chapter 9 the process of interaction design. fundamental activities understanding the requirements...
TRANSCRIPT
Chapter 9
The process of interaction design
Fundamental activities
Understanding the requirements Producing a design solution that satisfies
those requirements Producing an interactive version of the
solution Evaluating the design
User involvement
It is important to involve users in interaction design to ensure a development of usable products and that users will use them
Users’ activities, users’ goals Expectation management Ownership Degrees of user involvement
Expectation management
The process of making sure that the users’ views and expectations of the new product are realistic
Involving users throughout development helps with expectation management because they can see from an early stage what the product’s capabilities are and what they are not
Expectation management
They will also understand better how it will affect their jobs and lives, and what they can expect to do with the product
Users can also see the capabilities develop and understand, at least to some extent, why the features are the way they are
Training is another approach for managing expectations
Ownership
Users who are involved and feel that they have contributed to a product’s development are more likely to feel a sense of ‘ownership’ towards it and be receptive to it when it finally emerges
Degrees of user involvement
Different degrees of user involvement may be implemented Full-time vs. part-time Long-term vs. short-term
Users may be kept informed through Regular newsletters Workshops
What is a user-centered approach?
Three principles that would lead to a “useful and easy to use computer system” (Gould and Lewis, 1985) Early focus on users and tasks Empirical measurement Iterative design
Early focus on users and tasks
Understanding who the users will be (cognitive, behavioral, attitudinal characteristics)
Observing users doing their normal tasks, studying the nature of those tasks, and then involving users in the design process
Early focus on users and tasks
1) Users’ tasks and goals are the driving force behind the development What technologies are available to provide better
support for users’ goals?
2) Users’ behavior and context of use are studied and the system is designed to support them
Early focus on users and tasks
3) Users’ characteristics are captured and designed for
4) Users are consulted throughout development from earliest phases to the latest and their input is seriously taken into account
Early focus on users and tasks
5) All design decisions are taken within the context of the users, their work, and their environment
Empirical measurement
Identify specific usability and user experience goals
Products can be empirically evaluated at regular stages as it is developed, to ensure that the final product is as intended
Iterative design
Iteration allows designs to be refined based on feedback
Iteration is inevitable because designers never get the solution right the first time
Four basic activities of interaction design
Identifying needs and establishing requirements for the user experience Who target users are What kind of support an interactive product could
usefully provide
These needs form the basis of the products’ requirements and underpin subsequent design and development
Four basic activities of interaction design
Developing alternative designs that meet those requirements Conceptual design describes what the product
should do, what it should look like, and how it should behave
Physical design considers the detail of the product including colors, sounds, and images to use, menu design, and icon design
Four basic activities of interaction design
Building interactive versions of the designs Paper-based prototypes Role playing
Four basic activities of interaction design
Evaluating what is being built throughout the process and the user experience it offers Number of errors users make using it How appealing it is How well it matches the requirements
Iteration is one of the key characteristics of a user-centered approach
Some practical issues
Who are the users? What do we mean by needs? How do you generate alternative designs? How do you choose among alternatives?
Who are the users?
Many interpretations of ‘users’ Those people who interact directly with the
product to achieve a task
Holtzblatt and Jones (1993) Those who manage direct users Those who receive products from the system Those who test the system Those who make the purchasing decision Those who use competitive products
Who are the users?
Stakeholders are “people or organizations who will be affected by the system and who have a direct or indirect influence on the system requirements” (Kotonya and Sommerville, 1998)
Stakeholders
The net of stakeholders is really quite wide
It is not necessary to involve all of the stakeholders in a user-centered approach, but it is important to be aware of the wider impact of any product you are developing
Identifying the stakeholders for your project means that you can make an informed decision about who should be involved and to what degree
Who are the users?
The group of stakeholders includes Development team and its managers Direct users and their managers Recipients of the product’s output People who may lose their jobs because of the
introduction of the new product etc.
Example
Design a travel organizer User group: You Stakeholders
People you are going to see Airlines you book flight with Staff in the hotels you might stay at Restaurants on the route chosen for your journey
What do we mean by ‘needs’?
It is not simply a question of asking people, “What do you need?” and then supplying it, because people don’t necessarily know what is possible
Instead, we have to approach it by understanding the characteristics and capabilities of the users, what they are trying to achieve, how they achieve it currently, and whether they would achieve their goals more effectively and have a more enjoyable experience if they were supported differently
What do we mean by ‘needs’?
A user’s characteristics and capabilities may vary and will have an impact on the product’s design Cognitive characteristics Physical characteristics
Size of hands Motor abilities Height Strength
Cultural diversity and experience
What do we mean by ‘needs’?
It is imperative that representative users from the real target group be consulted
New invention – imagine who might want to use and what they might want to do with it
It is always useful to start by understanding similar behavior that is already established
How do you generate alternative designs?
Normally, innovations arise through cross-fertilization of ideas from different applications, the evolution of an existing product through use and observation, or straightforward copying of other, similar products
How do you generate alternative designs?
Alternatives come from looking at other, similar designs, and the process of inspiration and creativity can be enhanced by prompting a designer’s own experience and by looking at others’ ideas and solutions
Design is a process of balancing constraints and constantly trading off one set of requirements with another, and the constraints may be such that there are very few viable alternatives available
How do you choose among alternative designs?
Design decisions will be informed by the information gathered about users and their tasks, and by the technical feasibility of an idea
Two categories of decisions: Externally visible and measurable features Internal system characteristics
External characteristics
Examples: Building – ease of access, amount of natural light
in rooms, width of corridors, number of power outlets
Photocopier – physical size, speed and quality of copying, different sizes of paper it can use
Internal characteristics
Examples: Building – number of power outlets depends on:
wiring within the building capacity of main power supply
Photocopier – choice of materials used in photocopier depends on: its friction rate how much it deforms under certain conditions
Interaction design
External characteristics – users’ viewpoint It does take 30 seconds for the web page to load It does take 1 hour for a cell phone text message
to arrive Internal characteristics – hidden from the
users’ view Technical decisions that influence why it takes 30
seconds for a web page to load
Interaction Design
The tasks that users will perform should influence design decisions no less than technical issues
How do you choose among alternative designs?
We choose between alternative designs by letting users and stakeholders interact with them and by discussing their experiences, preferences, and suggestions for improvement -> Prototyping
Another basis on which to choose between alternatives is ‘quality,’ but this requires a clear understanding of what ‘quality’ means -> Usability engineering
Prototyping
Prototyping involves producing a limited version of the product with the purpose of answering specific questions about the design’s feasibility or appropriateness
Usability engineering
Usability engineering involves specifying quantifiable measures of product performance, documenting them in a usability specification, and assessing the product against them
Lifecycle models: showing how the activities are related
From: www.id-book.com
Lifecycle models in software engineering
Waterfall lifecycle model Spiral lifecycle model Rapid Applications Development (RAD) Agile development
Waterfall lifecycle model
From: www.id-book.com
The opportunity to review and evaluate with users was not built into this model.
Spiral lifecycle model Suggested in 1988 by Barry Boehm Important features:
Risk analysis Prototyping Iterative framework so ideas can be checked and
evaluated Development is driven by risks involved in developing the
system rather than the intended functionality Explicitly encourages considering alternatives
Good for large and complex projects but not simple ones
From: www.id-book.com
Spiral lifecycle model
From: www.id-book.com
Rapid Applications Development (RAD)
Attempts to take a user-centered view and to minimize the risk caused by requirements changing during the course of the project
The ideas behind RAD began to emerge in the early 1990s, also in response to the inappropriate nature of the linear lifecycle models based on the waterfall
Rapid Applications Development (RAD)
Two key features: Time-boxing Joint Application Development (JAD)
Time-boxing
Time-boxing: time-limited cycles of approximately six months, at the end of which a system or partial system must be delivered Breaks down a large project into many smaller
projects Delivers product incrementally Enhances flexibility in terms of development
techniques used and the maintainability of the final system
Joint Application Development (JAD)
Users and developers come together to elicit the requirements of the system
Intensive requirements gathering sessions
A Lifecycle for RAD (Rapid Applications Development)
From: www.id-book.com
Agile Development
Example: Extreme Programming Each iteration is between one and three
weeks A product of value being delivered at the end
of each iteration Customer should be on-site with developers Customer should be an end-user
Lifecycle models in HCI
Star lifecycle model Usability engineering lifecycle
The Star lifecycle model
• Suggested by Hartson and Hix (1989)
• Important features:—Evaluation is at the center of activities, and whenever an activity is completed, its result(s) must be evaluated
—No particular ordering of activities; development may start in any one, provided that you first go through the evaluation activity
—Derived from empirical studies of interface designers
From: www.id-book.com
The Star Model (Hartson and Hix, 1989)
From: www.id-book.com
Usability engineering lifecycle model
Reported by Deborah Mayhew in 1999 Important features:
Holistic view of usability engineering Detailed description of how to perform usability tasks Specifies how usability tasks can be integrated into traditional
software development lifecycles Stages of identifying requirements, designing, evaluating,
prototyping Can be scaled down for small projects Uses a style guide to capture a set of usability goals
From: www.id-book.com
Summary
Four basic activities in the design process1. Identify needs and establish requirements2. Design potential solutions ((re)-design)3. Choose between alternatives (evaluate)4. Build the artefact
User-centered design rests on three principles1. Early focus on users and tasks2. Empirical measurement using quantifiable &
measurable usability criteria3. Iterative design
Lifecycle models show how these are related
From: www.id-book.com