The 4 Design Assumptions Costing You Money

Have you ever heard the saying, “when you assume, you make a you-know-what out of “u” and “me?’” It may sound a bit cliché, but it’s actually great advice, and it even applies to designing a website or app. If a site or app is designed purely based on assumptions and without data gathered from testing, it can result in a product that is hard to use. Not only does this reflect poorly on the designer, it also gives the user a poor experience. (Lead image source: Benoît Meunier)

While assumptions may save you time now, the time saved won’t be worth all the money you’ll spend and trouble you’ll go through to fix them later. This is especially true when you consider that testing need not be an expensive task. Through our studies at, we’ve found that there are four common assumptions that you’re better off testing instead.

Design Assumption 1: Users Understand Your Controls

Everybody thinks differently, which is something I’m sure you’ve considered when coming up with your awesome site or app design. But you have to be sure to consider that when people try to accomplish a specific task without instructions, sometimes they just don’t do what you’d expect.

As we found in our studies of iOS 7, this holds especially true when replacing an action that has practically become ingrained in the muscle-memory of your users: closing apps on an iOS device.

For years, iOS users were able to close apps by double tapping the home key, then long pressing the app icons and tapping on the red “minus” icons to close their desired apps. Apple replaced the last two steps in iOS 7 with a upward swipe, which frustrated many of the testers who participated in our study.


What we learned from this study is that you have to test your controls, no matter how intuitive you might think they are. Ask your users to accomplish a task that you find intuitive. See how they try to accomplish it and make adjustments based on your results.

Sure it takes a little more time to administer these tests and analyze the results, but in the end, you’ll have an app or site that you know is more intuitive to your users – and it’s backed by research rather than assumptions.

Design Assumption 2: Users Understand Your Symbols

Symbols are a great way to convey information visually. Where some designers run into trouble is assuming that symbols are universal. For example, if you were to see the sign below while looking for a restroom, would you know that you’ve found what you were looking for?

Water closet sign in a subway station. Credit: Europe For Visitors

If you didn’t know what “WC” stood for without looking it up, don’t worry, you’re not alone. This sign is a great example of why you should always test your users for symbol comprehension.

Take a look at this icon on Google Plus:

Is it a share button or is it a reply button?

Depending on your user demographic, it may be interpreted as a share icon or a reply icon, but the only way to find out for sure is to test. While your users may be able to figure out your symbols through the context of your app or site, why risk confusing your users and distracting them from the app or site you worked so hard to design?

Set up a scenario where your user needs to accomplish a task and have them pick between a set of symbols. Ask them which one they’d press or click to accomplish the task. As you compile your results, you’ll see which symbol is the most effective in communicating the action that you want your user to accomplish (A/B testing can come in handy here). You’ll also make the path to conversions that much easier for your users, which is a win-win situation for everyone.

Design Assumption 3: Users Read Instructions or Help Messages

When was the last time you read an instruction manual before using a new gadget? If you’re American, chances are you can’t remember. We’re so used to technology being intuitive, that we expect them to work right out of the box.

Sometimes, it’s not enough to have your instructions right in front of your users. Credit: The Far Side

When iOS 7 rolled out, users were prompted to take a look at a “How to Search” tutorial as part of the installation process. However, what we found during our study was that perhaps users got lost in the excitement of installing the new iOS and bypassed this tutorial.


Assuming (heh) that you haven’t already begun testing for your site or app’s intuitiveness, run a few tests on functions that might require instructions. Have testers run through the process step-by-step and see how they react when they’re finally required to complete the task.

You may find that like Apple’s iOS 7 instructions, your users are bypassing important tutorials that allow them to access certain features of your app. The last thing you’d want is for your users to miss out on that awesome new feature you’ve added. This is one way to help you find the most effective way to inform your users of your more advanced features.

Design Assumption 4: Users Use Your Site Under Ideal Conditions

This is especially true with your mobile users’ devices. Whether its having to turn down the backlight on a mobile device or laptop to conserve power, or using the device in direct sunlight, there are many different instances when your users won’t be viewing your site or app under ideal conditions.

Using a device in direct sunlight can be difficult at times

When designing your app for mobile devices, it’s important to keep in mind that legibility is key. Through our studies, we’ve found that it’s important to have enough contrast between your background and your text to maintain legibility in less than ideal lighting conditions.

As important as it is, legibility isn’t the only thing you should test for on your mobile app. Button sizes and widgets should be other things you should test in less than ideal conditions, and as you continue testing your app, you’ll find even more things to test and refine.

So how do you find out if your app works well in less than ideal conditions? Get out of the office and test. Grab your laptop or mobile device and head to your nearest cafe, park, or even a bar (using your mobile device after having a few drinks definitely counts as a less than ideal condition).

Observe how your testers are using your app in the wild and make note of any issues with legibility and functionality. You’ll find some great insights outside of a lab or office setting, and you have the added bonus of getting a bit of fresh air.

  • Anton Alohin

    I like the article, but it seems to me that you missed a crucial stage of testing process. Don’t you think both the developers and clients should be involved in testing, though at different stages of this process? I’m talking about user acceptance testing. Instead of making overestimated assumptions, you could let your product being tested in the “real world” by the intended audience. I’m totally agree with you, that due to constant demand on developers to keep the budget low, testing is an easy target for reduction of costs. So why shouldn’t they use a real user’s experience to make final changes before releasing?