Psychology · Sp
Social
proof.
Social proof is our habit of copying what other people do, especially when we're unsure. The research says the details matter: proof from people like the buyer, in the same situation, works far better than general praise or big numbers.
Written by Dan Picken, a marketer applying published research. Last checked 27 October 2026.From the hotel towel study. Bars show the order of the results, not exact sizes.
What the
research says.
Evidence: StrongReviews and ratings have strong evidence. The famous 'people like you' sign effects are less consistent than marketing books suggest, so test them.
In a well-known hotel study, guests reused their towels more when the sign said most guests did, compared with the usual environmental message. In that original study, they reused them most of all when the sign said guests who had stayed in that same room did.
The lesson for marketing isn't 'show more reviews'. It's 'show proof from people the buyer sees as like themselves'. A review from someone in the same suburb, or the same kind of business, does more than a thousand anonymous stars.
A later replication is worth knowing about. Bohner and Schlüter repeated the towel study in German hotels and found the descriptive-norm message worked no better than the standard environmental message, and the same-room effect was inconsistent. Both messages beat no message at all.
Reviews themselves have stronger evidence. Northwestern's Spiegel Research Center found a product with five reviews was 270% more likely to be bought than one with none, with the effect bigger for higher-priced products. Buying odds peaked between 4.0 and 4.7 stars, and fell as ratings approached a perfect 5.0.
In your
marketing.
Search results
Review stars and counts in your Google Business Profile, and named local reviews on location pages.
Trades
Ads
Proof from the same kind of customer: 'Used by 40 Central Coast cafés' beats 'Trusted by thousands'.
Hospitality
Product pages
Reviews filtered to people like the visitor: same size, same use, same problem.
E-commerce
Health
Testimonials about clinical outcomes aren't allowed in health advertising. Show the clinic, the team and service feedback instead.
Health
Weak proof,
strong proof.
The same business, with proof that says nothing next to proof that persuades.
| Industry | Weak | Strong |
|---|---|---|
| Trades | 'Trusted by thousands' | A review from a neighbour two suburbs away about the same job |
| E-commerce | '5 stars, 2,000 reviews' | Reviews filtered to buyers with the same size, use or problem |
| B2B | A wall of famous logos | A company your size, in your industry, named with permission |
| Hospitality | 'Best café on the Coast' | Recent reviews mentioning the thing the visitor searched for: dogs, brunch, parking |
| Health | Patient outcome stories | Service feedback only: on time, friendly, easy to book. Clinical testimonials aren't allowed |
Try it
Which reviews
should you show?
Paste your reviews, one per line. Each gets a specificity score: does it mention the job, the place, the problem, a detail? Show the specific ones on the pages they match, not the generic five-star ones.
Best to show first
- Paste some reviews, or load the example.
Try this
Show reviews from customers in the same suburb or industry as the visitor.
It backfires when
Reviews feel vague or come from people nothing like the buyer.
In my experience
What I see most: a wall of five-star reviews that all say 'great service', and nothing from someone the visitor recognises as like them. Two specific reviews from people in the same suburb, or with the same problem, do more than twenty vague ones. Specific beats plentiful.
Test it on
your own buyers.
- 1
Pick one page
Your busiest service or product page, where people decide.
- 2
Swap the proof
Replace generic praise with two or three specific reviews from people like that page's buyer.
- 3
Compare the same weeks
Enquiries or sales for four weeks before and after, against a page you didn't change.
- 4
Ask honestly
Ask every customer for a review. Google's policy bans asking only the happy ones.
Questions
people ask.
How many reviews do I need?
There's no magic number. What helps more is reviews that mention the specific job, product or worry the visitor has, from someone like them.
Can I use testimonials in my ads?
In most industries, yes, if they're real. In regulated health services, testimonials about clinical aspects aren't allowed.
Do perfect 5-star ratings help?
Not as much as you'd think. The Spiegel Research Center found buying odds peaked between 4.0 and 4.7 stars and fell as ratings approached 5.0, possibly because perfect scores look too good to be true.
Can I only show my best reviews?
Be careful. The ACCC says leaving out negative reviews can be as misleading as fake ones. Choosing the most relevant reviews for a page is fine. Hiding the bad ones isn't.
Did the hotel towel study replicate?
Partly. A German replication found both message types beat no message, but the 'other guests' message wasn't better than the standard one. Social proof is real. The size of the effect depends on the situation.
Keep going
Where is this costing
you sales?
Takes a minute. Audits come back within 1 to 2 business days. For anything else, I'll get back to you as soon as possible.
What happens next
- 1I'll ask for read-only access, or just your website for a search audit.
- 2I go through it and write up the 3 biggest fixes.
- 3A 20-minute call to walk you through it. No pitch unless you ask.