为什么英语演讲稿(4篇范文)

第1篇 ted英语演讲稿：我们为什么要睡觉

简介：一生中，我们有三分之一的时间都在睡眠中度过。关于睡眠，你又了解多少?睡眠专家russell foster为我们解答为什么要睡觉，以及睡眠对健康的影响。

what i'd like to do today is talk about one of my favorite subjects, and that is the neuroscience of sleep.

now, there is a sound -- (alarm clock) -- aah, it worked -- a sound that is desperately, desperately familiar to most of us, and of course it's the sound of the alarm clock. and what that truly ghastly, awful sound does is stop the single most important behavioral experience that we have, and that's sleep. if you're an average sort of person, 36 percent of your life will be spent asleep, which means that if you live to 90, then 32 years will have been spent entirely asleep.

now what that 32 years is telling us is that sleep at some level is important. and yet, for most of us, we don't give sleep a second thought. we throw it away. we really just don't think about sleep. and so what i'd like to do today is change your views, change your ideas and your thoughts about sleep. and the journey that i want to take you on, we need to start by going back in time.

"enjoy the honey-heavy dew of slumber." any ideas who said that? shakespeare's julius caesar. yes, let me give you a few more quotes. "o sleep, o gentle sleep, nature's soft nurse, how have i frighted thee?" shakespeare again, from -- i won't say it -- the scottish play. [correction: henry iv, part 2] (laughter) from the same time: "sleep is the golden chain that ties health and our bodies together." extremely prophetic, by thomas dekker, another elizabethan dramatist.

but if we jump forward 400 years, the tone about sleep changes somewhat. this is from thomas edison, from the beginning of the 20th century. "sleep is a criminal waste of time and a heritage from our cave days." bang. (laughter) and if we also jump into the 1980s, some of you may remember that margaret thatcher was reported to have said, "sleep is for wimps." and of course the infamous -- what was his name? -- the infamous gordon gekko from "wall street" said, "money never sleeps."

what do we do in the 20th century about sleep? well, of course, we use thomas edison's light bulb to invade the night, and we occupied the dark, and in the process of this occupation, we've treated sleep as an illness, almost. we've treated it as an enemy. at most now, i suppose, we tolerate the need for sleep, and at worst perhaps many of us think of sleep as an illness that needs some sort of a cure. and our ignorance about sleep is really quite profound.

why is it? why do we abandon sleep in our thoughts? well, it's because you don't do anything much while you're asleep, it seems. you don't eat. you don't drink. and you don't have sex. well, most of us anyway. and so therefore it's -- sorry. it's a complete waste of time, right? wrong. actually, sleep is an incredibly important part of our biology, and neuroscientists are beginning to explain why it's so very important. so let's move to the brain.

now, here we have a brain. this is donated by a social scientist, and they said they didn't know what it was, or indeed how to use it, so -- (laughter) sorry. so i borrowed it. i don't think they noticed. okay. (laughter)

the point i'm trying to make is that when you're asleep, this thing doesn't shut down. in fact, some areas of the brain are actually more active during the sleep state than during the wake state. the other thing that's really important about sleep is that it doesn't arise from a single structure within the brain, but is to some extent a network property, and if we flip the brain on its back -- i love this little bit of spinal cord here -- this bit here is the hypothalamus, and right under there is a whole raft of interesting structures, not least the biological clock. the biological clock tells us when it's good to be up, when it's good to be asleep, and what that structure does is interact with a whole raft of other areas within the hypothalamus, the lateral hypothalamus, the ventrolateral preoptic nuclei. all of those combine, and they send projections down to the brain stem here. the brain stem then projects forward and bathes the cortex, this wonderfully wrinkly bit over here, with neurotransmitters that keep us awake and essentially provide us with our consciousness. so sleep arises from a whole raft of different interactions within the brain, and essentially, sleep is turned on and off as a result of a range of

okay. so where have we got to? we've said that sleep is complicated and it takes 32 years of our life. but what i haven't explained is what sleep is about. so why do we sleep? and it won't surprise any of you that, of course, the scientists, we don't have a consensus. there are dozens of different ideas about why we sleep, and i'm going to outline three of those.

the first is sort of the restoration idea, and it's somewhat intuitive. essentially, all the stuff we've burned up during the day, we restore, we replace, we rebuild during the night. and indeed, as an explanation, it goes back to aristotle, so that's, what, 2,300 years ago. it's gone in and out of fashion. it's fashionable at the moment because what's been shown is that within the brain, a whole raft of genes have been shown to be turned on only during sleep, and those genes are associated with restoration and metabolic pathways. so there's good evidence for the whole restoration hypothesis.

what about energy conservation? again, perhaps intuitive. you essentially sleep to save calories. now, when you do the sums, though, it doesn't really pan out. if you compare an individual who has slept at night, or stayed awake and hasn't moved very much, the energy saving of sleeping is about 110 calories a night. now, that's the equivalent of a hot dog bun. now, i would say that a hot dog bun is kind of a meager return for such a complicated and demanding behavior as sleep. so i'm less convinced by the energy conservation idea.

but the third idea i'm quite attracted to, which is brain processing and memory consolidation. what we know is that, if after you've tried to learn a task, and you sleep-deprive individuals, the ability to learn that task is smashed. it's really hugely attenuated. so sleep and memory consolidation is also very important. however, it's not just the laying down of memory and recalling it. what's turned out to be really exciting is that our ability to come up with novel solutions to complex problems is hugely enhanced by a night of sleep. in fact, it's been estimated to give us a threefold advantage. sleeping at night enhances our creativity. and what seems to be going on is that, in the brain, those neural connections that are important, those synaptic connections that are important, are linked and strengthened, while those that are less important tend to fade away and be less important.

okay. so we've had three explanations for why we might sleep, and i think the important thing to realize is that the details will vary, and it's probable we sleep for multiple different reasons. but sleep is not an indulgence. it's not some sort of thing that we can take on board rather casually. i think that sleep was once likened to an upgrade from economy to business class, you know, the equiavlent of. it's not even an upgrade from economy to first class. the critical thing to realize is that if you don't sleep, you don't fly. essentially, you never get there, and what's extraordinary about much of our society these days is that we are desperately sleep-deprived.

so let's now look at sleep deprivation. huge sectors of society are sleep-deprived, and let's look at our sleep-o-meter. so in the 1950s, good data suggests that most of us were getting around about eight hours of sleep a night. nowadays, we sleep one and a half to two hours less every night, so we're in the six-and-a-half-hours-every-night league. for teenagers, it's worse, much worse. they need nine hours for full brain performance, and many of them, on a school night, are only getting five hours of sleep. it's simply not enough. if we think about other sectors of society, the aged, if you are aged, then your ability to sleep in a single block is somewhat disrupted, and many sleep, again, less than five hours a night. shift work. shift work is extraordinary, perhaps 20 percent of the working population, and the body clock does not shift to the demands of working at night. it's locked onto the same light-dark cycle as the rest of us. so when the poor old shift worker is going home to try and sleep during the day, desperately tired, the body clock is saying, "wake up. this is the time to be awake." so the quality of sleep that you get as a night shift worker is usually very poor, again in that sort of five-hour region. and then, of course, tens of millions of people suffer from jet lag. so who here has jet lag? well, my goodness gracious. well, thank you very much indeed for not falling asleep, because that's what your brain is craving.

one of the things that the brain does is indulge in micro-sleeps, this involuntary falling asleep, and you have essentially no control over it. now, micro-sleeps can be sort of somewhat embarrassing, but they can also be deadly. it's been estimated that 31 percent of drivers will fall asleep at the wheel at least once in their life, and in the u.s., the statistics are pretty good: 100,000 accidents on the freeway have been associated with tiredness, loss of vigilance, and falling asleep. a hundred thousand a year. it's extraordinary. at another level of terror, we dip into the tragic accidents at chernobyl and indeed the space shuttle challenger, which was so tragically lost. and in the investigations that followed those disasters, poor judgment as a result of extended shift work and loss of vigilance and tiredness was attributed to a big chunk of those disasters.

so when you're tired, and you lack sleep, you have poor memory, you have poor creativity, you have increased impulsiveness, and you have overall poor judgment. but my friends, it's so much worse than that.

(laughter)

if you are a tired brain, the brain is craving things to wake it up. so drugs, stimulants. caffeine represents the stimulant of choice across much of the western world. much of the day is fueled by caffeine, and if you're a really naughty tired brain, nicotine. and of course, you're fueling the waking state with these stimulants, and then of course it gets to 11 o'clock at night, and the brain says to itself, "ah, well actually, i need to be asleep fairly shortly. what do we do about that when i'm feeling completely wired?" well, of course, you then resort to alcohol. now alcohol, short-term, you know, once or twice, to use to mildly sedate you, can be very useful. it can actually ease the sleep transition. but what you must be so aware of is that alcohol doesn't provide sleep, a biological mimic for sleep. it sedates you. so it actually harms some of the neural proccessing that's going on during memory consolidation and memory recall. so it's a short-term acute measure, but for goodness sake, don't become addicted to alcohol as a way of getting to sleep every night.

another connection between loss of sleep is weight gain. if you sleep around about five hours or less every night, then you have a 50 percent likelihood of being obese. what's the connection here? well, sleep loss seems to give rise to the release of the hormone ghrelin, the hunger hormone. ghrelin is released. it gets to the brain. the brain says, "i need carbohydrates," and what it does is seek out carbohydrates and particularly sugars. so there's a link between tiredness and the metabolic predisposition for weight gain.

stress. tired people are massively stressed. and one of the things of stress, of course, is loss of memory, which is what i sort of just then had a little lapse of. but stress is so much more. so if you're acutely stressed, not a great problem, but it's sustained stress associated with sleep loss that's the problem. so sustained stress leads to suppressed immunity, and so tired people tend to have higher rates of overall infection, and there's some very good studies showing that shift workers, for example, have higher rates of cancer. increased levels of stress throw glucose into the circulation. glucose becomes a dominant part of the vasculature and essentially you become glucose intolerant. therefore, diabetes 2. stress increases cardiovascular disease as a result of raising blood pressure. so there's a whole raft of things associated with sleep loss that are more than just a mildly impaired brain, which is where i think most people think that sleep loss resides.

so at this point in the talk, this is a nice time to think, well, do you think on the whole i'm getting enough sleep? so a quick show of hands. who feels that they're getting enough sleep here? oh. well, that's pretty impressive. good. we'll talk more about that later, about what are your tips.

so most of us, of course, ask the question, "well, how do i know whether i'm getting enough sleep?" well, it's not rocket science. if you need an alarm clock to get you out of bed in the morning, if you are taking a long time to get up, if you need lots of stimulants, if you're grumpy, if you're irritable, if you're told by your work colleagues that you're looking tired and irritable, chances are you are sleep-deprived. listen to them. listen to yourself.

what do you do? well -- and this is slightly offensive -- sleep for dummies: make your bedroom a haven for sleep. the first critical thing is make it as dark as you possibly can, and also make it slightly cool. very important. actually, reduce your amount of light exposure at least half an hour before you go to bed. light increases levels of alertness and will delay sleep. what's the last thing that most of us do before we go to bed? we stand in a massively lit bathroom looking into the mirror cleaning our teeth. it's the worst thing we can possibly do before we went to sleep. turn off those mobile phones. turn off those computers. turn off all of those things that are also going to excite the brain. try not to drink caffeine too late in the day, ideally not after lunch. now, we've set about reducing light exposure before you go to bed, but light exposure in the morning is very good at setting the biological clock to the light-dark cycle. so seek out morning light. basically, listen to yourself. wind down. do those sorts of things that you know are going to ease you off into the honey-heavy dew of slumber.

okay. that's some facts. what about some myths?

teenagers are lazy. no. poor things. they have a biological predisposition to go to bed late and get up late, so give them a break.

we need eight hours of sleep a night. that's an average. some people need more. some people need less. and what you need to do is listen to your body. do you need that much or do you need more? simple as that.

old people need less sleep. not true. the sleep demands of the aged do not go down. essentially, sleep fragments and becomes less robust, but sleep requirements do not go down.

and the fourth myth is, early to bed, early to rise makes a man healthy, wealthy and wise. well that's wrong at so many different levels. (laughter) there is no, no evidence that getting up early and going to bed early gives you more wealth at all. there's no difference in socioeconomic status. in my experience, the only difference between morning people and evening people is that those people that get up in the morning early are just horribly smug.

(laughter) (applause)

okay. so for the last part, the last few minutes, what i want to do is change gears and talk about some really new, breaking areas of neuroscience, which is the association between mental health, mental illness and sleep disruption. we've known for 130 years that in severe mental illness, there is always, always sleep disruption, but it's been largely ignored. in the 1970s, when people started to think about this again, they said, "yes, well, of course you have sleep disruption in schizophrenia because they're on anti-psychotics. it's the anti-psychotics causing the sleep problems," ignoring the fact that for a hundred years previously, sleep disruption had been reported before anti-psychotics.

so what's going on? lots of groups, several groups are studying conditions like depression, schizophrenia and bipolar, and what's going on in terms of sleep disruption. we have a big study which we published last year on schizophrenia, and the data were quite extraordinary. in those individuals with schizophrenia, much of the time, they were awake during the night phase and then they were asleep during the day. other groups showed no 24-hour patterns whatsoever. their sleep was absolutely smashed. and some had no ability to regulate their sleep by the light-dark cycle. they were getting up later and later and later and later each night. it was smashed.

so what's going on? and the really exciting news is that mental illness and sleep are not simply associated but they are physically linked within the brain. the neural networks that predispose you to normal sleep, give you normal sleep, and those that give you normal mental health are overlapping. and what's the evidence for that? well, genes that have been shown to be very important in the generation of normal sleep, when mutated, when changed, also predispose individuals to mental health problems. and last year, we published a study which showed that a gene that's been linked to schizophrenia, which, when mutated, also smashes the sleep. so we have evidence of a genuine mechanistic overlap between these two important systems.

other work flowed from these studies. the first was that sleep disruption actually precedes certain types of mental illness, and we've shown that in those young individuals who are at high risk of developing bipolar disorder, they already have a sleep abnormality prior to any clinical diagnosis of bipolar. the other bit of data was that sleep disruption may actually exacerbate, make worse the mental illness state. my colleague dan freeman has used a range of agents which have stabilized sleep and reduced levels of paranoia in those individuals by 50 percent.

so what have we got? we've got, in these connections, some really exciting things. in terms of the neuroscience, by understanding the neuroscience of these two systems, we're really beginning to understand how both sleep and mental illness are generated and regulated within the brain. the second area is that if we can use sleep and sleep disruption as an early warning signal, then we have the chance of going in. if we know that these individuals are vulnerable, early intervention then becomes possible. and the third, which i think is the most exciting, is that we can think of the sleep centers within the brain as a new therapeutic target. stabilize sleep in those individuals who are vulnerable, we can certainly make them healthier, but also alleviate some of the appalling symptoms of mental illness.

so let me just finish. what i started by saying is take sleep seriously. our attitudes toward sleep are so very different from a pre-industrial age, when we were almost wrapped in a duvet. we used to understand intuitively the importance of sleep. and this isn't some sort of crystal-waving nonsense. this is a pragmatic response to good health. if you have good sleep, it increases your concentration, attention, decision-making, creativity, social skills, health. if you get sleep, it reduces your mood changes, your stress, your levels of anger, your impulsivity, and your tendency to drink and take drugs. and we finished by saying that an understanding of the neuroscience of sleep is really informing the way we think about some of the causes of mental illness, and indeed is providing us new ways to treat these incredibly debilitating conditions.

jim butcher, the fantasy writer, said, "sleep is god. go worship." and i can only recommend that you do the same.

thank you for your attention.

(applause)

第2篇 ted英语演讲稿：我们为什么快乐？

when you have 21 minutes to speak, two million years seems like a really long time. but evolutionarily, two million years is nothing. and yet in two million years the human brain has nearly tripled in mass, going from the one-and-a-quarter pound brain of our ancestor here, habilis, to the almost three-pound meatloaf that everybody here has between their ears. what is it about a big brain that nature was so eager for every one of us to have one?

well, it turns out when brains triple in size, they don't just get three times bigger; they gain new structures. and one of the main reasons our brain got so big is because it got a new part, called the "frontal lobe." and particularly, a part called the "pre-frontal cortex." now what does a pre-frontal cortex do for you that should justify the entire architectural overhaul of the human skull in the blink of evolutionary time?

well, it turns out the pre-frontal cortex does lots of things, but one of the most important things it does is it is an experience simulator. flight pilots practice in flight simulators so that they don't make real mistakes in planes. human beings have this marvelous adaptation that they can actually have experiences in their heads before they try them out in real life. this is a trick that none of our ancestors could do, and that no other animal can do quite like we can. it's a marvelous adaptation. it's up there with opposable thumbs and standing upright and language as one of the things that got our species out of the trees and into the shopping mall.

now -- (laughter) -- all of you have done this. i mean, you know, ben and jerry's doesn't have liver-and-onion ice cream, and it's not because they whipped some up, tried it and went, "yuck." it's because, without leaving your armchair, you can simulate that flavor and say "yuck" before you make it.

let's see how your experience simulators are working. let's just run a quick diagnostic before i proceed with the rest of the talk. here's two different futures that i invite you to contemplate, and you can try to simulate them and tell me which one you think you might prefer. one of them is winning the lottery. this is about 314 million dollars. and the other is becoming paraplegic. so, just give it a moment of thought. you probably don't feel like you need a moment of thought.

interestingly, there are data on these two groups of people, data on how happy they are. and this is exactly what you expected, isn't it? but these aren't the data. i made these up!

these are the data. you failed the pop quiz, and you're hardly five minutes into the lecture. because the fact is that a year after losing the use of their legs, and a year after winning the lotto, lottery winners and paraplegics are equally happy with their lives.

now, don't feel too bad about failing the first pop quiz, because everybody fails all of the pop quizzes all of the time. the research that my laboratory has been doing, that economists and psychologists around the country have been doing, have revealed something really quite startling to us, something we call the "impact bias," which is the tendency for the simulator to work badly. for the simulator to make you believe that different outcomes are more different than in fact they really are.

from field studies to laboratory studies, we see that winning or losing an election, gaining or losing a romantic partner, getting or not getting a promotion, passing or not passing a college test, on and on, have far less impact, less intensity and much less duration than people expect them to have. in fact, a recent study -- this almost floors me -- a recent study showing how major life traumas affect people suggests that if it happened over three months ago, with only a few exceptions, it has no impact whatsoever on your happiness.

why? because happiness can be synthesized. sir thomas brown wrote in 1642, "i am the happiest man alive. i have that in me that can convert poverty to riches, adversity to prosperity. i am more invulnerable than achilles; fortune hath not one place to hit me." what kind of remarkable machinery does this guy have in his head?

well, it turns out it's precisely the same remarkable machinery that all off us have. human beings have something that we might think of as a "psychological immune system." a system of cognitive processes, largely non-conscious cognitive processes, that help them change their views of the world, so that they can feel better about the worlds in which they find themselves. like sir thomas, you have this machine. unlike sir thomas, you seem not to know it. (laughter)

we synthesize happiness, but we think happiness is a thing to be found. now, you don't need me to give you too many examples of people synthesizing happiness, i suspect. though i'm going to show you some experimental evidence, you don't have to look very far for evidence.

as a challenge to myself, since i say this once in a while in lectures, i took a copy of the new york times and tried to find some instances of people synthesizing happiness. and here are three guys synthesizing happiness. "i am so much better off physically, financially, emotionally, mentally and almost every other way." "i don't have one minute's regret. it was a glorious experience." "i believe it turned out for the best."

who are these characters who are so damn happy? well, the first one is jim wright. some of you are old enough to remember: he was the chairman of the house of representatives and he resigned in disgrace when this young republican named newt gingrich found out about a shady book deal he had done. he lost everything. the most powerful democrat in the country, he lost everything. he lost his money; he lost his power. what does he have to say all these years later about it? "i am so much better off physically, financially, mentally and in almost every other way." what other way would there be to be better off? vegetably? minerally? animally? he's pretty much covered them there.

moreese bickham is somebody you've never heard of. moreese bickham uttered these words upon being released. he was 78 years old. he spent 37 years in a louisiana state penitentiary for a crime he didn't commit. he was ultimately exonerated, at the age of 78, through dna evidence. and what did he have to say about his experience? "i don't have one minute's regret. it was a glorious experience." glorious! this guy is not saying, "well, you know, there were some nice guys. they had a gym." it's "glorious," a word we usually reserve for something like a religious experience.

harry s. langerman uttered these words, and he's somebody you might have known but didn't, because in 1949 he read a little article in the paper about a hamburger stand owned by these two brothers named mcdonalds. and he thought, "that's a really neat idea!" so he went to find them. they said, "we can give you a franchise on this for 3,000 bucks." harry went back to new york, asked his brother who's an investment banker to loan him the 3,000 dollars, and his brother's immortal words were, "you idiot, nobody eats hamburgers." he wouldn't lend him the money, and of course six months later ray croc had exactly the same idea. it turns out people do eat hamburgers, and ray croc, for a while, became the richest man in america.

and then finally -- you know, the best of all possible worlds -- some of you recognize this young photo of pete best, who was the original drummer for the beatles, until they, you know, sent him out on an errand and snuck away and picked up ringo on a tour. well, in 1994, when pete best was interviewed -- yes, he's still a drummer; yes, he's a studio musician -- he had this to say: "i'm happier than i would have been with the beatles."

okay. there's something important to be learned from these people, and it is the secret of happiness. here it is, finally to be revealed. first: accrue wealth, power, and prestige, then lose it. (laughter) second: spend as much of your life in prison as you possibly can. (laughter) third: make somebody else really, really rich. (laughter) and finally: never ever join the beatles. (laughter)

ok. now i, like ze frank, can predict your next thought, which is, "yeah, right." because when people synthesize happiness, as these gentlemen seem to have done, we all smile at them, but we kind of roll our eyes and say, "yeah right, you never really wanted the job." "oh yeah, right. you really didn't have that much in common with her, and you figured that out just about the time she threw the engagement ring in your face."

we smirk because we believe that synthetic happiness is not of the same quality as what we might call "natural happiness." what are these terms? natural happiness is what we get when we get what we wanted, and synthetic happiness is what we make when we don't get what we wanted. and in our society, we have a strong belief that synthetic happiness is of an inferior kind. why do we have that belief? well, it's very simple. what kind of economic engine would keep churning if we believed that not getting what we want could make us just as happy as getting it?

with all apologies to my friend matthieu ricard, a shopping mall full of zen monks is not going to be particularly profitable because they don't want stuff enough. i want to suggest to you that synthetic happiness is every bit as real and enduring as the kind of happiness you stumble upon when you get exactly what you were aiming for. now, i'm a scientist, so i'm going to do this not with rhetoric, but by marinating you in a little bit of data.

let me first show you an experimental paradigm that is used to demonstrate the synthesis of happiness among regular old folks. and this isn't mine. this is a 50-year-old paradigm called the "free choice paradigm." it's very simple. you bring in, say, six objects, and you ask a subject to rank them from the most to the least liked. in this case, because the experiment i'm going to tell you about uses them, these are monet prints. so, everybody can rank these monet prints from the one they like the most, to the one they like the least. now we give you a choice: "we happen to have some extra prints in the closet. we're going to give you one as your prize to take home. we happen to have number three and number four," we tell the subject. this is a bit of a difficult choice, because neither one is preferred strongly to the other, but naturally, people tend to pick number three because they liked it a little better than number four.

sometime later -- it could be 15 minutes; it could be 15 days -- the same stimuli are put before the subject, and the subject is asked to re-rank the stimuli. "tell us how much you like them now." what happens? watch as happiness is synthesized. this is the result that has been replicated over and over again. you're watching happiness be synthesized. would you like to see it again? happiness! "the one i got is really better than i thought! that other one i didn't get sucks!" (laughter) that's the synthesis of happiness.

now what's the right response to that? "yeah, right!" now, here's the experiment we did, and i would hope this is going to convince you that "yeah, right!" was not the right response.

we did this experiment with a group of patients who had anterograde amnesia. these are hospitalized patients. most of them have korsakoff's syndrome, a polyneuritic psychosis that -- they drank way too much, and they can't make new memories. ok? they remember their childhood, but if you walk in and introduce yourself, and then leave the room, when you come back, they don't know who you are.

we took our monet prints to the hospital. and we asked these patients to rank them from the one they liked the most to the one they liked the least. we then gave them the choice between number three and number four. like everybody else, they said, "gee, thanks doc! that's great! i could use a new print. i'll take number three." we explained we would have number three mailed to them. we gathered up our materials and we went out of the room, and counted to a half hour. back into the room, we say, "hi, we're back." the patients, bless them, say, "ah, doc, i'm sorry, i've got a memory problem; that's why i'm here. if i've met you before, i don't remember." "really, jim, you don't remember? i was just here with the monet prints?" "sorry, doc, i just don't have a clue." "no problem, jim. all i want you to do is rank these for me from the one you like the most to the one you like the least."

what do they do? well, let's first check and make sure they're really amnesiac. we ask these amnesiac patients to tell us which one they own, which one they chose last time, which one is theirs. and what we find is amnesiac patients just guess. these are normal controls, where if i did this with you, all of you would know which print you chose. but if i do this with amnesiac patients, they don't have a clue. they can't pick their print out of a lineup.

here's what normal controls do: they synthesize happiness. right? this is the change in liking score, the change from the first time they ranked to the second time they ranked. normal controls show -- that was the magic i showed you; now i'm showing it to you in graphical form -- "the one i own is better than i thought. the one i didn't own, the one i left behind, is not as good as i thought." amnesiacs do exactly the same thing. think about this result.

these people like better the one they own, but they don't know they own it. "yeah, right" is not the right response! what these people did when they synthesized happiness is they really, truly changed their affective, hedonic, aesthetic reactions to that poster. they're not just saying it because they own it, because they don't know they own it.

now, when psychologists show you bars, you know that they are showing you averages of lots of people. and yet, all of us have this psychological immune system, this capacity to synthesize happiness, but some of us do this trick better than others. and some situations allow anybody to do it more effectively than other situations do. it turns out that freedom -- the ability to make up your mind and change your mind -- is the friend of natural happiness, because it allows you to choose among all those delicious futures and find the one that you would most enjoy. but freedom to choose -- to change and make up your mind -- is the enemy of synthetic happiness. and i'm going to show you why.

dilbert already knows, of course. you're reading the cartoon as i'm talking. "dogbert's tech support. how may i abuse you?" "my printer prints a blank page after every document." "why would you complain about getting free paper?" "free? aren't you just giving me my own paper?" "egad, man! look at the quality of the free paper compared to your lousy regular paper! only a fool or a liar would say that they look the same!" "ah! now that you mention it, it does seem a little silkier!" "what are you doing?" "i'm helping people accept the things they cannot change." indeed.

the psychological immune system works best when we are totally stuck, when we are trapped. this is the difference between dating and marriage, right? i mean, you go out on a date with a guy, and he picks his nose; you don't go out on another date. you're married to a guy and he picks his nose? yeah, he has a heart of gold; don't touch the fruitcake. right? (laughter) you find a way to be happy with what's happened. now what i want to show you is that people don't know this about themselves, and not knowing this can work to our supreme disadvantage.

here's an experiment we did at harvard. we created a photography course, a black-and-white photography course, and we allowed students to come in and learn how to use a darkroom. so we gave them cameras; they went around campus; they took 12 pictures of their favorite professors and their dorm room and their dog, and all the other things they wanted to have harvard memories of. they bring us the camera; we make up a contact sheet; they figure out which are the two best pictures; and we now spend six hours teaching them about darkrooms. and they blow two of them up, and they have two gorgeous eight-by-10 glossies of meaningful things to them, and we say, "which one would you like to give up?" they say, "i have to give one up?" "oh, yes. we need one as evidence of the class project. so you have to give me one. you have to make a choice. you get to keep one, and i get to keep one."

now, there are two conditions in this experiment. in one case, the students are told, "but you know, if you want to change your mind, i'll always have the other one here, and in the next four days, before i actually mail it to headquarters, i'll be glad to" -- (laughter) -- yeah, "headquarters" -- "i'll be glad to swap it out with you. in fact, i'll come to your dorm room and give -- just give me an email. better yet, i'll check with you. you ever want to change your mind, it's totally returnable." the other half of the students are told exactly the opposite: "make your choice. and by the way, the mail is going out, gosh, in two minutes, to england. your picture will be winging its way over the atlantic. you will never see it again." now, half of the students in each of these conditions are asked to make predictions about how much they're going to come to like the picture that they keep and the picture they leave behind. other students are just sent back to their little dorm rooms and they are measured over the next three to six days on their liking, satisfaction with the pictures. and look at what we find.

first of all, here's what students think is going to happen. they think they're going to maybe come to like the picture they chose a little more than the one they left behind, but these are not statistically significant differences. it's a very small increase, and it doesn't much matter whether they were in the reversible or irreversible condition.

wrong-o. bad simulators. because here's what's really happening. both right before the swap and five days later, people who are stuck with that picture, who have no choice, who can never change their mind, like it a lot! and people who are deliberating -- "should i return it? have i gotten the right one? maybe this isn't the good one? maybe i left the good one?" -- have killed themselves. they don't like their picture, and in fact even after the opportunity to swap has expired, they still don't like their picture. why? because the reversible condition is not conducive to the synthesis of happiness.

so here's the final piece of this experiment. we bring in a whole new group of naive harvard students and we say, "you know, we're doing a photography course, and we can do it one of two ways. we could do it so that when you take the two pictures, you'd have four days to change your mind, or we're doing another course where you take the two pictures and you make up your mind right away and you can never change it. which course would you like to be in?" duh! 66 percent of the students, two-thirds, prefer to be in the course where they have the opportunity to change their mind. hello? 66 percent of the students choose to be in the course in which they will ultimately be deeply dissatisfied with the picture. because they do not know the conditions under which synthetic happiness grows.

the bard said everything best, of course, and he's making my point here but he's making it hyperbolically: "'tis nothing good or bad / but thinking makes it so." it's nice poetry, but that can't exactly be right. is there really nothing good or bad? is it really the case that gall bladder surgery and a trip to paris are just the same thing? that seems like a one-question iq test. they can't be exactly the same.

in more turgid prose, but closer to the truth, was the father of modern capitalism, adam smith, and he said this. this is worth contemplating: "the great source of both the misery and disorders of human life seems to arise from overrating the difference between one permanent situation and another ... some of these situations may, no doubt, deserve to be preferred to others, but none of them can deserve to be pursued with that passionate ardor which drives us to violate the rules either of prudence or of justice, or to corrupt the future tranquility of our minds, either by shame from the remembrance of our own folly, or by remorse for the horror of our own injustice." in other words: yes, some things are better than others.

we should have preferences that lead us into one future over another. but when those preferences drive us too hard and too fast because we have overrated the difference between these futures, we are at risk. when our ambition is bounded, it leads us to work joyfully. when our ambition is unbounded, it leads us to lie, to cheat, to steal, to hurt others, to sacrifice things of real value. when our fears are bounded, we're prudent; we're cautious; we're thoughtful. when our fears are unbounded and overblown, we're reckless, and we're cowardly.

the lesson i want to leave you with from these data is that our longings and our worries are both to some degree overblown, because we have within us the capacity to manufacture the very commodity we are constantly chasing when we choose experience.

thank you.

第3篇 ted英语演讲稿：为什么节食减肥没效果？

简介：在美国，80%的女孩在她们10岁的时候便开始节食。神经学家sandra aamodt结合自己的亲身经历，讲述大脑是如何控制我们的身体的。节食减肥为何没效果?来听听她的说法吧!

three and a half years ago, i made one of the best decisions of my life. as my new year's resolution, i gave up dieting, stopped worrying about my weight, and learned to eat mindfully. now i eat whenever i'm hungry, and i've lost 10 pounds.

this was me at age 13, when i started my first diet. i look at that picture now, and i think, you did not need a diet, you needed a fashion consult. (laughter) but i thought i needed to lose weight, and when i gained it back, of course i blamed myself. and for the next three decades, i was on and off various diets. no matter what i tried, the weight i'd lost always came back. i'm sure many of you know the feeling.

as a neuroscientist, i wondered, why is this so hard? obviously, how much you weigh depends on how much you eat and how much energy you burn. what most people don't realize is that hunger and energy use are controlled by the brain, mostly without your awareness. your brain does a lot of its work behind the scenes, and that is a good thing, because your conscious mind -- how do we put this politely? -- it's easily distracted. it's good that you don't have to remember to breathe when you get caught up in a movie. you don't forget how to walk because you're thinking about what to have for dinner.

your brain also has its own sense of what you should weigh, no matter what you consciously believe. this is called your set point, but that's a misleading term, because it's actually a range of about 10 or 15 pounds. you can use lifestyle choices to move your weight up and down within that range, but it's much, much harder to stay outside of it. the hypothalamus, the part of the brain that regulates body weight, there are more than a dozen chemical signals in the brain that tell your body to gain weight, more than another dozen that tell your body to lose it, and the system works like a thermostat, responding to signals from the body by adjusting hunger, activity and metabolism, to keep your weight stable as conditions change. that's what a thermostat does, right? it keeps the temperature in your house the same as the weather changes outside. now you can try to change the temperature in your house by opening a window in the winter, but that's not going to change the setting on the thermostat, which will respond by kicking on the furnace to warm the place back up.

your brain works exactly the same way, responding to weight loss by using powerful tools to push your body back to what it considers normal. if you lose a lot of weight, your brain reacts as if you were starving, and whether you started out fat or thin, your brain's response is exactly the same. we would love to think that your brain could tell whether you need to lose weight or not, but it can't. if you do lose a lot of weight, you become hungry, and your muscles burn less energy. dr. rudy leibel of columbia university has found that people who have lost 10 percent of their body weight burn 250 to 400 calories less because their metabolism is suppressed. that's a lot of food. this means that a successful dieter must eat this much less forever than someone of the same weight who has always been thin.

from an evolutionary perspective, your body's resistance to weight loss makes sense. when food was scarce, our ancestors' survival depended on conserving energy, and regaining the weight when food was available would have protected them against the next shortage. over the course of human history, starvation has been a much bigger problem than overeating. this may explain a very sad fact: set points can go up, but they rarely go down. now, if your mother ever mentioned that life is not fair, this is the kind of thing she was talking about. (laughter) successful dieting doesn't lower your set point. even after you've kept the weight off for as long as seven years, your brain keeps trying to make you gain it back. if that weight loss had been due to a long famine, that would be a sensible response. in our modern world of drive-thru burgers, it's not working out so well for many of us. that difference between our ancestral past and our abundant present is the reason that dr. yoni freedhoff of the university of ottawa would like to take some of his patients back to a time when food was less available, and it's also the reason that changing the food environment is really going to be the most effective solution to obesity.

sadly, a temporary weight gain can become permanent. if you stay at a high weight for too long, probably a matter of years for most of us, your brain may decide that that's the new normal.

psychologists classify eaters into two groups, those who rely on their hunger and those who try to control their eating through willpower, like most dieters. let's call them intuitive eaters and controlled eaters. the interesting thing is that intuitive eaters are less likely to be overweight, and they spend less time thinking about food. controlled eaters are more vulnerable to overeating in response to advertising, super-sizing, and the all-you-can-eat buffet. and a small indulgence, like eating one scoop of ice cream, is more likely to lead to a food binge in controlled eaters. children are especially vulnerable to this cycle of dieting and then binging.

several long-term studies have shown that girls who diet in their early teenage years are three times more likely to become overweight five years later, even if they started at a normal weight, and all of these studies found that the same factors that predicted weight gain also predicted the development of eating disorders. the other factor, by the way, those of you who are parents, was being teased by family members about their weight. so don't do that. (laughter)

i left almost all my graphs at home, but i couldn't resist throwing in just this one, because i'm a geek, and that's how i roll. (laughter) this is a study that looked at the risk of death over a 14-year period based on four healthy habits: eating enough fruits and vegetables, exercise three times a week, not smoking, and drinking in moderation. let's start by looking at the normal weight people in the study. the height of the bars is the risk of death, and those zero, one, two, three, four numbers on the horizontal axis are the number of those healthy habits that a given person had. and as you'd expect, the healthier the lifestyle, the less likely people were to die during the study. now let's look at what happens in overweight people.

the ones that had no healthy habits had a higher risk of death. adding just one healthy habit pulls overweight people back into the normal range. for obese people with no healthy habits, the risk is very high, seven times higher than the healthiest groups in the study. but a healthy lifestyle helps obese people too. in fact, if you look only at the group with all four healthy habits, you can see that weight makes very little difference. you can take control of your health by taking control of your lifestyle, even if you can't lose weight and keep it off.

diets don't have very much reliability. five years after a diet, most people have regained the weight. forty percent of them have gained even more. if you think about this, the typical outcome of dieting is that you're more likely to gain weight in the long run than to lose it.

if i've convinced you that dieting might be a problem, the next question is, what do you do about it? and my answer, in a word, is mindfulness. i'm not saying you need to learn to meditate or take up yoga. i'm talking about mindful eating: learning to understand your body's signals so that you eat when you're hungry and stop when you're full, because a lot of weight gain boils down to eating when you're not hungry. how do you do it? give yourself permission to eat as much as you want, and then work on figuring out what makes your body feel good. sit down to regular meals without distractions. think about how your body feels when you start to eat and when you stop, and let your hunger decide when you should be done. it took about a year for me to learn this, but it's really been worth it. i am so much more relaxed around food than i have ever been in my life. i often don't think about it. i forget we have chocolate in the house. it's like aliens have taken over my brain. it's just completely different. i should say that this approach to eating probably won't make you lose weight unless you often eat when you're not hungry, but doctors don't know of any approach that makes significant weight loss in a lot of people, and that is why a lot of people are now focusing on preventing weight gain instead of promoting weight loss. let's face it: if diets worked, we'd all be thin already. (laughter)

why do we keep doing the same thing and expecting different results? diets may seem harmless, but they actually do a lot of collateral damage. at worst, they ruin lives: weight obsession leads to eating disorders, especially in young kids. in the u.s., we have 80 percent of 10-year-old girls say they've been on a diet. our daughters have learned to measure their worth by the wrong scale. even at its best, dieting is a waste of time and energy. it takes willpower which you could be using to help your kids with their homework or to finish that important work project, and because willpower is limited, any strategy that relies on its consistent application is pretty much guaranteed to eventually fail you when your attention moves on to something else.

let me leave you with one last thought. what if we told all those dieting girls that it's okay to eat when they're hungry? what if we taught them to work with their appetite instead of fearing it? i think most of them would be happier and healthier, and as adults, many of them would probably be thinner. i wish someone had told me that back when i was 13.

thanks.

(applause)

第4篇 ted英语演讲稿：为什么x代表未知？

i have the answer to a question that we've all asked. the question is, why is it that the letter x represents the unknown? now i know we learned that in math class, but now it's everywhere in the culture -- the x prize, the x-files, project x, tedx. where'd that come from?

about six years ago i decided that i would learn arabic, which turns out to be a supremely logical language. to write a word or a phrase or a sentence in arabic is like crafting an equation, because every part is extremely precise and carries a lot of information. that's one of the reasons so much of what we've come to think of as western science and mathematics and engineering was really worked out in the first few centuries of the common era by the persians and the arabs and the turks.

this includes the little system in arabic called al-jebra. and al-jebr roughly translates to "the system for reconciling disparate parts." al-jebr finally came into english as algebra. one example among many.

the arabic texts containing this mathematical wisdom finally made their way to europe -- which is to say spain -- in the 11th and 12th centuries. and when they arrived there was tremendous interest in translating this wisdom into a european language.

but there were problems. one problem is there are some sounds in arabic that just don't make it through a european voice box without lots of practice. trust me on that one. also, those very sounds tend not to be represented by the characters that are available in european languages.

here's one of the culprits. this is the letter sheen, and it makes the sound we think of as sh -- "sh." it's also the very first letter of the word shalan, which means "something" just like the the english word "something" -- some undefined, unknown thing.

now in arabic, we can make this definite by adding the definite article "al." so this is al-shalan -- the unknown thing. and this is a word that appears throughout early mathematics, such as this 10th century derivation of proofs.

the problem for the medieval spanish scholars who were tasked with translating this material is that the letter sheen and the word shalan can't be rendered into spanish because spanish doesn't have that sh, that "sh" sound. so by convention, they created a rule in which they borrowed the ck sound, "ck" sound, from the classical greek in the form of the letter kai.

later when this material was translated into a common european language, which is to say latin, they simply replaced the greek kai with the latin x. and once that happened, once this material was in latin, it formed the basis for mathematics textbooks for almost 600 years.

but now we have the answer to our question. why is it that x is the unknown? x is the unknown because you can't say "sh" in spanish. (laughter) and i thought that was worth sharing.

(applause)