Social Proof
Edited by Paweł Raja, PhD · Published · Updated
Definition
Social Proof is the phenomenon where people look to the behavior of others to guide their own decisions, especially in ambiguous situations.
Why it happens: the psychology of social proof
Social proof is the tendency to treat other people's behaviour as evidence of the right thing to do, especially when a situation is uncertain. Robert Cialdini popularised the term in Influence (1984), but the underlying mechanism was described decades earlier.
Deutsch and Gerard (1955) separated two reasons we follow others. Informational influence is copying because others probably know something we don't. Normative influence is copying to fit in and avoid disapproval. Social proof is mostly informational, which is why it is strongest when we are unsure.
Classic experiments show how strong the pull is. In Asch's conformity studies, participants often went along with a unanimous group that gave an obviously wrong answer about line lengths. In Milgram, Bickman and Berkowitz's (1969) street experiment, the more people stood looking up at a building, the more passers-by stopped and looked up too.
Social proof can backfire. Telling people what the average person does pulls everyone toward the average. In Schultz et al. (2007), households that used less energy than their neighbours increased their use after learning the neighbourhood norm, until an approving smiley face was added. Social proof is also different from pluralistic ignorance, where most people privately reject a norm but wrongly assume everyone else accepts it.
Social Proof examples
Reusing towels in hotel rooms increases significantly when guests are told '75% of guests in this room reused their towels'.
- A visible queue outside a restaurant attracts more diners, who read the line as a signal of quality.
- A checkout page showing 'booked 12 times today' nudges hesitant shoppers to commit.
How to design for it (nudge strategy)
Display real-time, localized statistics of popular choices (e.g., '9 out of 10 homeowners in your district have upgraded their insulation').
Ethical use: design for choices people would endorse on reflection — a nudge, not sludge. Be transparent and keep opting out easy.
The evidence (2)
- Increasing National Tax Compliance via Social Norms
Public Policy · Payment Rate within 23 Days: 67.5% → 83% (+15.5 pts) · n = 140,000 taxpayers
- Residential Energy Conservation via Neighbor Benchmarks
Energy · Percentage Household Energy Savings: 0.1% → 2.1% (+2.0 pts) · n = 600,000 households
Key studies
Distinguished informational from normative social influence.
Deutsch, M., & Gerard, H. B. (1955). A study of normative and informational social influences upon individual judgment. Journal of Abnormal and Social Psychology, 51(3), 629–636. DOI →
Participants frequently conformed to a unanimous but clearly wrong group judgment.
Asch, S. E. (1956). Studies of independence and conformity: I. A minority of one against a unanimous majority. Psychological Monographs, 70(9), 1–70. DOI →
Larger crowds looking up drew more passers-by to stop and look up.
Milgram, S., Bickman, L., & Berkowitz, L. (1969). Note on the drawing power of crowds of different size. Journal of Personality and Social Psychology, 13(2), 79–82. DOI →
Telling guests that most others reused their towels raised reuse above a standard environmental appeal, most of all when the norm referred to guests in the same room.
Goldstein, N. J., Cialdini, R. B., & Griskevicius, V. (2008). A room with a viewpoint: Using social norms to motivate environmental conservation in hotels. Journal of Consumer Research, 35(3), 472–482. DOI →
Descriptive norms made low energy users consume more (a 'boomerang'); adding an approving message prevented it.
Schultz, P. W., Nolan, J. M., Cialdini, R. B., Goldstein, N. J., & Griskevicius, V. (2007). The constructive, destructive, and reconstructive power of social norms. Psychological Science, 18(5), 429–434. DOI →
Students overestimated peers' comfort with campus drinking — pluralistic ignorance, a related but distinct phenomenon.
Prentice, D. A., & Miller, D. T. (1993). Pluralistic ignorance and alcohol use on campus. Journal of Personality and Social Psychology, 64(2), 243–256. DOI →
Key research
- Social Norms and Energy ConservationHunt Allcott · Journal of Public Economics (2011)
- The Behavioralist as Tax Collector: Using Natural Field Experiments to Enhance Tax ComplianceMichael Hallsworth, John A. List, Robert D. Metcalfe, Ivo Vlaev · Journal of Public Economics / NBER (2017)
- Misperceived Social Norms: Women Working Outside the Home in Saudi ArabiaLeonardo Bursztyn, Alessandra L. González, David Yanagizawa-Drott · American Economic Review / NBER (2020)
Related biases
Social Proof: frequently asked questions
What is social proof bias?
Social proof bias is the tendency to assume that what many other people are doing is correct, and to copy it, particularly when you are uncertain what to do.
What are examples of social proof?
Choosing the restaurant with a queue, buying the product marked 'bestseller', reusing hotel towels after learning most guests do, and paying tax on time after being told most people in your area already have.
Is social proof the same as the bandwagon effect or herd behavior?
They are closely related. Social proof is the psychological mechanism (others' behaviour as information); the bandwagon effect and herding describe the resulting pattern of many people converging on the same choice.
When does social proof backfire?
When the norm you publicise is undesirable ('many people don't pay on time') or when people who already do better than average learn the average and drift toward it. Pairing the norm with approval of the desired behaviour reduces this.
Cite this page
Behavioral Economics Lab. "Social Proof – Definition, Examples & Evidence." Behavioral Economics Lab, https://www.behavioraleconomicslab.com/biases/social-proof.