Asch’s Conformity Experiment

Solomon Asch, with ex­per­i­ments origi­nally car­ried out in the 1950s and well-repli­cated since, high­lighted a phe­nomenon now known as “con­for­mity.” In the clas­sic ex­per­i­ment, a sub­ject sees a puz­zle like the one in the nearby di­a­gram: Which of the lines A, B, and C is the same size as the line X? Take a mo­ment to de­ter­mine your own an­swer . . .


The gotcha is that the sub­ject is seated alongside a num­ber of other peo­ple look­ing at the di­a­gram—seem­ingly other sub­jects, ac­tu­ally con­fed­er­ates of the ex­per­i­menter. The other “sub­jects” in the ex­per­i­ment, one af­ter the other, say that line C seems to be the same size as X. The real sub­ject is seated next-to-last. How many peo­ple, placed in this situ­a­tion, would say “C”—giv­ing an ob­vi­ously in­cor­rect an­swer that agrees with the unan­i­mous an­swer of the other sub­jects? What do you think the per­centage would be?

Three-quar­ters of the sub­jects in Asch’s ex­per­i­ment gave a “con­form­ing” an­swer at least once. A third of the sub­jects con­formed more than half the time.

In­ter­views af­ter the ex­per­i­ment showed that while most sub­jects claimed to have not re­ally be­lieved their con­form­ing an­swers, some said they’d re­ally thought that the con­form­ing op­tion was the cor­rect one.

Asch was dis­turbed by these re­sults:1

That we have found the ten­dency to con­for­mity in our so­ciety so strong . . . is a mat­ter of con­cern. It raises ques­tions about our ways of ed­u­ca­tion and about the val­ues that guide our con­duct.

It is not a triv­ial ques­tion whether the sub­jects of Asch’s ex­per­i­ments be­haved ir­ra­tionally. Robert Au­mann’s Agree­ment The­o­rem shows that hon­est Bayesi­ans can­not agree to dis­agree—if they have com­mon knowl­edge of their prob­a­bil­ity es­ti­mates, they have the same prob­a­bil­ity es­ti­mate. Au­mann’s Agree­ment The­o­rem was proved more than twenty years af­ter Asch’s ex­per­i­ments, but it only for­mal­izes and strength­ens an in­tu­itively ob­vi­ous point—other peo­ple’s be­liefs are of­ten le­gi­t­i­mate ev­i­dence.

If you were look­ing at a di­a­gram like the one above, but you knew for a fact that the other peo­ple in the ex­per­i­ment were hon­est and see­ing the same di­a­gram as you, and three other peo­ple said that C was the same size as X, then what are the odds that only you are the one who’s right? I lay claim to no ad­van­tage of vi­sual rea­son­ing—I don’t think I’m bet­ter than an av­er­age hu­man at judg­ing whether two lines are the same size. In terms of in­di­vi­d­ual ra­tio­nal­ity, I hope I would no­tice my own se­vere con­fu­sion and then as­sign >50% prob­a­bil­ity to the ma­jor­ity vote.

In terms of group ra­tio­nal­ity, seems to me that the proper thing for an hon­est ra­tio­nal­ist to say is, “How sur­pris­ing, it looks to me like B is the same size as X. But if we’re all look­ing at the same di­a­gram and re­port­ing hon­estly, I have no rea­son to be­lieve that my as­sess­ment is bet­ter than yours.” The last sen­tence is im­por­tant—it’s a much weaker claim of dis­agree­ment than, “Oh, I see the op­ti­cal illu­sion—I un­der­stand why you think it’s C, of course, but the real an­swer is B.”

So the con­form­ing sub­jects in these ex­per­i­ments are not au­to­mat­i­cally con­victed of ir­ra­tional­ity, based on what I’ve de­scribed so far. But as you might ex­pect, the devil is in the de­tails of the ex­per­i­men­tal re­sults. Ac­cord­ing to a meta-anal­y­sis of over a hun­dred repli­ca­tions by Smith and Bond . . . 2

. . . Con­for­mity in­creases strongly up to 3 con­fed­er­ates, but doesn’t in­crease fur­ther up to 10–15 con­fed­er­ates. If peo­ple are con­form­ing ra­tio­nally, then the opinion of 15 other sub­jects should be sub­stan­tially stronger ev­i­dence than the opinion of 3 other sub­jects.

Ad­ding a sin­gle dis­sen­ter—just one other per­son who gives the cor­rect an­swer, or even an in­cor­rect an­swer that’s differ­ent from the group’s in­cor­rect an­swer—re­duces con­for­mity very sharply, down to 5–10% of sub­jects. If you’re ap­ply­ing some in­tu­itive ver­sion of Au­mann’s Agree­ment to think that when 1 per­son dis­agrees with 3 peo­ple, the 3 are prob­a­bly right, then in most cases you should be equally will­ing to think that 2 peo­ple will dis­agree with 6 peo­ple.3 On the other hand, if you’ve got peo­ple who are emo­tion­ally ner­vous about be­ing the odd one out, then it’s easy to see how adding a sin­gle other per­son who agrees with you, or even adding a sin­gle other per­son who dis­agrees with the group, would make you much less ner­vous.

Un­sur­pris­ingly, sub­jects in the one-dis­sen­ter con­di­tion did not think their non­con­for­mity had been in­fluenced or en­abled by the dis­sen­ter. Like the 90% of drivers who think they’re above-av­er­age in the top 50%, some of them may be right about this, but not all. Peo­ple are not self-aware of the causes of their con­for­mity or dis­sent, which weighs against any at­tempts to ar­gue that the pat­terns of con­for­mity are ra­tio­nal.4

When the sin­gle dis­sen­ter sud­denly switched to con­form­ing to the group, sub­jects’ con­for­mity rates went back up to just as high as in the no-dis­sen­ter con­di­tion. Be­ing the first dis­sen­ter is a valuable (and costly!) so­cial ser­vice, but you’ve got to keep it up.

Con­sis­tently within and across ex­per­i­ments, all-fe­male groups (a fe­male sub­ject alongside fe­male con­fed­er­ates) con­form sig­nifi­cantly more of­ten than all-male groups. Around one-half the women con­form more than half the time, ver­sus a third of the men. If you ar­gue that the av­er­age sub­ject is ra­tio­nal, then ap­par­ently women are too agree­able and men are too dis­agree­able, so nei­ther group is ac­tu­ally ra­tio­nal . . .

In­group-out­group ma­nipu­la­tions (e.g., a hand­i­capped sub­ject alongside other hand­i­capped sub­jects) similarly show that con­for­mity is sig­nifi­cantly higher among mem­bers of an in­group.

Con­for­mity is lower in the case of blatant di­a­grams, like the one at the be­gin­ning of this es­say, ver­sus di­a­grams where the er­rors are more sub­tle. This is hard to ex­plain if (all) the sub­jects are mak­ing a so­cially ra­tio­nal de­ci­sion to avoid stick­ing out.

Fi­nally, Paul Crowley re­minds me to note that when sub­jects can re­spond in a way that will not be seen by the group, con­for­mity also drops, which also ar­gues against an Au­mann in­ter­pre­ta­tion.

1Solomon E. Asch, “Stud­ies of In­de­pen­dence and Con­for­mity: A Minor­ity of One Against a Unan­i­mous Ma­jor­ity,” Psy­cholog­i­cal Mono­graphs 70 (1956).

2Rod Bond and Peter B. Smith, “Cul­ture and Con­for­mity: A Meta-Anal­y­sis of Stud­ies Us­ing Asch’s (1952b, 1956) Line Judg­ment Task,” Psy­cholog­i­cal Bul­letin 119 (1996): 111–137.

3This isn’t au­to­mat­i­cally true, but it’s true ce­teris paribus.

4For ex­am­ple, in the hy­poth­e­sis that peo­ple are so­cially-ra­tio­nally choos­ing to lie in or­der to not stick out, it ap­pears that (at least some) sub­jects in the one-dis­sen­ter con­di­tion do not con­sciously an­ti­ci­pate the “con­scious strat­egy” they would em­ploy when faced with unan­i­mous op­po­si­tion.