Summary: Users are more tolerant of minor usability issues when they find an interface visually appealing. This aesthetic-usability effect can mask UI problems and can prevent issue discovery during usability testing. Identify instances of the aesthetic-usability effect in your user research by watching what your users do, as well as listening to what they say.

It’s a familiar frustration to usability-test moderators: You watch a user struggle through a suboptimal UI, encountering many errors and obstacles. Then, when you ask the user to comment on her experience, all she can talk about is the site’s great color scheme.

Instances like this are often the result of the aesthetic-usability effect.

Definition: The aesthetic-usability effect refers to users’ tendency to perceive attractive products as more usable. People tend to believe that things that look better will work better — even if they aren’t actually more effective or efficient.

In other words, users have a positive emotional response to your visual design, and that makes them more tolerant of minor usability issues on your site. In most cases, this is a positive thing from your perspective. This effect is a major reason why a good user experience can’t just be a functional UI — designing an interface that’s attractive as well as functional is worth the resources.

The aesthetic-usability effect was first studied in the field of human–computer interaction in 1995. Researchers Masaaki Kurosu and Kaori Kashimura from the Hitachi Design Center tested 26 variations of an ATM UI, asking the 252 study participants to rate each design on ease of use, as well as aesthetic appeal.

They found a stronger correlation between the participants’ ratings of aesthetic appeal and perceived ease of use than the correlation between their ratings of aesthetic appeal and actual ease of use. Kurosu and Kashimura concluded that users are strongly influenced by the aesthetics of any given interface, even when they try to evaluate the underlying functionality of the system. In his 2004 book Emotional Design, our colleague Don Norman explores this concept in depth as it applies to everyday objects.

Bear in mind that the aesthetic-usability effect has its limits. A pretty design can make users more forgiving of minor usability problems, but not of larger ones. (As the first law of e-commerce states, if the user can’t find the product, the user can’t buy the product. Even great-looking sites will have no revenue if they suffer from poor findability.) Form and function should work together. When interfaces suffer from severe usability issues, or when usability is sacrificed for aesthetics, users tend to lose patience. On the web, people are very quick to leave.

Interpreting Positive Comments About Visuals During User Research

Understanding the aesthetic-usability effect is critical for decision making in resource allocation during the product-planning phase, but it also has implications for interface evaluation. User researchers must know how to spot this effect during usability testing, and how to interpret it.

When the aesthetic-usability effect happens in real life for your users, it’s a good thing. It means your team’s investment in creating a beautiful UI is paying off and connecting with your target audience. However, when the aesthetic-usability effect happens during user research, it can prevent you from discovering usability issues.

You can identify instances of the aesthetic-usability effect during user research by paying close attention to what users do and how it relates to what they say.

So let’s imagine we’re facilitating an in-person qualitative usability-test session. We observe the participant struggling through a few tasks on a site, but his final feedback is a vague comment on the attractiveness of the interface.

Whenever we hear this kind of feedback that seems out of place, we need to consider three possibilities.

The participant might feel pressure to comment on something… anything. Users (especially novice ones) often find it easier to give feedback on the visual design of sites.

on something… anything. Users (especially novice ones) often find it easier to give feedback on the visual design of sites. The participant might feel pressure to say nice things about the site. These empty compliments tend to happen when participants believe you had a hand in creating the site.

about the site. These empty compliments tend to happen when participants believe you had a hand in creating the site. The aesthetic-usability effect is interfering. Let’s say we rule out the first two possibilities — we think our user is comfortable in the session and doesn’t feel pressure to say something or give empty compliments. This may be a true instance of the aesthetic-usability effect. Clearly, there are usability problems to be fixed, but it’s a sign that our visual design may be doing its job.

Once we determine why our user is giving positive feedback on visual design after a negative experience, we can try to work around the problem.

Pressure to Comment

Some people are naturally uncomfortable with silence. Reduce the pressure to say something on your participants by establishing a low-stress vibe early in your session.

Reassure participants frequently that what they’re doing and saying is helpful.

Remember that the communication between a moderator and a participant isn’t the same as a regular conversation — the right amount of silence is part of the process.

Give participants plenty of opportunity to comment during the session by asking open-ended questions, but don’t push them too hard if they don’t have anything to say.

Pressure to Be Nice

Again, some people are naturally eager to please, and that will show up during sessions. But you can avoid this problem by distancing yourself from what you’re testing.

Before beginning each test session, emphasize that you didn’t design the site (even if you’re a researcher technically on the design team), that you’re there to learn from the participant, and that negative comments won’t hurt your feelings. It’s more valuable to hear hard truths than false praise!

Try (as much as possible) not to register emotional reactions to their comments in your face or body language. This is harder than it sounds, and takes practice. Try to keep a consistent demeanor of pleasant, nonthreatening, mild interest.

Aesthetic-Usability Effect

Sometimes you can work around the aesthetic-usability effect by probing users to think beyond the visual layer of the UI. But be careful not to lead the witness. Use vague questions like, “Do you have any comments about how easy or difficult it was to find this information?”

You might also return the user to a page or stage in the process that seemed particularly challenging, and ask them to describe what happened.

Sometimes probing questions will help, but not always. Be willing to let it go and move on to the next task.

“Great Color Scheme” Doesn’t Mean Your Visual Design Is Working

Bear in mind, when you hear positive feedback about a visual design during a test session, it doesn’t necessarily mean that your visual design is working. As described above, it’s possible that your users feel pressured to make a comment or to say nice things about your site.

Additionally, your visual design may be attractive, but it may not support usability. When that’s the case, users might still make positive comments. The visual hierarchy of the site may not help users understand its content, or a lack of signifiers may degrade interaction.

Conclusion

Aesthetically pleasing interfaces are worth the investment. Visual designs that appeal to your users have the side effects of making your site appear orderly, well designed, and professional. Users are more likely to want to try a visually appealing site, and they’re more patient with minor issues.

However, this effect is at its strongest when the aesthetics serve to support and enhance the content and functionality of the site. Additionally, this effect often influences user comments during research. As always, listen to what users say, but, first and foremost, take into account what they do.

References

Kurosu, M., & Kashimura, K. (1995). Apparent Usability vs. Inherent Usability. Conference companion on Human factors in computing systems - CHI '95.

Norman, D. A. (2004). Emotional Design: Why We Love (Or Hate) Everyday Things. New York: Basic Books.