One way to evaluate the quality of the user experience offered by a web interface is to put it to the test against a series of criteria whose relevance is based on expertise and experience. This is the principle of heuristic evaluation, a technique formalized for the web more than 25 years ago!
More than 25 years ago, Jakob Nielsen listed 10 criteria that can be used to perform the heuristic evaluation of a web interface . These well-known criteria are recalled in an article published on the Nielsen Norman Group website , the American user interface and user experience consulting company, founded in 1998 by Jakob Nielsen and Don Norman. Entitled 10 Usability Heuristics for User Interface Design , this article dates from April 1994! However, it remains a reference of its kind for all those who want to use the heuristic method to evaluate the quality of a web interface (it is also the most popular article on the site). Of course, as its author also reminds us, this list is not a substitute for a more in-depth analysis or even for a list of detailed and formalized guidelines. It is a global evaluation tool that can be used in the field of user experience (for example as part of a UX audit process) in the same way as many others.
#1 Give feedback to your users ("Visibility of system status")
In concrete terms, this means that The interface must inform the user at all times about the status of the actions he or she performs on this interface. For example, if they have sent a form, they must be conspicuously served with a message indicating that the form has been sent (e.g. with a text message). Same thing, if the user clicks on "add to cart" or "log in", he must be informed that this action has been taken into account and he must "see" this concrete consideration (for example with a number next to the cart icon or a progress bar indicating a page load). Of course, your feedback must make sense to the user and above all be related to his actions. Thus, there is no need to inform them that the CMS that your interface uses to manage content has been updated.
Let your users know that their actions are being taken into account
#2 Use the codes of real life ("Match between system and the real world")
This criterion considers that An interface is well designed as long as it uses the communication codes that the user otherwise uses in the real world (as opposed to the digital world). So if you're looking for a button title that allows you to perform a specific action, start by asking yourself how you would make that action understood in the real world.
Also note that the transposition from one world to another is not as complicated as one imagines. A supermarket basket and a virtual basket represent the same action (collecting material or virtual goods with a view to buying them). Also note that beyond the words, the choice of icons or colors also have a transposition into the real world. In nature, red is equated with danger. In your interface too, a red link should have a meaning of this type.
An error message written in a language that has nothing in common with everyday language
#3 The user must be able to control the system ("User control and freedom")
A well-designed interface is An interface that allows the user to undo or undo an action at any time . This criterion incorporates what is commonly called the right to make mistakes. Indeed, a user has the right to make mistakes. Whatever the reason, it is necessary to offer him solutions that allow him to exercise this right to make mistakes. For example, the possibility of emptying your basket. If you don't, there is little chance that the user will return to your interface because they will know that they will not be free to their actions.
Always give the user the choice to undo or undo an action
#4 Don't stray from the beaten track ("Consistency and standards")
Since the web has existed, users have developed a certain number of more or less immutable usage habits on interfaces. This is how a certain number of norms or standards have been put in place little by little, establishing a kind of intrinsic logic specific to any interface. Example: a call to action will be materialized by a colored rectangle. The thumb icon, also popularized by Facebook, has become a standard to indicate that you like content. Comply with the major standards and conventions in force , this is the 4th heuristic factor stated by Nielsen.
#5 Prevention is better than cure
The well-known adage corresponds to this 5th criterion, which states that A web interface has every interest in anticipating the user's mistakes as much as possible before they make them. What for? Because by doing this, you save your user's time for action, avoid their anger or frustration and on the contrary increase their satisfaction (and therefore their desire to use your interface again). By offering a system that allows you to suggest predefined queries, search engines anticipate, for example, users' spelling mistakes. You get it: this 5th criterion implies having tested your interface from top to bottom to minimize counterproductive scenarios for your users.
#6 Recognition rather than recall
To understand this principle, take the case of drop-down lists that allow you to choose a different font (for example in Word or Photoshop). What do you notice? The name of each available font is written in the corresponding font. In the end, to choose your typeface, you will therefore base yourself on the visual rendering of it rather than its proper name. Apply this principle to your interfaces and you will see that you will gain in usability. Here again, the principle of economy of our brain arises in this 6th heuristic criterion. When confronted with a group of individuals, it is easier (more economical) to recognize someone by their face than to remember their name.
#7 Address as many people as possible ("Flexibility and efficiency of use")
Not all of your users have the same skill level. Some are experts, others beginners. Therefore, you will need to offer an interface that meets a wide level of expertise. How? For example, by offering advanced options for expert users. Or keyboard shortcuts. They will thus be able to express their level of use in accordance with their skills. In short, design your interface in a flexible way, with solutions that are aimed at as many people as possible.
#8 Aesthetic and minimalist design
“ Communicate, don't decorate ”. This is the principle enacted by the 8th heuristic commandment elaborated by Nielsen. What exactly does it tell us? The design of an interface should, as far as possible, be free of any graphic element or process that does not provide any useful information for the user. In design, all these irrelevant elements are often referred to as "noise". Thus, the addition of a color to a text must make sense, that is, the use of this specific color in this specific place contains a meaning and does not only have an aesthetic meaning. If you can justify the graphic choices in functional terms, then your design is meaningful to the user. And therefore a good indicator of the UX quality of your interface.
Google, or the expression of functional minimalism par excellence
#9 Clear, visible and solution-oriented error messages
Despite all the efforts you make to manage error message prevention, you will inevitably have cases where the error messages in question will arise. In this case, the basic principle is to clearly indicate this error to the user by displaying it in a visible way, in a language that is understandable to him and finally, guiding him to how to correct this error . As in life, it is possible to point out the error in a humorous way (e.g. a creative 404 page) so as not to create a negative emotion in the user. And if you explain to him how to correct his mistake by himself, you will even arouse a form of satisfaction in him.
#10 Offer your help ("Help and documentation")
A well-designed interface should be aimed at as many people as possible, remember? (cf. criterion 7). Therefore, a good interface should always have a Help part, even in an ideal world. Of course, it may seem tedious and cumbersome to offer such a solution, but again, think of lost users who may well need to work on some tips on how to get started, for example. There are many possibilities in this area to make the experience as "painless" as possible. For example, by offering video tutorials or FAQs.
A question of common sense!
In many ways, these 10 Nielsen heuristic criteria seem disconcertingly simple as they seem to stem from obvious common sense. However, we realize that most of the web interfaces we use rarely meet all these criteria and sometimes even less than 50% of them. In doing so, we thought it would be interesting to refresh our memory in order to re-discover these major general principles of design, a kind of 10 commandments of user experience.
