture. In modern years, children receive longer education compareto the old times.
More people go to high school or even universities, theyreceived higher education which cause them to have a higher chance of having ahigher IQ score as schooling is a good prediction for verbal IQ (Cahan , 1989). This can be support by the study that shows African-Americans whodid not receive formal education score lower on IQ test (Neisser. U, 1997).
Havinga longer year in school also caused the test-taking sophistication. Test-takingsophistication refers to the effect that on IQ score when people have a higherchance of performing a test, leading to a higher awareness and understanding ofIQ tests in modern years. On the other hand, parents nowadays are much moreconcerned about their children’s development. They may be sincerer in helpingtheir children to develop their cognitive abilities which may lead to a gain inIQ score. It may also be that the culture of the environment has a dramaticchange overtime, with different visual medias emerging, and all the complexvisual information displayed requires a large amount of visual processing.
Thismay help the public to gain their skills in visual analysis which is requiredfor test like the matrix tests (Gf). Other researchers believed that nutrition or healthcareimprovement could be the main cause of the Flynn Effect (Lynn, 1990; 1998).Comparing to old days, nutrition intake for people in modern times aresignificantly higher than before, which lead to some degree of biologicalchanges in the population, like height or life span. Previous studies haveshown that the size of head and brain had increased overtime (Jantz, 2000) and studies have shown thatthe volume of the cerebral is positively correlated with IQ score (Reiss etal., 1996). Another evidence supporting the nutrition hypothesis is whencomparing the entire IQ score distribution curve in different time periods(e.g.
a sample of distribution curve in 1970 and one in 2000). If the gain inIQ is due to cognitive stimulation, the distribution curve will have a gainalong the whole curve because there are no reasons to say that the cognitivestimulation will primarily affect the most deprived. However for nutrition, wewould expect a primary growth in the medium and lower level of the curve. Astudy using the entire distribution curve was done, and the results supportsthe idea of the nutrition hypothesis (Colom et al.
, 2005). It is really difficult for us to study how the ‘general’nutrition has influenced our cognitive abilities. Therefore, researchers haveconcentrated in two major areas of nutrition, micronutrients and breastfeeding.Micronutrients are divided into minerals and vitamins, two different types. Weusually just require a relatively small amount and it plays a crucial role tothe development and regulation of our body. In this essay, we will discuss theeffect of essential fatty lipids, iodine and multivitamin and mineralsupplements to the development of intelligence.
Fatty lipids play an essential role in the development ofour brain, it is important for brain development and functioning. Around 60% ofour brain’s dry weight is composed of fatty lipids. And between that 60%, 20%are docosahexaenoic acid (DHA) which is a form of omega-3 fatty acid; andarachonic acid (AA), which is a form of omega-6 fatty acid. These are the twomain components of the grey matter in the brain (Benton, 2010). On the otherhand, essential fatty lipids are also the main components of the brain tissue.They are used to build neuronal membranes and are also used to enhance thegrowth of neuronal and dendritic spine which are crucial in the processes ofsignal processing and neural transmission.
Previous studies have shown thatlong chain polysaturated fatty acids (LCPUFA) such as omega-3 and omega-6 fattyacids are usually insufficient in both adults and children (Schuchardt et al.,2010). Daniels et al.
(2004) had reported a positive correlation between theamount of fish intake from the mother during pregnancy and cognitivedevelopment in their children, as fish is the main source of food that we canobtain essential fatty acids. There are also studies shown that with a highmaternal fish intake, their children will perform better in language and socialskills (Daniels et al., 2004). Also, the same study showed that a lower IQ wasobserved when the children’s mother consumed less seafood during pregnancy. However, there are also some conflicting studies showingthat essential fatty acids have little or no effect on the development ofintelligence. A study have shown that for a 7 years old smaple, no difference wasobserved in their IQ score between children that are supplemented andnon-supplemented children (Helland et al.
, 2008). This may be caused becausethe development of the cognitive system was influenced by too many otherfactors. Also, the association between the supplemented group and thenon-supplemented group may be too small for the test to detect at this laterage. In conclusion, the findings were inconsistent, with some studiessuggesting that essential fatty lipids are positively associated with IQ andsome indicating that the effect was minimal. The reason behind this maybe thatthe intervention experiment designs were not consistent, each have differentgroups of participants, having different dosage and duration of supplementationand the children were measured with different tests and at different ages.
In areview by Ryan et al. (2010), they discovered that a significant positiveoutcome in cognitive development of children is achieved if the supplementationduration and dosage is high. Iodine is used to produce thyroid hormones in the body,which is essential in neurodevelopment and is used in different neurologicalprocess, for example neural cell differentiation, maturation and migration(Zimmermann, 2009).
Previous studies have shown that infants have a higherpossibility of having cretinism if their mother have experience severe iodinedeficiency during pregnancy (Forrest, 2004). Also, comparing mothers who livedin iodine deficient areas and those who lived in iodine sufficient areas, onaverage their children were 12.3 points lower in IQ scores (Qian et al., 2005).On the other hand, studies have shown that for mothers who have beensupplemented for iodine, their children will have better performance indifferent motor and cognitive skills, like gross and fine motor coordination,socialization and psychomotor development (Berbel et al., 2009; Velasco et al.,2009).
The studies mentioned above all suggested that Iodine is crucial forchildren’s cognitive development. However, there also studies that haveobtained opposite results. For example, a study had reported that infants of motherswho had high amount of iodine through multivitamin supplementation have lowerpsychomotor development than infants born to mothers with less amount of iodinesupplementation (Murcia et al.
, 2011). Generally,previous researches have suggested that iodine plays a crucial role inchildren’s cognitive development, although there is some inconsistency in someinterventional studies.We discussed the use of individual supplements in the above paragraphs, butnutrients react with each other to perform its function (Benton, 2010).
Also, amalnutrition diet usually result not only with one single deficiency butmultiple micronutrient deficiencies. Therefore, we should also consider theeffect of multivitamin and mineral supplementation on IQ. A recent review in2011 considering 18 studies, have shown that multivitamin and mineralsupplementation has a positive association with brain development in children(Leung et al., 2011). Also, researchers found that these supplementationsresulted in improvements in different aspect of areas, like higher fluidintelligence, improved motor development, better visual attention and spatialability (Eilander et al., 2010; Prado et al., 2012). Through theseobservational studies, we can conclude that multivitamin and mineralsupplementation do have a significant effect in the development of ourcognitive system.
Breastfeeding has always been a highly-debated topicregarding its effects on intelligence. Studies and meta-analysis have foundthat the IQ of breastfeeding children born in normal birth weight and low birthweight is 2.7 and 5.
2 points higher respectively than infants who hadartificial milk (Anderson et al., 1999). A later review point out that majorityof the studies have a positive association between breastfeeding and cognitivedevelopment in children, and the IQ of breastfeeding children are on average2-5 points higher than non-breastfeeding children at any age (Michaelsen etal., 2009). It has been proposed that the association between breastfeeding andincrease in IQ is due to the concentration difference of LCPUFA (e.
g. DHA) inbreast milk and formula milk. Although lots of studies confirms the associationbetween the two, these effects usually declined significantly after controllingfor other confounding variables such as mother’s socioeconomic state andmaternal IQ. In conclusion, the association of whether breastfeeding have aneffect on cognitive development is still questionable.
Although there are still lots of uncertainties regarding theeffect of nutrition on developing intelligence, lots of people in the generalpopulation still believe that nutrition or supplementation can increase theirIQ. This can be shown by the increasing amount of supplementation brandavailable this days. This is mainly achieved by the media through reportingdifferent studies which claim there was a significant effect. In general, I donot think that the public fully believe in the effect of nutrition.
However,they may think that it’s still worth a try as taking these supplements will nothave any major side effects. This can be true if you do not exceed the safetydosage of those supplements. In conclusion, both cognitive stimulation and nutrition eachdo have different supporting studies, but there are too many confoundingvariables to be considered. Therefore, there still isn’t a clear explanation onthe cause of Flynn Effect.
With the advance in future technology, I believe wecan perform more accurate measures on the topic and in the future moremysteries will be solved.