Understanding intelligence doesn’t feel like it takes much, well, intelligence.

“When we say that someone is smart, we understand intuitively what that means,” said University of Illinois psychology professor Aron Barbey, the author of a new paper published in Trends in Cognitive Sciences, which makes the case that the brain’s dynamic properties — how it is wired but also how that wiring shifts in response to changing intellectual demands — are the best predictors of intelligence in the human brain. “Usually, we’re referring to how good they are at making decisions and solving particular types of problems. But recently in neuroscience, there’s been a focus on understanding in biological terms how general intelligence arises.”

Scientists have long understood that the brain is modular, with different regions supporting specific abilities, Barbey said. When regions, or modules, work together to form a network, specific abilities come together to allow us to master a skill or complete a task.

“For example, brain regions within the occipital lobe at the back of the brain are known to process visual information,” he said. But interpreting what one sees requires the integration of information from other brain modules. “To identify an object, we also must classify it. That doesn’t depend only on vision. It also requires conceptual knowledge and other aspects of information processing, which are supported by other brain regions.”

You can think of your brain as Facebook; each of the brain’s skill networks comprise a variety of modules, or, say, Facebook groups, each of which comprise smaller sub-networks of friends, family, and colleagues (i.e. neurons) of individual members. (One recent study suggests that it is actually the strength of connection between these smaller sub-networks and other modules’ sub-networks, that actually determine intelligence.)

Unlike Facebook, however, where everyone is a ‘friend,’ neural networks come in two different varieties believed to support two different types of information processing, Barbey said.

“There are the pathways that encode prior knowledge and experience, which we call ‘crystallized intelligence.’ And there are adaptive reasoning and problem-solving skills that are quite flexible, called ‘fluid intelligence,'” he said.

Crystallized intelligence involves robust connections, the result of months or years of neural traffic along well-worn network pathways. Fluid intelligence, however, involves weaker, more transient connections that form temporary networks when the brain tackles unique or unusual problems.

“Rather than forming permanent connections, we are constantly updating our prior knowledge, and this involves forming new connections,” Barbey said. The more readily the brain forms and reforms its connectivity in response to changing needs, the better it works, he said.

Although researchers have known that flexibility is an important characteristic of human brain function, only recently has the idea emerged that flexibility provides the basis for human intelligence, he said.

“What my colleagues and I have come to realize is that general intelligence does not originate from a single brain region or network. Emerging neuroscience evidence instead suggests that intelligence reflects the ability to flexibly transition between network states,” Barbey said.

What does this mean for you? It means the traditional view of IQ as a fixed, finite amount of brains is on its way out; because if intelligence is all about mental flexibility, then the degree of one’s intelligence is, well, flexible.

“It is possible that due to their biological predispositions, some individuals develop brain networks that favor intelligent behaviors or more challenging cognitive tasks. However, it is equally as likely that the frequent use of the brain for cognitively challenging tasks may positively influence the development of brain networks,” explained Ulrike Basten, of Goethe University, Frankfurt, a leader of the recent research into sub-network connections. In other words, it’s possible to become more intelligent by grappling with more cognitive challenges.

It also reinforces the importance of play in early childhood, which has been shown to forge new neural networks and shape children’s brain architecture (in a way that an early academic setting doesn’t), laying the foundation of cognitive flexibility and intelligence. Little wonder that the skills built through play are the best predictor of children’s academic success in eighth grade.

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