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Hi Sonja,
No, I currently have no plans to
write a Modal vs A-Modal article but on the other hand, if there
is demand :-) ....
The issue with Modal vs A-Modal is
one primarily of predicting what the User wants to do and in what
order. This problem becomes more and more difficult as the scale
of a system gets bigger. The more features in a system, the harder
it is to predict who will use it and what they will do precisely.
Going with an A-Modal design allows the designer to delegate that
choice to the user. If you have modal system, the user is linked
into a procedure or process which the designer envisaged for them.
With A-Modal they get to choose for themselves.
There are other more complex issues.
For example, you may have a problem domain and user environment
which involves Users who are frequently interupted and have to
switch tasks often. With a modal system, the user usually has to
complete a task or abort the task before starting another one. An
A-Modal design resolves this issue.
It is true that modal designs are
easier for occasional and inexperienced users. ATM machines use
modal designs. The skill in the design is that the designer must
know when to use Modal procedures e.g. Wizards, in the appropriate
places. I am not against modal designs. In fact I believe that
they are hugely important for usability and design, however, modal
sections of an application must be chosen wisely.
A-Modal design will almost certainly
lead to a smaller development effort. It means that the design is
primarily functional. That is there is screens and menu options
which perform a set of functions. The User is responsible for
choosing which order to execute those functions. Modal design is
procedural. In the same way that Functional Code is more loosely
coupled leading to improved re-use and reduced development effort,
so this is true of screen design. David Ruble correctly identified
this and documented his measure of Window Cohesion in his book
which I reviewed.
A-Modal designs support different
User Roles better and with less development effort. For example, a
set of different Role Players within an organisation may need to
access the same data but for different purposes and in a different
order. An A-Modal design means that one design fits all. With a
Modal design, you would need to develop screens and a storyboard
of screens for each separate Role Player. This may lead to a
simpler to use, faster to learn system, but it is more restricted
and much more expensive to develop.
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