Page 35 -

4 Chapter 1 What is interaction design?

How does the "marble" answering machine differ from the voice-mail system?

It uses familiar physical objects that indicate visually at a glance how many
messages have been left.
It is aesthetically pleasing and enjoyable to use.
It only requires one-step actions to perform core tasks.
It is a simple but elegant design.
It offers less functionality and allows anyone to listen to any of the messages.

The marble answering machine was designed by Durrell Bishop while a stu-
dent at the Royal College of Art in London (described by Crampton-Smith, 1995).
One of his goals was to design a messaging system that represented its basic func-
tionality in terms of the behavior of everyday objects. To do this, he capitalized on
people's everyday knowledge of how the physical world works. In particular, he
made use of the ubiquitous everyday action of picking up a physical object and
putting it down in another place. This is an example of an interactive product de-
signed with the users in mind. The focus is on providing them with an enjoyable ex-
perience but one that also makes efficient the activity of receiving messages.
However, it is important to note that although the marble answering machine is a
very elegant and usable design, it would not be practical in a hotel setting. One of
the main reasons is that it is not robust enough to be used in public places, for ex-
ample, the marbles could easily get lost or taken as souvenirs. Also, the need to
identify the user before allowing the messages to be played is essential in a hotel
setting. When considering the usability of a design, therefore, it is important to
take into account where it is going to be used and who is going to use it. The marble
answering machine would be more suited in a home setting-provided there were
no children who might be tempted to play with the marbles!

1.2.1 What to design
Designing usable interactive products thus requires considering who is going to be
using them and where they are going to be used. Another key concern is under-
standing the kind of activities people are doing when interacting with the products.
The appropriateness of different kinds of interfaces and arrangements of input and
output devices depends on what kinds of activities need to be supported. For exam-
ple, if the activity to be supported is to let people communicate with each other at a
distance, then a system that allows easy input of messages (spoken or written) that
can be readily accessed by the intended recipient is most appropriate. In addition,
an interface that allows the users to interact with the messages (e.g., edit, annotate,
store) would be very useful.
The range of activities that can be supported is diverse. Just think for a
minute what you can currently do using computer-based systems: send messages,
gather information, write essays, control power plants, program, draw, plan, cal-
culate, play games-to name but a few. Now think about the number of inter-
faces and interactive devices that are available. They, too, are equally diverse: