And here is the third and last part of the usability heuristics according to Norman Nielsen group. This time it will be about the next block of heuristics- feedback.
This part consists of four heuristics — show status, prevent errors, support error recovery and provide help.
Show status
The system should always keep users informed about what is going on, through appropriate feedback within reasonable time.
One of the places where this principle is violated is the app update on iOS. When there are a lot of app updates , the exact time of the update is never indicated. The user never knows how many times it will last.
During the iOS update, I am also always frustrated, because I never know how many time it will last.
Prevent errors
Even better than good error messages is a careful design which prevents a problem from occurring in the first place. Either eliminate error-prone conditions or check for them and present users with a confirmation option before they commit to the action.
Here it is important to understand the difference between the slip and mistake and to prevent them accordingly. A slip occurs when a user has a right mental model and intention, but unintentionally performs some other task then intended. This article describes how to prevent slips.
A mistake occurs when the user has a false mental model and expects the other outcome from the system that was intended. The other article describes the ways of preventing mistakes and making sure that the users have the correct mental models.
The strategies for preventing slips include:
Include helpful constraints:
For example in the calendar article the invalid dates are not selectable and are grayed out. The return date should be after the departure date.
In twitter, it is not possible a at all to tweet before entering several characters.
Offer suggestions
For example in airbnb during the input of the place it is suggested that you choose the place you have already chosen before.
Choose good defaults
In facebook, there is the possibility to define the group of users who will see the future posts per default. This group is suggested each time when creating a post.
Use forgiving formatting
Using the forgiving formatting allows user to quickly scan the contents of the input or information. Humans can better process information in chunks, so it is better to divide numeric information in parts to make it easily understandable by humans. This input field for IBAN number is better usable if the digit are divided to chunks to easily control them.
In uber, during registration the phone number is automatically broke into the chunks to make it more recognizable.
Strategies for preventing mistakes:
Follow design conventions
Each and every user that interacts with your website or application has been trained by thousands of other designers to expect common interactive elements to look and work a certain way, and error-prone conditions can arise when your website deviates from those conventions.
So it is essential to follow common design conventions, for example google marerial design.
In this tweet the so called “UX muscle memory” is explained with an example.
Communicate affordances:
This attribute of the design that indicated how it can be used is often referred to as the object’s signifier. The affordance itself is the way in which the object can be interacted with (buttons can be pushed, form fields can have typed input added), and the visual cues that communicate this to the user are known as the signifier of the affordance.
For example this element implies that it has to be swiped right to switch between the options.
Preview results
A good style in UX design is to show the preview of results before the user makes an action. This allows to evaluate the decision and to rethink it before an error was made.
The most common example is the print preview before a document is printed.
Strategies for preventing both slips and mistakes:
Remove memory burdens
The user cannot hold large pieces of information in the memory for a long time. The strategy is always to show all the information users need to perform a task. A good approach is to imagine that your users could be interrupted by a phone call after every step in a multistep process.
When searching flights on skyscanner the list shown only the times of flights. The dates are shown only at the top, so when scrolling the dates disappear from the users view. The user may forget which date they entered first.
Confirm before destructive actions
It is important to make the user think twice before executing some critical action.
Support undo
Another important principle is to allow the users to make undo action after certain actions are performed.
In Gmail, it is possible to undo delete while deleting several messages. The undo action appears on the popup message appearing right after deleting the messages.
Warn before errors are made.
Twitter offers great option to see how many characters too much you entered in a tweet. The user sees that the tweet is too long even before trying to tweet it.
Provide help
Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user’s task, list concrete steps to be carried out, and not be too large.
On booking.com the user gets hints on the meaning of the functionalities:
Support error recovery
Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.
Google chrome offers a little game if there is no internet connection- a great application of gamification!
This is an example of very unfortunate error message texting because it is completely not understandable by user.
