By the end of the lesson, you understand that usability is not the same as fast clicking or spectacle. You can recognize problems of system status visibility, consistency, error prevention, and the user's language in a task flow, and you can formulate a justified improvement direction for them.
Why do we need principles?
Even without research we are not completely blind: most usability errors follow recurring patterns. Over decades the profession has developed a few rules of thumb that help to notice typical problems quickly. They do not replace research, but they give useful glasses: if we look at a screen and know what to look for, we find many more errors.
What makes an interface usable?
Usability is the extent to which a task can be carried out effectively, efficiently, and satisfactorily. Three aspects are worth seeing separately:
Effectiveness: does the user reach the goal?
Efficiency: how much time, how many steps, how much effort does it take?
Satisfaction: how do they feel along the way (uncertain, confident)?
We always examine usability in a task. In an administration system, a rare, complicated function can be acceptable if an expert uses it and the risk is high; for a routine task done several times a day, the same number of steps is already a serious burden. There is no "simple" interface in every situation: the question is whether it is understandable in proportion to the task, the person, and the consequence.
Nielsen's ten heuristics
The best-known usability rule set is Jakob Nielsen's ten heuristics. A heuristic here is an empirical rule of thumb: not a law, but a question you can ask at every screen. The table below briefly shows what each one means and what it looks like in Mai program.
#
Heuristic
What does it mean?
Example from Mai program
1
Visibility of system status
The user knows what is happening
After registering, it shows "Your registration has arrived", it does not stay silent
2
Match between system and the real world
Speaks the user's language
"Free" and "Tonight", not "price=0", "date=today"
3
User control and freedom
There is a way back, undo
The registration can be cancelled with one click
4
Consistency and standards
The same thing behaves the same way
Every event card shows the same data in the same place
5
Error prevention
Reduces the chance of error
Already at the field it signals if the email format is wrong
6
Recognition rather than recall
No need to remember
The selected filters are visible above the result list
7
Flexibility and efficiency of use
Good for beginners and experienced users
Saved filters for the returning user
8
Aesthetic and minimalist design
Only the necessary information
The card shows only the data important for the decision
9
Help users recognize, diagnose, and recover from errors
Understandable error message, path to fix
"The event is full. Similar events tonight: …"
10
Help and documentation
Available, short, tailored to the task
A short explanation next to the registration requirement
Source: Jakob Nielsen, 10 Usability Heuristics for User Interface Design (Nielsen Norman Group).
Let us look more closely at those we will also use in the following lessons.
The system status should be visible
Status visibility is signaling what the system is doing and what result it has reached. After saving, the system should not stay silent; during loading it should not seem as if the button did not respond; in a longer process, progress should be perceptible. Status indication is especially important when the user risks time, money, or personal data.
After sending a booking, a "Successful" message is not enough if it does not say what became successful. A stronger feedback: "Your registration has been created: Thursday, 19:30. We sent a confirmation to this email address. You can cancel at the latest 24 hours before." This is not decoration, but the closing of the task.
The user's language and mental model
A mental model is the user's idea of how the system works. The system's internal categories often do not match the concepts in the user's head. On a university site, "credit recognition procedure" may be officially accurate, but a first-year student may be looking for the phrase "counting a previous course". The right label is not a simplification, but a connection between the user's goal and the system's operation.
So do not only ask whether the text is correct. Also ask what a person expects when clicking a label, and how they know they are in the right place. Metaphors must also be handled with care: an icon or name speeds things up only if it builds on a shared meaning. In chapter 5 we will see how to uncover the mental model systematically.
Consistency, freedom, and error prevention
Elements with the same role should behave similarly. If blue, underlined text is a link everywhere, it should not be mere decoration in a single place. If the back arrow takes you back one step, it should not delete the filled-in data along the way. Consistency reduces the learning burden, because the user can apply their earlier experience. Consistency primarily means the same meaning and behavior, not the same look.
Error prevention is reducing the possibility or consequence of an erroneous action. User freedom means there is a safe way back: undo, editing, a saved draft, or a clear exit. This is not possible in every case (for example, a final bank transfer has different rules), but that is exactly why the system must prevent the error before the action. Good error prevention can be a sensible default value, hiding an impossible option or explaining its disabling, or summarizing critical data before submission.
Recognition over recall
Human short-term memory is limited. Do not expect the user to remember an identifier, rule, or amount from a previous screen. The relevant information should be there at the place of the decision. This does not mean that all data must be written out on every screen; the detail necessary for the task must be made available, in a clear grouping.
Heuristic evaluation: how to use it?
A heuristic evaluation is an examination in which one or more professionals walk through the interface based on the heuristics and list the problems. It is quick and cheap, but does not replace a test with users: the professional can also be wrong, and looks at it from a different point of view than the target user. In homework 3 you will carry out a short heuristic evaluation.
Useful steps:
Choose a specific task (for example "registering for an event").
Go through its steps, and at each screen ask: which heuristic does it violate or fulfill?
Write the finding as an observation ("After registering no confirmation appears"), then assign the heuristic (1 – status visibility).
Rate the severity (we detail the severity scale in chapter 8).
Propose an improvement direction, not a finished solution.
Worked example: a failed fee payment in Mai program
When buying a ticket for a paid event, the site signals only: "Transaction failed." The usability problem is not only the brevity of the text. The user does not know whether their card was charged, whether their place was kept, whether they can try paying again, and if so, how. The improvement plan has to handle this uncertainty: a clear status, whether the booking is kept or not, the next step, and available help. The error message thus becomes part of the process, not the end of the process.
According to the heuristics: 1 (status visibility: I don't know what happened with the payment), 9 (recognizing and recovering from errors: no way to fix), 3 (control: I cannot undo or start over).
Common misconceptions
Claim
Clarification
"Fewer elements is always simpler."
If the necessary information is missing, the user makes up for it with an external search or guessing; this is more complicated overall.
"The user made an error, so it is enough to signal it."
The job of the system is to reduce the chance, consequence, and cost of fixing the error.
"Consistency means components that look identical."
Primarily it means the same meaning and behavior.
"Heuristics make testing unnecessary."
A heuristic evaluation is a quick pre-screening; real obstacles are shown only by a test with users.
In brief
Usability is tied to the task, the person, and the consequence: effectiveness, efficiency, satisfaction.
The ten heuristics are rule-of-thumb questions with which typical problems can be recognized quickly.
Status visibility, the mental model, consistency, and error prevention are the backbone of the later lessons.
A heuristic evaluation is pre-screening, not a substitute for user testing.
Review questions
Where in your project do you need to give status feedback?
Which of your internal or professional terms should be translated into user language?
What critical error could you prevent, not just signal afterwards?
Which information do you force the user to remember today?
Which two heuristics does the last app you found annoying violate most often?
Usability principles
Objectives
By the end of the lesson, you understand that usability is not the same as fast clicking or spectacle. You can recognize problems of system status visibility, consistency, error prevention, and the user's language in a task flow, and you can formulate a justified improvement direction for them.
Why do we need principles?
Even without research we are not completely blind: most usability errors follow recurring patterns. Over decades the profession has developed a few rules of thumb that help to notice typical problems quickly. They do not replace research, but they give useful glasses: if we look at a screen and know what to look for, we find many more errors.
What makes an interface usable?
Usability is the extent to which a task can be carried out effectively, efficiently, and satisfactorily. Three aspects are worth seeing separately:
We always examine usability in a task. In an administration system, a rare, complicated function can be acceptable if an expert uses it and the risk is high; for a routine task done several times a day, the same number of steps is already a serious burden. There is no "simple" interface in every situation: the question is whether it is understandable in proportion to the task, the person, and the consequence.
Nielsen's ten heuristics
The best-known usability rule set is Jakob Nielsen's ten heuristics. A heuristic here is an empirical rule of thumb: not a law, but a question you can ask at every screen. The table below briefly shows what each one means and what it looks like in Mai program.
Source: Jakob Nielsen, 10 Usability Heuristics for User Interface Design (Nielsen Norman Group).
Let us look more closely at those we will also use in the following lessons.
The system status should be visible
Status visibility is signaling what the system is doing and what result it has reached. After saving, the system should not stay silent; during loading it should not seem as if the button did not respond; in a longer process, progress should be perceptible. Status indication is especially important when the user risks time, money, or personal data.
After sending a booking, a "Successful" message is not enough if it does not say what became successful. A stronger feedback: "Your registration has been created: Thursday, 19:30. We sent a confirmation to this email address. You can cancel at the latest 24 hours before." This is not decoration, but the closing of the task.
The user's language and mental model
A mental model is the user's idea of how the system works. The system's internal categories often do not match the concepts in the user's head. On a university site, "credit recognition procedure" may be officially accurate, but a first-year student may be looking for the phrase "counting a previous course". The right label is not a simplification, but a connection between the user's goal and the system's operation.
So do not only ask whether the text is correct. Also ask what a person expects when clicking a label, and how they know they are in the right place. Metaphors must also be handled with care: an icon or name speeds things up only if it builds on a shared meaning. In chapter 5 we will see how to uncover the mental model systematically.
Consistency, freedom, and error prevention
Elements with the same role should behave similarly. If blue, underlined text is a link everywhere, it should not be mere decoration in a single place. If the back arrow takes you back one step, it should not delete the filled-in data along the way. Consistency reduces the learning burden, because the user can apply their earlier experience. Consistency primarily means the same meaning and behavior, not the same look.
Error prevention is reducing the possibility or consequence of an erroneous action. User freedom means there is a safe way back: undo, editing, a saved draft, or a clear exit. This is not possible in every case (for example, a final bank transfer has different rules), but that is exactly why the system must prevent the error before the action. Good error prevention can be a sensible default value, hiding an impossible option or explaining its disabling, or summarizing critical data before submission.
Recognition over recall
Human short-term memory is limited. Do not expect the user to remember an identifier, rule, or amount from a previous screen. The relevant information should be there at the place of the decision. This does not mean that all data must be written out on every screen; the detail necessary for the task must be made available, in a clear grouping.
Heuristic evaluation: how to use it?
A heuristic evaluation is an examination in which one or more professionals walk through the interface based on the heuristics and list the problems. It is quick and cheap, but does not replace a test with users: the professional can also be wrong, and looks at it from a different point of view than the target user. In homework 3 you will carry out a short heuristic evaluation.
Useful steps:
Worked example: a failed fee payment in Mai program
When buying a ticket for a paid event, the site signals only: "Transaction failed." The usability problem is not only the brevity of the text. The user does not know whether their card was charged, whether their place was kept, whether they can try paying again, and if so, how. The improvement plan has to handle this uncertainty: a clear status, whether the booking is kept or not, the next step, and available help. The error message thus becomes part of the process, not the end of the process.
According to the heuristics: 1 (status visibility: I don't know what happened with the payment), 9 (recognizing and recovering from errors: no way to fix), 3 (control: I cannot undo or start over).
Common misconceptions
In brief
Review questions