ILLUSTRATIONS: Doug Chayka for The Boston Globe

THE ANTICIPATION KICKS in before you've even parked the car, just looking out the open window at the winding, towering roller coaster track. With the sun shining down from above, the scent of fried dough in the air, and a whole day ahead dedicated to nothing but pleasure, you've arrived at a place that is all but synonymous with summer in America.

An amusement park is like no other patch of land on earth. Full of bright colors, tantalizing games, infinite ice cream, and of course, amazing thrill rides that give you the power to speed or fly, they open every year to teeming crowds on a quest for fun. Lights flash everywhere; high-tech steel rides sit alongside old-fashioned diversions like face-painting stations and strength-testing machines; the laughter of children mingles with carnival music and happy screams of terror.

"You walk in and you sort of just go, 'Whoa,'" said British historian Josephine Kane, the author of a 2013 book on early amusement park design called "The Architecture of Pleasure." "There's an immediate sense of sensory overload and chaos."

But if the scene feels anarchic to you, there's another way to think about the experience. The people who designed the rides, set up the games, and decided where to put the churro stands didn't do it at random. The modern amusement park is, beneath the flash and the chaos, a carefully tuned psychological machine - a creation honed for more than a century to perfectly deliver a huge range of cognitive and physiological delights, pushing buttons you didn't even know you had.

When the first amusement parks sprouted up during the late 19th and early 20th centuries, they were often set up by people from the world of theater, with deep experience in the mystical arts of making people feel things. "There's a very particular way that [parks] were designed," said Kane, a postdoctoral fellow at the University of Westminster, "[so that] you'd come off one ride and sort of float through the crowd, in a kind of swirling motion, and get sucked into another ride or another stall or booth."

Today, as designs have evolved and improved - and modern psychology has unlocked more and more insights into what our bodies and brains crave - the amusement park has become almost a handbook to the ways the human brain can be switched on. It is "a whole system designed to manipulate you into experiencing different kinds of pleasure," said David Linden, a neuroscientist at the Johns Hopkins University School of Medicine and the author of the book "The Compass of Pleasure," about how the brain processes the things that make us feel good.

The tricks an amusement park plays on you don't always happen the way you'd think. Games are designed to play on the appeal of almost, but not quite, winning; thrill rides like the Giant Drop tap into the strange mechanism in your brain that allows you to enjoy the rush of a simulated near-death experience. Even some aspects of the park that you'd never list as "fun" are gears in the machine: the maps that tell you where to go, the throngs around the food stands, the lines you have to endure to get to the more popular rides.

To understand the amusement park is to understand your own brain in ways you haven't before - an almost unique window into the range of things that create that feeling we call "fun." So step right up and enjoy the ride, as we take you inside the anatomy of a typical amusement park: a machine engineered for your conscious and subliminal delight, surprise, and excitement, right up until it's time to head back to the real world.

The 9 ways amusement parks hijack your brain:

AFRAID AND LOVING IT
Thrill rides are the spiritual heart of the modern amusement park. Why do so many people enjoy being made to feel like they could die at any second? One theory emphasizes how good we feel after we return to solid ground, our bodies intact. But as any dedicated thrill-seeker will tell you, the experience itself - the radical narrowing of one's attention, the feeling of time slowing down - can be its own source of pleasure. A pair of Dutch design experts from the Delft University of Technology argued in a recent paper that this altered state comes from pairing mortal fear with a "protective frame" that assures people they are safe. Citing the work of British psychologist Michael Apter, they suggest this state can be its own reward: "potentially refreshing, enchanting, empowering, exciting, or profound."

ANOTHER WORLD
One roller coaster at Six Flags New England plunges you into Batman's world; on another you fight Bizarro. Just a bunch of licensing deals? Not quite. Immersive, otherwordly rides date back to the origins of amusement parks. According to historian Josephine Kane, parks divert us in part by giving us access to experiences that feel beyond the bounds of reality. A century ago this often meant rides that simulated travel to exotic places. These days, travel no longer feels so removed from everyday life. Having superpowers does.

THE NOSTALGIA EFFECT
Even a sophisticated amusement park may have a distinctly old-timey side, to say nothing of county fairs. The mechanized contraptions, the primitive games, the carnival-like atmosphere - even if you never ride a vintage carousel, these may be affecting you. Research has shown that when people are prompted to feel nostalgia, they report feeling more optimistic about the future, and more confident that life has meaning.

LOVE AND NOVELTY
An amusement park may not seem like the most romantic place on earth, but research suggests it's a better spot for a date than you'd think: anthropologist Helen Fisher, author of "Why We Love," says people are more likely to become attracted to each other in situations that are novel and exciting. Research suggests people are at higher risk for falling in love on vacation, "processing novel stimuli and having novel pleasures," according to Linden. A day at an amusement park has more of those than you normally get in a week.

THE JOY OF 'ALMOST'
Many of the classic midway games are neatly engineered to capitalize on what Johns Hopkins neuroscientist David Linden calls the "near-miss effect" - the thrill of getting so close to victory you can taste it. That plastic ring you nearly looped around one of those glass bottles? The softball just bouncing out of the milk can? It's no ordinary failure; it's a failure designed to give you a jolt of pleasure - one that pushes you to take just one more shot. And then another.

TRY ME
Many iconic carnival games are hard because they demand unfamiliar skills, like hitting a target with a squirt gun until the balloon on top explodes. Learning those skills exerts a particular pull on us, according to Chris Lewis, an expert on addictive games. Citing the concept of "flow theory," Lewis said there's an almost euphoric state of mind induced by a game that makes you feel like you're progressively improving. "It's when a game hits that sweet spot, where the player thinks, 'I'm not succeeding at this yet but I feel like I could' - that's when you keep handing the money over."

BEST LINE EVER!
Even those frustrating lines contribute to our experience, research suggests. When people see a long line, they tend to conclude that whatever lies at the end of it must be pretty valuable. If done right, waiting in line can even boost your enjoyment of the overall experience: A 2010 study published in the Journal of Marketing Research found that amusement park guests who focused on the number of people behind them in line expressed more excitement about the ride they were going on, and were more likely to enjoy it, than those who focused on the number of people in front of them.

TAKE A LEFT NEAR THE BULBOUS THING
Typically, maps and signposts succeed by being direct and efficient. Not so at amusement parks. "You want to encourage wandering and serendipity and spending money," said Chris Calori, author of the book "Signage and Wayfinding Design." And yet, said expert Mark VanderKlipp, it is important that visitors can easily find the nearest bathroom or food stand. Hence the curious hybrid known as the amusement park map, a cartoonish rendering without any straight lines from point A to point B - but where the facilities are clearly and unmistakably marked.

GATHER 'ROUND THE CORN DOG
Many of us wouldn't stuff ourselves with cheese fries, funnel cake, and cotton candy under normal circumstances. But according to social psychologists, being surrounded by huge groups of strangers tends to break down impulse control: We feel anonymous, less like ourselves, and more inclined to indulge in behaviors we wouldn't otherwise. And even if you feel strong, watch out: A 2010 study from the University of Georgia showed that being around people with poor self-control is contagious.

→ This Summary Essay was last updated 05 Jan 2018 12:40 PST ←