The idea that intelligence can be measured by a single number - your IQ - is wrong, according to a recent study led by researchers at the University of Western Ontario.
The study, published in the journal Neuron on Wednesday, involved 100,000 participants around the world taking 12 cognitive tests, with a smaller sample of the group undergoing simultaneous brain-scan testing.
"When we looked at the data, the bottom line is the whole concept of IQ - or of you having a higher IQ than me - is a myth," said Dr. Adrian Owen, the study's senior investigator and the Canada Excellence Research Chair in Cognitive Neuroscience and Imaging at the university's Brain and Mind Institute. "There is no such thing as a single measure of IQ or a measure of general intelligence."
Rather, the study determined three factors - reasoning, short-term memory and verbal ability - that combined to create human intelligence or "cognitive profile."
IQ testing is used by many educators to measure intelligence, including in public schools in Ontario.
The researchers advertised their tests through New Scientist magazine and on discovery.com. Word quickly spread around the world, far surpassing the expectations of researchers, who expected only a few thousand participants. It became the largest online study on intelligence, allowing them to gather data across demographic, age and gender lines.
The scientists also used brain-scanning (fMRIs) on some of the subjects. "If there is something in the brain that is IQ, we should be able to find it by scanning. But it turns out there is no one area in the brain that accounts for people's so-called IQ. In fact, there are three completely different networks that respond - verbal abilities, reasoning abilities and short-term memory abilities - that are in quite different parts of the brain," Owen said.
Among the study's other findings:
* While aging has a detrimental effect on reasoning and short-term memory, it leaves verbal abilities "completely unimpaired."
* Smoking has a negative impact on verbal abilities and short-term memory but does not affect reasoning skills.
* People who play video games performed "significantly better" in terms of both reasoning and short-term memory.
* Products that are advertised to improve brain function aren't effective. "People who `brain-train' are no better at any of these three aspects of intelligence than people who don't," Owen said.
People can still take the tests at cambridgebrainsciences.com/theIQchallenge