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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