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As described at the start of this chapter, design is an iterative cycle
of understanding, creating, and evaluating. Understanding begins
with observations of people, task analysis, and knowledge of human
characteristics. This understanding informs the creation of
mockups and prototypes, which are immediately evaluated as designers
and users experience their creations. We have seen that the
human factors specialist performs a great deal of informal evaluation
during the systemdesign phases. These evaluations produce
a deeper understanding of the design problemwhich leads to revisions.
More formal evaluations are also required. These evaluations
must carefully assess the match of the system to human capabilities,
as well as the ability of the systemto support the tasks of the
person. Chapter 3 describes evaluation methods in detail.

Y Informal evaluation guides
the iterative design, but formal
evaluation is needed
to ensure design objectives
have been met

2.6 Summary

In this chapter we described some of the techniques used to understand
user needs and to create systems to meet those needs.
Designers who skip the front-end analysis techniques that identify
the users, their needs, and their tasks risk creating technologycentered
designs that tend to fail. The techniques described in
this chapter provide the basic outline for creating human-centered
systems: develop an understanding of people’s needs through observation
and then test that understanding with prototypes that
can be quickly adjusted to better meet people’s needs. A critical
step in designing human-centered systems is to define the human
factors requirements. Many of these requirements depend on cognitive,
physical, and social considerations.

“Indifference towards people
and the reality in which they
live is actually the one and
only cardinal sin in design.”
(D. Rams) [46]

Additional Resources

One of the best resources for task analysis is Guidebook to Task
Analysis [53], which describes 41 differentmethods for task analysis
with detailed examples. For a more general set of designmethods
an excellent source is Universal Methods of Design: 100 Ways to
Research Complex Problems, Develop Innovative Ideas, and Design
Effective Solutions [54], as is Guide toMethodology in Ergonomics:
Designing for human use [41].

TaskArchitect is a computer-based tool for implementing some
of these tasks analysis methods (http://www.taskarchitect.com).
Human factors specialists usually rely on many sources of information
to guide their involvement in the design process, including
previous published research, data compendiums, human factors
standards, and more general principles and guidelines.

Data compendiums provide detailed information concerning
human factors aspects of system design. One example is the fourvolume
publication by Boff and Lincoln [55], Engineering Data
Compendium: Human Perception and Performance.

Human Factors design standards are another formof information
to support design. Standards are precise recommendations
that relate to very specific areas or topics. One of the commonly
used standards in human factors is the Human Engineering Department
of Defense Design Criteria Standard MIL-STD-1472G [56].
This standard provides requirements for areas such as controls,
visual and audio displays, labeling, anthropometry, workspace design,
environmental factors, and designing for maintenance, hazards,
and safety. Other standards include the ANSI/HFES-100 VDT
standard and the ANSI/HFES-200 ANSI/HFES 200 Human Factors
Engineering of Software User Interfaces [57].

Human Factors principles and guidelines provide more general
information than standards. Standards do not provide solutions
for all design problems. For example, there is no current
standard to tell a designer where to place the controls on a camera.
The designer must look to more abstract principles and guidelines
for this information. Human factors principles and guidelines
cover a wide range of topics, some more general than others.
Rams, Nielsen, and Tognazzini provide general principles for
design [46, 47, 48], and Van Cott and Kinkade provide human factors
guidelines for equipment design [58]. The following chapters
reference specific guidelines related to physical facilities medical
devices, and vehicle design.