User-Centered Design and Task
Analysis (Part 1)
Shawnee State University
Department of Industrial and Engineering Technologies
Copyright © 2008 by Janna B. Gallaher
What is User Centered Design
User-centered design (UCD) is an approach to design that grounds
the process in information about the people who will use the
product. UCD processes focus on users through the planning,
design and development of a product.
Four main activities in user centred design:
Specify the context of use
Specify the requirements
Create design solutions
Evaluate designs
Design Approaches
The process of design
Devise concepts and metaphors
Develop screen flow and navigational model
Create low-fidelity prototype designs
Conduct usability testing on low-fidelity prototypes
Create high-fidelity detailed design
Do usability testing again
Document standards and guidelines
Create a design specification
Design Approach: Graphic Design
Balance, Rhythm, Proportion, Dominance, Unity
Design Approach: Alternative System
Development Processes
Lifecycle model (SDLC – system development life cycle)
“One [well-known] study found that 80 percent of software life-cycle
costs occur during the maintenance phase. Most maintenance costs
are associated with “unmet or unforeseen” user requirements and
other usability problems.”
General Steps:
 Evaluate existing system
 Define new system requirements
 Design new system
 Develop new system
 Put new system to use
 Evaluate after implementation
 Maintain system
Various SDLC Methodologies
Waterfall model
Rapid application development model
Joint Application development
Fountain Model
Spiral Model
Build and Fix
Synchronize-and Stabilize
Design Approach: Alternative System
Development Processes
Waterfall model
A sequential software development model in which development is
seen as flowing steadily downward through each phase.
Each phase must be 100% complete before moving on to the next
Phases of the waterfall model:
 Requirements analysis
 Design
 Construction
 Integration
 Testing and debugging
 Installation
 Maintenance
Design Approach: Alternative System
Development Processes
Participatory design
Gives users a voice in the design process
Enables technical and non-technical participants to participate
Provide an opportunity for developers to meet, work with an
understand their users
Provide a forum for identifying issues
Provide an opportunity to get or enhance user buy-in.
Are highly productive
Use techniques which can be easily learned and applied in
future activities.
Design Approach: Alternative System
Development Processes (continued)
Iterative design
User interfaces should be designed using an iterative
approach since almost no interface can be flawless from the
Involves steady refinement of the design based on user
testing and other evaluation methods.
Problems encountered in one iteration are fixed and then
another iteration is evaluated
Design Approach: Task Analysis
The analysis of how a task is accomplished, including a detailed
description of both manual and mental activities, task and
element durations, task frequency, task allocation, task
complexity, environmental conditions, necessary clothing and
equipment, and any other unique factors involved in or required
for one or more people to perform a given task.
Design Approach: Design Specification
A template used to frame the specification
Design Approach: Design Analysis
Objects and actions
As Graphical User Interfaces (GUI) are replacing the text mode
command based languages, the concern is now shifted to the
visual representation and display of the user's tasks objects and
e.g. “...the Object-Action model maps to real life environment. If
you want to move a paper from a folder to another, you simply
start by selecting the paper you will move not by initiating a move
action and then selecting the paper.”
Social Organization and Work
Relates to the human as an interacting social being
Includes a concern with the nature of work
Concerned with the notion that human systems and
technical systems mutually adapt to each other and
must be considered as a whole.
Social Organization: Points of View
Industrial engineering
Concerned with people and systems
Operations research
Using mathematical modeling techniques to characterize systems
Rasmussen's cognitive engineering
Instead of describing what workers should do (normative) or what they
presently do (descriptive), CWA is formative, describing what workers
could do to achieve work purposes.
Aarhus participatory design approach
Social Organization: Points of View
Hewitt's open systems
Carl Hewitt:
Model of a society of experts communicating to supplement
the model of a single very intelligent human being
 http://www.cypherpunks.to/erights/history/actors/AIM-410.pdf
Virtual processors or streams that act as objects which
represent a function or process
 http://dli.iiit.ac.in/ijcai/IJCAI-73/PDF/027B.pdf
Social Organization: Models of Human
Opportunistic planning
Open procedures
Human-Computer Communication