Projections also intersect with Nielsen's heuristics. Nielsen says that a user-friendly interface takes into account the specifics of the audience that will use it. This will affect the tone of communication, the choice of terms, the choice of icons and images.
Feedback
Feedback is the feedback we receive from the world in a broad sense. The human body is always looking for feedback from the real world - how heavy is it in our hands, what shape is it, is the water cold, is the road slippery, etc. This helps us not only to successfully use things, but also, from an evolutionary point of view, to survive in general.
Feedback must be instant. Otherwise, users will have time to doubt what is happening and make a mistake, load the system with additional signals or simply stop performing the task, using your product and just get angry because it became unclear what is happening.
For example, in my building there are very specific elevators. If you press the 10th floor, they take you to the 9th and then pause a little, i.e. there is no more physical sensation of movement, no engine noise either. People in the know believe that the elevator is "smart" and gets there by inertia whatsapp australia to save electricity. But a person who finds himself in this elevator for the first time manages to start panicking in these few seconds and think that he is stuck in an unfamiliar building.
Feedback should also always be commensurate with the tasks. Too much feedback is also bad - a person either stops responding to it and misses a really important signal, or just gets irritated and may stop using a digital product or thing. A microwave, having finished heating up your food, usually makes one melodic "ding". But my microwave stubbornly beeps 5 times, although it has obviously stopped and there is no problem or danger in the fact that a person may not hear it the first time. This is usually irritating. Of course, you can't change the signal.
Here, too, we can see an intersection with Jakob Nielsen's heuristics. Feedback is essentially the system's status. Nielsen says that the user should understand at any given moment what the system is doing, whether it has frozen, whether the action has been completed successfully, and whether he needs to do anything else.
Conceptual models
A conceptual model is how you imagine the system to work. It doesn't matter whether your conceptual model corresponds to the real explanation of how the system works. What matters is that the interface reflects your model. Even if in reality the system undergoes quantum transitions, and you think that the system is controlled by little people, then the little people should be in the interface.