Computer Human Interaction
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Usable/Unusable
"We can't actually tell when a website is usable. We
can only tell when a website is unusable." Frustrating is the opposite of usable.
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Frustrating Designs
Why do designers create frustrating sites? There are many website where, given enough patience
and time, any user will eventually figure it out no matter how much pain the user experiences in the process.
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
HumanComputer Interaction: An Overview
In this chapter you will learn about:
The benefits of making a website more usable The history and goals of Human-Computer Interaction The methodology of User-Centered Development
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Introduction
Have you ever been unable to find something in a
website that you know is there? Have you ever been enraged by a useless or misleading error message? Have you ever wondered why a website needs to know your e-mail address, and left the site for fear it might be misused?
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
It doesn't have to be that way
You can design websites that
Are pleasant and convenient for your users Let them accomplish their goals
The key: think about your users
Learn about them Watch them work, in their workplace Interview them, also in their workplace
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Benefits of Usable Web Sites
Gaining a competitive edge Reducing development and maintenance costs Improving productivity Lowering support costs
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Gaining a competitive edge, continued
Conversion rate is the percentage of visitors who
take an action you want them to take, such a making a purchase Increasing the conversion rate lowers the cost of individual sales Ease of use is the most important driver of high conversion rates And there is gold in improving the conversion rate, which was 3.2% in May, 2003
Copyright 2004 by Prentice Hall Chapter 1: Introduction to HCI
Reducing development and maintenance costs
Learn about users first, and you will avoid
Implementing features users don't want Creating features that are annoying or inefficient High cost of making changes late in the development
cycle
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Improving productivity
For e-commerce, productivity means that users find
what they want--and succeed in buying it For a company intranet, productivity means employees become more efficient
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Lower support costs
Calls to customer support are very expensive for the
vendor: estimates range from $12 to $250 per call A website that reduces support calls can save major dollars
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
What is HCI?
"Human Computer Interaction is a discipline
concerned with the design, evaluation and implementation of interactive computing systems for human use and with the study of the major phenomena surrounding them."
As defined by the Special Interest Group on Human-
Computer Interaction (SIGCHI) of the Association for Computing Machinery (ACM)
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
A major cost shift
50 years ago the cost of a computer would pay the
salaries of 200 programmers for a year
People were expected to work hard to save computer
time
Today the salary of one programmer for a year will
buy 200 computers--each vastly more powerful than the early machines
Now the goal is to make computers easy to use, to save
people time
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
How do we make computers easy to use?
By applying the principles of Human-Computer
Interaction By being, as an HCI practitioner, the advocate for the user
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Examples of interactive computing systems
Single PC - capable of displaying web pages Embedded devices, for example in cars and in cell
phones Handheld Global Positioning Systems for outdoor activities Software that allows collaboration
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Goals of HCI
To develop or improve the Safety Utility Effectiveness Efficiency Usability Appeal . . . of systems that include computers
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Safety
Safety of Users--think of
Air traffic control Hospital intensive care
Safety of Data--think of
Protection of files from tampering Privacy and security
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Utility and effectiveness
Utility: what services a system provides; examples:
Information Instruction Purchases
Effectiveness: user's ability to achieve goals;
examples:
Find desired information Enter credit card data
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Utility and effectiveness are distinct
A web site might provide all necessary services, but if
users can't find the items they want to buy, the lacks site effectiveness
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Efficiency
A measure of how quickly users can accomplish their
goals or finish their work using the system
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Usability
Ease of learning Ease of use Can be an entire graduate course!
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Appeal
How well users like the system
First impressions Long-term satisfaction
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
UserCentered Development Methodology
User-centric, not data-centric
Involves users in the design process Usability can be quantified and measured
Highly Iterative
Involves testing and revision
Interdisciplinary and eclectic, building on a dozen
different disciplines
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Fields that HCI builds on
Computer Science
Implementation of website or other interface
Engineering
Faster, cheaper equipment
Ergonomics
Design for human factors
Graphic design
Visual communication
Technical writing
Textual communication
Copyright 2004 by Prentice Hall Chapter 1: Introduction to HCI
Fields that HCI builds on, continued
Linguistics, artificial intelligence
Speech recognition, natural language processing
Cognitive psychology
Perception, memory, mental models
Sociology
How people interact in groups
Anthropology
Study of people in their work settings
A highly eclectic field, obviously, which offers both
challenges and satisfactions
Copyright 2004 by Prentice Hall Chapter 1: Introduction to HCI
The stages of usercentered development
Needs analysis User and task analysis Functional analysis Requirements analysis Setting usability specifications Design Prototyping Evaluation
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Needs analysis
Summarizes the nature and purpose of the system
Type of system (website, video game, spreadsheet) People it will serve Benefits it will provide
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
User and task analysis
User analysis - characterizes the people who will use
the site:
General considerations (age, education, experience with
computers)
Task analysis - what users will do
User's goals - what they want to accomplish Tasks or activities carried out to achieve the goals
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Functional analysis
Functionality or computer services that users will
need and what will be automated
Close correspondence between functions and tasks
Examples: travel site task: "find all flights to xyz,
ordered by price"
Needs search function and sorting capability
Music CD site: task "buy a CD"
Needs secure on-line transaction functionality
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Requirements analysis
Describes the formal specifications required to
implement the system:
Data dictionaries Entity-relationship diagrams Object oriented modeling
Similar to software engineering
Copyright 2004 by Prentice Hall
Chapter 1: Introduction to HCI
Setting ...