POPULAR culture has, on average, grown more complex and intellectually challenging over the past 30 years. Where most commentators assume a race-to-the-bottom and a dumbing down, I see a progressive story: mass culture growing more sophisticated, demanding more cognitive engagement with each passing year. Think of it as a kind of positive brainwashing: the popular media steadily, but almost imperceptibly, making our brains sharper as we soak in entertainment usually dismissed as so much lowbrow fluff. I call this upward trend the Sleeper Curve, after the classic sequence from Woody Allen’s mock sci-fi film in which scientists from 2029 are astounded that 20th-century society failed to grasp the nutritional merits of cream pies and hot fudge.

The forces propelling the Sleeper Curve include changes in technology that enable new kinds of entertainment; new forms of online communications that cultivate audience commentary about works of pop culture; changes in the economics of the culture industry that encourage repeat viewing; and deep-seated appetites in the human brain that seek out reward and intellectual challenge.

For the Sleeper Curve to make sense, we need a new way of measuring the social values of entertainment, one that places less emphasis on the message conveyed by that entertainment, and more on the work that our brain has to do to interpret it. Pop culture is not necessarily more entertaining than before, nor have its moral lessons grown more profound. But it is making us smarter. Most of what we casually dismiss as junk culture has been steadily increasing the intellectual demands placed on the audience.

I suspect that the Sleeper Curve is the single most important new force altering the mental development of young people today, and I suspect that it is largely a force for good: enhancing our cognitive faculties, not dumbing them down. And yet you almost never hear this story in popular accounts of today’s media. Instead you hear dire stories of addiction, violence, mindless escapism. We’re a nation of reality-programme addicts and Nintendo freaks. Lost in that account is the most interesting trend of all: that the popular culture has been growing increasingly more complex over the past few decades, exercising our minds in powerful new ways.

The problem with judging new cultural systems on their own terms is that the presence of the recent past inevitably colours your visions of the emerging form, highlighting the flaws and imperfections. And you can’t get much more conventional than the conventional wisdom that kids today would be better off spending more time reading books, and less time zoning out in front of their video games. Reading books enriches the mind, playing video games deaden it.

For the record, I think that the virtues of reading books are great. We should all encourage our kids to read more. But even the most avid reader is inevitably going to spend his or her time with other media — games, television, movies, the internet. The question is whether those other forms of culture have intellectual or cognitive virtues in their own right — different from, but comparable to, reading. I hope to persuade you of two things: 1) by almost all the standards we use to measure reading’s cognitive benefits — attention, memory, following threads and so on — the non-literary culture has been steadily growing more challenging over the past 30 years; and 2) increasingly, the nonliterary popular culture is honing different mental skills that are just as important as the ones exercised by reading books.

The most powerful examples of both these trends are found in the world of video games. And the first and last thing that should be said about the experience of playing today’s video games, the thing you almost never hear in the mainstream coverage, is that games are fiendishly, sometimes maddeningly, hard.

The dirty little secret of gaming is how much time you spend not having fun. You may be frustrated; you may be confused or disorientated; you may be stuck. When you put the game down and move back into the real world, you may find yourself mentally working through the problem you have been wrestling with, as though you were worrying a loose tooth.

Anyone who has spent more than a few hours trying to complete a game knows the feeling: you get to a point where there is a sequence of tasks that you have to complete to proceed further, but the tasks themselves are more like chores than entertainment. And yet the great bulk of the population performing these tasks every day is composed of precisely the demographic group most averse to doing chores: kids whom you virtually have to lock in their room to get them to do their maths homework.

You often hear video games included on the list of the debased instant gratifications that abound in our culture. But compared with most forms of popular entertainment, games turn out to be all about delayed gratification, sometimes so long delayed that you wonder if the gratification is ever going to show. The clearest measure of the cognitive challenges posed by modern games is the sheer size of the cottage industry devoted to publishing game guides, a relatively new development, which you need because the complexity of the games can be overwhelming: you are stuck in the middle of a level, with all the exits locked and no sign of a key. Or the password for the control room you thought you found two hours ago turns out not to work. Or you have no real idea what you are supposed to do next. At a certain point — perhaps when you find yourself reading the help guides over dinner — you start saying to yourself: remind me why this is fun?

So why does anyone bother playing these things? And why does a seven-year-old soak up, for instance, the intricacies of industrial economics in the game form of SimCity 2000 when the same subject would send him screaming for the exits in a classroom? To date, there has been little direct research into the question of how games get children to learn without realising that they are learning. But I believe a strong case can be made that the power of games to captivate largely involves their ability to tap into the brain’s natural reward circuitry.

In the game world reward is everywhere. The universe is literally teeming with objects that deliver very clearly articulated rewards: more life, access to new levels, new equipment, new spells. Most of the crucial work in game interface design focuses on keeping players notified of potential rewards available to them, and how much these rewards are currently needed. Most games offer a fictional world where rewards are larger, and more vivid, more clearly defined than life.

“Seeking” is the perfect word for the drive these designs instil in their players. You want to win the game, of course, and perhaps you want to see the game’s narrative completed. In the initial stages of play, you may just be dazzled by the game’s graphics. But most of the time, when you’re hooked on a game, what draws you in is an elemental form of desire: the desire to see the next thing. In a sense neuroscience has offered up a prediction here, one that games obligingly confirm. If you create a system in which rewards are both clearly defined and achieved by exploring an environment, you will find human brains drawn to those systems, even if they are made up of virtual characters and simulated sidewalks. It is not the subject matter that attracts; it is the reward system that draws those players in, and keeps their famously short attention spans locked on the screen.

You might reasonably object at this point that I have merely demonstrated that video games are the digital equivalent of crack cocaine. If they have been unwittingly designed to lock into our brain’s reward architecture, then what positive value are we getting from that intoxication? Here, again, you must shed your expectations about older cultural forms to make sense of the new. Game players are not soaking up moral counsel, life lessons or rich psychological portraits. With the occasional exception, the actual content of the game is often childish or gratuitously menacing. Much of the role play inside the gaming world alternates between drive-by shooting and princess-rescuing.

De-emphasising the content of game culture shouldn’t be seen as a cop-out. We ignore the content of many activities that are widely considered to be good for the brain or the body. No one complains about the simplistic, militaristic plot of chess games. We teach algebra to children knowing full well that the day they leave the classroom, 99 per cent of those kids will never again directly employ their algebraic skills. Learning algebra isn’t about acquiring a specific tool; it’s about building up a mental muscle that will come in handy elsewhere. You don’t go to the gym because you’re interested in learning how to operate a Stairmaster; you go to the gym because operating the Stairmaster does something laudable to your body.

So it is with games. It’s not what you’re thinking about when you’re playing a game, it’s the way you’re thinking that matters. Far more than books or movies or music, games force you to make decisions. Novels may activate our imagination and music may conjure up powerful emotions, but games force you to decide, to choose, to prioritise. All the intellectual benefits of gaming derive from this fundamental virtue, because learning how to think is, ultimately, about learning to make the right decisions: weighing evidence, analysing situations, consulting your long-term goals, then deciding. No other pop cultural form engages the brain’s decision-making apparatus in the same way. From the outside, the primary activity of a gamer looks like a fury of clicking and shooting. But if you peer inside the gamer’s mind, the primary activity turns out to be another creature altogether: making decisions, some of them snap judgments, some of them long-term strategies.

• Everything Bad is Good For You, by Steven Johnson, Allen Lane, £10. Order it for £8.50, plus 99p p&p, from Times Books First, 0870 1608080.