HCI - Human-Computer Interaction

A program is often judged only on its GUI (rightly or rongly).

there is no method which, when followed, gives a good GUI (and what does 'good' mean?
there are principles and guidelines.

Eg of a set of priciples

user familiarity (see below)
minimal surprise
recoverability
guidance
consistency

e.g of a guideline:
Users can't understand boolean logic


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Goals

The program should assist a user to achieve their goals, e.g:

do a task
easily?
fast?
have fun?

Some form of 'task analysis' is often done.

If goals are not met, the GUI is not suitable.

Users don't always want a 'fancy' GUI (eg.sales processing - paid by speed?)

Interaction Styles

Direct manipulation - uses familiar objects:

calendar
button
...etc

often termed 'desktop metaphor'

...but a GUI based on the real world might be too restrictive
(e.g a computer calendar can scroll over years easily)

Command-line - eg


javac fred.java
java fred

For operating systems:

lots of commands
with many parameters

Unix e.g:


          chmod 600 *.html

Benefits:

preferred by some expert users
we can build-up files containing a series of commands, and execute them with one command.

but - not for novices

Principle of familiarity

you don't have a free hand when designing a GUI
you CAN create new controls (e.g circular volume control knob) but often you stick to those in your toolkit.

There are conventions, e.g:

what is under the File menu, where the help is...
shading of buttons...

(Microsoft publish guidelines on these)

Error messages

slow down the user
can the program handle the error rather than tell the user? (sometimes it can...)

Evaluation

May involve:

statistical tests
video of users
questionaire
'thinking aloud'

Even a limited evaluation may be effective.

Alan Cooper - Mr. VB says...

HCI design is not guesswork
HCI evaluation cannot produce good design.
programs have different patterns of use, e.g Word, an unzipper.
good interfaces are invisible.

Common ground - design patterns

provide a large set of reusable patterns for HCI.

Look at 'Go back to a safe place' in the booklet - have you seen it in use?