Human See, Human Do: A Practical Marketing Lesson from the Science of Persuasion

By: Mary Flaherty

Remember your mother saying, "If all your friends jumped off a cliff, would you?" Although she was being over-the-top (and a bit annoying), your mother was right, in principle: We naturally look to what others are doing to help us decide what to do.

This "social proof" principle, explains Robert Cialdini, author of the bestselling book Influence: Science and Practice,1 is one marketers can use to make their messages more persuasive.

To demonstrate this, Cialdini and his colleagues approached a hotel that used an in-room request card to encourage guests to reuse their towels rather than request fresh towels each day. They wanted to see whether by changing only a few words on the request card they could influence guest behavior.

In their experiment, they designed two cards. One used the original, standard environmental protection message: reusing towels helps conserve resources and protect the environment. A second card used slightly changed wording to indicate that the majority of guests staying at the hotel reused their towels at least once during their stay. The result: Guests in the rooms featuring the new card (social proof appeal) were 26% more likely to reuse their towels.

The hotel saved money on laundry and all it took was a no-cost change in wording. That's pretty powerful when you're thinking about your own efforts to influence or persuade potential clients.

Cialdini then sought to find out whether we are influenced even more by the behavior of those who have had similar experiences to ours (even when those experiences don't appear clearly relevant to the situation at hand).

In a follow-up experiment, he showed just that. When a request card indicated that the majority of people staying in this particular guest room reused their towels, there was a 33% increase in towel reuse (a 7% improvement on the first experiment's results).

Applying the Principle

So, how can you use the social proof appeal in your firm's sales and marketing activities?

  • Employ statistics that communicate the popularity of your service., for example, touts its 47,700 customers up front on its homepage.
  • Use testimonials, case studies, and success stories from satisfied clients in your presentations to prospective clients, on your web site, and in your sales collateral.
  • The more similar the person giving the testimonial is to the prospect, the more persuasive the message becomes. So make sure you have a library of testimonials and case studies or success stories that represent the different company demographics (size, geography, etc.) and industry verticals for the market(s) you serve.
  • When you run a seminar or other event for potential clients, invite your best clients. Strategically seat happy clients near prospective clients to increase the likelihood your prospects will hear about the benefits your clients have received from working with you directly from your clients.

Each of these persuasive tactics builds on our natural inclination to be influenced by the behavior of others. But, don't stop here—read Cialdini's newest book, Yes! 50 Scientifically Proven Ways to Be Persuasive, it's chock-full of strategies to help you be more persuasive in all aspects of your life.

One bonus lesson: Cialdini says there is one word that will make you more persuasive by more than 50%. That word? Because. Since we are psychologically structured to need reasons, you'll get significantly more yeses by adding the word because to your requests. So, seek out Cialdini's research, because it can help you become more persuasive.


1 Listen to Robert B. Cialdini on NPR's Talk of the Nation: Science Friday (August 22, 2008 episode):

Mary Flaherty, Director, Content Strategy & Development, at, directs overall strategy and development for the site. She develops research, case studies, how-to tools, interviews, and other premium site content. Mary’s career spans more than 20 years in higher education publishing and research, as well as professional services marketing. You can reach her at and follow her on Twitter at @MaryFlaherty.