An individual’s IQ score — long-held as the standard measure of human intelligence — is not a valid way of assessing brainpower, say Canadian researchers.
A team from Western University is debunking the concept of general intelligence, saying that there is no single component that can account for how a person performs various mental and cognitive tasks.
Instead, human intelligence is made up of multiple and distinct components, each of which must be looked at independently.
The study, published today in the journal Neuron, included the largest online intelligence survey on record, which recruited more than 100,000 participants.
"The uptake was astonishing," said Adrian M. Owen, the project’s senior investigator. "We expected a few hundred responses, but thousands and thousands of people took part, including people of all ages, culture and creeds from every corner of the world."
The survey, which was open to anyone in the world with an internet connection, asked respondents to complete 12 cognitive tests that tapped into memory, reasoning, attention and planning abilities.
The results showed that how people performed at the tests could only be explained with at least three distinct components: short-term memory, reasoning and verbal ability.
No single measure, such as an intelligence quotient, or IQ score, could account for how well, or how poorly, people did.
The researchers also used a brain-scanning technique known as functional magnetic resonance imaging (fMRI) to look at the brains of a select group of participants as they performed different tasks.
They found that each cognitive component related to distinct circuits in the brain, supporting the idea of multiple specialized brain systems, each one with its own capacity.