Since IQ tests are always standardised to 100, one way to
measure this increase is to have new test subjects take older tests. When
Americans today take IQ tests from a century ago, they score an extraordinarily
high average IQ of 130. Conversely, Flynn argues, if the American’s of 100
years ago took today’s tests, they would have an average IQ of 70 – the recognised
cut-off for people with intellectual disabilities. Progress is most pronounced
in the Raven’s Matrices: a non-verbal test designed to measure abstract
reasoning (example below). These findings are colloquially known as the ‘Flynn
effect’.
Above: US gains in IQ. Source: BBC
Above: Ravens Progressive
Matrices, which should be familiar to anyone who sat the 11+.
Test Wiseness
When I first heard of this effect, I was quite sceptical. My
initial reaction was that the improvement was most likely due to humans getting
better at sitting IQ tests (a phenomenon known as ‘test wiseness’) – not due to
their getting more intelligence. For example, in Estonia, when psychologists Olev
and Aasa Must laid IQ tests from the 1930s alongside papers from 2006, they found
an increase in correct answers – but also incorrect ones. Students had realised
they would not be penalised for incorrect answers – they had become better at
‘gaming’ the system.
I no longer think this explanation captures the entire
story. Firstly, standardised IQ tests have been an accepted part of American
culture for a long time; secondly, the frequency of IQ testing has waned during
the last 50 years. In other words, people have ‘gotten used’ to taking IQ tests
while simultaneously have had less chance to practice them. Despite this, IQ
increases have remained steady over the last 50 years (at about 3 points per
decade). Test wiseness alone struggles to explain this fact, which has led
theorists to propose several alternative explanations that couch these gains in
the vastly different world we inhabit.
Education
For example, one explanation cites the vast increase in the
quantity and quality of education as the main reason for the improvement in IQ
scores. Globally, more people are in school than ever before. Curriculums have
also shifted further towards mathematics and natural sciences, requiring a
greater emphasis being placed on classification, logical consistency and abstract
reasoning (Blair et al., 2005). This shift away from memorisation towards
abstraction has permeated through all levels of schooling. For example, in Ohio
in 1910, 14-year olds would have sat state examinations which predominantly
tested them for concrete, socially-valuable information, such as the names of
all 45 state capitals. In 1990, these same examinations had shifted to almost
exclusively abstract questions like “why is the largest city in the state
rarely the capital?”. The tenor of education has changed: children are more
encouraged to think in the abstract and take the hypothetical seriously –
traits we tend to associate with fluid intelligence and higher IQ scores.
Environment
These shifts in education practices have occurred
contemporaneously with a radically changing working environment. In 1900, only
3% of Americans worked in professions deemed ‘cognitively demanding’, such as
doctors, lawyers or bankers. Today, this figure has risen to 35%. Not only
this, but there has been an ‘upgrading’ of these professions: a doctor today
must confront a much more complex and information-laden working environment
than a doctor a century ago.
The world around us has also changed. Society asks us to
solve a wider range of cognitive problems and process a much larger amount of
information than before. To deal with this, we have developed mental models to
categorise, analyse and make sense of an increasingly chaotic world. These
models are often faulty: but our sheer frequency of using them stretches our cognitive
faculties to a degree incomparable with a century ago.
One of the most striking ways the world has changed is in it
becoming more visual. From pictures on the wall to movies to television to
video games, each successive generation has been exposed to far richer optical
displays than the one before. Beyond merely looking at pictures, we also
analyse them. Picture puzzles, mazes, exploded views and complex montages appear
everywhere—on cereal boxes, on McDonald's wrappers, in the instructions for assembling
toys and in books intended to help children pass the time. This may have helped
us develop a skill deemed an important component of intelligence: visual
reasoning. Indeed, the fact that the greatest IQ gains can be seen in Ravens
Progressive Matrices (which predominantly test for visual reasoning) may stand
testament to the importance of this trend.
Humans 2.0
What to make of all this? It is important not to get carried
away. A human brain today is indistinguishable from a human brain a century ago[1]:
100 years is far too brief a period for evolutionary processes to have taken
place - nature has not upgraded us to a smarter breed of human. Instead, if we
are to take the Flynn effect seriously, it makes more sense to view it as a
case of nurture over nature. Consider two identical twins, one of whom becomes
a professional athlete while the other becomes an investment banker. At autopsy
these twins would look physically very different, despite their similar
physiology at birth. In the same way, a human born today will have to endure
far more rigorous cognitive training than one born a century ago. While they
may have had similar brains at birth, comparing their brains during middle age
will likely reveal significant discrepancies in a range of cognitive functions
– discrepancies which reflect the different demands placed on them by the
different worlds they inhabit.
[996 words]
References
For anyone interested in this topic, I would recommend James
Flynn’s Ted Talk on why our IQ levels are higher than our grandparents. Blair
et al. (2005) provide a compelling case for curriculum change being the primary
driver of the increase in test scores. The BBC News article also provides a
nice overview.
- BBC News, ‘Are humans getting cleverer?’ https://www.bbc.com/news/magazine-31556802
- Blair et al. (2005), ‘Rising mean IQ: Cognitive demand of mathematics education for young children, population exposure to formal schooling and the neurobiology of the prefrontal cortex’
- Flynn, J. ‘Why our IQ levels are higher than our grandparents’ https://www.youtube.com/watch?v=9vpqilhW9uI&t=36s
- Kings College London, ‘A Cross-Temporal Meta-Analysis of Raven’s Progressive Matrices: Age groups and developing versus developed countries’
[1] One
challenge to this view stems from the observation that human beings are taller today
than a century ago, having grown at a rate of 1cm per decade. It is not inconceivable
that this increase in height has led to a corresponding increase in brain size.
Some scientists, such as Richard Lynn, argue that this could account for the entirety
of the Flynn effect. I omit a full discussion of this explanation, as the
evidence for the link between height and brain size and between brain size and
intelligence is inconclusive.
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