1- Introduction (annotated).pdf

Introduction to Human Computer Interaction Human Computer Interaction Outline 1. Human Computer Interaction: de4nition of 2. Why study user interface design? Important... 3. History 4. Goals of HCI 5. Five key ideas in HCI 6. Optical Illusions 7. Understanding...

Introduction to Human Computer Interaction Human Computer Interaction Outline 1. Human Computer Interaction: de4nition of 2. Why study user interface design? Important... 3. History 4. Goals of HCI 5. Five key ideas in HCI 6. Optical Illusions 7. Understanding users 8. User productivity, adoption and usability 9. Disciplines contributing to HCI 10. HCI engineering as a branch of software engineering 11. User interface malfunctions 12. Case studies in user interface malfunction 13. Key points to review What is HCI?  20551 peoble affect the computer or system > - ji & pa jus jej JTh frea/es'/envolvent (5) &-j Communication function in the past De8nition – HCI emphasise on the two directive Face to not ji, ii face free y Respons &, 10. :& 1g)) 8: comuncation &s j sigvis 2 & Smartphone best The study of people and computing and the way they influence each other is wasi's - - mechanism in Deep HLl 2 3 & A set of processes, dialogues, and actions through which a human user employs and interacts with a computer ↳ interaction Jago-61 - Perform a specific task - - discription & & A discipline concerned with the design, evaluation and implementation of --- ·interactive computing systems for human use with the study of major phenomena surrounding them. - e , , -Let's a9 %, 4 x - ‫أحد التخصصات التي تهتم بتصميم وتقييم وتنفيذ أنظمة الحوسبة‬ ‫التفاعلية لالستخدام البشري مع دراسة الظواهر الرئيسية املحيطة‬.‫بها‬ Automated teller machine  - we have the syste euser will interact with the user The Respond system & /, will give Sound Human-Computer Interaction (HCI) gall user Human - - Direct ○ the end-user of a program % ○ the others in the organization Not directly directly using the system, but they will affected by the results/ The System system Client-DAta json- Computer saf ○ the machine the program runs on Hardware & 195 i Laptop-mopile Phone Input Output Top Descr touchscre a - Interaction g -59 ○ the user tells the computer what they want The User ○ the computer communicates with results Reaust Jen )g Send Screen jjx Touch Zil interface 56)) text/sef commut ( (b) = timely manry pic) jp. jus ↑ dis Respond j5X1 M. A. Wadud &  Why Study User Interface Design? 75% or more of -development eXort can go into the user interface ○ 40% to 70% is typical 506 s 02-i) ○ A study by65s - Nielsen (2003) shows that if corporations spend 10% of their development budget on = &usability, they can improve usability by 135% - = s User interface software is becoming more complex 54 - ○ Complexity increase is faster than other aspects of systems 25- ○ Graphical user interfaces have provided the biggest jump in complexity What we had earlier? (j) jiji ○ Applications tend to grow to 4ll available computing resources =es God 14.1 , UI is a gene usably Notes Jevopet 201 ja U2 Wis is user& &(1) Task / Fungion & & & Usability &80 de [Sys1 M. A. Wadud  Why Study User Interface Design? ‫ وجدت دراسة أخرى‬ (cont’d) ‫ من املواقع الرئيسية تنتهك املبادئ التوجيهية األساسية‬%51 ‫○ أن‬ &.‫للتصميم‬ ; -% Another study found sig -· 9 ○ 51% of major websites violate the most basic design guidelines. - & GUE J% 25555- &g) - guideline These studies and more demonstrate that ○ there is a need for a more systematic treatment of HCI in the development process and ○ more HCI experts are needed. usable more accably more usable , aceable , Intuitive M. A. Wadud  jS@) Financial bene8ts & Costs of improved user interfaces There are direct 4nancial bene4ts from improved user interfaces a0* Stil six , useis ↑ Task intiv foruses , esl Increased user productivity des error -1 ○ Direct 4nancial ↳ savings a wond cost - · Inte ↑ Increased revenues from sales > - - ○ The system is more attractive and customer satisfaction is higher sm I - , lod ↓ ,+2 Decreased training and support- - costs - &1 & 1 % ,02 ○ The system is more intuitive 85 % 1. - Is ↓ Decreased maintenance cost ○ The system does what user wants We ut gene i go , user e 2) ent wil % njs ! , ○ Much maintenance involves 4xing UI problems ○ Maitnance i Pay a little during development, application/product release! g or pay a- lot after = y Si - ul it make &s aus ‫ أو ادفع‬،‫تتضمن الكثير من أعمال الصيانة مشكالت في واجهة املستخدم ○ ادفع القليل أثناء التطوير‬ simple M. A. Wadud ‫الكثير بعد ذلك‬  Financial bene8ts & Costs of improved user interfaces (Cont’d) But work ○ StaX must be trained in user interface analysis and design to be able 6418 sevaltese ○ Users must participate % ○ UI design tools are needed 212( i The benefits almost always outweigh the costs · Elle M. A. Wadud  S What Constitute a Good Interface? A good user interface: : 50% is & &'s disI I ○ Achieves necessary performance by- operator, control, -- and - maintenance personnel 19 : %541 - ⑬ 20 Task ○ Minimizes skill and personnel requirements and training time ‫يقلل من متطلبات املهارات واملوظفني ووقت التدريب‬ ○ Achieve reliability of Human-Computer arrangement Si (reliability, availability, security, and = data integrity) · (4) ○ Fosters design standardization within and among - systems (integration, consistency, portability) - y %) ‫تعزيز توحيد معايير التصميم داخل األنظمة وفيما بينها )التكامل واالتساق‬ (‫والقدرة على النقل‬ M. A. Wadud RelaiaPIy : system work in Right way , in perfect coustion. Avaliapity : The user will be able to access the system whenever neef of want. security : only Authorised user will be able to access data uniguty :: Yeod 2 115) Good UI Guideline Estander & -> Good UI oprefor & :J= yes &y &1518 : ① preformance by [ controles -Maitnance teach & 100% , ③ relaipity ,Avalipity Securay , intgrty Standraistion ① design -constisty = Integration => portlity  Measureable Goals of a Good Interface - Good UI 06, j5 Some measureable goals: i ○ Time to learn how to operate the system ○ Speed of performance ○ Error rate ○ User’s retention time of information presented ○ User’s satisfaction with the system M. A. Wadud  History Early days of computing: ↑ ↑ - 5 ,513 1 milion $ - ○ Computers cost more than people - ○ Computers had little functionality↓ Complexcomputain a exterie a , Requires ○ Mainly research used by experts /Resersher I The UI was unimportant focus on the important/ Improving control e conned if Early 1970s thewacomputer could user ○ Field of ‘Man Machine Interface’ (MMI) born. S ○ Term changed gradually to ‘User Interface’ (UI) ○ Ideas for 4rst ‘Graphical User Interface’ (GUI) d Z with risul Icon Dynabook at Xerox Text based command/menu & 1 : [. won a They Replay 35 , , 22 computer, Design , 5 : abortale easy to Market use personal for children. Gut dind)%1842 sp Late 1970s and 1980s Marketing 20000 iss Products were called ‘user friendly’ ↳No science in this: Just a market buzzword but First real GUI’s developed ‫نظام تجاري لدمج الشامل‬ Xerox Star --> Smalltalk and Macintosh the Gut E commercial system to incorporate comprehensive Lunch First windows & & familer concept Six GUI > DS pointer , Icon , Menu , concept of g GUE small talk Programming language 25 - : IDe + guesdon , Guys 60 Text based system Instate of M. A. Wadud  History Early days of computing: ○ Computers cost more than people ○ Computers had little functionality ○ Mainly research used by experts The UI was unimportant Early 1970s ○ Field of ‘Man Machine Interface’ (MMI) born. ○ Term changed gradually to ‘User Interface’ (UI) ○ Ideas for 4rst ‘Graphical User Interface’ (GUI) Dynabook at Xerox Late 1970s and 1980s Products were called ‘user friendly’ No science in this: Just a market buzzword First real GUI’s developed Xerox Star --> Smalltalk and Macintosh M. A. Wadud  History (Cont’d) 1980s piog · Ji ○ Term ‘Human-Computer Interaction’ (HCI or CHI) came into use - wider scope than UI (help, work practices etc.) user experience , ○ MS-Windows ○ X-Windows (a computer software system and network protocol that provides a basis for graphical user interfaces (GUI) for networked computers) follow the Mac ○ Intense research into HCI 1990s and early 2000s ○ Virtual reality, speech and handwriting I/O Good BUT also Bad UI’s continue to be developed!!! M. A. Wadud  Goals of HCI jeis ↑ -19439 S Improve productivity and reduce costs through: Danger prevent I Safety: Ensure that ○ the system from harm. protect user Does the system prevent danger? and - E.g. Nuclear power plant, Aviation Engineering ‫ هندسة الطيران‬،‫على سبيل املثال محطة الطاقة النووية‬ si (ii) ○ 2 Functionality: we need to maximize the range of task that the system preform Si. S gis N , & How many things can the system do? Si , S &S Docunt-Email sin jSl& Microsoft - g - - efficient system will enable the user to ○ Emciency: time > - an timesa - z god quickly effort , effort there with minimum Tash Sig How few resources does it take to get a task done? ○ Usability : & How easy to learn and use is the system? M. A. Wadud  "] Protetupe-of g s 5 sett &d ? -L - gigt & - Mecanig Source: Dix, A., Finlay et al. (2004): Human-Computer Interac@on , 3rd Ed., Pearson Educa@on. M. A. Wadud  be Design with the user short system there exceptions need existing- Goals of HCI (Cont’d) mind match , , maping support funcondly asss: Confusion S 8% BUT J ,4166 Confusion : 5 &! gyss ○ High functionality (many ways of doing the same thing) can actually reduce usability Create confusion - Dis People should not have to change radically to 4t in with the system, the system should be designed to match their requirements. --- M. A. Wadud  Five Key Ideas in HCI -give I Goal outcome save file 054 9 - > - 03)495x ○ A state the user wants to reach -d2 , a. 1,2 - to be talking with somebody on the phone How easy user can receive to have saved a 4le ② understand the control 2 Visibility and information there system. presented by ○ Tips How easy easy user can understand and receive & D pers , user go Is I Control needs to be visible ↓twencontra-af visable btwen - So wil controlis effect, Icon s ; Good mapping with their eXects Good mapin control 2 Y 5,4 He 359 yesJ : 3 Suggest functionality Button is > - 80 unavaiple in Gray Button ○ The UI should help the user always understand... / Loadin good ses · The current state of the system prossing a gave 9 is & save Insection What operations can be done and restal and user shall be able also could be taken withe system , W understand what Windows XP … shutdown and update! peej) qes > - the user can the meaning be able of to control sisoc ! E · - is ○ E.g. as window is shuffon ·. - When you position the cursor over a point on the screen, it should be clear what would happen if you clicked the mouse - S Feedback ○ When anything changes it should be made visible When you delete a 4le, the system should not just say ‘ready’ Geleffile o Automobile --- steering and wheel! massage Sit j - - d D conformation or j + 9201 XVaty Sjn raby X Gelefe - si M. A. Wadud stearing weal-gir jef %,  exit Pencile Five Key Ideas in HCI (Cont’d) & Affordance - ○ A technical term refers the property of objects ○ The set of operations and procedures that can be done to an object ‫القدرة املتصورة‬ jsio ○ ‘Perceived aXordance’ is what typical users think can be done to an -gig object > - ↑ a Should a door be pulled or pushed? Proprety flat What does this icon mean? & g ○ To improve visibility/feedback we need to: T - Choose objects with good perceived aXordance - Design the UI to generate better perceived aXordance Bush pull M. A. Wadud  continued Five Key Ideas in HCI (Cont’d) Task God S2 ○ An action the user wants to do J4923477499 to call somebody specfic task to save the 4le w ○ Goals beget tasks, tasks beget goals. s & Goals i task - & talk 3 ; 1) = &99 is specific Goal &506- is jolge M. A. Wadud  The Human: Following are the basic 4ve characteristics of the subject Human: To recive [ResPey 8 Information i/o: visual, auditory, haptic, movement Differenti channel stored it are Memory: Sensory, Long term, Short term (work term Menory) Processing and Applied: Reasoning, problem-solving, skill, error are Human capability Inquenced by emotion capably > Every human is diXerent from one another.  , &is jo 1997 Vision brain & 5, jus s A human sees through eyes. And it has two stages of human vision: l dis /To , - Physical reception - j 2Processing and interpretation of visual. Physical Reception ,7 -5 Signal 1 & /J I -120 An eye receives light from the environment and transforms into electrical energy. When light reqects from diXerent objects and enters into the retina in gives the 3D view of the object. When visual enters the eye it focuses inverted in the back of our eye. and last but not 55 least, there are color cones in the human eye which determine the color of an object. electrical ↑Interpreting the Signal: brain energy The size and depth of an image depend upon the distance of an eye from the object. Here optical illusions occur too like “Ponzo illusion” and “Muller Lyer illusion” 2) - - +  es S 9147 I Dis Optical Illusions a ~ 5% An optical illusion (also called a visual illusion) is characterized by visually perceived images that differ from objective reality. - The information gathered by the eye is processed in the brain to jes give a perception that does not tally with a physical measurement - of the stimulus source. (source: Wiki) , 1985 - · ja jign 100 % o &I is Duck Rabbit illusion Ex g M. A. Wadud  ~ 10 g, gug est context+ Environet , & M. A. Wadud (1) g  Understanding Users “Dual Processor" Theory: & ○ Every interactive system is a distributed system running on two processors: - Relation &2 btween 2 processer & I 2 ○ User interface design speci4es/constrains both: User behavior System behavior M. A. Wadud  I need to categorise the user ‫وأعرفهم‬ ‫وأفهمهم‬ Understanding Users (Cont’d) Users can be categorized: & ○ By class/role Determined by the pattern of use: e.g., manager, salesperson, shipper, client ○ By personality type Shy or reticent - Inarticulate 85 Disinterested or defensive estig Intimidated-> Involved designer! ○ By ability Physical disability innovative I/O may be needed 55 Colorblind - don’t use colors as the only means of conveying information Dyslexia or other cognitive glitches Illiteracy icons may be needed Computer illiteracy of Ignorance of domain/learner - some I - 5- Intimidated- > jj5) M. A. Wadud  od1 User Productivity & Usability of the User productivity = The prout of the funcounty Functionality (what the computer can do) - what the system Go + teachers , I Sustem * / 55 Usability (what people can do with the computer) - > couppisy + 956 , I 61 I Its func If either of these is zero, the system is useless func 95 % > - 55 exusabity - useless gip Factors Inquencing User Productivity useless ○ Kind and number of tasks/jobs/services system 22051 ○ Characteristics of users (ability, experience etc.) ○ Work environment (distractions etc.) ○ Training and documentation ○ Functionality and usability of available software and hardware M. A. Wadud  Ergonomics M. A. Wadud  Workstation ergonomics M. A. Wadud  A Model of Usability Factors M. A. Wadud  Disciplines Contributing to HCI Cognitive psychology ○ Capabilities and limitations of human senses and thought processes ○ People tend to select cognitive strategies that minimizes cognitive eXorts Ergonomics ○ Hardware and software emciency of use and safety Linguistics ○ Syntax and semantics of commands ○ Speech I/O Arti4cial intelligence ○ Speech I/O ○ Intelligent ‘guessing’ what the user wants to do ○ Knowledge representations of users and tasks Sociology and social psychology ○ Assisting people to work in groups with software ○ Ensuring software works in diXerent cultures country Engineering and industrial design --2. ○ Disciplined measurement-based approaches Y (ny) ○ Esthetics d ○ Storyboarding etc. M. A. Wadud Syk)  Human Information Processing (HIP) A model developed by Stuart Card, Tom Moran and Allen Newell (1983) Information process Attention - · 1 glo gisfe Memory Processors 1 2 3 Working Long-term Memory Memory Perception Cognition Motor ↳ ho , M. A. Wadud  Human Information Processing (HIP) – cont’d Attention Memory Processors working a Working Long-term eye Memory Memory Perception Cognition Motor The perceptual processor - senses, detects, and accepts inputs from the external - sources and stores parts of them into The eve - working memory  Human Information Processing (HIP) – cont’d Attention Memory Processors & Working Long-term Memory Memory Perception Cognition Motor js The cognitive processor interprets ‫يقوم املعالج املعرفي‬ (consults with long-term memory), ‫بالتفسير‬ manipulates and makes decision about ‫)يتشاور مع الذاكرة طويلة‬ 24 ،(‫املدى‬ ↳e - the inputs M. A. Wadud  Human Information Processing (HIP) – cont’d Attention Memory Processors Working Long-term Memory Memory Perception Cognition Motor The motor processor is responsible for interpreting cognitive decisions into physical -- actions M. A. Wadud Human Information Processing (HIP) – cont’d Attention is needed to facilitate and control the cognitive system. & i 25 Attention congton longterm & jays ⑮ Memory Processors Working Long-term Memory Memory Perception Cognition Motor a  expection ia > Human Cognitive system Odisas The %t between the user’s mental model of the system and the actual model of the I system a6ects complexity. ○ The greater the& %t, the easier it is to determine how to translate goals into action is · 5. 1 i used s expectation n understanding , Al & complexity So & and 25a , Perception and representation ○ Some displays can be hard to interpretsief -1 Blue foreground 2 I 2 Optical illusions color but not- did I 3 Contrast in- brightness eix T - - balance Ei Too many colors Distration - ○ There are two ways to use graphics: For modeling g direct - images of concepts For coding representing underlying ideas, e.g., displaying quantitative data ○ E.g. chart, curves ? 5 ,9 /  - -  my Reduct Relidity & also It It will save the eye D , what the syner provide try to percept ② missleating-coflion = when Examples  Blue Examples - clorss & brithnes 55 -  Bad User Interface 2 M. A. Wadud S  Es Bad User Interface & r M. A. Wadud & Good User Interface 252 Which one is better? -1 -19i Doping * DiFerent designs for elevator buKons.  Continued Human Cognitive system (Cont’d) : 69 1 Attention limitations & % 2. 9 ○ People can be readily distracted ↳ Provide cues about what to focus on - 2 B ○ People get lost in complexity. Structure information so it is easy to browse through not too many items - - not too few items - besTask &j , Grouping , 1Pos is grouped logically L 2 ○ People multitask 2. A & clear so users can jump backwards and Make the ‘state’ forwards State  Human Cognitive system (Cont’d) ↳ 3 Memory limitations users 3 A. ○ Short term memory can contain 7±2 ‘chunks’ Avoid situations where users have toDoremember more than this Logically group things so users can & chunk them 3. B○ The more meaningful, the more easily remembered (familiarity, imagery gi and consistency contribute to meaningfulness)> - o ,1 we 45 91 = Use eTective names and icons (even) animated ones Combine icons with words 5 5) Icons can be analogies, examples or abstract, but not arbitrary - 'sp. - can Watch out for cultural diTerences (e.g. washroom symbols) z - E 3 ○ People can more easily recognize than recall Use menus, icons, quick lookup  I A M 1 / : 12. 113 I 1. 4 2 - 1 2. 2: 21 7 - 2 : 2 2 -. - - 3 - - D Y 2 3 s & 4. 42. 2 3. S S-1 quick  uT 19 Evolution from plain SW- to usability Eng ○Normal software development (involving the UI) Focuses on physical and interaction elements Waterfall model dominates (sequential) Evaluation by functional spec reviews and testing ○ User interface development Focuses on users and tasks funcsa - Star model dominates (iterative) Evaluation by continuous user involvement Driven by heuristics and guidelines Integrates psychology etc. SeimtInquence on functionality Norm it ○ Usability engineering UI &S 9 Driven by engineering objectives Integrates rigorous engineering discipline Drives functionality s  - Jesing Is F A Five Level Conceptual Model of - UI 1. Task Level & %a What is to be done by the user tasaccive goal 2. Conceptual Level User’s intended mental model of the system - And how they use it will expect the system will perform 3. Interaction Style Level 2 3 Gul Z Command-driven, menu-driven, direct manipulation, hypermedia Design elements that are repeated throughout the system 4. Interaction Element Level Speci]c windows, dialogs, commands, menus 5. Physical Element Level bit Dbufe Bitmaps, characters, data structures each level At each level: Design must be done, Problems can occur For & 1 in parallel  2 D 1 s &a % wer.. what Tasks in order to achieve specific goal ↳ user need to set an Email & experience should function based on understanding believe the system. 2 use - How denis' email archive (2) Drag -> will Response command to system , system type 3-comment driven > - & - Specific combined that user interact with the system save as Dialy 15. 9 J5 filement atTop of screen 5-bitsbyte , A conceptual model of user interface system architecture Why layers? ○ Simpli]es software development and (maintenance g All layers: ○ Are developed in parallel 8 ○ In_uence each other ○ Included in complete system speci]cations ○ Evaluated together Evolution of layers: ○ Functional layer should need to change less often during iterative tuning of the interface - ○ All layers may need to change when business functions change but hopefully interaction styles should remain similar will change business function change think it * All lyer I & Interationstyle & & J ,&15 & & UI &SITC0 & Devoupet or Maitance 540 & 12 M function go in y Characteristicsstatiof Products and Applications not Each kind of application puts di6erent demands on the UI designer ○ Application for internal use vs. product for sale ○ Generic utility vs. task-speci]c tool ○ Walk-up-and-use vs. skilled usage · isAnd t go jejs Some design challenges: ○ Customizing a generic utility product so that it becomes a task- speci]c tool for internal use and vice versa ○ Converting an application requiring skilled usage to make it a walk-up-and-use application De%nition - A Walk-up-and-use system is a system that needs to be so self-explanatory that %rst-time or one-time users can use the system e6ectively without any prior introduction/training. Examples are automatic teller machines (ATMs), ticket machines, public informations systems, museum displays, etc the system System that need to be so suffix Diffract Demands User Interface Malfunctions Joel Us a 16 X Systemiit good , Key idea – ○ “There are no good user interfaces... just user interfaces that ]t” ○ A truly bad user interface never ]ts ○ But among the ‘good’ ones, some will suit one task/user; some will suit another To maximize %tness – ○ we must minimize the occurrence of ‘malfunctions’ in the context of the expected use of the system  % 8 875 Inconstity Nargof , - a De8nitions of malfunction Malfunction A mismatch between what the user wants, needs or expects and what the system provides Consequences of malfunction ○ “A breakdown in usability” 20 user % & ○ “An obstacle to performing a desired task” You should know that: justo○ Occasional malfunctions are normal ○ Systematic or frequent malfunctions need to be ]xed 37 =  develper *3 * gis 73 Related ideas to ‘malfunction’ Error Development ○ Identi]able mistake on the part of the designer Defect ○ A- deviation from what the user needs devipe's jjd G gas 6 = = X * 243 3 L 3= 2 +3 A malfunction is a usability defect ○ A defect in the smooth functioning of the user/computer system! /is ○ Users may not be aware of many malfunctions malfunctions may only be located through careful analysis they may be subtle  :Malfunction Analysis We need a disciplined approach to analyzing malfunctions ○ Provides feedback into the redesign process 1. Play protocol, searching for malfunctions 2. Answer four distinct questions: Q1. How is the malfunction manifested? What do you notice and who noticed it? - in the interaction is it occurring? Q2. At what stage Goal forming, action decision, action execution, interpretation of results takeeptal 2 Styl2 intraction Q3. At what level of the user interface is it occurring? & intraction elect Physical element level to task level Sphysical Q4. Why is it occurring? What is its root cause? 3. List and prioritize possible cures  How is the D manifested?malfunction a) Malfunctions detected by the system (easiest to detect) ○ Examples: omission of an argument incorrect date format ○ Make systems so that users do not make mistakes! Solution : % iS ○ Better prompts, consistency, visible examples, more forgiving- of > alternatives nu The Start Y - delb) Malfunctions detected by the user during operation ○ Examples: taking a wrong path in menu hierarchy the not ]nding required help hot mit / somepou couple -0 : not being able to perform a certain action not being able to tell which state system is in is Solution : state je? ○ Improve functionality, feedback, clarity, simplicity How is the malfunction manifested? (Cont’d) c) Malfunctions undetected (until later) E ○ Examples: output produced is wrong due to wrong inputs unnecessary work performed button format file 40 20% jistib % (20% Solution : 55 89 ○ Improve feedback indicating consequences of input; simplify d) Ine6iciencies ○ Examples: Jeff excessive response time excessive think time unnecessarily long command sequences unnecessary repetitions complex operations that require use of reference Solution : ○ Simplify, speed system up - - What Stage in the Interaction the Malfunction Occur? a) When the user decides on a GOAL (i.e. user forms an intent to do inappropriate thing) ○ Examples: decides to empty a ]eld because user thinks it is unimportant (when it is important) decides to charge default exchange rate (when should obtain current exchange rate) Solution : ○ Lead user through better task; better feedback; better training b) When the user speci%es the ACTION(i.e. action does not match the goal) ○ Examples: deletes the record instead of emptying a ]eld charge reciprocal of exchange rate Solution : ○ Improve clarity, feedback, prompts, conceptual model  What Stage in the Interaction the Malfunction Occur? c) When the system executes the action - EXECUTION ○ Examples: - Defects in functionality Solution : ○ Fix functionality in normal way d) When the user interprets the resulting system state - RESULT ↳ ○ Example: saywest online thinks system has ‘hung’ when it has not Si thinks bank account has been debited when it has not Procking thinks some data must be entered when it is the default cannot understand resulting error message Stunes Solution : ○ Better feedback, better conceptual model  Different Stage Malefaction & 2 user fel 4) See & Currum Rate 83 , prossing 1 , At Which Level Does the Malfunction Occur? a) Task level (Task and goals not supported) by me system ○ Example System does not support the task, i.e. what the user wants to do cannot be done by the system Functionality is not provided Solution: ○ Add functionality b) Conceptual level (User has wrong mental model; does ○ Example 4 not understand intended conceptual model) &: dis c j thinks that money is being deducted from bank account when it is being charged to a credit card thinks that dragging a ]le to the desktop means they are no longer on the disk Copy a shortcut link and assumes ]le is copied. Solution : ○ make conceptual model clearer ○ improve metaphors At Which Level Does the Malfunction Occur? c) Interaction style level (system wide problem) ○ Examples: does not know how to pull down a menu scrolls a page instead of a line goes to next screen instead of scrolling retypes command after an error instead of editing it Solution : ○ make operation of the interface more intuitive and consistent d) Interaction element level (speci%c detail inappropriate) ○ Examples: selects wrong button because label is misinterpreted speci]es invalid command syntax speci]es wrong code for option Solution : ○ More attention to details of the interface, simpli]cation At Which Level Does the Malfunction Occur? e) Physical element level (Physical execution incorrect) ○ Examples: d is presses wrong key accidentally s'keypoard clicks on wrong pixel in image s > out-types machine (actions lost) - screen types ahead when system is computing; keystrokes later applied to wrong action Solution : ○ Defenses to protect user from consequences; better hardware design; ]x bugs in code - =>s t unde reso option neih dr , Error recavary Mulfahioa program - Input conforation - Erro recovery undo-reso option Why Does the Malfunction Occur? a) Lack of (on the part of the user): ○ Motivation: Poor job satisfaction ○ Attention: External event - user is pre-occupied with other things. ○ Input information processing: No feedback provided to tell user what is going on or cues provided by the system are not recognized or cues are misinterpreted Solution: Clearer, more consistent feedback ○ Discrimination: user is unable to tell certain things apart e.g. red/green color discrimination e.g. two icons that are similar Solution: Improved expression of information -Y  2) # Why Does the Malfunction Occur? ○ Physical coordination: e.g. wrong item selected because of diTiculty positioning cursor with mouse. Solution: Alternate interaction mechanisms, better feedback + Voice/report , 2 ○ Recall: User did not remember command , syntax etc. Forget isolated terms sorach t Solution: Better mnemonics, online help, quick lookup mechanisms, command completion - ○ Knowledge / lack of learning: User does not have business or software knowledge to make right choice. Why Does the Malfunction Occur? b) Learning di6iculties that cause malfunctions: ○ Learning is diTicult users get frustrated learning takes time; can be hard to apply ○ Learners make ad-hoc interpretations they may not recognize their problem they may falsely think they have a problem ○ Learners generalize from what they know they assume computers work like manual methods they assume consistency E.g. baby girl trying to play gameboy, it is also an example of mental model vs. conceptual model ○ Learners have trouble following directions they often ignore them even if they see them they do not easily understand them  Fecorr Problems S Why Does the Malfunction Occur? ○ Problems and features interact they do not see that one problem can cause another ○ Prerequisites and side-eTects confuse learners ○ Help facilities do not always help they do not know what to ask for too much detail is often provided ○ Other causes of malfunctions: Excessive resource demands External events (e.g. noise) Misleading or inadequate training Unrealistic task de]nitions Intrinsic human variability Summary ○ Goals of HCI: Improve safety functionality eTiciency usability ○ Visibility and feedback *○ ATordance and perceived aTordance ○ Goal = state; task = action T○ Human/computer as system running on 2 processors ○ Types, classes and abilities of users ○ Productivity = functionality * usability ○ Usability factors & e.g. learnability, ]t, acceptability ○ Contributing disciplines e.g. linguistics, Arti]cial Intelligence - Summary (Cont’d) ○ Human cognitive system - Limitations on: perception attention memory ○ Task analysis vs. functional analysis ○ Star model with evaluation at centre ○ UI levels task conceptual model interaction style interaction element physical element ○ Usability engineering ○ Layered approach ○ Malfunction as a kind of defect (of usability) Summary (Cont’d) ○ Human cognitive system - Limitations on: perception attention memory ○ Task analysis vs. functional analysis ○ Star model with evaluation at centre ○ UI levels task conceptual model interaction style interaction element physical element ○ Usability engineering ○ Layered approach ○ Malfunction as a kind of defect (of usability)