What You Need to Know About Mobile App Usability Testing

Every professional UX/UI design agency includes usability testing as one of the necessary stages of app or software system development. Some of the clients think that it is unnecessary to test the product if all the requirements have been implemented correctly and refuse to spend money on it. However, this approach is wrong. UX testing reflects whether your product will be useful to users and how likely they are going to use it as is. Only by providing the best UX to the clients can you be sure that the business goals of the product will be met.

In this post, you will learn why you should test your product and how to prepare a prototype mobile application for UX testing.

Why Test a Mobile App Prototype?

The usability testing of prototypes reduces the cost of design and programming because it allows us to ensure quality assurance and to identify usability problems of a future application in the early stages: incomprehensible icons and signatures and spaces in the interaction logic can be eliminated quickly and easily.

With the prototype, you can test the operability of the future application so you can determine whether users understand the names of the menu sections or how to use the navigation (especially if it is non-standard). As a result, unsuccessful solutions and problems are cut off at the prototype level, and proven interface solutions are sent to development. That is why this is often done by UX/UI design companies that care about the high quality of their products.

Prototype Requirements for Testing

The main requirement for a prototype for usability testing is this: the prototype should be as realistic as possible. That is to say, it should be such that the respondent is completely immersed in the tasks and that the moderator does not have to explain the behavior of the interface or tell the respondent that “this is a prototype limitation.” The prototype should not tell the respondent where to click. The allocation of active zones is convenient for presentation and transfer of the prototype to development, but in tests, this violates user interaction.
Here are some of the requirements to respect when preparing the prototype for testing.


A prototype for testing should be presented at least in technical design.

Ideally, it is advisable to test the prototype in a final design similar to a future application. Such a test will not only detect interface problems but also help to identify usability problems associated with the appearance of the interface.

If you don’t have time to draw the final design, test the prototypes in a technical design that combines high detail content and a simple visual series (minimum colors, some illustrations, and icons are indicated schematically).

Conceptual (not detailed) prototypes are suitable only for testing basic ideas; it is difficult for users to see the future application in them.


The prototype should fit the screen (illustration on the right) and cannot be smaller or larger than the screen (illustrations on the left and in the center, respectively).

The correct scale affects the perception of the prototype. When the prototype is smaller than the screen size, it is annoying because it interferes with perception and highlights the “artificiality” of the prototype. Even worse, when the prototype is larger than the screen some of the elements may simply fall out of the respondent’s field of view; horizontal scrolling will appear, which greatly complicates the work with the application. So in the illustration above, the middle prototype had one of the items on the bottom menu and a basket in the upper right corner at the edge of the screen.

For maximum realism, you need to achieve the full adaptation of the prototype for the device. This is not difficult to achieve in the early stages of work. One way is to immediately create a prototype for a specific test device. Another, at the beginning of the work, is to make sure that the software allows you to display the prototype in the correct scale on any mobile device.


A realistic prototype should imitate all kinds of interactivity of the future application, otherwise, testing will not be able to reveal all aspects of the planned interaction with the interface. In addition to the basic transitions between pages by a button or link it can be: vertical scroll, horizontal scroll, floating and pinned elements, pop-up menu, modal windows, flops, swipe, etc.


The user must believe in the data shown on the screen. For example, when testing financial applications, the amount of money should not be in billions. The user falls out of context, seeing discrepancies, and so the moderator has to explain what is happening on the screen. Ideally, the content should change in accordance with the actions of the user, as in a real application. For example, a credit card balance should be reduced after payment and, of course, the prototype should not have comic content.

If the user believes in the data on the screen, it will be easier for them to plunge into the situation and we will see a live and immediate response to the prototype on the test.

Prototype Display Device

Software for prototyping often allows you to simulate a smartphone on a computer screen. Unfortunately, the resemblance is purely external.

Interacting with an interface using a mouse cursor is fundamentally different from finger control. For example, the user can more accurately and quickly “hover” over the interface elements with the mouse, never blocking the icons and signatures with their hand. In addition, there are non-prototype elements on the screen; for example, the interface of the viewer program and the computer operating system.

Mobile Browser

Sometimes a prototype can be shown in a browser on a smartphone. In this case, the user will be distracted by the browser interface – the address and toolbar. And in the case of remote access to the prototype file, there will be delays when loading pages. That is, the realism of testing will again be reduced. Therefore, such a solution is also best avoided.

Correctly Chosen OS

The interfaces of mobile operating systems are gradually getting closer, but still, iPhone and Android devices differ in interaction patterns. Some important frequency actions in systems occur in different ways. For example, to return to the previous page, the Android user clicks on the triangle in the lower left, and the iOS user clicks on the arrow in the upper left or swipes right.

The usual gestures on a “foreign” system can distort the test results so in order to increase realism (and to avoid customer questions), it is correct to test the application prototype on a smartphone with the operating system for which the application is intended.

Final Thoughts

Having prepared your mobile app prototype for usability testing, you need to improve the usability of the mobile application and then conduct a control test to make sure that the application has actually improved.

Usability testing for a mobile application is important to its overall success with the target audience. A usability audit is recommended both at the prototype stage and after the release of the mobile application. As well as a couple of times a year for the timely elimination of errors and to stay relevant.

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