Information Technology Reference
In-Depth Information
usability evaluations of in-car computing
devices should incorporate a wide range of
measures relevant to the different levels of
the driving task. For instance, at the strategic
level, observation techniques and surveys
are of relevance, whereas verbal protocols,
interviews and questionnaires can capture the
behaviour of drivers at the tactical level. As
noted by Parkes, such an approach provides
“complete, rather than partial, pictures of
product usability” (p.1445).
instrumentation (e.g. cameras, speed sensors)
whereas subjective data is often captured using
survey or interview-based approaches. Clearly,
such a method provides an ecologically valid test
of a system, and is particularly appropriate to the
late stages of the design process where a robust
prototype is available. Nevertheless, field trials
can be extremely expensive and various ethical
and liability considerations must be accounted for.
An example of a field trial that was carried out in
Sweden concerned drivers' use of intelligent speed
adaptation systems (whereby a vehicle's speed is
automatically kept within the speed limit for the
current area)—Wallen, Warner and Aberg (2005).
There is presently considerable research in-
vestigating specific methods for use in the design
and evaluation of in-car user-interfaces. As noted
by Preece, Rogers and Sharp (2002), in deciding
on any HCI method, the design team must con-
sider the overall goals of the work, specific ques-
tions to be addressed, the practical and ethical
issues and how data will need to be analysed and
reported. For in-car computing, these principles
still hold, and many of the same global techniques
used in the HCI area (for example, questionnaires,
interviews, guidelines/checklists) will be used.
However, by necessity, bespoke methods (or at
least specific versions of generic methods) are
required that account for the particular complex,
safety-critical characteristics of the driving con-
text. The following section summarises key
methods currently used and highlights some of
the important research issues under investigation.
Moreover, primary advantages and disadvan-
tages are given. Table 1 summarises some of the
key issues.
Road Trials
Drivers take part in a short-term (normally less
than one day) focused study using a system in an
instrumented car on public roads (occasionally on
test tracks). For such trials, a wide range of vari-
ables may be measured and analysed (e.g. visual
behaviour, workload, vehicle control, subjective
preference) depending on the aims of the study.
Road trials enable more experimental control than
field trials, but are still potentially affected by a
wide range of confounding variables (e.g. traffic
conditions, weather). Furthermore, such a method
remains costly to implement and requires robust
protocols to ensure the safety of all concerned.
Many road trials are reported in the literature,
particularly concerning information and entertain-
ment/productivity oriented systems. For instance,
Burnett and Joyner (1997) describe a study which
evaluated two different user-interfaces for vehicle
navigation systems.
Field Trials
Simulator Trials
Participants are given a car fitted with an operation-
al system for several months for use in everyday
activities. This method tends to look at broad issues
relating to the long-term use of a system, for ex-
ample, drivers' acceptance of the technology, and
whether any behavioural adaptation effects arise.
Objective data can be measured using on-board
Drivers take part in a short-term (normally less
than one day) focused study using a system fit-
ted or mocked up within a driving simulator. The
faithfulness that a simulator represents the driving
task (known as its fidelity) can vary considerably,
Search WWH ::
Custom Search