Information Technology Reference
In-Depth Information
Another strength of good interface metaphors is coherence—all of the
elements “go together” in natural ways. Folders go with documents, which
go with desktops. To the extent that this works, the mimetic context is sup-
ported, and people can go about their business in a relatively uninterrupted
way. But there are two ways to fall off the desktop. One is when you start
looking for the other things that “go with” it, and you can't fi nd them. In the
original version of this topic, I mentioned fi ling cabinets, telephones, blot-
ters for doodling and making notes, or even an administrative assistant; to-
day, that would be a terabyte hard drive, Skype, Stickies, and agents like Siri
(whom I would fi re, by the way). I still can't doodle very well on my Mac, but
that's probably about me (and the fact that I don't have a tablet peripheral).
The metaphor may in fact have played some positive role in the develop-
ment of these deskly affordances. The more common way to fall off the desk-
top is to fi nd something on it that doesn't “go with” everything else, thereby
undermining or exploding the mimetic context; for example, a trashcan that
either (1) works to “throw away” fi les
or
(2) works to eject disks or drives:
fundamentally differing operations overloaded on to a single “object.”
1
A third, highly rated strength of interface metaphors is their value in
helping people learn how to use a system. The diffi culty comes in helping a
person make a graceful transition from the entry-level, metaphorical stage
of understanding into the realm of expert use, where power seems to be
concentrated specifi cally in those aspects of a system's operation for which
the metaphor breaks down. In this context, the usefulness of a metaphorical
approach can be understood as a trade-off between the reduced learning
load and the potential cognitive train-wrecks that await down the track.
DESIGN HEURISTIC
Interface metaphors have limited usefulness. What you
gain now you may have to pay for later.
A dramatic notion of representation provides a good alternative to meta-
phor in at least three ways. First, we can effectively represent actions that are
quite novel by establishing causality and probability (the notion of probable
1. The fi x for this in OSX is still clumsy. Dragging the icon for a disk drive towards the trash
icon on the application bar causes the trash icon to change from a trashcan to an “eject” button;
an improvement, but still confusing.
