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2.4 Interface metaphors 57

puter interface in terms familiar to them-whether they are computer-phobic or
highly experienced programmers. Metaphorically based commands used in Unix,
like "lint" and "pipe," have very concrete meanings in everyday language that,
when used in the context of the Unix operating system, metaphorically represent
some aspect of the operations they refer to. Although their meaning may appear
obscure, especially to the novice, they make sense when understood in the context
of programming. For example, Unix allows the programmer to send the output of
one program to another by using the pipe (1) symbol. Once explained, it is easy to
imagine the output from one container going to another via a pipe.

Can you think of any bizarre computing metaphors that have become common parlance
whose original source of reference is (or always was) obscure?

Cornrnen t A couple of intriguing ones are:
Java-The programing language Java originally was called Oak, but that name had
already been taken. It is not clear how the developers moved from Oak to Java. Java
is a name commonly associated with coffee. Other Java-based metaphors that have
been spawned include Java beans (a reusable software component) and the steaming
coffee-cup icon that appears in the top left-hand corner of Java applets.
Bluetooth-Bluetooth is used in a computing context to describe the wireless technol-
ogy that is able to unite technology, communication, and consumer electronics. The
name is taken from King Harald Blue Tooth, who was a 10th century legendary
Viking king responsible for uniting Scandinavia and thus getting people to talk to
each other.

Opposition to using interface metaphors
A mistake sometimes made by designers is to try to design an interface metaphor
to look and behave literally like the physical entity it is being compared with.
This misses the point about the benefit of developing interface metaphors. As
stressed earlier, they are meant to be used to map familiar to unfamiliar knowl-
edge, enabling users to understand and learn about the new domain. Designing
interface metaphors only as literal models of the thing being compared with has
understandably led to heavy criticism. One of the most outspoken critics is Ted
Nelson (1990) who considers metaphorical interfaces as "using old half-ideas as
crutches" (p. 237). Other objections to the use of metaphors in interaction design
include:
Breaks the rules. Several commentators have criticized the use of interface
metaphors because of the cultural and logical contradictions involved in accommo-
dating the metaphor when instantiated as a GUI. A pet hate is the recycle bin (for-
merly trash can) that sits on the desktop. Logically and culturally (i.e., in the real
world), it should be placed under the desk. If this same rule were followed in the
virtual desktop, users would not be able to see the bin because it would be oc-
cluded by the desktop surface. A counter-argument to this objection is that it does