The past century has seen massive increases in IQ test scores. Professor James Flynn, discoverer of this "Flynn effect", has endeavoured to solve the puzzle of why we're getting smarter. Now he offers a new picture of human intelligence that is both surprising and illuminating.
Think of a dog, and then think of a rabbit. Quick: what do they have in common? If you immediately thought, "Rabbits and dogs both bear their young alive. Therefore, they are both mammals", you'd score well on an Intelligence Quotient (IQ) test.
But James Flynn, international authority on intelligence theory and emeritus professor at Otago University, says that if you were asked the same question a hundred years ago your answer would almost certainly have been radically different: "You use dogs to hunt rabbits."
Our grandparents would have done significantly worse on today's IQ test, despite the practical nature of their answer, says Flynn. "How many of us hunt any more? Very few. It's not like 1900 where all rural kids had hunting dogs and the population was mainly rural."
After reading the marking guides, Flynn discovered that abstract, scientific answers get higher scores on today's test. "I could see the answers they were giving credit for, and it was a terrible handicap to look for utilitarian connections," he says. "The world is now meant to be classified - you detach logic from concrete reality."
Thus our classification of dogs and rabbits has wide-ranging implications for our understanding of intelligence. Flynn, in his new book What Is Intelligence? Beyond the Flynn Effect, argues that the way we now see the world resolves the decades-old mystery that has plagued IQ researchers: are we really smarter than our ancestors?
Flynn, now 73, discovered in 1981 that IQ scores were steadily rising - a phenomenon that has become known inter?nationally as the "Flynn effect". This effect is present in every one of the more than 30 countries, including New Zealand, for which there is data.
The gains, he says, had been disguised ever since the tests became widely used in the early 1900s. How? Because of the convention that IQ scores are scaled to ensure that the average person scores exactly 100. Today, people sitting a test issued in 1900 would average 130.
The Flynn effect threw the academic subfield of intelligence theory into a tailspin, says Professor Nickolas Mackintosh of Cambridge University.
Flynn's initial finding that today's generation score better - suggesting that we are brighter than our forebears - "indeed overturned some received wisdom, and generated a considerable puzzle", says Mackintosh, head of Cambridge's department of experimental psychology.
Psychologists and critics thought that outsider Flynn - who trained as a moral philosopher and in 1981 headed the political science department at Otago - was barking up the wrong tree.
Some cognitive psychologists argued that the gains were entirely due to improvements in nutrition. Yet the effect persisted even during periods of wartime starvation in Japan and Europe. Others suggested that Flynn's findings were entirely explained by the widespread expansion of compulsory education over the past century and had nothing to do with innate intelligence.
Flynn, in response, gathered more data to see whether the parts of IQ tests dependent on education (such as information retention and vocabulary) were responsible for the puzzling rise.
Raven's Matrices, measuring an individual's ability to place abstract shapes into a series, is considered to be the least educationally loaded intelligence test. Flynn says that in November 1984 he received a "bombshell" in his letterbox.
The letter in question was from a Dutch psychologist and showed vast improvements in Raven's Matrices, dwarfing any other component of IQ. The Flynn effect was confirmed.
Kids are getting smarter in some measures of intelligence - though not markedly so at doing sums or general knowledge. The Wechsler Intelligence Scale for Children (WISC), one of the most popular IQ tests, recorded surprisingly skewed gains across different categories. Although compulsory education has broadened over the period, the components of intelligence linked to formal schooling have seen the smallest gains (see box, page 21).
"This really threw the cat among the pigeons," says Flynn. Although the Flynn effect appears to be slowing in some countries (those in Scandinavia) and accelerating in others (the developing world, especially Kenya), dozens of historic studies using outdated IQ tests not adjusted for the Flynn effect were immediately rendered junk science.
And since the US Supreme Court has ruled that, because they lack mental capacity, inmates with an IQ lower than 70 cannot be executed, Flynn has even been called as an expert witness in capital punishment cases. He adjusts the IQ scores of Death Row inmates downwards.
Most intriguingly, the Flynn effect laid bare a series of paradoxes that have befuddled theorists ever since. The level of gains, across every country for which there is data, suggests that nurture is far more important than nature. Yet studies also show a strong correlation between the IQs of identical twins raised apart - far higher than for fraternal twins raised in the same household - raising a tricky question. Flynn: "How can environment be both so feeble and so potent?"
And, of course, there's the perplexing issue of the relative stupidity of our grandparents. As Flynn says, "Either the children of today are far brighter than their parents, or IQ tests are not a good measure of intelligence. And if children are brighter, why are we not struck by the extraordinary subtlety of our children's conversation?"
When Flynn began seriously looking at intelligence, he showed little regard for the academic convention that scholars should stick to their disciplines.
Mackintosh, speaking from England, says Flynn's successful extra-curricular foray into the field was "very unusual".
"Many people outside the field have written about IQ tests, and although some have received publicity for their writing, none of them had had much impact within the field because their writings have usually been tendentious, ill-informed and full of their own preconceived opinions - not terms anyone could possibly apply to Flynn's work."
Mackintosh is among a number of high-profile fans of the Otago professor. In January, Flynn was profiled by the Guardian and described as "one of the world's leading psychology theorists". This month, he departs on a 20-university speaking tour of the US to promote his book, and at Harvard will be introduced by noted evolutionary psychologist and author Steven Pinker.
Malcolm Gladwell, the New Yorker writer and author of Blink and The Tipping Point, has recently been in touch. And Steven Johnson, using the Flynn effect as inspiration, argued last year in his book Everything Bad Is Good for You that more sophisticated popular culture - compare episodes of The Sopranos with I Love Lucy - is part of the reason we are now smarter.
Earlier this year, the Psychometrics Centre of Cambridge University made Flynn a distinguished associate; the International Society for Intelligence Research named him "Scientist of the Year".
Yet, despite these accolades, Flynn remained perplexed by the paradoxes that his research had unearthed. "Either today's children are so bright that they should run rings around us, or their grandparents were so dull that it is surprising they could keep a modern society ticking over," writes Flynn - and neither explanation seemed plausible.
Despite what he describes as a "technical retirement" in 1997, Flynn remained in the field. "You can't just overturn decades of received wisdom without trying to make sense of the mess you've made," he says.
So, in a windowless office in Dunedin that doubles as the archives for the Otago University political science department, Flynn - his eyes still an intense blue - began looking for examples of pre-modern thinking. After coming across interviews conducted more than 30 years ago by Russian neurophysiologist Alexander Luria with peasants in remote corners of the Soviet Union, Flynn thought: "Eureka!"
You can almost taste the frustration of the Soviet scientist as he asked questions of logic many today would consider elementary:
Luria: There are no camels in Germany; the city of B is in Germany; are there camels there or not?
Peasant: I don't know, I have never seen German villages. If B is a large city, there should be camels there.
Luria: But what if there aren't any in all of Germany?
Peasant: If B is a village, there is probably no room for camels.
The insistence on answering questions on the basis of personal experience persisted when Luria asked about the similarities between animals:
Luria: What do a fish and a crow have in common?
Peasant: A fish - it lives in water. A crow flies. If the fish just lays on top of the water, the crow could peck at it. A crow can eat a fish, but a fish can't eat a crow.
Luria: Could you use one word for them both?
Peasant: If you call them "animals", that wouldn't be right. A fish isn't an animal and a crow isn't, either. A crow can eat a fish, but a fish can't eat a bird. A person can eat a fish but not a crow.
The proof as to how our ancestors thought differently is in the pudding. Or rather, in the fish pie. The key is in the marking schedule, says Flynn. Both answers given to Luria would have failed if given as part of an IQ test. The answer they were looking for was animals.
"It's not that our ancestors are less intelligent than we, they simply dealt with the environment in a way that made more sense for them," Flynn says.
These tests give most credit for abstract logic - emphasising the scientific links between the animal kingdom rather than how specific animals relate to the dinner table.
Dogs and rabbits are simply seen differently today. We're not necessarily brighter than our grandparents, but we do now think in ways that have made taking IQ tests much easier.
Given the basis of the Flynn effect, it was disconcerting indeed that the man who made his name showing that IQ rates have risen inexorably over time appeared on TVNZ's Close Up in early July and was asked by host Paul Henry: "Professor James Flynn, it is your proposition, then, that as a society we are dumbing down?"
Flynn's answer was curt: "No."
An article the previous weekend in the Sunday Star-Times implicated Flynn as a eugenicist, selectively quoting him as supporting giving poorer and less-educated mothers the contraceptive pill through tap water in order to boost national intelligence.
But the very reason Flynn waded into the IQ debate in the first place was to debate with those who use IQ data to argue that genetic deficiencies explain the poor status of minorities, and that Third World countries are impoverished because of their stupidity.
A member of the National Association of the Advancement of Colored People (NAACP) in the American South during the McCarthy era (he came to New Zealand in 1963) and latterly a candidate and finance spokesperson for the Alliance Party, Flynn says his "effect" was the best evidence that the environment - not genes - is the primary determinant of intelligence.
In fact, Flynn says he argued to the Sunday Star-Times for wholesale social welfare policies to improve the environment for families - accelerating his effect. Contraceptives in the tap water were an alternative method for those worried about the relatively minor effect of genetics, compared with environmental influences, on national IQ rates.
But despite the Flynn effect, studies of identical twins appear to show the opposite. Even if raised apart, these twins shared similar characteristics, including IQ. These phenomena appear to contradict each other, says Flynn, but don't necessarily mean the debate is moot: minor genetic differences are magnified as people grow up.
Confused? Flynn talks basketball and of two hypothetical identical twins who are both, due to their genes, just a "little bit taller and quicker than average. John goes to school in one city, plays basketball a bit better on the playground, plays on a team, gets to play on a high school team where he gets really professional coaching."
Meanwhile, brother Joe goes to a different school many miles away. "And precisely because he is taller and quicker than average to exactly the same degree, he is likely to have a similar experience and life history," says Flynn. Society amplifies small genetic differences, illustrated by the extra attention both John and Joe receive in basketball training and coaching.
"Genetic advantages that may have been quite modest at birth have a huge effect on eventual basketball skills by getting matched with better environments. It's not difficult to apply the analogy to IQ. One child is born with a slightly better brain than another. Which of them will tend to like school, be encouraged, start haunting the library, get into top-stream classes and attend university?"
The degree to which nurture trumps nature, Flynn believes, is by a ratio of 3:1.
Outside academia, Flynn's research has shaken Death Row. In 2002, the Supreme Court ruled in Atkins v Virginia that executing the intellectually disabled qualified as "cruel and unusual punishment" and was therefore unconstitutional.
The definition of "intellectually disabled" used in the courts (until recently called "mentally retarded") is an IQ of 70 or lower. Subsequently, Flynn has been in hot demand by lawyers seeking to keep their clients away from the electric chair or the lethal-injection room.
In fact, as one Texas judge noted last year: "Discussion of the Flynn effect has, since the Atkins decision, suddenly come to the fore of death-penalty mental-retardation claims."
Flynn says he has filed affidavits in half a dozen death penalty cases where those convicted were deemed fit for trial on the basis of outdated IQ tests that scored the defendant in the low 70s.
"When the defendant took the [IQ test] at age 13 in 1991," wrote Flynn in one such affidavit, "he was being compared not to his peers but to the 13-year-olds of 1972 [when the test was normed]. The 13-year-olds in those days were worse performers and so he ranked higher against them than his peers. This gave him an inflated IQ of 71."
Calculating that, due to the Flynn effect, this individual would have scored 65 on an up-to-date test, Flynn concludes: "Do we really want to make the death penalty a lottery dependent on what test a school psychologist happens to use?"
So far, Flynn's involvement in cases has only generated stays of execution, but several cases are progressing further through the courts. The Fourth Circuit Court of Appeals, in Walker v True, ruled in 2005 that the Flynn effect must be taken into account when ruling on intellectual disability.
Studies featuring old IQ tests have not only been used to wrongly put people to death, but also have inadvertently been used to support everything from child labour to claims that criminals are inherently smarter.
In 1995, four researchers studied child labourers in India to determine whether working all day instead of going to school was a negative in terms of their education. The average IQ of the child labourers tested was 130 - putting the cadre of young workers in the top two percent of intelligence.
"Taking the IQs at face value," writes Flynn, "they drew the conclusion that sweated labour was good for children's intelligence (they also decided it was good for them physically)."
And closer to home, a 1988 New Zealand study found that prisoners had above-average IQs. "Could it be that having better genes for intelligence predisposed one for criminality? The test used, of course, was radically obsolete," he writes.
With these cautionary tales in mind, it isn't surprising that, despite spending the best part of 25 years studying IQ, Flynn has never felt the inclination to sit such a test himself.
"I've never bothered. While it's a wonderful tool for research and for looking at group differences and the theory of intelligence, what's the point of testing yourself?"
After all, what is the inherent worth of a high IQ score, anyway? Flynn says he wouldn't be caught dead at a Mensa gathering.
"I think it's crazy," he says of the society for those with a minimum IQ of 132. "I can imagine wanting to be around people who read novels or appreciate music, but these must be people of very low self-esteem that they have to convince themselves they are important by qualifying for Mensa."
Flynn reckons noted philosopher Karl Popper, a one-time lecturer at Canterbury University who came up with the scientific principle of falsification, was onto something: "He said that whatever his intelligence was, it wasn't so low as to make him want to sit around with people whose only attribute was that they did well on IQ tests."
Not that Flynn wishes to entirely distance himself from Mensa, as he suspects his eponymous effect may be responsible for some swollen heads. "Why don't they retest everyone who's presently a member with a test that's just been normed? They'd probably have to clean out about half their membership!
"I'd be happy," he chuckles, "to help them out with that."