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| Different
applications have different interface layouts, depending
on what they do. But why is it that word processing packages
all look the same? This is no co-incidence. Interface
designers depend on your familiarity of the genre to help
you learn. Your mental model of what the software can
do matches what it does, and helps you predict what it
can do. Many interface designs use metaphor – the
most familiar to us would be the ‘desktop’,
which has ‘files’ and ‘folders’,
just like the physical desktop in an office. Metaphors
help us to understand what the computer can do, but they
can only go so far. Beyond a certain level metaphors break
down, and software functions have to be learned.
Interfaces
use icons, little symbols that explain a function, like
‘file open’, for example. It’s quite
easy for people to remember pictures, which is why icons
work well for concrete objects, such as tools, files,
messages. But their descriptive power is limited when
the concept is abstract, such as ‘use’ or
‘sort’. Icons, when used in interface design,
have to be clearly understood, and their function has
to be consistent, both within a software package and
between software packages. A magnifying glass should
mean ‘zoom’ no matter what package you use.
Human-computer
interaction is all about cognition. We have to be able
to learn quickly what a software package does and we
have to be able to predict what it can do. Good user
interface design allows us to learn quickly and work
(and play!) quickly. Bad user interface design confuses
us and leaves us frustrated and ready to give up. Throwing
a brick at your computer is also human-computer interaction
– but there’s not much communication going
on!
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Alexander
Muir from the Open University explains usability. |
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