Social Proof.

The term was popularised in 1984 by the psychologist Robert Cialdini in his book 'Influence'. Its core is an everyday one: a restaurant with full tables seems more trustworthy than an empty one, a product with many reviews safer than one without. The more uncertain a decision and the less experience someone has with it, the stronger this effect. This applies especially to services whose quality cannot be checked before purchase, such as a website, a renovation or consulting.

On websites there are several forms. Testimonials with name and company, reviews on Google or other platforms, references with concrete projects, logos of well-known clients, figures such as number of projects or years in business, and media mentions. The most effective evidence is concrete and verifiable: a project you can look at, a client you can google, a figure with a source.

That is exactly where the risk lies. Invented reviews, client quotes without approval or inflated figures get noticed, sooner or later. They breach platform guidelines and, in Switzerland, can violate the Federal Act against Unfair Competition (UWG) if they are misleading. Search engines and language models also increasingly weigh whether statements can be substantiated. An honest sentence such as 'We do not yet have a reference for this service' does less harm than evidence that turns out to be false.

Social proof cannot be bought, but it can be collected systematically: ask for a review after every completed project, prepare testimonials as drafts and send them for approval, document references with permission and measure results wherever possible. Where evidence has the greatest effect on a page is a question of conversion optimisation; locally, Google reviews are the most visible form, and they play a central role in local SEO.