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CHAPTER

Working with human 15

subjects

15.1 INTRODUCTION
Research into human-computer interaction (HCI) almost invariably involves the par-
ticipation of human subjects. Whether you are running a focus group, leading a col-
laborative design process, running a controlled study, or conducting an ethnographic
investigation, you need to engage people in your work.
Although this may sound simple, it isn't. As anyone who has done so can tell you,
working with human subjects involves many challenges. Finding the right subjects is
often difficult and time consuming, especially for evaluation of systems designed for
specific populations or situations.
The real fun can begin when the subjects are ready to begin participating in your
study. Research ethics require that participants must be treated fairly and with re-
spect. This means that they must be provided with information about the nature of
the study, which they can use to make a meaningful decision as to whether or not they
really want to be involved. This notion of informed consent is a critical component of
modern research on human subjects.
Although some of the details may differ, the general challenges involved in find-
ing and informing research subjects apply to any form of research involving human
participants, regardless of the type of person involved. The additional challenges that
online research presents in each of these areas are described in Section 15.3 and in
Chapter 16. Although different research communities may have a preference for one
or the other, this chapter uses the terms subject and participant interchangeably.

15.2 IDENTIFYING POTENTIAL PARTICIPANTS
You've just built a novel two-handed interface for an architectural modeling tool. Your
design allows users to use one device in their dominant hand to draw lines while a sec-
ond device can be used to pan and zoom, allowing easier and more fluid construction
of lines and boundaries. Having implemented a prototype supporting these capabili-
ties, you'd like to run some usability tests to see how well your ideas work in practice.
This leaves you with a problem: who should participate in your study? There are
plenty of potential users with two hands, but having the physical ability to manipulate
your tool is just a start. People without the appropriate training and experience will
be unable to tell you if your tool succeeds in its primary goal—supporting the work

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