TED日本語 - キース・チェン: 言語が貯蓄能力に与える影響


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TED日本語 - キース・チェン: 言語が貯蓄能力に与える影響

TED Talks


Could your language affect your ability to save money?


Keith Chen


経済学者が言語学の分野から学べることとは?行動経済学者キース・チェンが自身の研究から見出した興味深いパターンを紹介します。未来の概念のない言語(It will rain tomorrow ではなく It rain tomorrow が許容される言語)と高い貯蓄率の間には強い相関関係があるのです。


The global economic financial crisis has reignited public interest in something that's actually one of the oldest questions in economics, dating back to at least before Adam Smith. And that is, why is it that countries with seemingly similar economies and institutions can display radically different savings behavior?

Now, many brilliant economists have spent their entire lives working on this question, and as a field we've made a tremendous amount of headway and we understand a lot about this. What I'm here to talk with you about today is an intriguing new hypothesis and some surprisingly powerful new findings that I've been working on about the link between the structure of the language you speak and how you find yourself with the propensity to save. Let me tell you a little bit about savings rates, a little bit about language, and then I'll draw that connection.

Let's start by thinking about the member countries of the OECD, or the Organization of Economic Cooperation and Development. OECD countries, by and large, you should think about these as the richest, most industrialized countries in the world. And by joining the OECD, they were affirming a common commitment to democracy, open markets and free trade. Despite all of these similarities, we see huge differences in savings behavior.

So all the way over on the left of this graph, what you see is many OECD countries saving over a quarter of their GDP every year, and some OECD countries saving over a third of their GDP per year. Holding down the right flank of the OECD, all the way on the other side, is Greece. And what you can see is that over the last 25 years, Greece has barely managed to save more than 10 percent of their GDP. It should be noted, of course, that the United States and the U.K. are the next in line.

Now that we see these huge differences in savings rates, how is it possible that language might have something to do with these differences? Let me tell you a little bit about how languages fundamentally differ. Linguists and cognitive scientists have been exploring this question for many years now. And then I'll draw the connection between these two behaviors.

Many of you have probably already noticed that I'm Chinese. I grew up in the Midwest of the United States. And something I realized quite early on was that the Chinese language forced me to speak about and -- in fact, more fundamentally than that -- ever so slightly forced me to think about family in very different ways.

Now, how might that be? Let me give you an example. Suppose I were talking with you and I was introducing you to my uncle. You understood exactly what I just said in English. If we were speaking Mandarin Chinese with each other, though, I wouldn't have that luxury. I wouldn't have been able to convey so little information. What my language would have forced me to do, instead of just telling you, "This is my uncle," is to tell you a tremendous amount of additional information. My language would force me to tell you whether or not this was an uncle on my mother's side or my father's side, whether this was an uncle by marriage or by birth, and if this man was my father's brother, whether he was older than or younger than my father. All of this information is obligatory. Chinese doesn't let me ignore it. And in fact, if I want to speak correctly, Chinese forces me to constantly think about it.

Now, that fascinated me endlessly as a child, but what fascinates me even more today as an economist is that some of these same differences carry through to how languages speak about time. So for example, if I'm speaking in English, I have to speak grammatically differently if I'm talking about past rain, "It rained yesterday," current rain, "It is raining now," or future rain, "It will rain tomorrow." Notice that English requires a lot more information with respect to the timing of events. Why? Because I have to consider that and I have to modify what I'm saying to say, "It will rain," or "It's going to rain." It's simply not permissible in English to say, "It rain tomorrow."

In contrast to that, that's almost exactly what you would say in Chinese. A Chinese speaker can basically say something that sounds very strange to an English speaker's ears. They can say, "Yesterday it rain," "Now it rain," "Tomorrow it rain." In some deep sense, Chinese doesn't divide up the time spectrum in the same way that English forces us to constantly do in order to speak correctly.

Is this difference in languages only between very, very distantly related languages, like English and Chinese? Actually, no. So many of you know, in this room, that English is a Germanic language. What you may not have realized is that English is actually an outlier. It is the only Germanic language that requires this. For example, most other Germanic language speakers feel completely comfortable talking about rain tomorrow by saying, "Morgen regnet es," quite literally to an English ear, "It rain tomorrow."

This led me, as a behavioral economist, to an intriguing hypothesis. Could how you speak about time, could how your language forces you to think about time, affect your propensity to behave across time? You speak English, a futured language. And what that means is that every time you discuss the future, or any kind of a future event, grammatically you're forced to cleave that from the present and treat it as if it's something viscerally different. Now suppose that that visceral difference makes you subtly dissociate the future from the present every time you speak. If that's true and it makes the future feel like something more distant and more different from the present, that's going to make it harder to save. If, on the other hand, you speak a futureless language, the present and the future, you speak about them identically. If that subtly nudges you to feel about them identically, that's going to make it easier to save.

Now this is a fanciful theory. I'm a professor, I get paid to have fanciful theories. But how would you actually go about testing such a theory? Well, what I did with that was to access the linguistics literature. And interestingly enough, there are pockets of futureless language speakers situated all over the world. This is a pocket of futureless language speakers in Northern Europe. Interestingly enough, when you start to crank the data, these pockets of futureless language speakers all around the world turn out to be, by and large, some of the world's best savers.

Just to give you a hint of that, let's look back at that OECD graph that we were talking about. What you see is that these bars are systematically taller and systematically shifted to the left compared to these bars which are the members of the OECD that speak futured languages. What is the average difference here? Five percentage points of your GDP saved per year. Over 25 years that has huge long-run effects on the wealth of your nation.

Now while these findings are suggestive, countries can be different in so many different ways that it's very, very difficult sometimes to account for all of these possible differences. What I'm going to show you, though, is something that I've been engaging in for a year, which is trying to gather all of the largest datasets that we have access to as economists, and I'm going to try and strip away all of those possible differences, hoping to get this relationship to break. And just in summary, no matter how far I push this, I can't get it to break. Let me show you how far you can do that.

One way to imagine that is I gather large datasets from around the world. So for example, there is the Survey of Health, [ Aging ] and Retirement in Europe. From this dataset you actually learn that retired European families are extremely patient with survey takers. (Laughter) So imagine that you're a retired household in Belgium and someone comes to your front door. "Excuse me, would you mind if I peruse your stock portfolio? Do you happen to know how much your house is worth? Do you mind telling me? Would you happen to have a hallway that's more than 10 meters long? If you do, would you mind if I timed how long it took you to walk down that hallway? Would you mind squeezing as hard as you can, in your dominant hand, this device so I can measure your grip strength? How about blowing into this tube so I can measure your lung capacity?" The survey takes over a day. (Laughter) Combine that with a Demographic and Health Survey collected by USAID in developing countries in Africa, for example, which that survey actually can go so far as to directly measure the HIV status of families living in, for example, rural Nigeria. Combine that with a world value survey, which measures the political opinions and, fortunately for me, the savings behaviors of millions of families in hundreds of countries around the world.

Take all of that data, combine it, and this map is what you get. What you find is nine countries around the world that have significant native populations which speak both futureless and futured languages. And what I'm going to do is form statistical matched pairs between families that are nearly identical on every dimension that I can measure, and then I'm going to explore whether or not the link between language and savings holds even after controlling for all of these levels.

What are the characteristics we can control for? Well I'm going to match families on country of birth and residence, the demographics -- what sex, their age -- their income level within their own country, their educational achievement, a lot about their family structure. It turns out there are six different ways to be married in Europe. And most granularly, I break them down by religion where there are 72 categories of religions in the world -- so an extreme level of granularity. There are 1.4 billion different ways that a family can find itself.

Now effectively everything I'm going to tell you from now on is only comparing these basically nearly identical families. It's getting as close as possible to the thought experiment of finding two families both of whom live in Brussels who are identical on every single one of these dimensions, but one of whom speaks Flemish and one of whom speaks French; or two families that live in a rural district in Nigeria,one of whom speaks Hausa and one of whom speaks Igbo.

Now even after all of this granular level of control, do futureless language speakers seem to save more? Yes, futureless language speakers, even after this level of control, are 30 percent more likely to report having saved in any given year. Does this have cumulative effects? Yes, by the time they retire, futureless language speakers, holding constant their income, are going to retire with 25 percent more in savings.

Can we push this data even further? Yes, because I just told you, we actually collect a lot of health data as economists. Now how can we think about health behaviors to think about savings? Well, think about smoking, for example. Smoking is in some deep sense negative savings. If savings is current pain in exchange for future pleasure, smoking is just the opposite. It's current pleasure in exchange for future pain. What we should expect then is the opposite effect. And that's exactly what we find. Futureless language speakers are 20 to 24 percent less likely to be smoking at any given point in time compared to identical families, and they're going to be 13 to 17 percent less likely to be obese by the time they retire, and they're going to report being 21 percent more likely to have used a condom in their last sexual encounter. I could go on and on with the list of differences that you can find. It's almost impossible not to find a savings behavior for which this strong effect isn't present.

My linguistics and economics colleagues at Yale and I are just starting to do this work and really explore and understand the ways that these subtle nudges cause us to think more or less about the future every single time we speak. Ultimately, the goal, once we understand how these subtle effects can change our decision making, we want to be able to provide people tools so that they can consciously make themselves better savers and more conscious investors in their own future.

Thank you very much.


世界的な金融危機を受けてまた関心を集めていることがあります 経済学においては最も古く少なくとも ― アダム・スミス以前から続く問いです 「経済活動や制度が類似する国々で貯蓄行動が大いに異なるのは何故か」

聡明な経済学者たちが一生をかけ答えを追求してきました その甲斐あって議論は大きく前進してきましたし 多くのことが明らかになりました 今日ご紹介するのは私が研究している新たな仮説と 言語の構造と貯蓄傾向の関連性についての 驚くほど大きな新発見です 貯蓄率や言語について簡単に説明した後 その 関連性を紐解いていきます

まずは OECD経済協力開発機構の ― 加盟国について考えてみましょう OECD諸国は概して裕福な先進工業国と言えるでしょう また OECDに加盟する以上民主主義や自由市場 ― 自由貿易に取り組むという意思を表明しています こうした共通点はありますが貯蓄傾向は大きく異なっています

このグラフの左の方をご覧いただくと 多くのOECD諸国では毎年GDPの4分の1以上を貯蓄しています 3分の1以上を貯蓄に回している国もあります 反対側を見ていくと右端はギリシャです ここ25年以上ギリシャの貯蓄率は 辛うじてGDPの10%を越える程度で推移してます もちろんアメリカとイギリスがそのすぐ隣にいることも見逃せません

さて こうした貯蓄率における違いに 言語が関係している可能性があるのでしょうか 言語間には根本的な相違があり ― その相違点について 言語学者や認知科学者が研究を重ねてきました このことが後で貯蓄の話に関連してきます

お気づきかと思いますが私は中国人です アメリカの中西部で育ちました 幼少期にあることに気付いたんです 中国語で家族のことを話そうとすると そもそも思考の段階から 英語とは違うのだということです

具体的な例を挙げますね 例えば 皆さんを私の「おじ」に紹介するとしましょう 英語では "uncle" で問題ありませんね しかし これが中国語だと そう簡単には済みません 情報が足りないのです 中国語では「おじ」に 膨大な情報を付与しなければ 何を言っているか伝わらないのです 「おじ」と言っても それが母方なのか 父方なのか 血縁なのか 姻戚なのか 父方であれば 父の兄なのか 弟なのか これらは全て中国語では無視できない必須項目です 中国語で正確に話そうとすると このような事を考えざるを得ないのです

私はこういうことで延々と楽しめる子でしたが 今日 経済学者として私が心をつかまれるのは 「時」についても言語間で同様の相違があるという点です 例えば 英語を話す場合には文法に違いが出ます 過去なら"It rained yesterday" 現在ならば"It is raining now" 未来は"It will rain tomorrow" 英語では事象のタイミングについて情報が不可欠です いつ言うかによって 未来形に変える必要が出てくるのです "It rain tomorrow" は英語では許されません

ところが中国語ではそれでいいのです 英語では奇妙でも 中国語なら大丈夫です 過去でも現在でも未来でも"It rain" と言って構いません つまり中国語には英語のような時制の区切りがないのです

英語と中国語の関係が特別に薄いせいでしょうか? 違います ご存じのとおり英語はゲルマン語派ですが 実は英語には例外的な特徴があります ゲルマン語派で時制があるのは英語だけです 英語以外のゲルマン語派では 明日の雨について"Morgen regnet es" つまり ― "It rain tomorrow" と言って差し支えありません

行動経済学者である私はある面白い仮説を思いつきました 「時」についての捉え方や言語的な制約が いつの間にか 行動傾向にも影響しているのではないか? 英語には未来形がありますから 皆さんが英語で将来について話す場合には 文法的に現在から切り離す必要があり 直感的に遠いものと見なします その遠いものという感覚が 英語を使うたびに現在と将来を切り離していくとすると 将来というものは 現在から遠く離れたものに感じられ 貯蓄する気が薄れます 未来形のない言語では 現在と未来が一体化しています 日頃から現在と未来を同一視していると 貯蓄する気になりやすいのです

これは突飛な理論ですが 私は大学教授なのでこれも仕事のうちです 実際に理論を検証する方法を考え 言語学の文献を当たりました 面白いことに 世界には未来形のない言語を話す地域が 固まって存在しているのです 北欧のこの地域の言語には未来の概念がありません 面白いことに データを見ていくと 未来の概念のない言語を話す人々と 高額の貯蓄を持つ人々がほぼ一致することがわかりました

ヒントはこれです 先程のOECDのグラフに戻りましょう 貯蓄率の高い国は体系的に左に寄っています 未来形のある言語を話す国と比べると こうです 平均差を求めてみると 貯蓄率の違いは年間でGDPの5%ずつなので 25年経てば国の資産に莫大な影響を与えることになります

何か関係ありそうな気配ですが 国ごとの違いというのは 内容が多岐に渡りますから一概には言えません そこで 私がここ1年研究してきたことをご紹介します 経済学者の持てるありとあらゆるデータを駆使し 国ごとの違いを極力排除して 相関関係はないと証明したいのですが 結論から言って相関を認めざるを得ません 検証過程を説明しましょう

たとえば世界中から大量のデータを集めます 「欧州における健康・加齢・退職の調査」を見ると ヨーロッパの退職者世帯はこのような調査に対し ― 非常に忍耐強いことがわかります (笑) 退職してベルギーに家を構えたとします誰かが訪ねてきて 「すみません持ち株の明細を見せてもらえませんか? お宅の価格をご存じですか?教えてもらえます? 10メートル以上の廊下はありますか? その廊下をあなたが何秒で歩くか計ってもいいですか? 利き手でこの装置を思いっきり握ってもらえますか? 握力を測りますから このチューブに息を吹き込んでください肺活量を測ります」 調査は一日以上を続きます (笑) さらにUSAIDによるアフリカの途上国の ― 「人口保健調査」も資料に加えます たとえばナイジェリアの農村部の世帯のHIV感染状況まで 調べているような資料です 「世界価値観調査」も使えます 世界のあらゆる国で何百万もの世帯の政治的見解や ― ラッキーなことに貯蓄行動まで調べてある資料です

そうしたデータを全て組み合わせるとこうなります ご覧の9カ国では ― 未来形のある言語とない言語その両方が使われています ここから 評価が可能な条件について 類似するデータを組み合わせて統計分析のためにペアを作ります 条件を揃えた上で言語と貯蓄率の間に 関連性があるかどうか調べるというわけです

コントロールできる特性は 生まれ育った国 性別や年齢などの属性 各国の基準で見た所得レベル 学歴や家族構成の詳細です 欧州では結婚の形態だけで6種類もありますから さらに 宗教によって細分化しました 世界には72の宗教分類がありますから 非常に細かくなりますね 世帯ごとの属性は全部で14億種類に分類されます

ここでは 特性が類似する世帯を抽出し 比較した内容だけを抜粋してお話します ほとんど思考実験のようなものです 言語以外の属性が全て共通する ― ブリュッセル在住の2世帯で 一方はフレミッシュ語他方はフランス語 あるいはナイジェリアの農村部の2世帯で 一方はハウサ語他方はイボ語という具合です

このように細かく条件を絞り込んで分析した場合 未来形のない言語話者の方が貯蓄が多いか? その通り 任意の年に「貯蓄した」と回答する確率は 未来形のない言語を話す人の方が30%高いのです 累積効果も見られます 未来形のない言語を話す人々は退職までに所得を継続的に貯蓄し 退職時点での貯蓄は25%多くなっています

さらに掘り下げてみましょう せっかく健康に関するデータが手元にありますから 貯蓄のことを念頭において健康面でどうしているか たとえば喫煙について見てみましょう 喫煙は ある意味マイナスの貯蓄です 貯蓄は「将来の喜び」と引き換えの「現在の苦しみ」 喫煙は逆です 「将来の苦しみ」に変わる「現在の喜び」 それなら効果も逆になりそうですよね 実際その通りでした 未来形のない言語を話す人はそうでない人と比べ どの時期においても約20~24%喫煙率が低く 退職までに肥満になる確率も 13~17%低く 最近のセックスでコンドームを使った割合は21%高いという結果でした こうした数値的な差は枚挙に暇がありません 強い統計的効果なくして貯蓄行動なしと言っても 過言ではないでしょう

言語学者で経済学者でもあるイェール大学の仲間と共に 言語を使うたび 将来の捉え方に知らず知らずのうちに影響を及ぼす ― その仕組みを解明すべく本格的に研究を始めました 最終的な目標としては 小さな効果の積み重ねが意思決定を変える仕組みを解明し 皆さんがより意識的に貯蓄に励み 将来に向け有効な投資ができるよう 役に立つツールを提供したいと考えています



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