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Mark Pearl


Aims of this Chapter

  • Consider what doing interaction design involves
  • Explain some advantages of involving users in development
  • Explain the main principles of a user-centred approach
  • Ask and provide answers for some important questions about the interaction design process
  • Introduce the idea of a lifecycle model to represent a set of activities and how they are related
  • Describe some lifecycle models from software engineering and HCI and discuss how they relate to the process of ID
  • Present a lifecycle model of interaction design


What is involved in interaction design

Design involves working on requirements, designing a solution, producing the solution and evaluating it.

Design is about trade offs – cost vs. effectiveness etc. and so key to design is generating alternatives.

Involving users and others in design process means that the designs and potential solutions need to be communicated to people other than the original designer. There are many ways of doing this.

The importance of involving users

The best way to make sure that development continues to take users activities into account is to involve real users throughout the development. In this way developers can better understand user goals leading to a more appropriate more usable product. It also assists in setting expectations of the user.

Expectation management is the process of making sure that the users view and expectations of the new product are realistic.

It is better to exceed user expectations than to fall below them.

There are several ways to set user expectations including

  • Involving them throughout the design and developing stages
  • Have timely training

Degrees of user involvement

User involvement depends on what is involved and the nature of the product, on one end of the scale you can have the user involved all the time on the other end of the scale you could keep them informed via newsletters

How actively users should be involved is a matter of debate, too much user involvement can lead to issues and not enough user involvement can lead to poor solutions.

What is a user centred approach

Three principles that lead to a user centred approach

  • Early focus on users and tasks – see goals below
  • Empirical measurement – be able to measure what you are wanting to achieve
  • Iterative design – perform design in small steps

With an early focus on users and tasks it can be further broken down into categories

  • User tasks and goals are the driving force behind the development
  • User’s behaviour and context of use are studied and the system is designed to support them
  • User characteristics are captured and designed for
  • Users are consulted throughout development from earliest phases to the latest and their input is seriously taken into account
  • All design decisions are taken within the context of the users, their work, and their environment

Four Basic activities of Interaction Design

  1. Identifying needs and establishing requirements for the user experience
  2. Developing alternative designs that meet those requirements
  3. Building interactive versions of the designs
  4. Evaluating what is being built throughout the process and the user experience it offers

Some practical issues that need to be considered

  • Who are users?
  • What do we mean by needs?
  • How do you generate alternative designs?
  • How do you choose among alternatives?

Lifecycle models: showing how the activities are related

Some software engineering lifecycle models

  • The waterfall lifecycle model
  • The spiral lifecycle model
  • Rapid applications Development
  • Agile development

Lifecycle models in HCI

  • The star lifecycle model
  • The usability engineering lifecycle
  • Human centred design process for interactive systems

Star Lifecycle Model


Star Lifecyucle Model


  • Does not specify any ordering of activities
  • Activities are highly interconnected
  • Evaluation is central to this model – whenever an activity is complete it must be evaluated

Usability Engineering Lifecycle

Essentially has 3 tasks

  1. Requirements Analysis
  2. Design / Testing / Development
  3. Installation

ISO 13407 Human-centred design processes for interactive systems

International standard for providing guidance on human centred design activities.

Standard identifies four principles of human centred design

  1. Active involvement of users and clear understanding of user and task requirements
  2. An appropriate allocation of function between users and technology
  3. The iteration of design solutions
  4. Multi-disciplinary design

It specifies four human-centred design activities as being central to a system development project:

  1. To understand and specify the context of use
  2. To specify the user and organizational requirements
  3. To produce design solutions
  4. To evaluate designs against requirements


Posted on Saturday, November 5, 2011 7:38 AM UNISA INF 3720 | Back to top

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