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When McDonald's began advertising its $1 menu featuring the Big N' Tasty burger, some franchise owners were forced to sell them at a net loss; the popular item cost $1.07 to make. How could they afford to do this? Because McDonald's already knew you were going to buy fries and a Coke—products with big profit margins. It costs pennies to fill up a large drink, but you're charged more than a buck for it. This is a great deal for them and not such a great deal for us, but we can't help ourselves, because sugar lights up our brain's reward pathway.
Many recent neuroscience discoveries about food's effects on our brains and how we make decisions about food are actually gold-standard trade secrets from super chains such as McDonald's. With billions and billions served, they must be on to something.
1. Addictive properties of sugar
Nearly everything on McDonald's menu contains some sugar, from the drinks to the ketchup to the hamburger buns and fries. McDonald's knows that most people are going to shell out an extra dollar for a soft drink because sugar is addictive. Just as you can develop a physiological and psychological dependence on cocaine, you can become dependent on sugar.
Recent experiments have shown that sugar offers the hallmarks of addiction: bingeing, withdrawal and craving. Researchers kept rats from eating for 12 hours, then gave them unlimited access to food and sugar water for a brief period, and then took the food and sugar away again. They repeated this schedule for a few weeks. The rats formed a cycle of bingeing when given access to sugar, and over time they increased their intake to twice the amount from when they started. When the researchers stopped offering sugar or gave the rats an opioid blocker, which prevents the high by blocking some of the pleasurable effects in the brain, the rats showed signs of withdrawal, such as teeth-chattering and body tremors.
McDonald's recently added new menu items, including McCafe fruit smoothies, which pack in more sugar per serving than Coca-Cola. With that much sugar, McDonald's slogan is probably right: we're lovin' it.
2. The push of convenience
The fact that you can go to almost any city in the country and find a McDonald's within five minutes of driving contributes to the likelihood of compulsive eating. Similarly, recent epidemics of addiction to cocaine and heroin have accompanied increased availability and affordability of these drugs.
Part of the reason that convenience sways us so much is that we have a limited amount of impulse control. Some of us are better at resisting temptation, while some are more likely to give in. Dopamine activity in your nucleus accumbens, the brain's reward center, can disrupt your brain's decision making ability by interfering with your prefrontal cortex, the brain's impulse control region.
Dopamine has five unique types of receptors, numbered 1-5, but dopamine2 (D2) receptors seem to be most important for compulsive eating. Imaging studies show that for obese participants, fewer D2 receptors correspond to higher body-mass index. With fewer D2 receptors, they're more likely to eat compulsively; it becomes even harder to resist super-sizing their meal.
3. The brain's economy and the Value Meal
Low prices minimize the pain associated with parting with your hard-earned money. Decisions become difficult when two opposing forces try to sway you, in this case, spending money versus eating. The brain weights the costs and benefits of a decision in a region called the orbitofrontal cortex. Brain-imaging has shown that losing money can cause your brain to experience the same pattern of activity as when you stub your toe. Losing money hurts. Yet McDonald's manages to sidestep this problem by pricing a sandwich cheaper than the Sunday newspaper (which helps make up for the pain of your $40 filet mignon the night before). At McDonald's, you get the rewarding meal without the pain of losing money. They make the decision easy for your brain.
4. Our brains prefer high-calorie foods
As suggested by Jonah Lehrer in "The Frontal Cortex," our brains evolved during a time when food was scarce, so we became adept at choosing foods that packed calories.
In one recent experiment, scientists used genetically engineered mice that were missing sugar receptors and therefore unable to detect sweetness in food. The researchers then gave the mice free access to two water dispensers, one with sugar water and one with regular water. Initially, the mice showed no preference; sugar water tasted just like regular water. However, after several hours, the mice shifted to drinking almost exclusively from the sugar water dispenser. To ensure that the mice preferred the calories, but could not detect the taste, the researchers offered them water sweetened with sucralose (e.g. Splenda). The mice didn't take it.
When the scientists analyzed the mice brains, they found that the mice released dopamine in response to sugar water, even though they couldn't taste it, but not in response to regular water or sucralose. Our brains can tell the difference between high calorie foods and diet foods even if they taste the same.
5. Addictive properties of speed
Drugs have a hierarchy of addictive potential based on the speed that they reach your brain. Pills have to be swallowed, broken down in the stomach, pushed into the digestive tract and then absorbed into the blood stream before they can reach your brain. The reward you experience comes relatively long after you take the drug. Heroin skips the lag time; injecting it directly into your bloodstream sends it to your brain within seconds. The closer you can pair a stimulus with a reward, the stronger the association will be.
Similarly, fast food provides a quick fix for hunger. You don't even have to get out of your car to pick up a Big Mac. You place your order at the drive-thru and within two minutes you can take the first bite as you drive home. You can hardly get a pan hot enough to fry in that time. The sooner you have the burger in hand, the sooner it can trigger the release of the cocktail of rewarding chemicals in your brain.
6. Brains like branding
Just as Pavlov was able to get a dog to salivate at the sound of a bell, McDonald's gets your juices flowing anytime you hear their jingle. Pavlov showed that if he rang a bell before giving food to a dog, eventually the bell itself would whet its appetite.
Across the nation, McDonald's provides a consistent experience every time you enter its doors. The employees recite a scripted greeting, the menu looks the same, and the same images and logos are posted on the walls. The more consistent the experience, the more strongly your brain associates the Golden Arches with the meal that follows.
The brain's reward chemical is dopamine, a molecule that's released when you experience something you enjoy. However, one of the brilliant aspects of the brain is its ability to learn and make predictions about the world based on past experiences. When the brain learns that a certain cue is associated with a reward, dopamine neurons learn to fire whenever the cue appears, even before the reward is given. Dopamine does more than simply reward you; it also motivates you to seek the pleasure again. As soon as you see the cue, your brain begins to anticipate the reward. The anticipation is part of the pleasure. Would you like fries with that?
7. McNuggets stoke your memory
In a recent study, researchers gave children chicken nuggets in an unmarked container or in McNuggets packaging. Not surprisingly, kids preferred the ones that resembled a Happy Meal. Neuroscience research has shown that a big part of the pleasure of eating stems from memories tied to the food, not taste alone.
In a brain-imaging study of the Pepsi Challenge, Read Montague at Baylor College of Medicine first gave participants a blind taste test of Coca-Cola and Pepsi while in an MRI scanner. The subjects preferred Coca-Cola and Pepsi equally, and both of the sodas caused brain activity in the ventromedial prefrontal cortex, a region involved in pleasure and reward. However, when the subjects were told they were drinking Coke, they shifted their preference. Now, 75 percent preferred Coke. What's more, their brain activity changed. The hippocampus, the brain region crucial to memory formation, lit up with activity, suggesting that drinking Coca-Cola, rather than a generic soft-drink, stirs up your memories of Coca-Cola.
Similarly, eating a McNugget not only sates your appetite for chicken (and the glue that holds the McNugget together), it also reminds you of your childhood, the cool Transformers toy you got in your Happy Meal, and the first time you were big enough to order the 10-piece instead of the 4-piece.
參考譯文：
麥當勞開始了新的1美元食物宣傳攻勢，又大又美味的漢堡包引人駐足。這種大受歡迎的食物，平均制作成本就要1.07美元，一些加盟店主只能虧本出售。麥當勞會不會虧損呢？當然不會。因為麥當勞知道：人們買漢堡包的時候也會買上一杯可樂。這才是麥當勞的巨額利潤來源——一大杯可樂成本只需幾美分，麥當勞賣給你的價格卻不止1美元。麥當勞的如意算盤絕不可能讓我們占到便宜，問題是我們還是忍不住要光顧他們。這是為什么呢？答案就是麥當勞的讀心術——麥當勞知道你的腦子里想什么。
神經科學領域的很多新發現揭示了食物如何影響大腦、人如何選擇食物的奧秘。這些科學發現恰恰就是麥當勞等超級快餐連鎖如何盈利的商業機密。讓我們看看快餐業食物和服務背后的真相。
1 糖會成癮
麥當勞提供的幾乎所有食物都含糖——番茄醬、飲料、漢堡、薯條等等。麥當勞非常清楚，大多數人在麥當勞就餐時都會購買飲料，而喝含糖的飲料也會成癮。就像對可卡因產生心理依賴和軀體依賴，人也可以對糖產生依賴性。
最新研究發現小鼠對糖有各種成癮的表現：過度食用、戒斷和渴求。研究人員給小鼠禁食12小時后，在短時間內提供不限量的食物和糖水，然后撤走。研究人員重復這個周期幾周以后，小鼠在有糖水供應時會大飲特飲，每次的飲用量漸漸增加到開始時飲用量的兩倍。研究人員停止為小鼠提供糖水或給予阿片受體阻斷藥后，小鼠出現戒斷癥狀，如牙齒打顫、全身震顫。
麥當勞最近又推出一系列新的食物，其中麥咖啡水果沙冰的含糖量甚至超過可口可樂。原因可能真如麥當勞的宣傳語：我就喜歡！（I'm Lovin' it.）
2 便利讓人沖動
在美國所有城市，都能在5分鐘車程范圍內找到麥當勞餐廳。這很容易引起強迫性暴食。與之相似的情景是，最近可卡因、海洛因的出貨量增加、獲取方便，癮君子的數量隨之猛增。
便利讓人們動心的原因就是：人控制沖動的次數是有數量限制的。有人對誘惑有超強的抵抗力，也有人很容易就屈服，這種區別的根源應該歸因于大腦構造的區別。人腦中有個叫做伏隔核的部位，富含神經遞質多巴胺。伏隔核的功能是產生獎賞效應——這個腦區激動會帶給機體美好的感受和體驗。而伏隔核中多巴胺的作用也影響到負責控制沖動的前額葉皮層，人面對誘惑時的決斷力也因此被削弱了。
多巴胺受體有5種不同的類型。不過多巴胺2型受體（D2受體）似乎和強迫性暴食行為的關系最為密切。肥胖志愿者腦部成像的結果顯示：腦內D2受體越少，體重指數越高。腦內D2受體較少的人，也更容易出現強迫性暴食。
3 超值套餐和大腦經濟學
拱手送出辛苦掙來的錢固然讓人心痛，低價的誘惑又減輕了這種痛苦。這種情況下，金錢和美食委實難以選擇。人腦的前額皮質負責衡量付出和收益，大腦成像顯示：失去錢財時腦部活動的模式和被撞到腳趾時是一樣的。不過，麥當勞盡量避免受到人們這種心理活動的影響——他們把三明治的價格定得比一份周末報紙還便宜，甚至你前一天晚上為菲力牛排付出40美元造成的痛苦也會因此減輕。人們在麥當勞獲得的都是獎賞餐，毫無失去錢財的痛苦，這時大腦做出的決定一定是麥當勞喜歡的。
4 大腦喜歡高熱量食物
進化過程使大腦傾向于做出這樣的抉擇：食物匱乏的時候，我們優先選擇高熱量的食物。
最近科學家使用基因改造的小鼠進行了一項研究，這些小鼠對糖的味覺缺失，無法感受到食物中的甜味。小鼠可以自由使用兩個飲水機，一個飲水機中是糖水，另一個則裝著清水。最初，小鼠沒有表現出對哪種飲品的偏好，因為糖水對它們來說在口味上和清水毫無區別。不過，幾個小時之后，小鼠就幾乎只喝糖水了。為了驗證小鼠選擇糖水是因為糖水熱量高，而不是因為嘗到了甜味，研究人員又為小鼠準備了有甜味但低熱量的三氯蔗糖水。小鼠的選擇仍然是高熱量的糖水。
分析小鼠的大腦后發現，即使小鼠嘗不出糖水的甜味，糖水仍然能促進腦內釋放多巴胺；清水和三氯蔗糖水就沒這個效果。就算你的舌頭無法辨別高熱量食品和減肥食品有什么不同，你的大腦也有自己的判斷。
5 快捷也會成癮
毒品的成癮性和進入大腦的速度密切相關。食用的毒品需要先被吞下，在胃里分解，進入小腸，吸收進入血液，然后才能進入大腦，產生獎賞效應。海洛因就不需要費這么多周折，血管內注射幾秒鐘后就進入大腦。海洛因很容易讓人成癮的一個原因就是：刺激和獎賞越容易被聯系到一起，兩者之間的關系就越緊密。
同樣，快餐也能快捷地填飽你的肚子，激發大腦產生獎賞體驗。你甚至不需要停車就能拿到一個大漢堡；開車回家的路上經過穿梭餐廳2分鐘，你就可以大快朵頤。如果你自己下廚，這么點時間鍋還沒熱呢。麥當勞越快捷地把漢堡包交到你手上，你大腦里誘發獎賞體驗、讓你感覺愉快的化學物就釋放得越快。
6 大腦喜歡品牌攻勢
巴普洛夫在每次喂狗前搖鈴，一段時間之后，只搖鈴就能讓狗垂涎三尺，這就是著名的條件反射試驗。麥當勞當然也深諳此道。
所有的麥當勞給顧客的體驗都一樣——走進大門聽到千篇一律的員工問候，看到的菜單如出一轍，墻上的圖案和標志也是一模一樣。每次去麥當勞的體驗越是一致，大腦中食物和麥當勞之間的聯系就越強烈。
經歷愉快的體驗時，腦內會釋放和獎賞有關的化學物質——多巴胺。不過大腦的另一神奇之處是它能夠學習，并根據過去的經驗進行預測。如果大腦通過學習，在某些體驗和某種線索之間產生了關聯，只要這種線索出現，含有多巴胺的神經元就會興奮，不管令人愉快的體驗有沒有出現。此外，多巴胺不僅僅能激發獎賞體驗，還能促使人們再次尋求快感，期待也成了快感的一部分。你想吃薯條么？
7 麥樂雞勾起美好回憶
最近的一項研究中，研究人員給兒童準備了一些炸雞塊，其中一些是麥樂雞包裝的，另外一些則是沒有標識的。毫無意外，孩子們更喜歡前者——它們很像開心樂園餐中的雞塊。神經科學研究顯示，進食帶來的愉悅體驗不止來自唇舌的快感，還有很大一部分來自和食物有關的美好回憶。
2003年，百事可樂公司的“百事挑戰”系列營銷活動中有一個著名的試驗，研究人員請受試者品嘗兩種可樂，但不告訴他們哪種是可口可樂，哪種是百事可樂，同時利用功能性磁共振對受試者的大腦進行掃描。品嘗后，表示喜歡兩種可樂的人各占一半。功能性腦掃描結果顯示：兩種可樂都誘發大腦腹內側前額葉皮質的活動，這個活動和愉悅感和獎賞過程有關。在被告知喝的是哪種可樂的時候，受試者的喜好似乎發生了變化，認為可口可樂更好喝的人數比例增加到了75%。更重要的是，他們的大腦活動發生了明顯變化。除了前額葉皮質，和記憶密切相關的海馬區也同時興奮。這說明，可口可樂不同于普通的軟飲料，它能引起人的美好回憶。
同樣，麥樂雞不僅滿足了你對雞塊的食欲，是不是也讓你想起歡樂的童年時光，開心樂園套餐里超酷的變形金剛，還有長大后第一次買大盒麥樂雞的情景呢？
原文鏈接：7 Things McDonald’s Knows About Your Brain
