6. Pleasure

Happiness is a warm puppy.

— CHARLIE BROWN

Happiness is a warm gun.

—THE BEATLES

To each his own.

— Traditional saying

WOE BETIDE THE HUMAN BEING who doesn't know what happiness is; yet woe to the writer who tries to define it. Warm guns and warm puppies are merely examples of happiness, not definitions of it.

My dictionary defines happiness as "pleasure"—and pleasure as a feeling of "happy satisfaction and enjoyment." As if that weren't circular enough, when I turn to the word feeling, I find that a feeling is defined as "a perceived emotion" while an emotion is defined as a "strong feeling."

No matter. As the Supreme Court justice Potter Stewart famously said about pornography (as opposed to art), it is hard to define, but "I know it when I see it." Happiness may mean sex, drugs, and rock-and-roll, the roar of the crowd, the satisfaction of a job well done, good food, good drink, and good conversation—not to mention what psychologist Mihaly Csikszentmihalyi calls a state of "flow," of being so absorbed in something you do well that you scarcely notice the passage of time. At the risk of offending hard-nosed philosophers everywhere, I propose to leave it at that. For my money, the real question is not how we define happiness, but why, from the perspective of evolution, humans care about it at all.

At first glance, the answer seems obvious. The standard story is that happiness evolved in part to guide our behavior. In the words of the noted evolutionary psychologist Randolph Nesse, "Our brains could have been wired so that [eating] good food, [having] sex, being the object of admiration, and observing the success of one's children were all aversive experiences [but] any ancestor whose brain was so wired would probably not have contributed much to the gene pool that makes human nature what it is now." Pleasure is our guide, as Freud (and long before him, Aristotle) noted, and without it, the species wouldn't propagate.^*

That much seems true. In keeping with the notion that pleasure serves as our guide, we automatically (and often unconsciously) sort just about everything we see into the categories "pleasant" and "unpleasant." If I show you a word like sunshine and then ask you to decide, as quickly as possible, whether the word wonderful is positive, you'll respond faster than you would if shown an unpleasant word instead (say, poison instead of sunshine). Cognitive psychologists call this accelerated response a positive priming effect; it means that we constantly and automatically categorize everything we encounter as good or bad.

This sort of automatic evaluation, largely the domain of the reflexive system, is remarkably sophisticated. Take, for example, the word water; is it pleasant? Depends on how thirsty you are. And sure enough, studies show that thirsty people show a bigger positive priming effect for the word water than people who are well hydrated. This occurs over the course of a few milliseconds, allowing pleasure to serve as a moment-by-moment guide. Similar findings—and this is the scary part—apply even in our attitudes toward other people: the more we need them, the more we like them. (To rather cynically paraphrase an old expression, from the perspective of the subconscious, a friend we need is a friend perceived.)

But the simple idea that "if it feels good, it must have been good for our ancestors" runs into trouble pretty quickly. To start with, many—arguably, most—things that give us pleasure don't actually do much for our genes. In the United States, the average adult spends nearly a third of his or her waking hours on leisure activities such as television, sports, drinking with friends—pursuits that may have little or no direct genetic benefit. Even sex, most of the time for most people, is recreational, not procreational. When I spend $100 on a meal at Sushi Samba, my favorite restaurant du jour, I don't do it because it will increase the number of kids I have, or because eating Peruvian-Japanese fusion food is the cheapest (or even most nutritious) way to fill my belly. I do it because, well, I like the taste of yellowtail ceviche—even if, from the perspective of evolution, my dining bills are a waste of precious financial resources.

A Martian looking down on planet Earth might note all this with puzzlement. Why do humans fool around so much when there is, inevitably, work to be done? Although other species have been known to play, no other species goofs around so much, or in so many ways. Only a few other species seem to spend much time having non-procreative sex, and none (outside labs run by inquisitive humans) watch television, go to rock concerts, or play organized sports. Which raises the question, is pleasure really an ideal adaptation, or (with apologies to Shakespeare) is there something klugey in Denmark?

Aha, says our Martian to itself; humans are no longer slaves to their genes. Instead of engaging in the activities that would yield the most copies of their genes, humans are trying to maximize something else, something more abstract—call it "happiness"—which appears to be a measure of factors such as a human's general well-being, its level of success, its perceived control over its own life, and how well it is regarded by its peers.

At which point, our Martian friend would be even more confused. If people are trying to maximize their overall well-being, why do they do so many things that in the long run yield little or no lasting happiness?

Perhaps nothing would puzzle this Martian more than the enormous amount of time that many people spend watching television. In America, the average is 2–4 hours per day. If you consider that the average person is awake for only 16, and at work for at least 8, that's a huge proportion of the average person's discretionary time. Yet day after day, audiences watch show after show, most containing either stories of dubious quality about fictional people or heavily edited "reality" portraits of people in improbable situations that the average viewer is unlikely ever to meet. (Yes, public television airs some great documentaries, but they never draw the ratings of Law & Order, Lost, or Survivor.) And here's the kicker: hard-core television watchers are, on average, less happy than those who watch only a little television. All that TV viewing might convey some sort of short-term benefit, but in the long term, an hour spent watching television is an hour that could have been spent doing something else—exercising, working on hobbies, caring for children, helping strangers, or developing friendships.

And then there are, of course, chemical substances deliberately designed to shortcut the entire machinery of reward, directly stimulating the pleasure parts of the brain (for example, the nucleus accumbens). I'm speaking, of course, of alcohol, nicotine, and drugs like cocaine, heroin, and amphetamines. What is remarkable about these substances is not the fact that they exist—it would be almost impossible to build a chemically based brain that wouldn't be vulnerable to the machinations of clever chemists—but rather the extent to which people use them, even when they realize that the long-term consequences may be life threatening. The writer John Cheever, for example, once wrote, "Year after year I read in [my journals] that I am drinking too much ... I waste more days, I suffer deep pangs of guilt, I wake up at three in the morning with the feelings of a temperance worker. Drink, its implements, environments, and effects all seem disgusting. And yet each noon I reach for the whiskey bottle."

As one psychologist put it, addictions can lead people down a "primrose path" in which decisions made in the moment seem—from the strict perspective of temporary happiness—to be rational, even though the long-term consequences are often devastating.

Even sex has its puzzling side. That sex is enjoyable is perhaps no surprise: if sex weren't fun for our ancestors, we simply wouldn't be here. Sex is, after all, the royal road to conception, and without conception there would be no life. Without life, there would be no reproduction, and legions of "selfish genes" would be out of work. It seems like a no-brainer that creatures that enjoy sex (or at least are driven toward it) will outpropagate those that do not.

But having a taste for sex is not the same as pursuing it nonstop, to the virtual exclusion of anything else. We all know stories of politicians, priests, and plain ordinary folk who destroyed their life in relentless pursuit of sex. Might a Martian question whether our contemporary need for sex is as miscalibrated as our need for sugar, salt, and fat?

The Martian would eventually come to realize that although the core notion of pleasure as motivator makes a good deal of sense, the pleasure system as a whole is a kluge, from top to bottom. If pleasure is supposed to guide us to meet the needs of our genes, why do we humans fritter away so much of our time in activities that don't advance those needs? Sure, some men may skydive to impress the ladies, but many of us ski, snowboard, or drive recklessly even when nobody else is watching. When such a large part of human activity does something that risks "reproductive fitness," there must be some explanation.

And indeed there is, but it's not about minds that are optimal, but about minds that are clumsy. The first reason should, by now, seem familiar: the neural hardware that governs pleasure is, like much of the rest of the human mind, split in two: some of our pleasure (like, perhaps, the sense of accomplishment we get from a job well done) derives from the deliberative system, but most of it doesn't. Most pleasure springs from the ancestral reflexive system, which, as we have seen, is rather shortsighted, and the weighting between the two systems still favors the ancestral. Yes, I may get a slight sense of satisfaction if I waive my opportunity to eat that crème brûlée, but that satisfaction would almost certainly pale in comparison to the kick, however brief, that I would get from eating it.^* My genes would be better off if I skipped dessert—my arteries might stay open that much longer, allowing me to gather more income and take better care of my future offspring—but those very genes, due to their lack of foresight, left me with a brain that lacks the wisdom to consistently outwit the animalistic parts of my brain, which are a holdover from an earlier era.

The second reason is more subtle: our pleasure center wasn't built for creatures as expert in culture and technology as we are; most of the mechanisms that give us pleasure are pretty crude, and in time, we've become experts at outwitting them. In an ideal world (at least from the perspective of our genes), the parts of our brain that decide which activities are pleasurable would be extremely fussy, responding only to things that are truly good for us. For example, fruits have sugar, and mammals need sugar, so it makes sense that we should have evolved a "taste" for fruit; all well and good. But those sugar sensors can't tell the difference between a real fruit and a synthetic fruit that packages the flavor without the nutrition. We humans (collectively, if not as individuals) have figured out thousands of ways to trick our pleasure centers. Does the tongue like sweetness of fruit? Aha! Can I interest you in some Life Savers? Orange soda? Fruit juice made entirely from artificial flavors? A ripe watermelon maybe good for us, but a watermelon-flavored candy is not.

And watermelon-flavored candy is only the start. The vast majority of the mental mechanisms we use for detecting pleasure are equally crude, and thus easily hoodwinked. In general, our pleasure detectors tend to respond not just to some specific stimulus that might have been desirable in the environment of our ancestors, but to a whole array of other stimuli that may do little for our genes. The machinery for making us enjoy sex, for example, causes us to revel in the activity, just as any reasonable evolutionary psychologist would anticipate, but not just when sex might lead to offspring (the narrowest tuning one might imagine), or even to pair bonding, but much more broadly: at just about any time, under almost any circumstance, in twos and threes and solo, with people of the same sex and with people of the opposite sex, with orifices that contribute to reproduction and with other body parts that don't. Every time a person has sex without directly or indirectly furthering their reproductivity, some genes have been fooled.

The final irony, of course, is that even though sex is incredibly motivating, people often have it in ways that are deliberately designed not to produce children. Heterosexuals get their tubes tied, gay men continue to have unprotected sex in the era of HIV, and pedophiles pursue their interests even when they risk prison and community censure. From the perspective of genes, all of this, aside from sex for reproduction or parental pair bonding, is a giant mistake.

To be sure, evolutionary psychologists have tried to find adaptive value in at least one of these variations (homosexuality), but none of the explanations are particularly compelling. (There is, for example, the "gay uncle" hypothesis, according to which homosexuality persists in the population because gay people often invest considerable resources in the offspring of their siblings.)^* A more reasonable accounting, in my view, is that homosexuality is just like any other variation on sexuality, an instance of a pleasure system that was only broadly tuned (toward intimacy and contact) rather than narrowly focused (on procreation) by evolution, co-opted for a function other than the one to which it was strictly adapted. Through a mixture of genetics and experience, people can come to associate all manner of different things with pleasure, and proceed on that basis.^†

The situation with sex is fairly typical. A substantial portion of our mental machinery seems to exist in order to assess reward (a proxy for pleasure), but virtually all of that machinery allows a broader range of options than might (from a gene's-eye view) be ideal. We see this with enjoyment of sugar—a hot fudge sundae just about always brings pleasure, whether we need the calories or not—but also with more modern compulsions, like addiction to the Internet. This compulsion presumably begins with an ancestral circuit that rewarded us for obtaining information. As the psychologist George Miller put it, we are all "informavores," and it's easy to see how ancestors who liked to gather facts might have outpropagated those who showed little interest in learning new things. But once again we have a system that hasn't been tuned precisely enough: it's one thing to get a kick from learning which herbs help cure open wounds, but another to get a kick from learning the latest on Angelina and Brad. We would probably all be better off if we were choosier about what information we sought, à la Sherlock Holmes, who notoriously didn't even know that the earth revolved around the sun. His theory, which we could perhaps learn from, goes like this:

A man's brain originally is like a little empty attic, and you have to stock it with such furniture as you choose. A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things, so that he has a difficulty in laying his hands upon it ... It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones.

Alas, Sherlock Holmes is only fictional. Few people in the real world have information-gathering systems as disciplined or as finely tuned as his. Instead, for most of us, just about any information can drive our pleasure meters. Late at night, if I allow myself access to the Internet, I'm liable to click here (World War II), click there (Iwo Jima), and then mindlessly follow another link (Clint Eastwood), only to stumble on a fourth (Dirty Harry), rapidly chaining my way from topic to topic, with no clear destination in mind. Yet each tidbit brings me pleasure. I'm not a history scholar, I'm not a film critic; its unlikely that any of this information will ever come in handy. But I can't help it; I just like trivia, and my brain isn't wired precisely enough to make me more discriminating. Want to stop my web surfing? Go ahead, make my day.

Something similar happens in our eternal quest for control. Study after study has shown that a sense of control makes people feel happy. One classic study, for example, put people in a position of listening to a series of sudden and unpredictable noises, played at excruciatingly random intervals. Some subjects were led to believe that they could do something about it—press a button to stop the noise—but others were told that they were powerless. The empowered subjects were less stressed and more happy—even though they hardly ever actually pressed the button. (Elevator "door close" buttons work on a similar principle.) Again, there would be adaptive sense in a narrowly focused system: organisms that sought out environments in which they had a measure of control would outcompete those that left themselves entirely at the mercy of stronger forces. (Better, for example, to wade in a slowly moving stream than a full-on waterfall.) But in modern life, we trick the machinery that rewards us for a sense of accomplishment, spending hours and hours perfecting golf swings or learning how to create a perfect piece of pottery—without discernibly increasing the number or quality of our offspring.

More generally, modern life is full of what evolutionary psychologists call "hypernormal stimuli," stimuli so "perfect" they don't exist in the ordinary world: the anatomically impossible measurements of Barbie, the airbrushed sheen of a model's face, the fast, sensation-filled jump cuts of MTV, and the artificial synthesized drum beats of the nightclub. Such stimuli deliver a purer kick than anything could in the ancestral world. Video games are a perfect case in point; we enjoy them because of the sense of control they afford; we like them to the extent that we can succeed in the challenges they pose—and we cease to enjoy them the minute we lose that sense of a control. A game that doesn't seem fair doesn't seem fun, precisely because it doesn't yield a sense of mastery. Each new level of challenge is designed to intensify that kick. Video games aren't just about control; they are the distillation of control: hypernormal variations on the naturally rewarding process of skill learning, designed to deliver as frequently as possible the kick associated with mastery. If video games (produced by an industry racking up billions of dollars in sales each year) strike some people as more fun than life itself, genes be damned, it is precisely because the games have been designed to exploit the intrinsic imprecision of our mechanism for detecting pleasure.

In the final analysis, pleasure is an eclectic thing. We love information, physical contact, social contact, good food, fine wine, time with our pets, music, theater, dancing, fiction, skiing, skateboarding, and video games; sometimes we pay people money to get us drunk and make us laugh. The list is virtually endless. Some evolutionary psychologists have tried to ascribe adaptive benefits to many of these phenomena, as in Geoffrey Miller's suggestion that music evolved for the purpose of courtship. (Another popular hypothesis is that music evolved for the purpose of singing lullabies.) Miller's flagship example is Jimi Hendrix:

This rock guitarist extraordinaire died at the age of 27 in 1970, overdosing on the drugs he used to fire his musical imagination. His music output, three studio albums and hundreds of live concerts, did him no survival favours. But he did have sexual liaisons with hundreds of groupies, maintained parallel long-term relationships with at least two women, and fathered at least three children in the U.S., Germany, and Sweden. Under ancestral conditions before birth control, he would have fathered many more.

But none of these hypotheses is especially convincing. The sexual selection theory, for instance, predicts that males ought to have more musical talent than females, but even if teenage boys have been known to spend untold hours jamming in pursuit of the world's heaviest metal, there's no compelling evidence that males actually have greater musical talent.^* There are thousands (or perhaps hundreds of thousands) of happily married women who devote their lives to playing, composing, and recording music. What's more, there's no particular reason to think that the alleged seducees (women, in Miller's account) derive any less pleasure from making music than do the alleged seducers, or that an appreciation of music is in any way tied to fertility. No doubt music can be used in the service of courtship, but the fact that a trait can be used in a particular way doesn't prove that it evolved for that purpose; likewise, of course, with lullabies.

Instead, many modern pleasures may emerge from the broadly tuned pleasure systems that we inherited from our ancestors. Although music as such—used for purposes of recreation, not mere identification (the way songbirds and cetaceans employ musical sounds)—is unique to humans, many or most of the cognitive mechanisms that underlie music are not. Just as much of language is built on brain circuits that are considerably ancient, there is good reason to think that music relies largely (though perhaps not entirely) on devices that we inherited from our premusical ancestors. Rhythmic production appears in rudimentary form in at least some apes (King Kong isn't alone in beating his chest), and the ability to differentiate pitch is even more widespread. Goldfish and pigeons have been trained to distinguish musical styles. Music likely also taps into the sort of pleasure we (and most apes) derive from social intimacy, the enjoyment we get from accurate predictions (as in the anticipation of rhythmic timing) and their juxtaposition with the unexpected,^* and something rather more mundane, the "mere familiarity effect" (mentioned earlier, in the context of belief). And in playing musical instruments (and in singing), we get a sense of mastery and control. When we listen to the blues, we do so, at least in part, so we won't feel alone; even the most angst-ridden teenager gets some pleasure in knowing that his or her pain is shared.

Forms of entertainment like music, movies, and video games might be thought of as what Steven Pinker calls "pleasure technologies"—cultural inventions that maximize the responses of our reward system. We enjoy such things not because they propagate our genes or because they conveyed specific advantages to our ancestors, but because they have been culturally selected for—precisely to the extent that they manage to tap into loopholes in our preexisting pleasure-seeking machinery.

The bottom line is this: our pleasure center consists not of some set of mechanisms perfectly tuned to promote the survival of the species, but a grab bag of crude mechanisms that are easily (and pleasurably) outwitted. Pleasure is only loosely correlated with what evolutionary biologists call "reproductive fitness"—and for that, we should be grateful.

Given how much we do to orient ourselves to the pursuit of pleasure, you'd expect us to be pretty good at assessing what's likely to make us happy and what's not. Here again, evolution holds some surprises.

A simple problem is that much of what makes us happy doesn't last long. Candy bars make us happy—for an instant—but we soon return to the state of mind we experienced before we had one. The same holds (or can hold) for sex, for movies, for television shows, and for rock concerts. Many of our most intense pleasures are shortlived.

But there's a deeper issue, which shows up in how we set our long-term goals; although we behave as if we want to maximize our long-term happiness, we frequently are remarkably poor at anticipating what will genuinely make us happy. As the psychologists Timothy Wilson and Daniel Gilbert have shown, predicting our own happiness can be a bit like forecasting the weather: a pretty inexact science. Their textbook case,^* which should give pause to assistant professors everywhere, concerns the young faculty member's inevitable quest for tenure. Virtually every major U.S. institution promises to its finest, most successful young professors a lifetime of academic freedom and guaranteed employment. Slog through graduate school, a postdoc or two, and five or six years of defining your very own academic niche, and if you succeed (as measured by the length of your résumé), you will gain tenure and be set for life.

The flip slide (rarely mentioned) is the slog that fails. Five to ten years spent working on a Ph.D., the postdocs, the half-decade of teaching, unappreciative undergraduates, the interminable faculty meetings, the struggle for grant money—and for what? Without a publication record, you're out of a job. Any professor can tell you that tenure is fantastic, and not getting tenure is miserable.

Or so we believe. In reality, neither outcome makes nearly as much difference to overall happiness as people generally assume. People who get tenure tend to be relieved, and initially ecstatic, but their happiness doesn't linger; they soon move on to worrying about other things. By the same token, people who don't get tenure are indeed often initially miserable, but their misery is usually short-lived. Instead, after the initial shock, people generally adapt to their circumstances. Some realize that the academic rat race isn't for them; others start new careers that they actually enjoy more.

Aspiring assistant professors who think that their future happiness hinges on getting tenure often fail to take into account one of the most deeply hard-wired properties of the mind: the tendency to get used to whatever's going on. The technical term for that is adaptation^* For example, the sound of rumbling trucks outside your office may annoy you at first, but over time you learn to block it out—that's adaptation. Similarly, we can adapt to even more serious annoyances, especially those that are predictable, which is why a boss who acts like a jerk every day can actually be less irritating than a boss who acts like a jerk less often, but at random intervals. As long as something is a constant, we can learn to live with it. Our circumstances do matter, but psychological adaptation means that they often matter less than we might expect.

This is true at both ends of the spectrum. Lottery winners get used to their newfound wealth, and others, people like the late Christopher Reeve, find ways of coping with circumstances most of us would find unimaginable. Don't get me wrong—I'd like to win the lottery and hope that I will never be seriously injured. But as a psychologist I know that winning the lottery wouldn't really change my life. Not only would I have to fend off all the long-lost "friends" who would come out of the woodwork, but also I'd face the inevitable fact of adaptation: the initial rush couldn't last because the brain won't allow it to.

The power of adaptation is one reason why money matters a lot less than most people think. According to literary legend, F. Scott Fitzgerald once said to Ernest Hemingway, "The rich are not like us." Hemingway allegedly brushed him off with the reply "Yes, they have more money," implying that wealth alone might make little difference. Hemingway was right. People above the poverty line are happier than people below the poverty line, but the truly wealthy aren't that much happier than the merely rich. One recent study, for example, showed that people making over $90,000 a year were no happier than those in the $50,000–$89,999 bracket. A recent New York Times article described a support group for multimillionaires. Another study reported that although average family income in Japan increased by a factor of five from 1958 to 1987, people's self-reports of happiness didn't change at all; all that extra income, but no extra happiness. Similar increases in the standard of living have occurred in the United States, again, with little effect on overall happiness. Study after study has shown that wealth predicts happiness only to a small degree. New material goods often bring tremendous initial pleasure, but we soon get used to them; that new Audi may be a blast to drive at first, but like any other vehicle, eventually it's just transportation.

Ironically, what really seems to matter is not absolute wealth, but relative income. Most people would rather make $70,000 at a job where their co-workers average $60,000 than $80,000 at a job where co-workers average $90,000. As a community's overall wealth increases, individual expectations expand; we don't just want to be rich, we want to be richer (than our neighbors). The net result is that many of us seem to be on a happiness treadmill, working harder and harder to maintain essentially the same level of happiness.

One of the most surprising things about happiness is just how poor we are at measuring it. It's not just that no brain scanner or dopamine counter can do a good job, but that we often just don't know—yet another hint of how klugey the whole apparatus of happiness really is.

Are you happy right now, at this very moment, reading this very book? Seriously, how would you rate the experience, on a scale of 1 ("I'd rather being doing the dishes") to 7 ("If this were any more fun, it would be illegal!")? You probably feel that you just "know" or can "intuit" the answer—that you can directly assess how happy you are, in the same way that you can determine whether you're too hot or too cold. But a number of studies suggest that our impression of direct intuition is an illusion.

Think back to that study of undergraduates who answered the question "How happy are you?" after first recounting their recent dating history. We're no different from them. Asking people about their overall happiness just after inquiring into the state of their marriage or their health has a similar effect. These studies tell us that people often don't really know how happy they are. Our subjective sense of happiness is, like so many of our beliefs, fluid, and greatly dependent on context.

Perhaps for that reason, the more we think about how we happy we are, the less happy we become. People who ruminate less upon their own circumstances tend to be happier than those who think about them more, just as Woody Allen implied in Annie Hall. When two attractive yet vacant-looking pedestrians walk by, Allen's character asks them to reveal the secret of their happiness. The woman answers first: "I'm very shallow and empty and I have no ideas and nothing interesting to say," to which her handsome boyfriend adds, "And I'm exactly the same way." The two stride gaily away. In other words, to paraphrase Mark Twain, dissecting our own happiness may be like dissecting frogs: both tend to die in the process.

Our lack of self-understanding may seem startling at first, but in hindsight it should scarcely seem surprising. Evolution doesn't "care" whether we understand our own internal operations, or even whether we are happy. Happiness, or more properly, the opportunity to pursue it, is little more than a motor that moves us. The happiness treadmill keeps us going: alive, reproducing, taking care of children, surviving for another day. Evolution didn't evolve us to be happy, it evolved us to pursue happiness.

In the battle between us and our genes, the kicker is this: to the extent that we see pleasure as a compass (albeit a flawed one) that tells us where we should be headed, and to the extent that we see happiness as a thermometer that tells us how we are doing, those instruments should, by rights, be instruments we can't fool with. Had our brains been built from scratch, the instruments that evaluated our mental state would no doubt behave a little like the meters electric companies use, which are instruments that we can inspect but not tinker with. No sensible person would buy a thermometer that displayed only the temperature that its owner wanted, rather than the actual temperature. But humans routinely try to outwit their instruments. Not just by seeking new ways of getting pleasure, but by lying to ourselves when we don't like what our happy-o-meter tells us. We "acquire" tastes (in an effort to override our pleasure compass), and, more significantly, when things aren't going well, we try to persuade ourselves that everything is fine. (We do the same thing with pain, every time we pop an Advil or an aspirin.)

Take, for example, your average undergraduate around the time I hand out grades. Students who get A's are thrilled, they're happy, and they accept their grades with pleasure, even glee. People with C's are, as you might imagine, less enthusiastic, dwelling for the most part not on what they did wrong, but what I did wrong. (Question 27 on the exam wasn't fair, we never talked about that in class, and how could Professor Marcus have taken off three points for my answer to question 42?) Meanwhile, it never occurs to the keeners in the front that I might have mistakenly been too generous to them. This asymmetry reeks, of course, of motivated reasoning, but I don't mean to complain; I do the same thing, ranting and raving at reviewers who reject my papers, blessing (rather than questioning) the wisdom of those who accept them. Similarly, car accidents are never our fault—it's always the other guy.

Freud would have seen all this self-deception as an illustration of what he called "defense mechanisms"; I see it as motivated reasoning. Either way, examples like these exemplify our habit of trying to fool the thermometer. Why feel bad that we've done something wrong when we can so easily jiggle the thermometer? As Jeff Goldblum's character put it in The Big Chill, "Rationalizations are more important than sex." "Ever go a week without a rationalization?" he asked.

We do our best to succeed, but if at first we don't succeed, we can always lie, dissemble, or rationalize. In keeping with this idea, most Westerners believe themselves to be smarter, fairer, more considerate, more dependable, and more creative than average. And—shades of Garrison Keillor's Lake Wobegon, where "the women are strong, the men are good looking, and all the children are above average"—we also convince ourselves that we are better-than-average drivers and have better-than-average health prospects. But you do the math: we can't all be above average. When Muhammad Ali said "I'm the greatest," he spoke the truth; the rest of us are probably just kidding ourselves (or at least our happy-o-meters).

Classic studies of a phenomenon called "cognitive dissonance" make the point in a different way.^* Back in the late 1950s, Leon Festinger did a famous series of experiments in which he asked subjects (undergraduate students) to do tedious menial tasks (such as sticking a set of plain pegs into an plain board). Here's the rub: some subjects were paid well ($20, a lot of money in 1959), but others, poorly ($1). Afterward, all were asked how much they liked the task. People who were paid well typically confessed to being bored, but people who were paid only a dollar tended to delude themselves into thinking that putting all those pegs into little holes was fun. Evidently they didn't want to admit to themselves that they'd wasted their time. Once again, who's directing whom? Is happiness guiding us, or are we micromanaging our own guide? It's as if we paid a sherpa to guide us up a mountain—only to ignore him whenever he told us we were going in the wrong direction. In short, we do everything in our power to make ourselves happy and comfortable with the world, but we stand perfectly ready to lie to ourselves if the truth doesn't cooperate.

Our tendency toward self-deception can lead us to lie not just about ourselves but about others. The psychologist Melvyn Lerner, for example, identified what he called a "Belief in a Just World"; it feels better to live in a world that seems just than one that seems unjust. Taken to its extreme, that belief can lead people to do things that are downright deplorable, such as blaming innocent victims. Rape victims, for example, are sometimes perceived as if they are to blame, or "had it coming." Perhaps the apotheosis of this sort of behavior occurred during the Irish potato famine, when a rather objectionable English politician said that "the great evil with which we have to contend is not the physical evil of the famine, but the moral evil of the selfish, perverse, and turbulent character of the people." Blaming victims may allow us to cling to the happy notion that the world is just, but its moral costs are often considerable.

A robot that was more sensibly engineered might retain the capacity for deliberative reason but dispense with all the rationalization and self-deception. Such a robot would be aware of its present state but prepared, Buddha-like, to accept it, good or bad, with equanimity rather than agony, and thus choose to take actions based on reality rather than delusion.

In biological terms, the neurotransmitters that underlie emotion, such as dopamine and serotonin, are ancient, tracing their history at least to the first vertebrates and playing a pivotal role in the reflexive systems of animals including fish, birds, and even mammals. Humans, with our massive prefrontal cortex, add substantial reflective reasoning on top, and thus we find ourselves with an instrument-fooling kluge. Virtually every study of reasoned decision making locates this capacity in the prefrontal cortex; emotion is attributed to the limbic system (and oribitofrontal cortex). A spot known as the anterior cingulate, souped up in human beings and other great apes, seems to mediate between the two. Deliberative prefrontal thought is piled on top of automatic emotional feelings—it doesn't replace them. So we've wound up with a double-edged kluge: our id perpetually at war with our ego, short-term and long-term desires never at peace.

What's the best evidence for this split? Teenagers. Teenagers as a species seem almost pathologically driven by short-term rewards. They make unrealistic estimates of the attendant risks and pay little attention to long-term costs. Why? According to one recent study, the nucleus accumbens, which assesses reward, matures before the orbital frontal cortex, which guides long-term planning and deliberative reasoning. Thus teenagers may have an adult capacity to appreciate short-term gain, but only a child's capacity to recognize long-term risk.

Here again, evolutionary inertia takes precedence over sensible design. Ideally, our judicious system and our reflexive system would mature at comparable rates. But perhaps because of the dynamics of how genomes change, biology tends, on average, to put together the evolutionarily old before the evolutionarily new. The spine, for example, a structure that is shared by all vertebrates, develops before the toes, which evolved more recently. The same thing happens with the brain—the ancestral precedes the modern, which perhaps helps us understand why teens, almost literally, often don't know what to do with themselves. Pleasure, in the context of a system not yet fully wired, can be a dangerous thing. Pleasure giveth, and pleasure taketh away.