1. CHAPTER 1: Usability of Interactive Systems
Designing the User Interface:
Strategies for Effective Human-Computer Interaction
Fifth Edition
Ben Shneiderman & Catherine Plaisant
in collaboration with Maxine S. Cohen and Steven M. Jacobs

2. Chapter_1 General Resources User Interface Video Links
Describe three populations of users with special needs. For each of these populations, suggest three ways current interfaces could be improved to better serve them.
Gary Perlman's HCI Bibliography
HCIBIB links to HCI sites
The HCI Bibliography: Most Frequent Authors
User Interface Video Links

3. Introduction
The Interdisciplinary Design Science of Human-Computer Interaction (HCI) combines knowledge and methods associated with professionals including:
Psychologists (incl. Experimental, Educational, Social and Industrial Psychologists)
Computer Scientists
Instructional and Graphic Designers
Technical Writers
Human Factors and Ergonomics Experts
Anthropologists and Sociologists
Devise an outline, consistent with the scientific method, which interface researchers should follow to validate their designs.

4. Key sites with Figures in Chapter 1
Facebook
Ebay auctions
Apple iTunes
Amazon
YouTube
Library of Congress
YAHOO!
Google

5. As noted in the book, some skeptics feel that accommodating diversity requires dumbing-down or lowest-common-denominator strategies. However, the authors claim that in their experience, rethinking interface designs to accommodate these diversity situations will result in a better product for all users. Give an example of a product that meets the specific needs of a certain group of people, yet gives all users a better experience.

6. Reduce Short-term Memory Load
Rule of thumb: Humans can remember 7 +/- 2 chunks of information
Displays kept simple
Multiple page displays should be consolidated
Training if using codes, mnemonics, long sequence of actions
Online access to command-syntax, abbreviations, codes, etc.
Suppose you need to design a system for users in both the United States and Japan. Present a list of cultural differences that you should be aware of so that a successful design can be made.
List several reasons why certain people resist using computers and suggest possible ways to you can alleviate these concerns.
Suggest three usability measures that can be directly used to produce a practical evaluation of a system. Keep the goals of efficiency and satisfaction in mind with these measures.

7. MHP – Working Memory
MHP – Model Human Process
Chunks in WM can interfere with each other due to LTM associations
Robert
Robin
Wing
Bird
Fly

8. MHP – Long-Term Memory
The cognitive processor can add items to WM but not to LTM
The WM must interact with LTM over a significant length of time before an item can be stored in LTM
This increases the number of cues that can be used to retrieve the item later
Items with numerous associations have a greater probability of being retrieved

9. MHP – Processor Timing
Perceptual—The perceptual system captures physical sensations by way of the visual and auditory receptor channels
Perceptual decay is shorter for the visual channel than for the auditory channel
Perceptual processor cycle time is variable according to the nature of the stimuli
Perceptual Processor cycle time = [50-200] msecs

10. MHP – Processor Timing
Cognitive—The cognitive system bridges the perceptual and motor systems
It can function as a simple conduit or it can involve complex processes, such as learning, fact retrieval, and problem solving
Cognitive coding in the WM is predominantly visual and auditory

11. MHP – Processor Timing
Cognitive coding in LTM is involved with associations and is considered to be predominantly semantic
Cognitive decay time of WM requires a large range
Cognitive decay is highly sensitive to the number of chunks involved in the recalled item

12. MHP – Processor Timing Cognitive decay of LTM is considered infinite
Cognitive processor cycle time is variable according to the nature of the stimuli
Motor—The motor system converts thought into action
Motor processor cycle time is calculated in units of discrete micro-movements

13. Human Computer Interface Impression Memory Scheme
Cognition Example: Perception/LTM interaction Read out the colours and time it T1
Human
Computer
Interface
Impression
Memory
Scheme
Motivations for Usability
Life-critical systems:
The FAA's Human Factors Research and Engineering Division
Human Factors at NASA Ames Research Facility
The US Nuclear Regulatory Commission
An introduction to human factors in medical devices
The Army Research Laboratory
Office of Naval Research Human Factors Group

14. Perception Speed: Time it, T2, T1 > T2
Green Purple Orange Red Blue Yellow

15. Memory is Associative
T E C T
Different interpretations, Why?

16. Model Human Processor (MHP)

20. Introduction (continued)
What are the Ramifications?
Success Stories: Microsoft, Linux, Amazon.com, Google
Competition: Firefox vs. Internet Explorer
Copyright Infringement Suits - Apple vs. Microsoft (Windows) and Napster vs. The music industry
Mergers: AOL and Time Warner
Corporate Takeovers: IBM's seizure of Lotus
Privacy and Security issues: identification theft, medical information, viruses, spam, pornography, national security

21. Introduction (continued)
Individual User Level
Routine processes: tax return preparation
Decision support: a doctor’s diagnosis and treatment
Education and training: encyclopedias, drill-and-practice exercises, simulations
Leisure: music and sports information
User generated content: social networking web sites, photo and video share sites, user communities
Internet-enabled devices and communication
Office, home, and entertainment applications:
New York Times online
The London Times online
Yahoo games
PBS Kids games
Movies.com
NetFlix movies

22. Introduction (continued)
Communities
Business use: financial planning, publishing applications
Industries and professions: web resources for journals, and career opportunities
Family use: entertainment, games and communication
Globalization: language and culture
10 principles of Usability in HCI

23. Introduction (continued)
The new “look and feel” of computers (Mac)
NetFlix movies
Internet radio
Google's edited list of links on
Quicken.com
Bluemountain.com greeting cards
Honeywell's site for computer controlled home comfort and security
The International Conference on Ubiquitous Computing
Microsoft Office Multimedia Demos

24. Introduction (continued)
The new “look and feel” of computers (Vista)

25. Introduction (concluded)
And smaller devices doing more…

28. Human Diversity
Physical abilities and physical workplaces:
Utah State Univ - WebAIM Center
Handicapped Access - Trace Institute
Anthropometry and workspace design class handout

31. Book overview Chapter 1: Chapter 2: Chapters 3-4: Chapters 5-9:
A broad overview of human-computer interaction from practitioner and research perspectives
Chapter 2:
Guidelines, principles, and theories
Chapters 3-4:
Managing design processes and evaluating designs
Chapters 5-9:
Interaction styles
Chapters 10-14:
Critical design decisions
Afterword:
Societal and individual impacts of user interfaces

32. Principles of Usability in HCI
Preece, Rogers and Sharp’s Experience Goals
Effectiveness: effective to use
Efficiency: efficeient to use
Safety: save to use
Utility: have good utility
Learnability: easy to learn
Memorability: easy to remember how to use
Cognitive and perceptual abilities:
Neisser's Perceptual Cycle
The effects of fitness level on cognitive processes paper

33. Usability requirements
Objectives
To identify who the end-users of the system will be.
To understand the relevant characteristics of end-users.
To specify usability requirements for the system.
Inputs -- System scope
E.g., context diagram, data flow diagram and/or data model;
System requirements
The critical, functional and non-functional aspects of the system.
User roles
I.e., future roles, if the organization is changing.
Personality differences:
Myers & Briggs Foundation
Big Five Personality Test

34. Usability requirements cont..
Products
User classes
A description of the subsets of the total population of end-users who are similar in terms of their system usage and personal characteristics. Usability requirements
A statement of a usability requirement that the GUI design must satisfy, including;   - what will be measured,
how it will be measured,
what level of measure is required.
Process
Identify user classes Describe the users in each class Identify critical usability requirements Specify measures and performance criteria Define performance levels Review and agree usability requirement specifications
Users with disabilities:
British Telecom: Safe colors for people with color-deficient vision
Improving GUI Accessibility for People with Low Vision
Audio Enhanced 3D Interfaces for Visually Impaired Users
Customized Computer Systems for People with Special Needs

35. Usability requirements (cont.)
The U.S. Human Engineering Design Criteria for Military Systems (1999) states these purposes:
Achieve required performance by operator, control, and maintenance personnel
Minimize skill and personnel requirements and training time
Achieve required reliability of personnel-equipment/software combinations
Foster design standardization within and among systems
Should improving the user’s quality of life and the community also be objectives?
Usability requires project management and careful attention to requirements analysis and testing for clearly defined objectives

36. Goals for requirements analysis
Discover the user’s needs
Determine what tasks and subtasks must be carried out
Include tasks which are only performed occasionally. Common tasks are easy to identify.
Functionality must match need or else users will reject or underutilize the product

37. Goals for requirements analysis
Ensure reliability
Actions must function as specified
Database data displayed must reflect the actual database
Appease the user's sense of mistrust
The system should be available as often as possible
The system must not introduce errors
Ensure the user's privacy and data security by protecting against unwarranted access, destruction of data, and malicious tampering

38. Goals for requirements analysis
Promote standardization, integration, consistency, and portability
Standardization: use pre-existing industry standards where they exist to aid learning and avoid errors (e.g. the W3C and ISO standards)
Integration: the product should be able to run across different software tools and packages (e.g. Unix)
Consistency:
compatibility across different product versions
compatibility with related paper and other non-computer based systems
use common action sequences, terms, units, colors, etc. within the program
Portability: allow for the user to convert data across multiple software and hardware environments

39. Goals for requirements analysis
Complete projects on time and within budget Late or over budget products can create serious pressure within a company and potentially mean dissatisfied customers and loss of business to competitors

40. Usability measures
Define the target user community and class of tasks associated with the interface
Communities evolve and change (e.g. the interface to information services for the U.S. Library of Congress)
5 human factors central to community evaluation:
Time to learn How long does it take for typical members of the community to learn relevant task?
Speed of performance How long does it take to perform relevant benchmarks?
Rate of errors by users How many and what kinds of errors are made during benchmark tasks?
Retention over time Frequency of use and ease of learning help make for better user retention
Subjective satisfaction Allow for user feedback via interviews, free-form comments and satisfaction scales

41. Usability measures (cont.)
Trade-offs in design options frequently occur.
Changes to the interface in a new version may create consistency problems with the previous version, but the changes may improve the interface in other ways or introduce new needed functionality.
Design alternatives can be evaluated by designers and users via mockups or high-fidelity prototypes.
The basic tradeoff is getting feedback early and perhaps less expensively in the development process versus having a more authentic interface evaluated.

42. Article from HCI Paper - Kasper Hornbæk Usability Measure
Hormback, Kasper, 2005, Current practice in measuring usability: Challenge, to usability studies and research, International Journal of Human-Computer Studies, elsevier, Denmark, August 2005,
Usability measures from 180 studies published in core HCI journals and proceedings.
Problems with the measures are:
if they cover usability;
broadly, how they are reasoned about;
if they meet recommendations on how to measure usability.
compare subjective and objective measures of usability
measures of learning and retention;
to study long-term use and usability;
too extend measures of satisfaction beyond post-use questionnaires;
validate and standardize the host of subjective satisfaction questionnaires used;
to study correlations between usability measures as a means for validation;
Conclusion: increased attention to the problems identified and challenges

43. Usability motivations
Many interfaces are poorly designed and this is true across domains:
Life-critical systems
Air traffic control, nuclear reactors, power utilities, police & fire dispatch systems, medical equipment
High costs, reliability and effectiveness are expected
Length training periods are acceptable despite the financial cost to provide error-free performance and avoid the low frequency but high cost errors
Subject satisfaction is less an issue due to well motivated users

44. Usability motivations (cont.)
Industrial and commercial uses
Banking, insurance, order entry, inventory management, reservation, billing, and point-of-sales systems
Ease of learning is important to reduce training costs
Speed and error rates are relative to cost
Speed of performance is important because of the number of transactions
Subjective satisfaction is fairly important to limit operator burnout

45. Usability motivations (cont.)
Office, home, and entertainment applications
Word processing, electronic mail, computer conferencing, and video game systems, educational packages, search engines, mobile device, etc.
Ease of learning, low error rates, and subjective satisfaction are paramount due to use is often discretionary and competition fierce
Infrequent use of some applications means interfaces must be intuitive and easy to use online help is important
Choosing functionality is difficult because the population has a wide range of both novice and expert users
Competition cause the need for low cost
New games and gaming devices!
For example, Nintendo Wii

46. Usability motivations (cont.)
Exploratory, creative, and cooperative systems
Web browsing, search engines, artist toolkits, architectural design, software development, music composition, and scientific modeling systems
Collaborative work
Benchmarks are hard to describe for exploratory tasks and device users
With these applications, the computer should be transparent so that the user can be absorbed in their task domain

47. Usability motivations (cont.)
Social-technical systems
Complex systems that involve many people over long time periods
Voting, health support, identity verification, crime reporting
Trust, privacy, responsibility, and security are issues
Verifiable sources and status feedback are important
Ease of learning for novices and feedback to build trust
Administrators need tools to detect unusual patterns of usage

49. Universal Usability Physical abilities and physical workplaces
Basic data about human dimensions comes from research in anthropometry
There is no average user, either compromises must be made or multiple versions of a system must be created
Physical measurement of human dimensions are not enough, take into account dynamic measures such as reach, strength or speed

50. Universal Usability (cont.)
Screen-brightness preferences vary substantially, designers customarily provide a knob to enable user control
Account for variances of the user population's sense perception
Vision: depth, contrast, color blindness, and motion sensitivity
Touch: keyboard and touchscreen sensitivity
Hearing: audio clues must be distinct
Workplace design can both help and hinder work performance

51. Universal Usability (cont.)
Cognitive and perceptual abilities
The human ability to interpret sensory input rapidly and to initiate complex actions makes modern computer systems possible
The journal Ergonomics Abstracts offers this classification of human cognitive processes:
Long-term and semantic memory
Short-term and working memory
Problem solving and reasoning
Decision making and risk assessment
Language communication and comprehension
Search, imagery, and sensory memory
Learning, skill development, knowledge acquisition, and concept attainment

52. Universal Usability (cont.)
They also suggest this set of factors affecting perceptual and motor performance:
Arousal and vigilance
Fatigue and sleep deprivation
Perceptual (mental) load
Knowledge of results and feedback
Monotony and boredom
Sensory deprivation
Nutrition and diet
Fear, anxiety, mood, and emotion
Drugs, smoking, and alcohol
Physiological rhythms
But note, in any application, background experience and knowledge in the task domain and the interface domain play key roles in learning and performance

53. Universal Usability (cont.)
Personality differences
There is no set taxonomy for identifying user personality types
Designers must be aware that populations are subdivided and that these subdivisions have various responses to different stimuli
Myers-Briggs Type Indicator (MBTI)
extroversion versus introversion
sensing versus intuition
perceptive versus judging
feeling versus thinking

54. Universal Usability (cont.)
Cultural and international diversity
Characters, numerals, special characters, and diacriticals
Left-to-right versus right-to-left versus vertical input and reading
Date and time formats
Numeric and currency formats
Weights and measures
Telephone numbers and addresses
Names and titles (Mr., Ms., Mme.)
Social-security, national identification, and passport numbers
Capitalization and punctuation
Sorting sequences
Icons, buttons, colors
Pluralization, grammar, spelling
Etiquette, policies, tone, formality, metaphors

55. Universal Usability (cont.)
Users with physical challenges
Designers must plan early to accommodate users with disabilities
Early planning is more cost efficient than adding on later
Businesses must comply with the "Americans With Disabilities" Act for some applications
Older Adult Users
Including the elderly is fairly easy
Designers should allow for variability within their applications via settings for sound, color, brightness, font sizes, etc. with less distracting animation

57. Universal Usability (concluded)
Younger users

59. Goals for our profession
Potential research topics
Reducing anxiety and fear of computer usage
Graceful evolution
Specification and implementation of interaction
Direct manipulation
Social media participation
Input devices
Online assistance
Information exploration
Funding for Research
NSF funding for HCI Research

60. Goals for our profession (cont.)
Providing tools, techniques, and knowledge for system implementers
Rapid prototyping is easy when using contemporary tools
Use general or self-determined guideline documents written for specific audiences
To refine systems, use feedback from individual or groups of users
Raising the computer consciousness of the general public
Many novice users are fearful due to experience with poor product design
Good designs help novices through these fears by being clear, competent, and nonthreatening