01- usability of interactive...

01- Usability ofInteractive Systems

COMP 388/441 HCI: 01 - Usability of Interactive Systems

HCI: General Motivation/Overview

Early computers were only usable by experts withstrong technical knowledge and not by average users(with limited technical knowledge)

UI designers combine technical knowledge withsensitivity to human needs and capacities

Consequently: HCI is strongly interdisciplinary HCI is a combination of: Psychology, Computer

Science, Graphic Design, Human Factors/Ergonomics,Anthropology, Sociology, Economy, Law, etc.


Lecture 01 - Overview


Usability Goals/RequirementsWhat to do? Introduces 4 (sets of) goals that should be pursuedwhen developing UIs (e.g., ascertain users’ needs, promoteconsistency, etc.)

Usability MeasuresHow to measure success? Introduces some usability measures thathelp to determine the effectiveness of the product in regard tousability (e.g., time to learn, rate of errors, etc.)

Usability MotivationWhy care at all? Provides some motivational aspects for HCI (e.g.,life critical systems, sociotechnical systems, etc.)

Universal UsabilityHow to cope with diversity of users? Discusses challenges thatface UI designers in regard to diverse user groups/communities (e.g.,different physical abilities, cultural differences, etc.)

UsabilityGoals/Requirements


Usability Goals/RequirementsOverview

When developing UIs you need to focus on qualityfeatures such as usability, universality, usefulness

UI designers must have a thorough understanding ofthe diverse communities of users and the tasks thatthey need to accomplish

Explicit goals are needed that help to ensure usability: Ascertain users’ needs Ensure proper reliability Promote appropriate standardization, integration, consistency,

and portability Complete projects on schedule and within budget


Usability Goals/Requirements (1)Ascertain users’ needs

Users’ needs ≈ the tasks and subtask that the userneeds to carry out when using the UI/product

Perform a task analysis: This will help to discover alsoinfrequent and exceptional tasks

Add appropriate extent of functionality (inadequate vs.clutter); possibly hide infrequently used functions butmake sure that advanced users can access themeffortlessly if required (e.g., calculator with differentviews for basic and scientific use)

Note: The target audience/user community is aninfluential factor in regard to the extent of functionalitythat you should offer


Usability Goals/Requirements (2)Ensure proper reliability

All actions that the user takes must reflect appropriateresults; presented information must be accurate

If you do not provide this kind of reliability users willquickly loose trust in your application and stop using it

It is important to use hardware, software, and/orarchitectures that support this kind of reliability (e.g.,high availability in networked applications)

Finally, consider privacy, security, data integrity, andthe possibility of malicious tampering


Usability Goals/Requirements (3)Promote appropriate standardization

Standardization ≈ use of common UI features acrossmultiple applications

Especially important with increasing number ofavailable applications and users

Standardization can be immensely beneficial Reduced learning time (≈ e.g., lower costs for businesses) Reduced error probability and frequency Reduced development time/costs

Example for desktop environments: Apple Computers,Microsoft Windows

Example in regard to human factors: ISO 9241:“Ergonomics Requirements for Office Work with VisualDisplay Terminals”


Usability Goals/Requirements (3)Promote appropriate integration

Examples: Unix “piping”-concept enables differentapplications to work together (e.g., who | lpr);compatibility across MS Office applications allows easyinformation exchange

You should consider similarities/relations in applicationsand make such exchange possible

Even tough “integration” does not immediately appearto be UI-related it is very important in this context as itinfluences the functionality and usability of yourapplication

It should be part of the UI designer’s responsibility torecognize such potentials and communicate it to otherproject members


Usability Goals/Requirements (3)Promote appropriate consistency

Consistency ≈ use of common action sequences, terms(e.g., “cancel” vs. “abort”), colors, font sizes, buttonsizes, data formats, etc.

3 scopes of consistency: Be consistent within one application Be consistent within related applications/application packages Be consistent within different versions of one application


Usability Goals/Requirements (3)Promote appropriate portability

Portability ≈ the potential of sharing an interface and thedata that is associated with it between multipleplatforms (i.e., software/hardware)

Some challenges are different display sizes,resolutions, interaction devices, web-browser features,data formats (e.g., “PDF” vs. “WORD-doc”)

Always assume that your UI may be used in variousheterogeneous environments

Sometimes the kind of target system is governed bycustomer requirements (e.g., an Intranet applicationwhere all users are required to use IE 5.5)

Use GUI Frameworks/APIs (e.g., Java Swing) and dataformats (e.g., XML, PDF) that support portability


Usability Goals/Requirements (4)Complete projects on schedule and within budget

Certainly a general goal for all software projects Sometimes UI designers forget about this goal,

however it is as crucial to UI design as it is to otherparts of the software development process

Every delay or increase in costs will affect your projectin one way or the other (e.g., the client switches toanother product)


Usability Measures


Usability MeasuresOverview

Assuming that the discussed usability goals areknown and applied, how can we determine that wesucceeded, how can we measure usability?

Use a set of well defined criteria/measures that helpto determine the effectiveness and usability of your UI

Note: This process varies based on different usercommunities, user expectations and tasks

This observation requires to follow 2 steps in yourevaluation process

1. Determine your communities and the set of tasks that youneed to benchmark

2. Define precise objectives for each task and community. Thiswill guide the evaluation process


Usability Measures5 Aspects

1. Time to learnHow long does it take a typical member of your user communityto learn how to use the UI in order to perform the defined tasks?

2. Speed of performanceHow long does it take to perform the benchmark tests?

3. Rate of errors by usersHow many and what kind of errors do users make in carrying outthe benchmark tasks? (Note: This is related to “speed ofperformance”)

4. Retention over timeHow well do users maintain their knowledge of how to useyour UI? (Note: This is related to “time to learn”)

5. Subjective satisfactionHow much did users like the UI or certain aspects of it?


Usability MeasuresConclusion

Commonly it is tough to perform equally well in all ofthe 5 objectives; there are trade-offs

Example: The use of shortcuts or abbreviationsincreases the time to learn but also increases thespeed of performance

You need to determine which of the 5 measures aremost important for your specific project andcommunity

Do not hesitate to communicate specific UI designgoals/objectives and the respective trade-offs toproduct managers and/or clients (e.g., if speed ofperformance is crucial, emphasize that the operationalproductivity of the UI will be better in favor of possibly longerlearning times)


Usability Motivation


Usability MotivationOverview

Many current UIs are still designed poorly However, well-designed UIs can bring great benefits

to the user and other stakeholders There are 5 distinct groups of systems/applications

that each have distinct characteristics and that eachprovoke specific motivational aspects for usability

1. Life-critical systems2. Industrial and commercial applications3. Office, home and entertainment applications4. Exploratory, creative and collaborative applications5. Sociotechnical systems


Usability MotivationLife-Critical Systems

Example: Air-traffic control, medical instruments,nuclear reactor control, etc.

Characteristics High costs are expected and accepted High reliability and effectiveness is a must Time-to-learn is commonly high High speed of performance and low error rates are crucial Subjective satisfaction is of less importance (we deal with

well-motivated professionals) Retention is obtained by frequent use and intensive practice


Usability MotivationIndustrial and Commercial Applications

Example: Banking software, inventory managementsystems, human resource management software(e.g, SAP, PeopleSoft), etc.

Characteristics Costs are a very important factor Reliability and operational efficiency is important but not as

crucial as it is with life-critical systems Time-to-learn should be low (as it lowers the costs) Speed of performance needs to be high (faster operating

speed potentially increases the organization’s profit) However, error rates should be low (trade-off with speed) Subjective satisfaction is of less concern After an initial training period, retention is obtained by very

frequent use


Usability MotivationOffice, Home and Entertainment Applications

Example: Email, word processing, games, mobilephone applications, etc.

Characteristics Should be easy to learn Should have low error rates Should be produced at low costs (due to high competition) Subjective satisfaction is important Retention should be supported by use of “easy-to-remember”

procedures and online-help Some critical issues: High competition, commonly

quick user frustration, use frequencies sometimesvery low, very diverse communities, choosingadequate extent of functionality is difficult


Usability MotivationExploratory, Creative and Collaborative Applications

Examples: WWW, search engines, music compositionsystems, architectural design systems, Wikis, Blogs,“Google Documents”, etc.

Characteristics User is commonly familiar with the task domain Motivation is high Expectations are high Usage-rate: occasional to frequent

Challenge: It is hard to describe/define benchmarktests because of the exploratory nature of theseapplications; in general: such applications are difficultto design and evaluate!


Usability MotivationSociotechnical Systems

≈ complex systems that involve many people,possibly over a long period of time

Example: Voting System, ID Verification System Such applications are often created by governmental

organizations Characteristics

Trust, privacy, and responsibility issues are very important It is also important to reduce chances of malicious tampering

or provision of incorrect information Need to provide appropriate feedback (e.g., voting system) Users may be extremely diverse Ease of learning is crucial (we commonly deal with many

novice and inexperienced users)


Universal Usability


Universal UsabilityOverview

Deals with diversity of users (e.g, physical abilities,cultural aspects, personal differences, etc.) but alsowith diversity of hard- und software systems

Diversity is accompanied by a variety of challenges 8 important user groups/issues

1. Physical abilities/physical workplaces2. Cognitive and perceptual abilities3. Personal differences4. Cultural and international diversity5. Users with disabilities6. Senior citizens7. Children8. Differences in soft- and hardware


Universal UsabilityPhysical abilities/physical workplaces

There is no average user (statistically there is, but notfrom a HCI standpoint)

Users are different in their physical abilities (e.g., armlength, size of fingers, strength of vision)

UI designers must either make compromises orprovide different versions or possibilities foradjustment (e.g., font size increase via “+”)

The nature of interaction devices (they are part of theUI) is also influenced by diverse physical abilities andworkplaces (e.g., keyboard design)


Universal UsabilityCognitive and perceptual abilities

You must understand the cognitive and perceptual abilities ofyour target group/user community

A classification of human cognitive processes provides the UIdesigner with a framework

Short-term and working memory, long-term and semantic memory Problem solving and reasoning, decision making and risk

management Language communication and comprehension Search, imagery, and sensory memory Learning, skill development, knowledge acquisition

Other factors that affect perceptual and motor performance are,for instance, monotony and boredom, fear, anxiety, mood, andemotions

Naturally, background experience and knowledge in the taskdomain influence the learning process and the user performance


Universal UsabilityPersonal differences

Different people have different preferences in usingcomputers (e.g, DM vs. command language)

The UI designer needs to understand the differentpersonalities. This helps to design successful UIs forspecific user groups

Problem: It is hard to specify a taxonomy forpersonality types; in other words, “personality” is hardto classify

3 possible ways (Note: None of these is a “silverbullet” approach, they need to be applied with care):

MBTI (Myers-Briggs Type Indicator) Big-Five-Test (≈ successor of the MBTI) Studies of user behavior


Universal UsabilityCultural and international diversity

Includes issues such as race, cultural, linguistic, andethnic backgrounds

Example for cultural differences: color “black” vs.“white” as an association with death

Globalization is an important factor in promoting theneed for adapting UIs to different cultures etc.

Some specific issues/examples: Characters, numbers, special characters (e.g., ß, §) Horizontal “right-to-left” and “left-to-right” vs. vertical “top-to-

bottom” reading Date and time formats (e.g., dd.mm.yyyy vs. mm/dd/yyyy) Address formats (e.g., “ZIP city” vs. “city, ZIP”) Numeric and currency formats (e.g., “.” vs. “,” as decimal

delimiter)


Universal UsabilityUsers with disabilities

In the U.S., federal agencies are required to ensureaccess to IT by employees and the public. Thisincludes an emphasis on users with disabilities

Examples: Vision impaired (provide different font size & color, screen

size, resolution, offer text-to-speach conversion, voice over) Hearing impaired (provide alternatives, for instance, text) Mobility impaired (provide different kinds of interaction

devices, for instance, a virtual keyboard) It is crucial to pay attention to such issues; commonly

the earlier they are recognized the less costly it willbe to implement the appropriate functionality

Finally: If you develop UIs for the government, it is amust to consider these issues


Universal UsabilitySenior citizens

Becoming older may have a negative impact on physical,cognitive and social abilities

Considering such issues in UI design is especially important asthe population constantly becomes older, which implicates ashift in your target audience/user community

Issues (examples): Visual and auditory acuity Speed of response/reaction Memory loss Decline in perceptual flexibility Increased difficulty in acquiring complex mental skills

The good news is that many of these issues can be addressed Note: Older adults tend to be more quickly frustrated or even

scared by technology; hence, it is especially important to providea sound user experience for this age group


Universal UsabilityChildren

Today children use software in even very young ages The goals are commonly: educational acceleration,

socialization with peers and giving the children apositive self-image

Problem: There are some diverse opinions in regardto the effect of use of computers on children

Also: It is important to balance the desire forchallenge with parental requirements for safety (e.g.,don’t give penalties, be encouraging, parental control)

The UI designer also needs to draw attention to thelimited abilities of children (e.g., physical limitations,language limitations, low capacity for abstraction)


Universal UsabilityDifferences in Soft- and Hardware

Soft- and hardware is constantly changing, evolving Always look ahead, plan in advance This might slow you down, however planning ahead

will most likely pay off in the future Some examples:

Connection speed in networked applications Display sizes Maintenance and conversion to multiple languages


The End

Questions?
