25%的人足以引發認識上的革命

戴維·努南

Social change—from evolving attitudes toward gender and marijuana to the rise of Donald Trump to the emergence of the Black Lives Matter and #MeToo movements2—is a constant3. It is also mysterious， or so it can seem. For example， “How exactly did we get here？” might be asked by anyone who lived through decades of fierce prohibition and now buys pot4 at one of the more than 2，000 licensed dispensaries across the U.S.

A new study about the power of committed minorities to shift conventional thinking offers some surprising possible answers. Published this week in Science5 the paper describes an online experiment in which researchers sought to determine what percentage of total population a minority needs to reach the critical mass necessary to reverse a majority viewpoint. The tipping point， they found， is just 25 percent. At and slightly above that level， contrarians6 were able to “convert” anywhere from 72 to 100 percent of the population of their respective groups. Prior to the efforts of the minority， the population had been in 100 percent agreement about their original position.

The experiment was designed and led by Damon Centola， associate professor in the Annenberg School of Communications at the University of Pennsylvania. It involved 194 people randomly assigned to 10 “independent online groups，” which varied in size from 20 to 30 people. In the first step group members were shown an image of a face and told to name it. They interacted with one another in rotating pairs until they all agreed on a name. In the second step Centola and his colleagues seeded each group with “a small number of confederates… who attempted to overturn the established convention （the agreed-on name） by advancing a novel alternative.”

For the second step， as Centola explains it， the researchers began with a 15 percent minority model and gradually increased it to 35 percent. Nothing changed at 15 percent， and the established norm remained in place all the way up to 24 percent.

The magic number， the tipping point， turned out to be 25 percent. Minority groups smaller than that converted， on average， just 6 percent of the population. Among other things， Centola says， that 25 percent figure refutes a century of economic theory. “The classic economic model—the main thing we are responding to with this study—basically says that once an equilibrium is established， in order to change it you need 51 percent. And what these results say is no， a small minority can be really effective， even when people resist the minority view.” The team’s computer modeling indicated a 25 percent minority would retain its power to reverse social convention for populations as large as 100，000.

But the proportion has to be just right： One of the groups in the study consisted of 20 members， with four contrarians. Another group had 20 members and five contrarians—and that one extra person made all the difference. “In the group with four， nothing happens，” Centola says， “and with five you get complete conversion to the alternative norm.” The five， neatly enough， represented 25 percent of the group population.

Real-life factors that can work against committed minorities—even when they reach or exceed critical mass—include a lack of interaction with other members， as well as competing committed minorities and what’s called “active resistance”—which pretty well describes the way many people in 2018 respond to political ideas with which they disagree. But even with such obstacles， Centola says the tipping point predicted in his model remains well below 50 percent.

Certain settings lend themselves to7 the group dynamics Centola describes in his study， and that includes the workplace. “Businesses are really great for this kind of thing，” he says， “because people in firms spend most of their day trying to coordinate with other people， and they exhibit the conventions that other people exhibit because they want to show that they’re good workers and members of the firm. So you can see very strong effects of a minority group committed to changing the culture of the population.”

The other environment in which the 25 percent effect is particularly evident， Centola says， is online—where people have large numbers of interactions with lots of other people， many of them strangers. This raises some tricky questions： Can a bot8 stand in for a member of a committed minority？ And can a committed minority be composed of bots and the real people the bots influence， so that bots are actually driving the change？ According to Centola， “In a space where people can’t distinguish people from bots， yes. If you get a concerted， focused effort by a group of agents acting as a minority view， they can be really effective.”

Yale sociologist Emily Erikson， who also studies social networks but was not involved with the study， sees the new paper partly as a warning. “In some sense it’s saying extreme voices can quickly take over public discourse，” she says. “Perhaps if we’re aware of that fact， we can guard against it.”

從對性別問題和對大麻的態度變化到特朗普崛起，乃至“黑命貴”運動和#MeToo反性侵運動，社會變化已成常態。社會變化也神秘莫測，或者說似乎如此。例如，幾十年間一直嚴禁大麻，而現在可以在分布于美國各地的2000多家特許藥房購買，任何經歷這一變化的人都可能會問：“我們到底是如何變成這樣的？”

有一項關于意志堅定的少數人具備改變傳統思維的新研究，可能提出了一些令人驚訝的答案。該研究發表在本周的《科學》雜志上。論文中描述了一次網絡實驗，在實驗中，研究人員力求確定少數人至少占總人群的多大比例就足以逆轉多數人觀點。他們發現，這個臨界點僅為25%。當持反對觀點者占或略高于總數的25%時，便能轉變他們各自小組中72%至100%的人的觀點。在少數人發揮影響力之前，小組成員百分之百認同他們原先的立場。

該實驗由賓夕法尼亞大學阿能伯格傳播學院副教授戴蒙·森托拉設計和主持。參與實驗的194人被隨機分成10個“獨立網絡小組”，各組人數為20至30人不等。實驗第一步，給各組成員看一張人臉，并要求他們為之取名;組內成員兩兩配對進行互動，然后輪換搭檔，直到全部成員達成共識。第二步，森托拉和同事們在每一組中植入“為數不多的同謀者……這些人提出一個新名字，以推翻小組既有的約定（即原已達成共識的名字）。”

森托拉解釋說，在第二步中，研究人員最初植入15%的少數人，然后逐漸增加到35%。少數人占15%時，情況毫無變化;直到比例升至24%，既有約定依然如故。

實驗發現，這個神奇的比例或臨界點是25%。少數人低于25%時，他們平均只能轉變6%的人。森托拉說，發現25%這個比例的價值之一是，它駁倒了一個歷時百年的經濟理論。“本研究主要針對一個古典經濟模型。該模型的基本論點是，均衡狀態一經形成，需要51%的反作用力才能將其改變。然而，這些實驗結果說明，事實并非如此。實際上，小比例的少數人也會起很大的作用，即使在人們抵制其觀點的情況下。”森托拉團隊的計算機模型表明，在多達10萬的人群中，25%的少數人仍具有逆轉社會常規的能力。

但這個比例必須恰到好處：參加此研究的一組有20名成員和4名持反對觀點者，另一組有20名成員和5名持反對觀點者，而正是那1人之差起了關鍵作用。森托拉說：“在有4名持反對觀點者的小組中，情況沒有變化;但有5名反對者時，所有成員都一致轉而同意反方觀點。”5這個數字，不多不少，恰好是小組人數的25%。

堅定的少數即使達到或超出臨界點，也有可能受阻于種種現實因素，包括缺乏與其他成員的互動、來自其他堅定少數派的競爭以及所謂的“積極抵制”因素（“積極抵制”很好地描述了2018年許多人面對他們不認同的政治觀念時的回應方式）。但森托拉認為，即使存在這些阻礙，他的模型所預測的臨界點仍然遠遠低于50%。

某些特定的環境易于發生森托拉在其研究中所描述的小組動態，例如職場。“企業就是很好的例子。”森托拉說，“公司員工一天中大部分時間都在努力與其他人協調。為了表明自己是公司的好員工、好成員，他們顯示出與公司其他人同樣的習慣。因此，努力想改變群體文化的少數派的影響會顯得特別強烈。”

森托拉說，網絡也是25%效應尤為明顯的環境。網上人與人之間有大量的互動，而且大多發生在陌生人之間。這就產生了一些棘手的問題：某個機器人會不會替代堅定少數派的某個成員？堅定的少數人會不會是由機器人和受機器人影響的真人組成，結果實際上是機器人在驅動改變？森托拉認為：“在人們無法區分真人與機器人的網絡空間里，答案是肯定的。如果你能讓一群代言者同心協力主張少數人的觀點，他們很可能會大有成效。”

同樣研究社交網絡但并未參與此項研究的耶魯大學社會學家埃米莉·埃里克松認為，這篇新論文在一定程度上是一個警告。她說：“在某種意義上，該論文在警示我們，極端的聲音可能會迅速取代公共話語。如果我們意識到這個事實，也許能夠防患于未然。”

（譯者單位：北京第二外國語學院）