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    IAS2223Human Computer Interaction

    Topic 1

    The Human, The Computer & TheInteraction

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    Input-Output Channel

    A persons interaction with the outside worldoccurs through information being received andsent: input & outputInteraction with computers:

    Output by computersResponse by providing input to the computer

    Input in human occurs mainly through sensesand output through the motor control of theeffectors

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    T he Human

    Limited in capacity to process information important implications for designInformation received and responds given via anumber of I/O channelInformation stored in memoryInformation processed and applied

    Emotion influenceShare common capabilities but each hasdifferences should not be ignored

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    contd

    F ive major sensesSight, hearing, touch, taste and smell

    Most important for HCI sight, hearing & touchEffectors:

    Limbs, fingers, eyes, head and vocal system

    Interaction with computersF ingers play the primary role (typing, mouse)Some use of voice, eye, head and body position

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    contd

    Applications that use GUI (graphical user interface) with menus, icons and windows

    How does the interaction go? (discuss)How do you receive information?

    Sight?Ear?

    Touch?

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    V ision

    Two stages in visionphysical reception of stimulus

    processing and interpretation of stimulus

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    mechanism for receiving light and transforming itinto electrical energy

    light reflects from objectsimages are focused upside-down on retinaretina contains rods for low light vision andcones for colour vision

    ganglion cells (brain!) detect pattern andmovement

    T he Eye - physical reception

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    Size and depthvisual angle indicates how much of view objectoccupies

    (relates to size and distance from eye)

    visual acuity is ability to perceive detail (limited)

    familiar objects perceived as constant size(in spite of changes in visual angle when far away)

    cues like overlapping help perception of size anddepth

    Interpreting the signal

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    contdB rightness

    subjective reaction to levels of lightaffected by luminance light emitted by an objectmeasured using photometer

    visual acuity increases with luminance as does flicker Colour

    made up of hue, intensity, saturationhue wavelength of light (blue short, green med, red long)intensity brightness of colour saturation - amount of whiteness8% males and 1% females colour blind

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    R eadingSeveral stages:

    visual pattern perceiveddecoded using internal representation of languageinterpreted using knowledge of syntax, semantics,pragmatics

    Reading involves saccades and fixationsPerception occurs during fixations

    Word shape is important to recognitionNegative contrast improves reading from computer screen

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    HearingProvides information about environment:distances, directions, objects etc.

    Physical apparatus:outer ear protects inner and amplifies soundmiddle ear transmits sound waves as vibrations to inner ear inner ear chemical transmitters are released and causeimpulses in auditory nerve

    SoundPitch - sound frequencyLoudness - amplitudeTimbre - type or quality

    Humans can hear frequencies from 20Hz to 15kHzless accurate distinguishing high frequencies than low.

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    T ouch

    Provides important feedback about environment.

    May be key sense for someone who is visuallyimpaired.

    Stimulus received via receptors in the skin:thermoreceptors heat and coldnociceptors painmechanoreceptors pressure

    (some instant, some continuous)

    Some areas more sensitive than others e.g. fingers.

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    Sensory memoriesIconicEchoicHaptic

    Short-term memoryor

    working memory

    Long-termmemory

    AttentionAttention R ehearsalR ehearsal

    A model of the structure of memoryHumanM

    emory

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    contd

    Our everyday activity relies on memoryMemory contains knowledge of actions or

    procedures Allows repeated actions, to use languages, touse new information received via sensesSense of identity preserving informationfrom past experiences

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    contd

    3 types of memory or memory functionsSensory buffers (sensory memory)

    Short-term memory (working memory)Long-term memory

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    Sensory memory

    Act as buffers for stimuli received throughsenses

    Exists for each sensory channelIconic memory (visual stimuli)Echoic memory (aural stimuli)Haptic memory (touch)

    Constantly overwritten by new informationRemains very briefly, about 0.5 seconds (iconic)Echoic: ability to ascertain direction from whichthe sound originates allows playback

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    Short-term M emory

    Acts as a scratch pad for temporary recall of information

    Store information which is only requiredCan be accessed rapidly, about 70ms

    Decays rapidly too 200 msLimited capacityUsually about 7 2 digits (or in chunks)

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    Long-term M emoryMain resourceStore factual information, experientialknowledge, procedural rules of behavior all

    things that we knowHuge capacity (could be unlimited)Slow access time (1/10 th of a second)F orgetting occurs more slowlyLong-term storage of informationThrough rehearsal

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    contdMay store information in a semantic network

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    Emotions

    Various theories of how emotion worksJames- Lange: emotion is our interpretation of aphysiological response to a stimuli

    Cannon: emotion is a psychological response to astimuliSchacter-Singer: emotion is the result of our evaluation of our physiological responses, in the lightof the whole situation we are in

    Emotion clearly involves both cognitive andphysical responses to stimuli

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    contd

    The biological response to physical stimuli is calledaffect

    Affect influences how we respond to situationspositive p creative problem solvingnegative p narrow thinking

    Negative affect can make it harder to do even easytasks; positive affect can make it easier to dodifficult tasks

    (Donald Norman)

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    Individual Differenceslong term

    sex, physical and intellectual abilitiesshort term

    effect of stress or fatiguechanging

    age

    Ask yourself:will design decision exclude section of user population?

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    Some direct applicationse.g. blue acuity is poor

    blue should not be used for important detail

    However, correct application generally requiresunderstanding of context in psychology, and anunderstanding of particular experimental conditions

    A lot of knowledge has been distilled inguidelines (chap 7)cognitive models (chap 12)experimental and analytic evaluation techniques

    P sychology and the Design of Interactive System

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    T he Computer

    Comprises various elements that affects theuser Input devices for interactive use allow dataentry, drawing, selection from screenOutput display device for interactive useVR and 3 D visualization

    Paper output and inputMemoryProcessing

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    InteractivityLong ago in a galaxy far away b atch processing

    punched card stacks or large data files preparedlong wait .

    line printer output and if it is not right

    Now most computing is interactiverapid feedback

    the user in control (most of the time)doing rather than thinking

    Is faster always better?

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    T ext Entry DevicesT he Keyboard

    Q WERTY layout the standard layoutUsed commonly in English-speaking countries

    AZERTY layout standard layout for F rench-speakingcountriesDVORAK layout similar to Q WERTY but assignsletters to different keys

    Designed to help people reach faster typing speed

    Reduce fatigue

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    Special Keyboard

    designs to reducefatigue for RSIfor one handed use

    e.g. the Maltron left-handed keyboard

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    P hone pad and T9 entry

    use numeric keys withmultiple presses2 a b c 6 - m n o3 - d e f 7 - p q r s4 - g h i 8 - t u v5 - j k l 9 - w x y z

    hello = 44 33 555[ pause ]555666surprisingly fast!

    T9 predictive entrytype as if single key for each letter

    use dictionary to guess the right wordhello = 4 3 556 but 26 -> menu am or an

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    Handwriting recognitionText can be input into the computer, using a penand a digesting tablet

    natural interaction

    Technical problems:capturing all useful information - stroke path, pressure, etc.in a natural manner segmenting joined up writing into individual lettersinterpreting individual letters

    coping with different styles of handwriting

    Used in PDAs, and tablet computers leave the keyboard on the desk!

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    Speech recognition

    Improving rapidly

    Most successful when:

    single user initial training and learns peculiaritieslimited vocabulary systems

    Problems withexternal noise interferingimprecision of pronunciationlarge vocabulariesdifferent speakers

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    Q uestion

    When do you use trackball instead of amouse?

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    Display DevicesCRT M onitor

    Stream of electrons emitted from electrongun, focused and directed by magnetic fields,hit phosphor-coated screen which glowsused in T Vs and computer monitors

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    Health Hazards of C RTX

    -rays: largely absorbed by screen (but not at rear!)UV - and IR-radiation from phosphors: insignificantlevelsRadio frequency emissions, plus ultrasound(~16kHz)

    Electrostatic field - leaks out through tube to user.Intensity dependant on distance and humidity. Cancause rashes.Electromagnetic fields (50Hz-0.5MHz). Createinduction currents in conductive materials, includingthe human body. Two types of effects attributed tothis: visual system - high incidence of cataracts inVDU operators, and concern over reproductivedisorders (miscarriages and birth defects).

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    Health Hints

    do not sit too close to the screendo not use very small fontsdo not look at the screen for long periods without abreakdo not place the screen directly in front of a brightwindowwork in well-lit surroundings

    Take extra care if pregnant.but also posture, ergonomics, stress

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    Other Display Devices

    LCD (liquid crystal display)3 D and VR display

    Random scanDirect view storage tube (D VST)Plasma

    V ideo wallsProjectedB ack-projected

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    Special DevicesSounds

    beeps, bongs, clonks, whistles and whirrs

    used for error indications

    confirmation of actions e.g. keyclick

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    P rinting & ScanningFonts

    F ont the particular style of textCourier font

    Helvetica font

    Palatino fontTimes Roman font w| b (special symbol)

    Size of a font measured in points (1 pt about 1/72)

    (vaguely) related to its heightTh is is ten point HelveticaTh is is twelve point

    Th is is fourteen point Th is is eigh teen point

    and t h is is twenty-four point

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    contd

    Pitchfixed-pitch every character has the same width

    e.g. Courier

    variable-pitched some characters wider e.g. Times Roman compare the i and the m

    Serif or Sans-serif sans-serif square-ended strokes

    e.g. Helveticaserif with splayed ends (such as)

    e.g. Times Roman or Palatino

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    R eadability of text

    lowercaseeasy to read shape of words

    UPPERCASEbetter for individual letters and non-wordse.g. flight numbers: B A79 3 vs. ba79 3

    serif fontsh elps your eye on long lines of printed textbut sans serif often better on screen

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    T he Interaction

    Address the translation between what theuser wants and what system does useinteraction modelsErgonomics looks at physical characteristicsof the interactionDialog between user and systemTakes place within a social andorganizational context affects both user andsystem

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    W hat is it?

    communication

    user system

    but is that all ?

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    Interaction terms

    domain the area of work under studye.g. graphic design

    goal what you want to achievee.g. create a solid red triangle

    task how you go about doing it ultimately in terms of operations or actions

    e.g. select fill tool, click over triangle

    Note traditional interaction use of terms differs a lot especially task/goal !!!

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    Donald Normans M odel

    Seven stagesuser establishes the goalformulates intention

    specifies action sequenceexecutes actionperceives system stateinterprets system stateevaluates system state with respect to goal

    Normans model concentrates on users view of theinterface

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    Execution/evaluation loop

    user establishes the goalformulates intentionspecifies actions at interfaceexecutes action

    perceives system stateinterprets system stateevaluates system state with respect to goal

    system

    evaluationexecutiongoal

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    contd

    user establishes the goalformulates intentionspecifies actions at interfaceexecutes action

    perceives system stateinterprets system stateevaluates system state with respect to goal

    system

    evaluationexecutiongoal

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    contd

    user establishes the goalformulates intentionspecifies actions at interfaceexecutes action

    perceives system stateinterprets system stateevaluates system state with respect to goal

    system

    evaluationexecutiongoal

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    Human Errors slips andmistakes

    slipunderstand system and goalcorrect formulation of actionincorrect action

    mistakemay not even have right goal!

    F ixing things?slip better interface designmistake better understanding of system

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    Abowd and Beale frameworkextension of Normantheir interaction framework has 4 parts

    user

    inputsystemoutput

    each has its own unique languageinteraction translation between languages

    problems in interaction = problems in translation

    Score

    Utask

    Ooutput

    Iinput

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    Ergonomics

    Study of the physical characteristics of interaction

    Also known as human factors but this canalso be used to mean much of HCI!

    Ergonomics good at defining standards andguidelines for constraining the way we designcertain aspects of systems

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    Ergonomics - examples

    arrangement of controls and displayse.g. controls grouped according to function or frequency of

    use, or sequentially

    surrounding environmente.g. seating arrangements adaptable to cope with all sizes of user

    health issuese.g. physical position, environmental conditions (temperature,

    humidity), lighting, noise,use of colour e.g. use of red for warning, green for okay,

    awareness of colour-blindness etc.

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    Common interaction styles

    command line interfacemenus

    natural languagequestion/answer and query dialogueform-fills and spreadsheets

    WIMPpoint and clickthreedimensional interfaces

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    Command line interface

    Way of expressing instructions to the computer directly

    function keys, single characters, short abbreviations, wholewords, or a combination

    suitable for repetitive tasksbetter for expert users than novicesoffers direct access to system functionality

    command names/abbreviations should bemeaningful!

    Typical example: the Unix system, DOS

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    M enus

    Set of options displayed on the screenOptions visible

    less recall - easier to use

    rely on recognition so names should be meaningful

    Selection by:numbers, letters, arrow keys, mousecombination (e.g. mouse plus accelerators)

    Often options hierarchically groupedsensible grouping is needed

    Restricted form of full WIMP system

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    Natural language

    F amiliar to user speech recognition or typed natural languageProblems

    vagueambiguoushard to do well!

    Solutionstry to understand a subsetpick on key words

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    Q uery interfaces

    Q uestion/answer interfacesuser led through interaction via series of questions

    suitable for novice users but restrictedfunctionalityoften used in information systems

    Q uery languages (e.g. S QL )used to retrieve information from databaserequires understanding of database structure andlanguage syntax, hence requires some expertise

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    Form-fills

    Primarily for data entryor data retrievalScreen like paper form.Data put in relevantplaceRequires

    good designobvious correctionfacilities

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    Spreadsheets

    first spreadsheet V ISICA LC, followed byLotus 1-2- 3MS Excel most common todaysophisticated variation of form-filling.

    grid of cells contain a value or a formulaformula can involve values of other cells

    e.g. sum of all cells in this columnuser can enter and alter data spreadsheetmaintains consistency

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    W IMP Interface

    W indowsIcons

    MenusP ointers

    or windows, icons, mice, and pull-down menus!

    default style for majority of interactive computer systems, especially PCs and desktop machines

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    P oint and click interfaces

    used in ..multimediaweb browsershypertext

    just click something!

    icons, text links or location on map

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    T hree dimensional interfaces

    virtual realityordinary window systems

    highlightingvisual affordanceindiscriminate use

    just confusing!3 D workspaces

    use for extra virtual spacelight and occlusion give depthdistance effects

    flat buttons

    or sculptured

    click me!

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    Elements of W IMP

    WindowsIcons

    MenusPointersB uttons

    PalettesToolbarsDialog boxes

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    Context

    Interaction affected by social and organizationalcontext

    other peopledesire to impress, competition, fear of failure

    motivation

    fear, allegiance, ambition, self-satisfactioninadequate systems

    cause frustration and lack of motivation