Introduction to User-Interface Design
- enabling technology:
New technological developments become useful for people when they can
master the interaction with these new devices or applications.
User-interface design is a critical factor in the success or failure
of a new technology.
It is not sufficient that the designated task can be performed by means of
a given user-interface.
The actual users of the interface must be able to perform the designated task
using the user-interface, and (learn to) be comfortable with it.
The user-interface enables the user to perform the tasks
a new technology is aimed at.
Following this
link to examples of enabling technology.
- no exact science:
User-interface design is a difficult subject in the study of computing science,
mostly because it not an exact science.
Given a user-interface for a computer application (or for mechanical devices)
there is no mathematical way to prove or disprove that
the interface fits the application and its users.
You cannot prove (mathematically) that a UI is good.
- different tasks and users:
Often a single application program and accompanying user-interface are
intended and used for a variety of tasks.
A program like MS-Word for instance is used for writing simple memos and
letters as well as for writing complex books with many illustrations,
mathematical formulas, tables, etc.
It needs to be usable by novices and casual users as well as by skilled
full-time typists.
Many user-interfaces are used by novices and experts,
and for simple and complex tasks.
- metaphors:
When a mechanical user-interface is to be replaced by a (computerized)
graphical user-interface it helps to use a metaphor that resembles the
mechanical device. Several typical GUI widgets are designed as such,
e.g. buttons and sliders.
However, metaphors can also be misleading, when the visual representation
closely resembles the mechanical device but when some widgets do not have the
same meaning or effect as their mechanical counterparts.
The same problem occurs when a user-interface is made to resemble the
user-interface for another application but similarly labeled widgets
do not activate similar functions.
A graphical representation resembling the mechanical device for which
the user-interface is intended or which it replaces makes the transition
towards a GUI easier.
Follow this link
to examples of the use of metaphors.
- input/output feedback:
A user-interface must provide output for every input, so the user knows
an input-event is accepted and handled.
Many operations are impossible without visual (or other) feedback,
because subsequent user actions depend on feedback about previous actions.
For instance, typing becomes difficult when characters are not echoed
virtually instantly.
Keeping a car on the road on a curved road is impossible when you don't
see where you're going.
- legal issues:
-
When trying to make a new user-interface easy to learn by making it resemble
other user-interfaces (graphical or mechanical) copyright issues come
into play.
Just like individual (plain English) words are not subject to copyright but
a document, poem or book composed of words is,
it is commonly assumed that plain widgets like buttons and sliders may be
copied, but complete user-interfaces or large parts thereof (like a complete
widget layout or a whole menu hierarchy) may not.
However, some artwork in a simple widget like an image-button may be
subject to copyright.
It is not always clear what may be copied from others and what may not.
-
User-interfaces may not endanger the privacy of users.
Although the protection of the users' privacy is for the most part the
task of the application (and not the interface), the user-interface must
ensure that passwords are not made visible on (public) screens,
and that confidential information is passed between the interface and the
application in a secure way (by means of encryption).
The user's privacy must not be endangered by the interface: passwords must
not be displayed; confidential information must be communicated between
interface and application in a secure way.
-
In (life-)critical applications, any confusion caused by the user-interface
may result in considerable damage and possible loss of life.
Both the layout of widgets and the graphical and textual output must
be thoroughly tested to find possible sources of confusion or other
unintentional errors.
Confusing user-interfaces may result in errors that cause considerable
damage and possible loss of life.