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How Cognitive Biases Shape Customer Testimonials to Increase Conversions

Posted by Jeremy Smith on Mar 17, 2016 3:49:35 PM

Features or qualities of a website that inspire trust in the minds of your customers can take several forms, but one of the most effective is customer testimonials. You — and more importantly, your site visitors — can’t ignore them.

In an earlier blog post about useful trust elements to add to e-commerce sites, I quoted a 2014 survey that says 88 percent of consumers have read online reviews to determine the quality of a local business, and 39 percent do so on a regular basis.

Statistics like that are pretty easy to come by. TechWyse recently topped a post with:

  • Customer testimonials have the highest effectiveness rating (89 percent) when influencing buyers, according to the “20 Captivating Marketing Statistics” infographic.
  • 90 percent of buying decisions are influenced by reviews.
  • 73 percent of consumers say positive customer reviews make them trust a business
  • 63 percent of consumers are more likely to purchase from a site if it has reviews.

Unbounce tells us that, “Customer testimonials are an essential part of social proof. They let us connect with those that are similar to us (in a similar niche) or those whom we aspire to be (big brands).”

So, we get it. We need customer testimonials on our e-commerce websites.

The Unanswered Question about Customer Testimonials

But why are customer testimonials useful?

Well, Entrepreneur says:

  • Testimonials build trust, as I said in the earlier post I referenced above.
  • Testimonials overcome skepticism, even from your “tough sell” customers, in part because they are not more sales talk from you, the profit-minded businessman.

Back at Unbounce, they cite the experiment by psychologist Stanley Milgram in which he had a group of people stand alongside a busy street and stare up at an office building. There was nothing happening up there, but Milgram found that 4 percent of people passing by would stop to join a single person staring upward, and that the number jumped to 40 percent if there were already 15 people staring up at the building. On top of this, 86 percent of passersby would at least look up to see what everyone else was looking at.

Milgram experiment crowd

(Image source)

As Robert Cialdini demonstrated in Influence, the Psychology of Persuasion, Unbounce continues, we are all prone to social pressures.

But why do they work? How does this happen to us? I want more.

Customer testimonials on a website repeatedly help increase conversion rates. I can find article after article telling me to add them to my site because they work, and how to do it. But they don’t tell me what I’m really doing.

They don’t tell me that I am playing off of a series of cognitive biases, which cause people to act, sometimes without thinking and sometimes in ways contrary to the facts before them.

But I want to tell you. Because the psychology behind creating the user experience at the core of conversion optimization is fascinating and, even better, useful.

Below I’m going to tell you why testimonials are effective, and how — because of the way these psychological quirks work — you can make them benefit you.

Keep reading to learn about cognitive biases we all share, and how with customer testimonials you can exploit them to keep customers confident in the product or service your website offers them.

8 Biases That Make Testimonials Work & What to Do About Them

A cognitive bias is a deviation of thought in which the mind violates logic to make judgments and draw inferences. It is, by definition, an error. Biases are caused by our instinctive need to simplify the vast load of stimuli we encounter moment to moment. We take a mental shortcut, and sometimes it leads us down the wrong path.

A customer testimonial, or a “social endorsement,” is a statement by someone who has done business with you, usually about their satisfaction (or lack thereof) with the experience. It is considered a strong form of word-of-mouth marketing.

Testimonials may take the form of videos as well as text. Reviews and ratings, the backbone of sites like Yelp and TripAdvisor and used to a great extent by large retailers like Amazon, are also customer testimonials.

Just getting a customer to provide a testimonial for you plays upon the confirmation bias.

The confirmation bias is the tendency to search for, interpret, focus on and remember information in a way that confirms one’s preconceptions. Having a customer write or record a testimonial for you will validate their feelings toward you and, assuming those feelings are positive, increase their loyalty to you.

Anderson Nicholson says, in a post for Smart Insights, the act of writing and sharing a positive product review can lead to an increase in the customer’s perception of your product’s value by up to 37 percent. He adds:

A customer is never more loyal than the moment directly after they’ve purchased your product, and this means it’s the perfect opportunity to request either a written testimonial or a social endorsement for your product or service.

This is one reason you often receive “comment cards” at the end of a restaurant meal or as you check out of a hotel.

Ask for a testimonial right after your customer has made a purchase or concluded whatever conversion you seek.

Now, let’s take a look at some other cognitive biases and what they tell us about how customer testimonials can work for you.

Bandwagon Effect

Everyone has heard of “jumping on the bandwagon.” As an instinctive bias, the bandwagon effect is a tendency to do or believe things simply because other people do or believe the same thing. This is the broadest of the biases we’re looking at here, and it is related to groupthink and herd behavior.

The bandwagon effect explains the results of the Milgram experiment above, where people stop and look up just because they see others doing it.

A Shutterstock post about the bandwagon effect reminded us of the Solomon Asch studies from the 1950s that showed how social pressure from the majority of a group can lead a lone individual to alter their behavior just to fit in. As the narrator of the Asch experiment video below says, “Group dynamics is one of the most powerful forces in human psychology.”

There is power in using multiple customer testimonials, no matter what they say. Having a lot of them makes use of the power of numbers. It’s like McDonalds saying “billions and billions served.”

“As more people come to believe in something, others also jump on the bandwagon, regardless of the underlying evidence,” psychologist Mohammed Ali N M writes. “The tendency to follow the actions or beliefs of others can occur because individuals directly prefer to conform, or because individuals derive information from others.”

The bandwagon effect is also related to what’s known as the “cascade effect” or the development of informational cascades. It’s like the domino effect: one person says it, then another, and everyone quickly falls in line.

Investopedia says online reviews can create informational cascades. “(P)eople often use what is recommended by others, rather than trying something out. This is based on the premise that the general public, on the whole, will make the correct decision, even though individual preferences vary.”

Gather and post as many testimonials as you can. Make it a routine part of doing business.

The Marketo page below had 60 videos from customers singing the praises of the marketing automation software company when the Rewatchable blog used it as an example of testimonials done right:

Marketo testimonials

Cheerleader Effect

The cheerleader effect tells us that people look more appealing in a group that they do alone. This is an actual visual illusion, which Scientific American compares to how the moon looks so much larger when it appears closer to the horizon.

We tend to view individuals as being more like the group average than they actually are. It’s another cognitive shortcut; we mentally search for the average group face without even thinking about it, and the average is more attractive than other group members’ individual faces, researchers say.

“Our visual system automatically computes general information about the entire set, including average size of group members, their average location, and even the average emotional expression on faces,” the Scientific American writer explains. “Thus, although the group contains many individual items, we naturally perceive those items as a set, and form our impressions on the basis of the collective whole.”

With an actual squad of cheerleaders, the effect is enhanced by their uniforms and coordinated movements.


Aspen Photo / Shutterstock.com

This argues for working to:

  • Obtain photos of your customers to go with their testimonials.
  • Have individuals wear business dress in their photos. If business dress does not set the appropriate tone for your site, have them dress as they should, but make it stylish.
  • Group testimonials together in a clean layout.
  • Picture your customers using your product or service.
  • Picture yourself with customers if you offer a personal service.

The cheerleader effect also tells us that our wingman (or wingmen) should be better looking than we are. But I digress.

This old StudioPress page presents a slideshow of 10 prominent bloggers with photos and their testimony. Grouped together, they look good and they look professional.

StudioPress testimonials

(Image source)

Conjunction Fallacy

The conjunction fallacy occurs because we tend to assume that specific conditions are more probable than general ones. The oft-cited illustration of the conjunction fallacy is known as “the Linda problem.”

Linda is 31 years old, single, outspoken and very bright. She majored in philosophy. As a student, she was deeply concerned with the issue of discrimination and social justice, and also participated in antinuclear demonstrations.

Which of the following is more probable: 1. Linda is a bank teller (A); 2. Linda is a bank teller and is active in the feminist movement (A and B)?

When the Linda problem is put to test participants, as many as 85 percent choose 2, which is logically incorrect.

The logical truth is that a conjunction — A and B — can never be more likely than either of its constituent parts. Because answer 2 (A and B) includes A, the other choice allowed, answer 1 is more probable.

This explanation of the conjunction fallacy reviews the math  that proves the theorem of probability theory, which says a conjunction is never more probable than its conjuncts.

But people think both; they don’t separate A and B.

Psychologists Amos Tversky and Daniel Kahneman said in their studies of the conjunction fallacy that people tend to choose the scenario that is most similar to (in other words, representative of) their preconceived ideas about what’s being described. They called this the “representativeness heuristic.”

Because the conjunction fallacy creates a bias toward believing specific scenarios, take advantage by presenting narrative testimonials that explain details of the customer’s interaction with your company and the outcome. Not, “the product was great,” but “I bought it at the last minute for my wife’s birthday and she said it was exactly what she wished for.”

The conjunction fallacy can also cause your customers to have expectations that are not real. For example, if your shipping procedures cite a range of delivery dates, this cognitive bias causes people to believe not just that both are possible (technically true), but that the shorter time is more likely, which, let’s face it …

Posting multiple testimonials that cite a range of positive customer experiences will help you counter the conjunction fallacy.

Halo Effect

The halo effect causes people to apply their general feelings about a person or thing to  specific traits of that person or thing. More generally and as applied in terms of testimonials, it describes how a likable personality or some specific desirable trait associated with a business may cause a favorably biased judgment in others.

Psychologist Edward Thorndike first coined the term in a 1920 paper titled The Constant Error in Psychological Ratings. He developed the theory by studying how military officers evaluated a variety of qualities in their subordinate soldiers. Thorndike found that high ratings of a particular quality correlated to high ratings of other characteristics, while negative ratings of a specific quality also led to lower ratings of other characteristics.

A negative halo effect is sometimes called the “horns effect,” as in devil’s horns.

The halo effect continues to be a big concern in the use of performance appraisals for managing employees or in grading students. Thorndike argued that employers and educators are unable to fairly rate an individual’s separate qualities.

In one aspect of the halo effect, if a customer likes one part of your website, they are likely to think favorably about others. This is another reason to create a good user experience on your landing pages.

But you can use capitalize on the halo effect by associating your product or service with authoritative people or simply people or companies that are well liked.

I have to admit I’ve never heard of Cision, but everyone knows and likes Kellogg’s cereal. They’re iconic. Having Kellogg’s (especially with the logo) at the top of a page of testimonials reflects well on Cision.

Cision Kellogg's testimonial

Have you ever been to a restaurant and seen pictures on the wall of celebrities who have eaten there? That’s an attempt to benefit from the halo effect. You can do the same thing with testimonials on your website if well-known or admired people have used your product and you ask them to provide a testimonial or just a photo of themselves using your product.

One way to do this if you don’t normally hob-nob with the in-crowd is to ask some local dignitaries to try your product for free in exchange for feedback that you can use on your site.

The proviso here is that, like with all testimonials, you have to be willing to post the not-so-good or even negative review. But, while negative reviews may actually be helpful, most celebrities or celebrity-wannabes will know better than to bad-mouth your product and make themselves look like a jerk. Many times they’ll feel obligated to say something nice, even though of course you said nothing about such a quid pro quo.

Identifiable Victim Effect

This bias is our tendency to respond to a single identifiable person who has been harmed or is in danger, but to ignore a large group of people at risk. It means that telling you about tens of thousands of children starving in Barrenfieldsistan makes your eyes glaze over, but the story or photo of one child will make those same eyes well with tears as they look for a button to click.

As explained elsewhere, when you read statistics, you activate the prefrontal cortex of your brain, which is responsible for high-level thought. But hearing or reading a story about a person activates the limbic system, which is responsible for your emotions.

Research by psychologist Paul Slovic, titled ‘If I Look at the Mass I Will Never Act’: Psychic Numbing and Genocide, concluded that, as Wired magazine put it, “human charity is ultimately rooted in our compassionate feelings, and not in some rational, utilitarian calculations.”

This is particularly useful for testimonials about products that solve problems, such as pest or mold eradication services, home security systems, etc. These testimonials need to tell a story about how a specific terrible situation was avoided or reversed thanks to you.

Clearly identifying the customer in such a testimonial adds authenticity. If it’s not a situation that could cause harm, and the customer agrees, use their full names (or at least first name and last initial), hometowns and a photo.

We’ve all heard statistics about crime, including domestic abuse. Instead of numbers, here’s a scary story from a couple who are happy they have a home security service:

ADT customer testimonial

(Image source)

The pest control service customers below don’t do anything for me. They’re all happy, but they’re just anonymous “customers” and none of their statements tell me that the service solved a problem. At the end a page with 45 testimonials, finally a Customer says this is the first year they haven’t had ants in the house.

Pest Service testimonials

(Image source)

Ingroup Bias

People have a tendency to give preferential treatment to and hold more positive feelings toward others whom they perceive to be members of their own group. This is known as the “ingroup bias.” We like our own kind, even as society works to strengthen diversity.

In fact, the ingroup bias is why society needs to work toward diversity; by and large, it doesn’t happen naturally.

A blog aimed at nonprofit organizations, in its discussion of the identifiable victim bias, says identification with a strong ideology can be more compelling than the identifiable victim effect when in comes to “in-group” dynamics.

Consider any war-torn country split by ethnicity or religion. The fighting may be for territory and resources, but it’s about an ingroup bias: our group is righteous, theirs is evil.

Research about “ingroup favoritism” shows that it is easily triggered and that groups harden once formed. Even strangers brought together for a study bond and become separate groups over the most trivial commonalities. “Within minutes of being divided into groups, people tend to see their own group as superior to other groups, and they will frequently seek to maintain an advantage over other groups.”

Therefore, you need to know who your customers are and make sure your testimonials specifically address them. If you have different landing pages for different customer segments, as you should, the testimonials you display should be specific to each of those segments.

If you have products that you market differently to men and women, for example, make sure you use male and female customer testimonials accordingly. If you sell children’s products, you might run a holiday campaign targeting grandparents and stock those pages with testimonials from older customers as opposed to the young parents you’d use elsewhere.

Risk-Compensation / Peltzman Effect

Chicago economist Sam Peltzman identified the risk-compensation bias in a controversial article titled “The Effects of Automobile Safety Regulation,” which was published in the Journal of Political Economy in 1975. Peltzman argued that mandatory seat belts in cars made in the U.S. had not led to fewer deaths in car accidents and, in fact, they caused drivers to be more reckless.

The risk-compensation bias says that the safer we are, the more risks we take.

Political conservatives apply the Peltzman effect to all forms of regulation. Peltzman himself also demonstrated that requiring banks to hold deposit insurance made banks take more risks, for instance.

For our purposes, the Peltzman effect says the more secure an e-commerce site is (or appears), the more likely users are to feel safe about the various conversions suggested by its CTAs.

Testimonials, as we said at the top of this article, are but one way to instill your users with trust in the safety of any transactions they engage in on your website. But with the proper wording, you can use the narrative of a testimonial to demonstrate that users can trust your business.

A testimonial from a customer who was originally unhappy but for whom you made things right, even with a refund, for example, can be very powerful, thanks to the Peltzman effect. It shows potential customers that you’ll have their back; they are safe in your hands.

The customer review below explains problems he encountered installing a lamppost, and how he resolved them, including breaking a piece and taking it back for a replacement with no problem. In the second image, the photos expand when clicked on to show the installation. The next review on the page (not shown) is negative, based on the installation problems the first customer was able to work through.

Lightpost customer review

Light post review - 2


It’d be easy enough to add some customer testimonials to your site just because you know they work and it’s the thing to do. But I hope I’ve shown you why they can help you and how.

So as you assess your site’s performance and work to enhance it with customer testimonials, consider the cognitive biases they may trigger and how they can help you meet your conversion objectives. Don’t forget that cognitive biases can be negative, too, and can cause friction or anxiety, which may lead to dropoffs in conversions.

Anything is better if it has a specific reason for being. Develop a hypothesis as to what you expect your customer testimonials to accomplish, and test them to see how they actually perform.

Your customer will be flattered that you thought of them, and you will reap the rewards when your site’s testimonials lead potential customers to believe they can feel good about doing business with you.

Topics: buyer psychology, Cognitive Bias, Conversion Optimization, Testimonials, Web Psychology

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