Customer Testimonials: are they really effective? Our experiment gives the answer

Customer testimonials can confer trust when you’re advertising for your company, we all know that (if you don’t, read this Ultimate Guide to Social Proof Marketing).

We rely on testimonials every day. Your friend raves about a new coffee shop, and you go check out their cold brew. Your co-worker says they’re so productive when they use this one tool, so you sign up for a trial.

We want to try new things because we’re excited about a better outcome, but there’s also a risk in trying something new. Testimonials from friends and co-workers—people we trust—seem to take away some of this risk. They lower the chance of error in “trial-and-error.”

But even with the warm and positive associations of customer testimonials, it’s still unclear if they are a great way to get people to buy what you’re selling.

We’ve decided to test the effectiveness of customer testimonial ads on Facebook, and share our results with you so you can make the best decisions for your brand.

Our experiment reveals that yes, customer testimonials DO lead to conversions, BUT… Keep on reading if you want to know!  😉

Customer testimonials in the digital era

The fine and delicate pottery and chinaware produced by Wedgwood in 1760, are the first products ever to receive a customer testimonial. The British manufacturer used the royal endorsements of Queen Charlotte (wife of George III) as a marketing device to show value in the company and promote others their product

Advertising has changed a lot in the digital era—but customer testimonials are still a tried and true method of enticing potential customers in print, media, and online ads.

While current customer testimonials might be a bit more honest and authentic nowadays, the concept of testimonials in advertising hasn’t changed much.


However, in our current age of advertising, customer testimonials have to square with online reviews on sites like TripAdvisor, Yelp, and Amazon. While in the past a potential customer may have taken an advertisement’s testimonial at face value, nowadays consumers are a bit more savvy, using these services to vet products and experiences.

For example, consider the glowing testimonials on the ubiquitous Quip toothbrush subscription service, and how starkly they differ from review sites like Highya:


The Quip testimonials are generic and aren’t tied to real and social proof, while Highya provides a platform for customer testimonials and honest troubleshooting from the company.

While in the past a potential customer may have taken an advertisement’s testimonial at face value, it’s clear that today’s consumers are a bit more savvy, using review platforms to vet products and experiences. But that doesn’t mean testimonials aren’t valuable anymore. You just have to take care to be authentic with your audience.

Smart Tip: If you’d like to pursue customer testimonials or engage in social proof, consider featuring crowdsourced reviews in order to improve perceptions of authenticity and build trust. Instead of highlighting unattributed testimonials, you’ll be able to show potential customers positive social proof, and nod to the fact that you value customer feedback.

Our Experimental Design

To test the effectiveness of traditional customer testimonial ads in light of these shifts, we decided to run an experiment comparing them to more standard Facebook ads which are heavy on imagery. We wanted to see if letting customer testimonials speak for themselves would get customers to convert.

To target the most relevant potential customers, we designed our experiment to target our custom warm audiences, which consists of people who had expressed interest in AdEspresso by downloading one of our eBooks, engaging with a post, or visiting our website within the past 7 days.

We then selected two different style ads and ran them with a $98 budget to see which would be the most effective. Below, you can see we chose our playful mascot with a promise of a free trial.

Below, you can see we chose our playful mascot with a promise of a free trial.

For our testimonial style ad, we ran an ad that was much more minimal in design, letting the testimonials of our customers speak for themselves:

With headshots and companies highlighted, these testimonials are authentic appraisals of the AdEspresso platform. They use social proof to nudge people towards converting based on straightforward testimony. These ads are meant to confer trust to prompt potential customers to try something new, rather than catching viewer’s attention with colorful graphics and large CTAs.

And the results say that…

Although this was a limited experiment, we were able to find a clear difference between the two ad strategies, finding that the visual ad was much more successful in generating conversions than the one with testimonials.

Here’s the raw data, as seen from the AdEspresso dashboard.

These are significant differences and indicate that the formats of the ads play a large role in the differing success and appeal of your campaigns.

Audiences excited by the brand association of the AdEspresso mascot and the free trial CTA are more inclined to click, visit AdEspresso’s site, and then convert. The minimalist customer testimonial ad is designed under the misinformed assumption that ad impressions alone will carry people towards conversions. Instead, you should prioritize getting an audience to click through and visit your site, which is where conversion really happens.

Using testimonials in the right contexts

These results make it clear that ad formatting can make the difference in the success of a Facebook campaign. But even with the clear win for visually inclined ads, you shouldn’t assume that this is a rigid rule that applies to all digital ads.

Additionally, it’s important to pay attention to the scope of the experiment. We tested one particular set of ads, which doesn’t mean that all customer testimonials are totally ineffective. It indicates that the busy, colorful graphics and the prominent free trial CTA registered more with viewers. The ad with the customer testimonial didn’t have these.

Our neurology gravitates towards visual stimulation. In 10 Scientific Reasons People Are Wired To Respond To Your Visual Marketing, we point out that images are processed at almost half the rate of text. It takes only 150ms to process an image, and another 100ms for our brains to assign meaning to it.

Pro Tip: If you want your Facebook ad to appeal to viewers in a near-instant, the safest bet is to use visual imagery to boldly make your brand’s case.

Building trust should be a core messaging strategy for your brand, and there are plenty of opportunities to let your audience know about the great customer experiences folks have had with your product. But there’s a time and place for everything.

Customer testimonials can be more useful at later stages of the conversion funnel since you want to foster active engagement. By prioritizing the use of visually interesting ads early in the funnel, you’ll be able to engage with a wider audience and get them to engage with your product on their own terms.