We've all heard of the IQ test, or Intelligence Quotient test. It supposedly measures how smart you are. What you might not have realised is that the scores or results that people achieve are adjusted, or 'fiddled'. This is to both get the average IQ to be 100 points, and to make sure that about two-thirds of people will lie in the IQ band between 85 and 115 points.
But you might not have heard that, averaged around the world, the typical IQ is not fixed – it seems to be creeping upwards, at about three points every decade.
This story begins back in 1948, when the psychologist R D Tuddenham examined the IQ scores of American men who had been conscripted into the military, between 1917 and 1943. He showed that their IQ was increasing by about 4.4 points every decade. This strange increase in IQ over the decades was rediscovered by Richard Lynn in 1982, and James Flynn in 1984 – and today it's known as the 'Flynn effect'.
IQ tests are limited – they do not measure musical or artistic creativity, or the so-called emotional quotient. So let's look at a typical IQ test, the Wechsler Intelligence Scale for Children (or WISC). It measures 10 separate cognitive skills. These include information (for example, on what continent is Mexico?), arithmetic, vocabulary, comprehension (why are houses in a street given numbers?), and similarities (how are dogs and rabbits related?).
Interestingly, it's the similarities test that seems to show the greatest increase in IQ scores over the decades.
Our society and intellectual environment have changed enormously over the last century, transitioning from 'concrete' to 'abstract'. So a century ago, the answer to: "How are dogs and rabbits related?" would have been the rather concrete: "you use a dog to hunt a rabbit". But today, the typical answer is the more abstract: "both dogs and rabbits are mammals".
So let's get back to the widely used WISC. Over the last two-thirds of a century, it has had to be re-calibrated three times. Why? To make sure that the average IQ of children is still 100. So the original WISC was released in 1947, recalibrated in the early 1970s and renamed the WISC-R, recalibrated again in the late 1980s and called the WISC III, and most recently recalibrated in the early 2000s and renamed the WISC IV. So if you give a child of today one of the early WISC IQ tests of the past, on average, today's children will score more than 100.
But what would the people of one century ago have scored, on average, if they took one of our modern IQ tests? Our great-great-grandparents would have scored an IQ of around 70, or less. Superficially, this implies that one century ago, our country was beset by a plague of mental retardation. This is obviously crazy.
One way to interpret this is to see your IQ not as something set in stone and unchangeable, but rather, more like a muscle that can alter itself and adapt to a changing environment. So IQ is a measure of how well we can deal with the current society we inhabit. In other words, it's a measure of how 'modern' we are.
What's causing the Flynn effect? We don't know yet, but there are various explanations being offered. They include our brain having to adapt to an environment that is more abstract, better nutrition during our formative years when the brain is growing, adding iodine to salt, fewer infections so that our growth is not hindered, smaller families that can spend more time and money on fewer kids, and so on.
This Flynn effect (of increasing scores on IQ tests) does seem to be real. It also seems to happen when countries get to a certain stage of health, education and welfare.
But we still don't understand its full ramifications. In his 2001 book, Intelligence: A very short introduction, the distinguished researcher Ian J Deary described the Flynn effect as 'officially mysterious'.
It just goes to show – the more you find out about stuff, the more you realise how little you know.
