There this by standardising scores that comes from


There has been a rise in IQ score for the world population
overtime. This effect was known as the Flynn Effect, named after James R. Flynn
who has been well known in recording the effects and getting public’s attention
to its implication. The Flynn Effect has started as early as the time IQ tests
emerged. Studies has been trying to record the IQ scores differences and it has
been 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 of
the same participant but using different versions of the same test. And it
shows that the same participant scores higher on the older version of the test.

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This causes the norms of IQ tests needed to be updated periodically, so that a
score of 100 is the median of the distribution. Like the Wechsler Intelligence
Scale for Children which was originally invented in 1949, its norm has been
updated in 1974, 1991, 2003 and more recently 2014. They achieve this by
standardising scores that comes from participants of the standardization
sample. Because of this standardisation, this means that the people a century
ago 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 people
nowadays, they would score on average 130.


The Flynn Effect not only shows the phenomenon of a rising
IQ scores in population, it also provided the evidence of supporting the theory
that intelligence is not only a genetically inherited, fixed variable. It can
also be affected by the environment. There are 2 main explanations proposed by
scientist to explain the causes of the Flynn Effect, we can refine them into
two major categories, Cognitive stimulation and Nutrition. Cognitive
stimulation 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 compare
to the old times. More people go to high school or even universities, they
received higher education which cause them to have a higher chance of having a
higher IQ score as schooling is a good prediction for verbal IQ (Cahan &
Cohen, 1989). This can be support by the study that shows African-Americans who
did not receive formal education score lower on IQ test (Neisser. U, 1997). Having
a longer year in school also caused the test-taking sophistication. Test-taking
sophistication refers to the effect that on IQ score when people have a higher
chance of performing a test, leading to a higher awareness and understanding of
IQ tests in modern years. On the other hand, parents nowadays are much more
concerned about their children’s development. They may be sincerer in helping
their children to develop their cognitive abilities which may lead to a gain in
IQ score. It may also be that the culture of the environment has a dramatic
change overtime, with different visual medias emerging, and all the complex
visual information displayed requires a large amount of visual processing. This
may help the public to gain their skills in visual analysis which is required
for test like the matrix tests (Gf).


Other researchers believed that nutrition or healthcare
improvement could be the main cause of the Flynn Effect (Lynn, 1990; 1998).

Comparing to old days, nutrition intake for people in modern times are
significantly higher than before, which lead to some degree of biological
changes in the population, like height or life span. Previous studies have
shown that the size of head and brain







had increased overtime (Jantz, 2000) and studies have shown that
the volume of the cerebral is positively correlated with IQ score (Reiss et
al., 1996). Another evidence supporting the nutrition hypothesis is when
comparing 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 in
IQ is due to cognitive stimulation, the distribution curve will have a gain
along the whole curve because there are no reasons to say that the cognitive
stimulation will primarily affect the most deprived. However for nutrition, we
would expect a primary growth in the medium and lower level of the curve. A
study using the entire distribution curve was done, and the results supports
the 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 have
concentrated in two major areas of nutrition, micronutrients and breastfeeding.

Micronutrients are divided into minerals and vitamins, two different types. We
usually just require a relatively small amount and it plays a crucial role to
the development and regulation of our body. In this essay, we will discuss the
effect of essential fatty lipids, iodine and multivitamin and mineral
supplements to the development of intelligence.


Fatty lipids play an essential role in the development of
our brain, it is important for brain development and functioning. Around 60% of
our 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; and
arachonic acid (AA), which is a form of omega-6 fatty acid. These are the two
main components of the grey matter in the brain (Benton, 2010). On the other
hand, 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 the
growth of neuronal and dendritic spine which are crucial in the processes of
signal processing and neural transmission. Previous studies have shown that
long chain polysaturated fatty acids (LCPUFA) such as omega-3 and omega-6 fatty
acids are usually insufficient in both adults and children (Schuchardt et al.,
2010). Daniels et al. (2004) had reported a positive correlation between the
amount of fish intake from the mother during pregnancy and cognitive
development in their children, as fish is the main source of food that we can
obtain essential fatty acids. There are also studies shown that with a high
maternal fish intake, their children will perform better in language and social
skills (Daniels et al., 2004). Also, the same study showed that a lower IQ was
observed when the children’s mother consumed less seafood during pregnancy.


However, there are also some conflicting studies showing
that essential fatty acids have little or no effect on the development of
intelligence. A study have shown that for a 7 years old smaple, no difference was
observed in their IQ score between children that are supplemented and
non-supplemented children (Helland et al., 2008). This may be caused because
the development of the cognitive system was influenced by too many other
factors. Also, the association between the supplemented group and the
non-supplemented group may be too small for the test to detect at this later
age. In conclusion, the findings were inconsistent, with some studies
suggesting that essential fatty lipids are positively associated with IQ and
some indicating that the effect was minimal. The reason behind this maybe that
the intervention experiment designs were not consistent, each have different
groups of participants, having different dosage and duration of supplementation
and the children were measured with different tests and at different ages. In a
review by Ryan et al. (2010), they discovered that a significant positive
outcome in cognitive development of children is achieved if the supplementation
duration and dosage is high.







Iodine is used to produce thyroid hormones in the body,
which is essential in neurodevelopment and is used in different neurological
process, for example neural cell differentiation, maturation and migration
(Zimmermann, 2009). Previous studies have shown that infants have a higher
possibility of having cretinism if their mother have experience severe iodine
deficiency during pregnancy (Forrest, 2004). Also, comparing mothers who lived
in iodine deficient areas and those who lived in iodine sufficient areas, on
average 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 been
supplemented for iodine, their children will have better performance in
different 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 for
children’s cognitive development. However, there also studies that have
obtained opposite results. For example, a study had reported that infants of mothers
who had high amount of iodine through multivitamin supplementation have lower
psychomotor development than infants born to mothers with less amount of iodine
supplementation (Murcia et al., 2011).  Generally,
previous researches have suggested that iodine plays a crucial role in
children’s cognitive development, although there is some inconsistency in some
interventional studies.

We discussed the use of individual supplements in the above paragraphs, but
nutrients react with each other to perform its function (Benton, 2010). Also, a
malnutrition diet usually result not only with one single deficiency but
multiple micronutrient deficiencies. Therefore, we should also consider the
effect of multivitamin and mineral supplementation on IQ. A recent review in
2011 considering 18 studies, have shown that multivitamin and mineral
supplementation has a positive association with brain development in children
(Leung et al., 2011). Also, researchers found that these supplementations
resulted in improvements in different aspect of areas, like higher fluid
intelligence, improved motor development, better visual attention and spatial
ability (Eilander et al., 2010; Prado et al., 2012). Through these
observational studies, we can conclude that multivitamin and mineral
supplementation do have a significant effect in the development of our
cognitive system.


Breastfeeding has always been a highly-debated topic
regarding its effects on intelligence. Studies and meta-analysis have found
that the IQ of breastfeeding children born in normal birth weight and low birth
weight is 2.7 and 5.2 points higher respectively than infants who had
artificial milk (Anderson et al., 1999). A later review point out that majority
of the studies have a positive association between breastfeeding and cognitive
development in children, and the IQ of breastfeeding children are on average
2-5 points higher than non-breastfeeding children at any age (Michaelsen et
al., 2009). It has been proposed that the association between breastfeeding and
increase in IQ is due to the concentration difference of LCPUFA (e.g. DHA) in
breast milk and formula milk. Although lots of studies confirms the association
between the two, these effects usually declined significantly after controlling
for other confounding variables such as mother’s socioeconomic state and
maternal IQ. In conclusion, the association of whether breastfeeding have an
effect on cognitive development is still questionable.


Although there are still lots of uncertainties regarding the
effect of nutrition on developing intelligence, lots of people in the general
population still believe that nutrition or supplementation can increase their
IQ. This can be shown by the increasing amount of supplementation brand
available this days. This is mainly achieved by the media through reporting
different studies which claim there was a significant effect. In general, I do
not 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 not
have any major side effects. This can be true if you do not exceed the safety
dosage of those supplements.


In conclusion, both cognitive stimulation and nutrition each
do have different supporting studies, but there are too many confounding
variables to be considered. Therefore, there still isn’t a clear explanation on
the cause of Flynn Effect. With the advance in future technology, I believe we
can perform more accurate measures on the topic and in the future more
mysteries will be solved.



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