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Social proof
People’s tendency is to regard the behaviour of others as the most appropriate way to act, especially in ambiguous situations.
A real social number helps. An invented one destroys trust in the rest of the screen.
When unsure how to act, we look at what others have done. Robert Robert CialdiniSystematised the principles of influence — social proof, scarcity, reciprocity — which this catalogue treats as tool and as risk.One reference in this work:2001Influence: science and practiceSee on Wikipedia ↗See in the bibliography → studied this principle for decades, and the detail he found is the most useful one: the more the reference resembles you, the more it weighs. In an interface, that separates the number that helps from the number that decorates. “12,000 customers” says little, “used by teams your size” says a lot.
What the brain does with it
The biological mechanism behind the effect, and how much of it was actually measured.
Faced with uncertainty, we look at what others do, and deviation from the group’s opinion is treated by the brain as an error to be corrected. KlucharevMeasured, in the Netherlands, the brain signal that appears when the person’s opinion diverges from the group’s. It is the basis of Social proof.One reference in this work:2009Reinforcement learning signal predicts social conformitySee in the bibliography → and colleagues measured exactly that: people who disagreed with the group produced, in the ventral striatumPart of the reward circuit that tallies gain and loss. It reacts more strongly to losing than to gaining the same amount — the asymmetry behind a good part of the decision biases in this catalogue.See in the glossary →, a signal with the signature of a reward prediction error, the same kind of signal that appears when something turns out worse than expected. And its intensity predicted how much the person would change their opinion afterwards. Disagreeing with the group is registered as a mistake to be corrected, and the size of the record says the size of the correction.
The body this law presumes
Who it was measured on, and what changes when the body on the other side is another.
Klucharev and colleagues measured the mechanism in 2009, in Nijmegen, with twenty-four women judging the attractiveness of women’s faces. The question that remains is whether the size of the effect travels. BondPooled 133 conformity experiments in 17 countries and measured how much culture changes the effect. Brazil is among the high-conformity ones.One reference in this work:1996Culture and conformity: a meta-analysis of studies using Asch’s (1952b, 1956) line judgmen…See in the bibliography → and Smith gathered 133 conformity experiments run in 17 countries and found that it does not: collectivist cultures yield to the majority more than individualist ones, and the difference is large, Fiji and Hong Kong at the top, France and the Netherlands at the bottom. Brazil is among the high-conformity ones, which matters for whoever designs from here.
How design translates it
What to do with it on a screen, without turning a finding into a rule.
How to measure this in your product
Download counts, ratings, comments and “best seller” badges are the direct application, and resemblance to the reader is what separates the number that helps from the one that decorates. Used responsibly, social proof increases trust and reduces the friction of the decision; and since it only works when the number is believed, an invented number does not bring down only its own credibility, it brings down that of everything else on the screen.
Onde vira manipulação
The same lever, pointed at the person on the other side.
Fabricated conformity metrics, such as inflated data and fake reviews, trigger imitative behaviour out of anxiety about exclusion. The ethical practice is to present real social data relevant to the user’s context.
Where it breaks
Where the law does not hold, holds less, or holds in reverse.
Social proof weighs more when the person does not know what to do, but it does not vanish when they do. AschOne reference in this work:1956Studies of independence and conformity: ISee in the bibliography → set up the task with no ambiguity at all, comparing lines of obvious length, and a third of the critical answers still followed the wrong majority. Ambiguity regulates how much the other serves as information, and what is left after that is not wanting to stand out, which works with the answer staring you in the face. Bond and Smith measured conformity across several cultures and the effect varies a lot, being stronger in collectivist cultures and falling over the decades in the United States. And the reverse breaks badly, because a low social number displayed prominently is social proof against you.
Um caso
A real product where this showed up, with what happened and where to check it.
The number that convinces is not the biggest
GoldsteinRan the hotel towel experiment, which shows that the social norm works better the closer the group cited.One reference in this work:2008A room with a viewpoint: using social norms to motivate environmental conservation in hotelsSee in the bibliography →, Cialdini and Griskevicius swapped the little card asking guests to reuse their towel, in hotel rooms, and went to measure what happened to the towels. The standard card appealed to the environment. A second said that most guests of that hotel reused theirs, and a third, that most guests of that very room did. The closest group is also the smallest, and it was the one that convinced most. On a screen the criterion is the same, closeness to the reader and not the size of the number. The invented figure is tempting here and costly when discovered, because social proof is the only lever on the screen that, once disproved, contaminates everything written around it.
Goldstein; Cialdini; Griskevicius, 2008
Neighbouring concepts
Structures measured in this very phenomenon
- ventral striatum
Sibling concepts
Fontes
Enunciado citado de Cialdini, 2001.
- CIALDINI, R. Influence: science and practice. 4. ed. Boston: Allyn & Bacon, 2001. Source
- GOLDSTEIN, N. J.; CIALDINI, R. B.; GRISKEVICIUS, V. A room with a viewpoint: using social norms to motivate environmental conservation in hotels. Journal of Consumer Research, v. 35, n. 3, p. 472-482, 2008. DOI
Leitura complementar: Social Proof in UX NN/g em inglês