Imagine you run a hotel chain that’s trying to help preserve the environment and cut costs by getting more guests to reuse their towels. You have 4 options for what the little cards in the bathroom say:

  1. Help our hotel save energy
  2. Partner with us to help save the environment
  3. The majority of guests at this hotel reuse towels
  4. The majority of guests who stayed in this room reuse towels

Which message do you use?

If you picked #4, you picked right. When a team of social psychologists ran this experiement with a major hotel chain, here’s what they found:

Message (Paraphrased) Towel Reuse
Help our hotel save energy 16%
Partner with us to help save the environment 31%
The majority of guests at this hotel reuse towels 44%
The majority of guests who stayed in this room reuse towels 49%


The Power of Social Proof

How could changing just a few words cause such an increase in towel reuse over the standard environmental message most hotels use? The answer lies in a principle psychologists call social proof — which says we frequently look to others to guide our behavior. We’re especially influenced by others that share similar traits to us, even when those traits are arbitrary (like what hotel room you stayed in).


This is my favorite story from Yes!, a fun book on persuasion science by 3 social pyschologists. One of them, Robert Cialdini, is the leader in the field and author of the classic book Influence: The Pyschology of Persuasion (1984). Yes!may look like a pseudo-science self-help book, but all of the examples are based on academic studies and tie back to core social psychology principles. It’s just more contemporary, digestable, and applicable than Influence and other books in the field.

At the end of each of the 50 chapters, the authors suggest everyday applications, most of them aimed at businesses. None of them are web-specific, but it’s easy to extend their recommendations to website content, application design, and web marketing. For example, inspired by the principle of social proof, we’re testing outquantified popularity claims on more and more client websites as well as testimonials that emphasize the customer’s location and industry. If you keep an eye out, you’ll notice a number of smart companies using these same tactics, like Basecamp does below.


The Power of a Head Start

Here’s another scenario from the book. You own a car wash and are trying to use loyalty cards to get more business. Which of the approaches below do you choose?

  1. Give customers a card that requires 8 stamps (car washes) to get a free car wash.
  2. Give customers a card that requires 10 stamps to get a free car wash, but that already has 2 stamps attached.

Here’s what experimenters found:

Approach Card Completion
8 stamps required 19%
10 stamps required with 2 already attached 34%


Even though the effort was the same (8 car washes), customers were more loyal in the 2nd approach because they were given a head start. We are more motivated to complete things that we’ve already started — and that motivation increases as we get closer to the goal.

The lesson from this according to Cialdini et al is this: when trying to get someone else to complete a goal, “try to point out how that person has already taken steps toward the completion of that task.” If your website has a multi-page web form or checkout process, you have a great opportunity to apply this principle. Make the first page(s) as simple as possible and show users their progress at the top of each page (e.g. “Step 2 of 4”, or as Amazon does it below).


These are just 2 examples from the book. There are 5 others in this blog post, and 40+ more in the book. Go read it! Then share your favorite takeaways on our blog.

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