The design of a thing should indicate how to work it without any need for signs, certainly without any need for trails and errors.
Two of the most important characteristics of good design are discoverability
and understanding. Discoverability: Is it possible to even
figure out what actions are possible and where and how to perform
them? Understanding: What does it all mean? How is the
product supposed to be used? What do all the different controls
and settings mean?
A design of a product should convey the correct message to the end user.
Why this design deficiency?
Because, Most of the designs of a product has been done by engineers who are very good at technology, not good on human behaviors.
We are designing things for people, so should understand both technology and people.
Human Centered Design: The design which meets the needs and requirements of the end user, even though they are unaware of their intentions.
Great designers produces pleasurable experiences.
Affordance: affordance of things. A relationship between people and things.
Affordances determine what actions are
possible. Signifiers communicate where the action should take place.
We need both.
Mapping: Natural mapping
Feedback: Result of an action.
A conceptual model is an explanation, usually highly simplified,
of how something works. A good conceptual model allows us to predict the effects of the actions.