e.g. UNIX, PASCAL, etc. No prior knowledge on the part of the user need be assumed. Each user
command has one function key related to it. e.g. Scroll bar in a word processor window. With this technique, decisions and choices may be made in any order
the user wishes. Menus are the most important User Interaction Technique - Act by selecting alternatives The techniques vary along the following dimensions. It is generally possible to use
any or all of the different Interaction Techniques to solve a given problem.
Relies on the user having prior knowledge of the language.
A good example of this is the 'page set-up' window displayed to the
user before printing out a document
There are many different types of menu.
e.g. Pull-down menus
Nested Menus
Permanently open tools menus (E.G. Palette in drawing application)
- Options are not always available
- Whilst it is possible to say that there are five distinct types of
Interaction Technique it may also be said that the first four Techniques
are merely extreme cases of menus.
1 - Visibility is one dimension of menus.(e.g.Headers may always be
visible but alternatives may not.
2 - Sequence Constraints: The user may or may not be required to work in
a fixed order
a) Forms may be filled in in any order.
b) Parallel windows can be opened (e.g. Netscape and PASCAL) allowing
the user to move between applications (In any order)
c) In Nested on-screen windows there are sequence constraints. (Cannot
go back to previous decision.)
3 - Error potential : Interaction techniques vary in the amount of error
which a user may be able to make.
a) In a simple pull down menu it may be difficult to make an error but
in command line languages there are a vast number of possibilities which
may lead to error.
b) This issue is not as straightforward as might appear. Errors vary not
just in their frequency, but in their 'damage level'. Accidently
performing an unintended function is not as severe as accidentally
deleting all one's files with the infamous rm * command in UNIX!
4 - Feedback
a) The worst kind of delayed feedback can be seen when using UNIX. User
types in a command and there is a long pause before any response.
b) At the other extreme, if we consider hypercard, it gives feedback
before the major action is even performed.
Another example is that of printers. User must know that they entered
print commands correctly before semantic feedback ( i.e. print set-up form
is displayed BEFORE 'print job being done' message)
5 - Do It Signal The end of a sequence may have to be signalled by a
special action. e.g. In print setup form, User must click on the 'OK' marker to
specify completion. In UNIX user presses return at the end of a command
line.
In Menus releasing the mouse-button completes a selection.
Looking back at input styles, styles tend to differ in whether they
support new users, or experienced users. Anything causing a lot of action
for one effect will slow down the experienced user but helps the new
user.
Also, if there is a fully visible style, it is particularly useful for new
users.
e.g. Setting margins on a document.
1) Command Languages: Invent a mini-language to specify margins
2) Direct Manipulation: Set tags could be used for moving margins
physically
3) Form Filling: User could set absolute limits by filling in a form.
4) Menus: A list of the fixed set of alternatives could be displayed to
the user.
Produced by Angus McGuire, John
Abbott, Tracey Stuart and the delightful Emma Purvis.