Applying Cognitive Psychology to System Development - Fundamentals and Assessment Tools for Occupational Ergonomics - page 518

24.2 Defining the Design Problem: Initial User Studies

Early in the design process, there are a number of questions that need to be asked, including:

. What needs am I trying to serve? From a problem-driven design perspective, what are the short-
comings of the existing products and methods that I am trying to improve upon? What benchmark
tasks should my product support? See Witkin and Altshuld (1995) for a discussion of methods for
conducting such needs assessments
. Who are the potential users I am trying to serve? What are the important defining dimensions that
identify the different populations, such as:
- expected frequency of use
- knowledge of the task domain
- familiarity with other products used for the same or similar tasks
- relevant physical, perceptual, psychomotor, or cognitive abilities
- the importance value of the needs to be served by the product

- the resources the user may be willing to expend to meet these needs (time, money, etc.)
- personal preferences and beliefs that influence the likelihood of purchasing and using the
product
- individual differences that exist along these dimensions?
. For those needs or tasks that are met by some existing product, how is the task currently
performed? See Rubenstein and Hersh (1984) and Preece (1994) for a discussion of how to
complete a descriptive task analysis or cognitive task analysis.
. What are the broader physical, organizational, social, and legal contexts in which the benchmark
tasks will be performed (Flach, 1998)?
. What different combinations of users, needs

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tasks, and contexts actually exist? How can this
representative set of use cases or scenarios be used to avoid cognitive narrowing (Smith and
Geddes, 2003) when making design decisions, making sure that the design accommodates all of
the use cases satisfactorily, rather than focusing on satisfying only a subset? See Carroll (1995)
and Rosson and Carroll (2001) for a discussion of scenario-based design.
. What key constraints should be considered during the design process, including acceptable levels for
- learning rates
- error rates
- productivity
- development time
- manufacturing costs
- marketing constraints
- development and operational costs?
. In terms of design for manufacturability (Helander and Nagamachi, 1992; Bralla, 1998) what
constraints does the design place on the production process?
. As I consider design alternatives, what are the key discriminators that could differentiate me from
my competitors, including possible differences in:
- usefulness
- usability
- aesthetic appeal
- cost
- quality
- durability
- service

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maintenance
- marketing strategy (including market entry time)
- product evolution plan?
. What are the alternative business plans for sustaining this product in the market? What impli-
cations does this have for the design?

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