There is evidence that reading can increase levels of all three major categories of intelligence. I believe my discovery of Spider-Man and other comic books turned me into a straight-A student.
- First, there is "crystallised intelligence" – the potpourri of knowledge that fills your brain. When you learn how to ride a bicycle, or the name of a new friend, you are gaining not just information but potentially useful knowledge that, in aggregate, forms the backbone of your ability to navigate and thrive in the world. By adding to that storehouse, reading increases your crystallised intelligence. That explains why some IQ tests include vocabulary words, which generally serve as a reliable proxy of how clever you are.
- But all of us know people with little "book knowledge" who are nonetheless sharp and insightful. "Fluid intelligence" is that ability to solve problems, understand things and detect meaningful patterns. Of course, you can read little or nothing at all and still be brilliant at "reading between the lines" of a conversation. But in today's world, fluid intelligence and reading generally go hand in hand. But if reading can increase fluid intelligence, the converse is also true: increased fluid intelligence also improves reading comprehension, according to studies by Jason Chein of Temple University in Philadelphia. He used "working memory" tasks that train people's ability to juggle and continually update multiple items of attention – to keep track of a moving dot, for instance, and recognise when it lands on a spot it occupied two, three or more moves ago. In papers published in scientific journals in 2010 and 2011, he showed that as both younger and older adults improved their performance on working-memory tasks, they were better able to comprehend reading materials.
- A third type of intelligence has gained widespread interest of late: "emotional intelligence", the ability to accurately read and respond to your own and others' feelings. It may seem odd to imagine that reading can improve your emotional intelligence. But in October, the journal Science published an extraordinary study showing that reading literary fiction can improve people's theory of mind (ToM) – their ability to understand others' mental states.