7 Human computer interaction (HCI) Human computer interaction (also known as user interface design) is the study of interaction between users and computers. Interactive computer systems Users initiate some action and system responds with some output System prompts users to do something, and users have to respond with more inputs These interactions take place through the user interface. An Interdisciplinary Design Science: Psychologists, Computer Scientists, Instructional and Graphic Designers, Technical Writers, Human Factors and Ergonomics Experts, Anthropologists and Sociologists
8 User interface design efforts UI accounts for 50% of: Design time Implementation time Maintenance time Code size A killer robot -Myers & Rosson, “Survey on user interface programming”, CHI ’92.
9 Successful applications Windows XP Google Amazon Warcraft etc……
10 Failure in user interface What am I supposed to do now? Where is the information of interest? Where is the information of interest? Vague messages
11 Design for Multiple Devices? Source: www.cs.berkeley.edu/~landay/research/talks/intel-seattle-patterns/patterns-damask-intel2003.ppt
12 Multi-model Humans perceive the world through senses. Touch, Smell, Sight, Hearing, and Taste Communication through one sense in known as a mode. Computer may process information through modes as well Keyboard, Microphone, Camera etc. Multimodal Interfaces try to combine two different modes of communicating.
14 Goals for requirement analysis Ascertain the users’ needs Ensure proper reliability Promote appropriate standardization, integration, consistency and portability Complete projects on schedule and within budget
15 Ascertain 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 Providing excessive functionality is a danger
17 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
18 Promote standardization, integration, consistency, and portability Standardization: Common user-interface features across multiple applications Use pre-existing industry standards where they exist to aid learning and avoid errors Integration: the product should be able to run across different software tools and packages
19 Promote standardization, integration, consistency, and portability Consistency: 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
20 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
22 User-friendliness “user-friendly”: easy to use; easy to learn; comprehensible; intelligible; and etc The notion of “user friendliness” is vague and subjective. Explicit and clear goals are necessary to develop usable systems for specific users in a specific context
23 Usability measures Define the target user community and class of tasks associated with the interface 5 human factors central to usability 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
24 Trade off Trade-offs in design options frequently occur. Learning time V.S. speed of performance Speed of performance V.S. rate of errors New functionality V.S. consistency Design alternatives can be evaluated by designers and users via mockups or high-fidelity prototypes.
25 Applications Different applications may have different usability goals Life-critical systems Industrial and commercial uses Office, home, and entertainment applications Exploratory, creative, and cooperative systems Social-technical systems
26 Life-critical systems Air traffic control, nuclear reactors, power utilities, police & fire dispatch systems High costs, reliability and effectiveness are expected Usability goals: Rapid Error-free performance Lengthy training periods are acceptable Subject satisfaction is less an issue due to well motivated users Retention is obtained by frequent use
27 Industrial and commercial uses Banking, insurance, order entry, inventory management, reservation, billing, and point-of- sales systems Usability goals: Ease of learning is important to reduce training costs Speed of performance is important because of the number of transactions Subjective satisfaction is fairly important to limit operator burnout
28 Office, home, and entertainment applications Word processing, electronic mail, computer conferencing, and video game systems, educational packages, search engines, mobile device, etc. Usability goals: Ease of learning, low error rates, and subjective satisfaction are paramount because use is often discretionary and competition is fierce Choosing the right functionality
29 Exploratory, creative, and cooperative systems Web browsing, search engines, artist toolkits, architectural design, software development, music composition, and scientific modeling systems Usability goals: Hard to evaluate those systems due to the exploratory nature of those applications With these applications, the interface should "vanish" so that the user can be absorbed in their task domain
30 Social-technical systems Complex systems that involve many people over long time periods, such as systems for Voting, health support, identity verification, crime reporting Usability goals: Ease of learning for novices and feedback to build trust Administrators need tools to detect unusual patterns of usage
32 Universal usability Diverse users: physical abilities, backgrounds, motivations, personalities culture, work style and etc Considering interfaces for different situations often results in a better product Curb cut in sidewalks for wheel-chair users Baby strollers, skateboard riders, travelers with wheeled luggage Ultimate goal – addressing the needs of all users
33 Physical abilities Hundreds of features: male and female, young and adult …… Either compromises must be made or multiple versions of a system must be created Keyboard Chair
34 Gender Differences Example: Games for girls Purple Moon SIMS 56 percent of the Sims audience are teenage girls Games for boys
35 Games - SOME INDUSTRY FACTS Seventy-five percent of American heads of households play computer and video games. In 2004, more than 248 million computer and video games were sold, almost two games for every household in America. The average game player is 30 years old and has been playing games for 9.5 years. The average game buyer is 37 years old. In 2005, 95 percent of computer game buyers and 84 percent of console game buyers were over the age of 18. Forty-three percent of all game players are women. In fact, women over the age of 18 represent a greater portion of the game-playing population (28 percent) than boys from ages 6 to 17 (21 percent). In 2004, 19 percent of Americans over the age of 50 played video games, an increase from nine percent in 1999 Females spend an average of two hours more per week playing games now than they did a year ago.
37 Cognitive and perceptual abilities The human ability to interpret sensory input rapidly and to initiate complex actions makes modern computer systems possible In any application, background experience and knowledge in the task domain and the interface domain play key roles in learning and performance
38 Personality differences Personality: Feeling VS. Thinking; Perceptive VS. judging; sensing VS. intuition Different personalities can lead to different behavior: File emails in a well-organized hierarchy Keep them all in the box and use search strategies to find what they want later
39 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 Grammar, spelling Etiquette, policies, tone, formality, metaphors
41 Internationalization of Icons Source: http://www.stanford.edu/class/cs147/
42 Universal Usability (cont.) Users with disabilities 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 Elderly Users Designer should allow for variability within their applications via settings for sound, color, brightness, font sizes, etc.
43 Key points Usability requirements: Ascertain the users’ needs; Ensure proper reliability; Promote appropriate standardization; integration, consistency and portability; and Complete projects on schedule and within budget Usability measures: Time to learn; Speed of performance; Rate of errors by users; Retention over time; and Subjective satisfaction Different applications have different usability goals Diversity is a challenging issue in the interface design
44 Tabbed dialog Source: Interface Hall of Shame
45 A better design Source: Interface Hall of Shame
46 Vague error messages Source: Interface Hall of Shame
47 Inconsistency Source: Interface Hall of Shame