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68 Chapter 2 Understanding and conceptualizing interaction

part of the visual display, you then need to consider the consequences of doing this
for the rest of the information that needs to be interacted with. Will it still be possi-
ble to structure the display to show the calendar as days in a week or a month, all
on one screen?
This part of the design process is highly dependent on the context and essen-
tially involves lots of juggling between design decisions. If you visit our website you
can try out some of the interactivities provided, where you have to make such deci-
sions when designing the physical layout for various interfaces. Here, we provide the
background and rationale that can help you make appropriate choices when faced
with a series of design decisions (primarily Chapters 3-5 and 8). For example, we ex-
plain why you shouldn't cram a screen full of information; why certain techniques
are better than others for helping users remember how to carry out their tasks at the
interface; and why certain kinds of agents appear more believable than others.

Assignment
The aim of this assignment is for you to think about the appropriateness of different kinds of
conceptual model that have been designed for similar kinds of physical and electronic artifacts.
(a) Describe the conceptual model that underlie the design of:
a personal pocket-sized calendarldiary (one week to a page)
a wall calendar (one month to a page, usually with a picturelphoto)
a wall planner (displaying the whole year)
What is the main kind of activity and object they are based on? How do they differ
for each of the three artifacts? What metaphors have been used in the design of
their physical interface (think about the way time is conceptualized for each of
them)? Do users understand the conceptual models these are based on in the ways
intended (ask a few people to explain how they use them)? Do they match the dif-
ferent user needs?
(b) Now describe the conceptual models that underlie the design of:
an electronic personal calendar found on a personal organizer or handheld
computer
a shared calendar found on the web
How do they differ from the equivalent physical artifacts? What new functionality
has been provided? What interface metaphors have been used? Are the functions
and interface metaphor well integrated? What problems do users have with these
interactive kinds of calendars? Why do you think this is?

Summary

This chapter has explained the importance of conceptualizing interaction design before try-
ing to build anything. It has stressed throughout the need always to be clear and explicit
about the rationale and assumptions behind any design decision made. It described a taxon-
omy of conceptual models and the different properties of each. It also discussed interface
metaphors and interaction paradigms as other ways of informing the design of conceptual
models.