For over a century, IQ scores have been viewed by scientists as placing an upper limit on what a person can ever achieve: a cognitive glass ceiling, a number tattooed on the soul. That dogma was shattered in 2008 with the publication of a major study showing that “fluid intelligence”—the ability to learn, solve novel problems, and get to the heart of things—can be significantly increased through training. But are the claims now coming from the flourishing brain-training industry really just a bunch of hype and happy talk?

Expanding upon one of the most-read New York Times Magazine features of 2012, SMARTER penetrates the hot new field of intelligence training to reveal what some researchers call a revolution in human intellectual abilities—and others insist is bogus baloney. To sort fact from self-help drivel, veteran science journalist Dan Hurley met with over 200 leading scientists and research participants from the United States and abroad. In lucid prose infused with wit and skepticism, Hurley tells the story of what he calls “the birth of a new science.” On the strength of 75 recently published, peer-reviewed, placebo-controlled clinical trials showing that training truly works (in contrast to just four studies showing no effects), Hurley delivers practical findings for people of every age and ability:

· Adults like Gabby Giffords, and legions of wounded warriors, recovering from traumatic brain injury

· Healthy older adults hoping to regain their mental sharpness

· Youths labeled as “learning disabled”

· Business executives seeking to gain an edge

· Cancer survivors battling “chemo brain”

Refusing to take researchers’ word for it, Hurley offered himself up as a human guinea pig, road-testing commercial brain-training programs, learning to play the Renaissance lute, joining an intense “boot camp” exercise class, attempting mindfulness meditation, and even undergoing transcranial direct-current stimulation (also known as getting his brain zapped). And while “smart pills” have long been a staple of science fiction and pharmaceutical research alike, Hurley found evidence supporting only one—a drug long reviled as one of the most addictive substances known: nicotine. By the end of the book, readers find out whether his efforts changed his performance on state-of-the-art measures of fluid intelligence. (Spoiler alert: his score on the gold-standard test known as the Raven’s progressive matrices increased by 16%.)

But SMARTER is not really about Hurley; it’s about the roiling field of intelligence research as an ever-growing majority of scientists shift from viewing fluid intelligence as something unchangeable, like eye color, to more like muscular strength, which increases with training. Taking on the defenders of the old faith that IQ is forever, including those who cite it in support of racist cant, Hurley chronicles top-level scientific meetings, including some convened by high-security military funders, where debates go from fierce to downright ugly.

SMARTER also goes after those who claim that intelligence doesn’t matter. Writers like Malcolm Gladwell (Outliers), Daniel Goleman (Emotional Intelligence) and Paul Tough (How Children Succeed) have made the case that IQ pales in importance to hard work, grit, and emotional poise. As Hurley writes: “Certainly IQ is not everything; perhaps it’s not even the most important thing, but it’s definitely one of them. It’s not the only reason, but it’s one of the reasons that Warren Buffett, Mark Zuckerberg, and Bill Gates are richer than you are. (Both Zuckerberg, who founded Facebook, and Sergey Brin, who cofounded Google, were selected in adolescence, in part on the basis of scoring high on standardized tests, to attend the Center for Talented Youth at Johns Hopkins, as was Stefani Joanne Angelina Germanotta, better known as Lady Gaga.) It’s how Malcolm Gladwell, Daniel Goleman, and Paul Tough wrote such awesome books. Because they’re smart, and because, as politically incorrect as it has become in polite society to say so, intelligence still matters.”

Certain to be debated, impossible to be ignored, SMARTER chronicles the startling transformation in our understanding of a fundamental human trait: the capacity for rational thought—the ability to learn—and whether a strict limit is set for each of us on the day of our birth, or whether we can do something about it.