Social Proof
People look to others' behaviour when deciding, especially under uncertainty.
Definition
One of Robert Cialdini's principles of influence. In ambiguous situations people infer correct behaviour from what others are doing. The effect is strongest when the others are perceived as similar to the observer.
Established research. Originates in published research and has been replicated. The effect is real. Its size in your product still needs measuring.
On this page
Forms that carry weight, strongest first
- Specific reviews from people identifiably similar to the reader, including the negative ones.
- Concrete usage numbers with a real denominator.
- Named customers with a stated use case, rather than a wall of logos.
- Aggregate ratings with the distribution visible, not only the average.
- Expert or editorial endorsement, when the source is credible to that audience.
Negative reviews increase trust
Products with only five-star reviews are read as filtered. Showing the distribution, and letting users read the critical reviews, consistently improves conversion relative to hiding them, because it makes the positive reviews credible.
In practice
Reviews with visible distribution
EcommerceShowing the full star distribution and allowing users to filter to one-star reviews makes the average believable. Suppressing critical reviews makes the whole set suspect.
Named customers over logo walls
B2B marketingOne customer with a stated problem and outcome outperforms twenty logos, because the reader can judge whether that customer resembles them.
Sources
Where a source establishes something narrower than the popular reading of it, the note says so.
Influence: The Psychology of Persuasion
R. B. Cialdini, Harper Business, 1984, revised 2021
Continue from here
Each link says what the connection is, so you can tell a principle from an alternative from a thing people mix this up with.
Applies when you are designing
Check your work
Review passes that test whether this was done properly.
- Design Ethics ChecklistChecklist
- Ecommerce ChecklistChecklist
Related concept
Connected closely enough to change how you apply this.
- Authority BiasCognitive bias
- Framing EffectCognitive bias