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Manoel Lucas
Manoel Lucas

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How do you evaluate the quality of your interface?

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Here, in Brazil, it's still common in small and medium-sized companies, especially those in which software development is not the main activity, that software projects are executed without having a design project beforehand. In this way, there is almost never an interface, navigation and user experience planning, which can result in software that is difficult to understand and inefficient.

If this is your reality and there is no designer able to perform the quality control of the developed interfaces (or if you are the designer and still don't perform this task), I bring some criteria that can help you and your team to build better software.

The quality of use criteria serve to assess whether the interface is adequate to what is expected of the software. Some authors indicate usability, user experience, accessibility and communicability as four of the best-known criteria. Of these, usability is usually the most known and used criterion. In addition, the criteria of readability, readability and visual consistency are essential to support design decisions.


Talking about usability is the same as talking about how easy it is to learn, use the interface, and how satisfied users are. Jakob Nielsen, king of usability, defines this criterion through a group of five factors that qualify how good the usability of the software is:

  1. Learnability: how much time and effort is required for the user to learn to manipulate the software;
  2. Memorability: how much time and effort will be required from the user to remember how to manipulate the software;
  3. Efficiency: how much time and effort is required for the user to complete a task correctly, with the help of the software;
  4. Safety: the ability of the software to avoid unwanted situations during its use, and to help the user to recover from them;
  5. Satisfaction: a subjective evaluation that reflects the sentimental and emotional effect that the use of the software has stimulated on the user.

Legibility and Readability

New technologies have expanded the ways of creating typographic fonts and using them in various presentation media. Typographic studies, which for a long time were focused only on printed media, now also cover digital media, such as computer screens, smartphones and tablets. Legibility and readability remain fundamental as quality criteria to provide a good reading experience, regardless of the support used.

Legibility can be considered as the level of clarity of characters in isolation, how quickly the reader can perceive and recognize them. Readability is related to reading comfort, to how easy it is for the reader to be able to read a segment of text without getting tired. A text with good readability and readability is a text that has a good hierarchy of information. This hierarchy must be built with fonts that have good contrast, good spacing between characters and different sizes in different categories (titles, subtitles, body text) to guide reading.

Visual Consistency

The human vision system gets used to recognizing and structuring shapes, colors and objects to construct meanings. This recognition process is called visual perception and is guided by principles widely known as gestalt principles. As people's visual perception is used to being guided by these principles, they should be considered in the software interface design to increase the chances of this interface being perceived and interpreted properly.

We could use seven gestalt principles as the most important for software:

  1. Proximity: close elements are perceived as a group;
  2. Similarity: elements that have a similar appearance are perceived as a group;
  3. Continuity: elements that even disconnected are perceived as a single form;
  4. Closure: it is the perception of a complete form from partially visible elements;
  5. Symmetry: tendency to decompose complex shapes into simpler shapes through symmetry;
  6. Figure/ground: tendency to perceive elements in the foreground or background;
  7. Common fate: coupled with the principles of proximity and similarity, is the tendency to perceive elements that move together as a group.

All these principles work together, making it necessary to think about the interface globally to ensure that all elements are properly perceived by users.


Be sure to pay attention to these quality criteria when planning and developing your software, they are basic rules that can solve complex problems. Don't try to guess what should be done just based on what you've already experienced, the best solution is to study and research, always!

Adapted from the original article, published in portuguese at

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