Aesthetic-Usability Effect “Sorry I do judge a book by its cover”

Eka Juliantara
5 min readJun 8, 2019
Book Illustration by

Since we were young, we told by our teacher to don’t judge a book by its cover. We told to read it first before giving a judgment. It’s because the true value of a book lies in its content, not in the cover. I very agree with that. But I have one question. What is the importance of the cover?

From our childhood story, the cover is not that important. The most important is the content. So, why don’t we just remove it? Otherwise, why does the cover design getting appeal nowadays? Why do we getting hard to look away from it? Finally, we buy a book just because “the cover”, why? Let see if you get the answer by the end of this story.

In psychology, emotional reactions to stimuli are called affective responses. Unconsciously, it happens very fast in our lower part of the brain. The same part that governs basic instinct like fear, sex, breathing, and blinking. For example, when we see the appeal design cover, it gives us the pre-conscious pleasant response. This response makes us predisposed to feel the book is great.

This state is called a positive-affect. Furthermore, when you in this state, our neurotransmitters broaden brain processing. Our muscle can relax and our brain is more active. The effects are increasing curiosity, creativity, confidence, and makes our brain learning effectively. As a result, we treat the book like our best friend.

Consciously, we believe in the book and its content. Then, we buy it to read later. What have we learned until now? Let me answer it “the well-designed thing is our best friend”. Because it is our best friend, we believe it and more tolerant of its minor usability issues. Not only happens on a book but everything includes apps.

In the UX world, this phenomenon is called Aesthetic-Usability Effect. The Aesthetic-Usability Effect 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.

Yesterday, I conduct an experiment to play with this effect. Not as great as Kurosu and Kashimura, but enough to satisfy our curiosity. I prepare 2 music player design. Let’s called it A and B. Like other music players, they have basic features (usability) that users need like play, prev, next, music info, duration, shuffle, repeat, etc. ‘A’ has pleasant interface than ‘B’. I hide shuffle and repeat feature on ‘A’ while ‘B’ has a complete feature (usability). I ask users to choose between ‘A’ and ‘B’. The result is 75% choosing ‘A’ while 25% choosing ‘B’. Why? I think ‘B’ has a complete feature that user needs. I think Aesthetic-Usability Effect play with me.

The result of ‘A’ and ‘B’.

Play in the field of product design, it’s important to know about it. It’s not a big deal to pay more to make our apps giving a pleasant first impression. Because it influences the long-term attitude of users toward our apps. Like bait on fishing. Users will tolerance of minor issue of our apps. Like a person who only smiles seeing his beloved pet messing his house. Nice motivation to keep leveling-up our design skill.

Like other effects, the Aesthetic-Usability Effect has a side effect or limitation too. Its major limitation is can’t hide major usability issues. Imagine a calculator without the ‘=’ button. No matter how appealing its interface. It keeps frustrating, isn’t it?

Another side effect is disturbing our usability testing. We conduct usability testing to make sure our design is easy to use by the user. “Easy to use by user” on other name is usability. Imagine, you as UX Researcher conducting usability testing. During the testing, the participant looks difficult when doing a task. But, when you ask about her experience. She tells you that the apps have a great color scheme. Frustrating, isn’t it?

Example of the paper prototype by

Maybe in the above case, the Aesthetic-Usability Effect is interfering. To tackle this side effect, I have one advice for us. Try to use a combination of lo-fi prototype and open-end question when conducting usability effect. Especially at the beginning of the process. With that, the participant attention not disturbing by ‘colour scheme’ thing anymore. We can gain a true participant’s feeling about the usability of our app.

Finally, we meet at the conclusions of this story. In short, Aesthetic-Usability Effect is an effect that makes users often perceive aesthetically pleasing design as design that’s more usable. So, users more tolerant of minor usability issues. As a designer, we need to aware of it. Keep levelling our design skill. For me, the design is nice when it helps the users. Thank you for being part of this story. I’m open the discussion, just leave me a text.



Eka Juliantara

Hi, I’m Eka; If I die someday, I want people to remember me as a man who designed something cool for Indonesian education.