Usability of Interactive SystemSession 01

Course : T0593 / Human - Computer InteractionYear : 2012

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Outline• Introduction• Usability Goals and Measures• Usability Motivations• Universal Usability

Introduction• Human-Computer Interaction (HCI) is the discipline

related to the design, evaluation, and implementation of interactive computer systems for use by humans, and studies of the phenomena associated with it. (Definition by ACM SIGCHI)

• Focus: of this course: Design and evaluation of user interface

• User interface is part of interactive computer system that allows human to interact with computer

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Example• The desktop applications are now enabling broad

user communities to prepare user generated content for millions of WWW users

• The web-based social networking and social media applications are accesible through billions of mobile devices

• User-interfaces produce the new ways to work, to compete, to collaborate, to battle in all aspects of the life

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Example• The UPS courier brings no more portable but

wearable computer• The competitors become the partners, e.g. Toyota

and Daihatsu, VW and Subaru• The building walls are great display for animated

advertisment• The user intefaces enable to improve the usability

Usability• According to the ISO/IEC 9126 the usability is a

set of attributes that bear on the effort needed for use, and on the individual assessment of such use, by a stated or implied set of users

• The attributes are understandability, Learn ability, Operability, and Attractiveness

Usability1. Understandability2. Learn ability3. Operability4. Attractiveness

Usability Goals and Measures• The ISO 9241 - The usability goals focus on

effectiveness, efficiency, and satisfaction• Usability measures (5 human factors central to

community evaluation):– Time to learn– Speed of performance– Rate of errors by users– Retention over time– Subjective satisfaction

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Usability MotivationsMany 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

Usability Motivations (Cont.)• Industrial and commercial systems:

– 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

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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

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Usability Motivations (Cont.)• Office, Home and Entertainment Applications

(cont)– 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

(Source: Pearson Addison - Wesley)

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Usability Motivations (Cont.)• Exploratory, Creative, and Cooperative System

– 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

Usability Motivations (Cont.)• Social - technical System

– 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

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Universal Usability• Diversity of human abilities, backgrounds,

motivations, personalities, cultures, and work styles is a challange for interface designers

• Understanding of differences between users is vital for participation by broadest set of users

• Mobile device use has begun to require for designs that are universal usable

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Universal Usability (Cont.)• Rethinking interface designs for different

situations often results in a better product for all users

• The rethinking covers considerations for users with disabilities, older adults, young users, etc and discussion for hardware and software diversity

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Universal Usability (Cont.)• Variation in physical abilities and physical

workplaces• Hundrets of people features: male – female, old –

young, European – Asian, underweight – overweight, tall – short, etc

• There is no average user• Solutions: Compromise (e.g. cellphone keypad) or

multiple version of system (screen-brightness preference)

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Universal Usability (Cont.)• The standard ANSI/HFES 100-2007 Human Factors

Engineering of Computer Workstations (2007) lists these concerns:– Work-surface and display-support height– Clearance under work surface for legs– Work-surface width and depth– Adjustability of heights and angles for chairs and work surfaces– Posture - seating depth and angle; back-rest height and lumbar

support– Availability of armrests, footrests, and palmrests

Universal Usability (Cont.)• Diverse cognitive and perceptual abilities

– 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

Universal Usability (Cont.)– It also suggests 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

Universal Usability (Cont.)• Peronality differences:

– Carl Jung’s Theories of Personality Types conjectured that there were four dichotomies:• extroversion versus introversion • sensing versus intuition • perceptive versus judging • feeling versus thinking

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

Universal Usability (Cont.)• Users with Disabilities:- Designers must early accommodate users with

vision, hearing, and mobility disabilities- There may be keyboard or mouse alternatives,

color-coding, font-size setting, contrast setting, textual alternatives to images, and web features such frames, links, and plug-in

Universal Usability (Cont.)• Older Adult Users:• Understanding the human factor of aging can

help designers to create user interfaces that facilitate access by older adult users

Universal Usability• Children – another community of users is children,

whose uses emphasize entertainment and education

(Source : Pearson Addison - Wesley)

• Even pre-reader can use computer-controlled toys, music generator and art tools

Supporting Materials• www.useit.com/alertbox/20030825.html• www.useit.com/alertbox/20030825.html• www.aw-bc.com/DTUI3/chapters/ch1.html/

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Q & A

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