User Centred Design
Overview
User Centred Design (UCD)
•
•
Human centred design processes for interactive systems, ISO 13407
(1999), states: "Human-centred design is an approach to interactive
system development that focuses specifically on making systems
usable. It is a multi-disciplinary activity."
In UCD, all "development proceeds with the user as the center of
focus." (Jeffrey Rubin, Handbook of Usability Testing: How to Plan,
Design, and Conduct Effective Tests) Rubin depicts the User-Centered
Design Process as follows:
– The users are in the center of a double circle.
– The inner ring contains: Context; Objectives; Environment and Goals.
– The outer ring contains: Task Detail; Task Content; Task Organization and
Task Flow.
•
•
•
User-Centered Design (UCD) is a user interface design process that
focuses on usability goals, user characteristics, environment, tasks,
and workflow in the design of an interface.
UCD follows a series of well-defined methods and techniques for
analysis, design, and evaluation of mainstream hardware, software,
and web interfaces.
The UCD process is an iterative process, where design and evaluation
steps are built in from the first stage of projects, through
implementation.
Task Detail
User
Task Flow
•
•
•
•
Context
Objectives
Environment
Goals
Task Organisation
Task Content
User Centred Design
Principles
• Early focus on users and tasks
– Structured and systematic information gathering (consistent
across the board)
– Designers trained by experts before conducting data
collection sessions
• Empirical Measurement and testing of product usage
– Focus on ease of learning and ease of use
– Testing of prototypes with actual users
• Iterative Design
– Product designed, modified and tested repeatedly.
– Allow for the complete overhaul and rethinking of design by
early testing of conceptual models and design ideas.
Source: Jeffrey Rubin, Handbook of Usability Testing: How to Plan, Design, and Conduct
Effective Tests
Jakob Nielsen’s
Ten Usability Characteristics
• Visibility of system status
– The system should always keep users informed about what is
going on, through appropriate feedback within reasonable time.
• Match between system and the real world
– The system should speak the users' language, with words,
phrases and concepts familiar to the user, rather than systemoriented terms. Follow real-world conventions, making information
appear in a natural and logical order.
• User control and freedom
– Users often choose system functions by mistake and will need a
clearly marked "emergency exit" to leave the unwanted state
without having to go through an extended dialogue. Support undo
and redo.
• Consistency and standards
– Users should not have to wonder whether different words,
situations, or actions mean the same thing. Follow platform
conventions.
Jakob Nielsen’s
Ten Usability Characteristics
•
Error prevention
– Even better than good error messages is a careful design which prevents a
problem from occurring in the first place. Either eliminate error-prone
conditions or check for them and present users with a confirmation option
before they commit to the action.
•
Recognition rather than recall
– Minimize the user's memory load by making objects, actions, and options
visible. The user should not have to remember information from one part of
the dialogue to another. Instructions for use of the system should be visible
or easily retrievable whenever appropriate.
•
Flexibility and efficiency of use
– Accelerators -- unseen by the novice user -- may often speed up the
interaction for the expert user such that the system can cater to both
inexperienced and experienced users. Allow users to tailor frequent
actions.
•
Aesthetic and minimalist design
– Dialogues should not contain information which is irrelevant or rarely
needed. Every extra unit of information in a dialogue competes with the
relevant units of information and diminishes their relative visibility.
Jakob Nielsen’s
Ten Usability Characteristics
•
Help users recognize, diagnose, and recover from errors
– Error messages should be expressed in plain language (no codes),
precisely indicate the problem, and constructively suggest a solution.
•
Help and documentation
– Even though it is better if the system can be used without documentation, it
may be necessary to provide help and documentation. Any such
information should be easy to search, focused on the user's task, list
concrete steps to be carried out, and not be too large.
What Is Task Analysis ?
• Task Analysis is used to identify the sequence of tasks required
to complete an activity.
• It involves breaking down tasks into discrete steps, and noting
the order in which they occur.
• This is most useful when designing a new system as the
computerised version should mimic the manual system in the
type of and ordering of tasks as closely as possible, so that
users can easily make the transition to the new computerised
system.
• It should also expose areas of under productivity which a
computerised system could automate.
• Any of the following methods can be used to collect information
about a system:
– Observation (ethnography)
– Interviews with users
– User logging
Task List Development
•
•
•
•
•
•
•
•
•
Identify the steps involved in the task
What information is used for each task?
What affects or causes error in task performance?
What are the good features of the system?
What are the bad features?
What skills are required for each task?
How are these skills acquired?
How are these skills maintained?
How do external factors (time constraints,
environment) affect the task?
• How could you 'improve' the experience of
undertaking the task?
User Classification
• There are 3 main types of user
– Novice
– Knowledgeable / intermittent user
– Expert / frequent user
• Users can however, be classified in any other way that is
appropriate to the system being built.
– Some users may have keyboard skills, others not.
– Some users may have knowledge of other similar systems, others
not.
• The advantages of classification mean that generalisations can
be made about users and their needs.
• This doesn’t necessarily mean that the best system has been
designed for every individual.
• It means that the system has been designed to fit the
generalisations for each user group.
User Classification
Novice
•
•
•
For the novice user of a system, progress is slow because of the
limitations of working memory.
Chunking is almost entirely absent.
Systems used by novices require more feedback and more
opportunities for closure.
User Classification
Guidelines for Novice Users
•
•
•
•
•
•
•
•
•
•
All initiatives should come from the computer – the novice may not know what
is to be done
Each required input should be brief – the shorter it is the more likely it is to be
remembered
Input procedures should be consistent with user expectations – humans search
for patterns and will generalise
No special training should be necessary – especially true in the case of web or
multimedia where the user is ‘on their own’
All system messages should be clear – in the language of the user, not the
designer
User decision should be made from a small set of options – the more of a
selection you offer, the harder it is to choose
Users should control the pace of interaction - they need to understand the
system and feel that they can control it, and not the reverse
User decision making should be a response to a specific request for action –
save - y/n?
Help should always be available – tutor / book / online
There should be sufficient feedback - closure
User Classification
Knowledgeable / Intermittent Users
•
These users need consistent structures, good help facilities, good
documentation.
Expert Users
•
•
•
•
•
These users have fast response time and will require brief feedback.
Experts organise their knowledge according to a higher conceptual
structure.
They can recall more than novices because their knowledge is
chunked.
Expert users will look for keyboard shortcuts, abbreviated sequences.
Experts can find constant confirmation screens irritating - use these
only when important.