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HCI

THE INTERACTION

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Portable word processor

LCD screen

Trackball or stylus for pointin

Real keyboard ! you can"t word processwit#out a reasonable keyboard and

s$all% low&power bubble&'et printer

Tourist infor$ation syste$ touc#screen only ! easy and direct interaction

Tractor&$ounted crop&sprayin controller

s$all dedicated LED display touc#&sensiti(e keypad

aain no $ice or styluses

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)#at is interaction*

T#e co$$unication between userand co$puter is known as Interaction

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+ODEL, O- INTERACTION

Interaction in(ol(es at least two participants. t#e user and t#e syste$

As bot# are (ery di/erent t#e interface $ust

t#erefore e/ecti(ely translate between t#e$to allow t#e interaction to be successful

T#e $odels pro(ide us t#e possible reasonfor an interface failure

Let"s discuss t#e Nor$an"s executionevaluation cycle0 but 1rst let us discuss t#eter$inoloies used by t#ese $odels

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T#e ter$s of interaction

Interacti(e syste$ Application do$ain

Tasks & are operations

2oals & desired output fro$ a perfor$ed task

Intention & is a speci1c action re3uired to $eett#e oal

Task analysis & in(ol(es t#e identi1cation of t#eproble$ space

System"s lanuae will be referred as t#e corelanguage and

t#e User"s lanuae we will be referred as t#etask language4

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T#e e5ecution!e(aluationcycle

T#e user for$ulates a plan of action%w#ic# is t#en e5ecuted at t#eco$puter interface4

)#en t#e plan% or part of t#e plan%#as been e5ecuted% t#e userobser(es t#e co$puter interface to

e(aluate t#e result of t#e e5ecutedplan% and to deter$ine furt#eractions4

T#ere are 6 staes in t#is $odel

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Nor$an"s $odel ofinteraction

74 Establis#in t#e oal4

84 -or$in t#e intention4

94 ,pecifyin t#e action se3uence4 :4 E5ecutin t#e action4

;4 Percei(in t#e syste$ state4

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E5a$ple of Nor$an"s +odel

Need $ore li#t ! oal

switc# on t#e desk la$p ! intention

reac# o(er and press t#e la$p switc#! action

If so$eone else is closer t#eintention $ay be di/erent but t#eoal re$ains t#e sa$e4

)#en you #a(e e5ecuted t#e actionyou percei(e t#e result and t#en youinterpret

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gulfs of execution and t#e

gulfs of evaluation4

)#at are 2ulfs*

T#e distance between t#e $entalrepresentations of t#e person and t#e

p#ysical co$ponents and states of t#een(iron$ent

di/erence between t#e user"s preparation

of t#e actions to reac# t#e oal and t#eactions allowed by t#e syste$4

T#is ulf can be reduced

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2ulf of E5ecution

2oin fro$ users" task concept tosyste$ concept. +ental $odel #eld by users tells t#e$

w#at to doT#is $ust $ake connection wit#

desiners" $odel t#at is con(eyed andsupported by t#e user interface

T#e closer t#e $atc#% t#e easier to 1ndand pursue a rele(ant oal

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,uestin 2oals to t#e =ser

+enu titles% folder na$es% applicationna$es% 444

Decreasin t#e distance (ia direct

$anipulation. =I controls appear as p#ysical analos of

real ob'ects0

>ey ideas are (isual representation%

i$$ediate and continuin feedback

Interestin ob'ect or $essae intrudes on atask

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2ulf of E(aluation

T#e ulf of e(aluation is t#e distance betweent#e p#ysical presentation of t#e syste$ stateand t#e e5pectation of t#e user

,$all ulf w#en syste$ pro(ides stateinfor$ation in a for$ t#at is easy to et% easy tointerpret% and $atc#es t#e t#inkin

T#e $ore e/ort t#at is re3uired on t#e part oft#e user to interpret t#e presentation% t#e lesse/ecti(e t#e interaction4

Re?ects a$ount of e/ort t#at a person e5erts tointerpret p#ysical state of a syste$

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T#e interaction fra$ework

Direct$anipulation

interfaces% suc# ast#ose found onco$$on desktopoperatin syste$slike t#e +acintos#and )indows%

$ake t#earticulation ofso$e 1le #andlinco$$ands easier

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DE,I2N -OC=, & @ideorecorder

Ine/ecti(e interaction is indicated by t#e usernot bein sure t#e @CR is set to record properly4

user #as pressed t#e keys on t#e re$ote controlunit in t#e wron order & articulatory proble$

re$ote control lacks t#e ability to selectc#annels & perfor$ance translation

@CR display panel does not indicate t#at t#e

prora$ #as been set & presentation proble$ user does not interpret t#e feedback properly &

obser(ational error

Any one or more of these deciencies would give rise toineective interaction.

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Hu$an error ! slips and$istakes

Hu$an errors are often classi1ed intoslips and mistakes

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ER2ONO+IC,

Erono$ics is traditionally t#e studyof t#e p#ysical c#aracteristics of t#einteraction

A pri$ary focus is on userperfor$ance

erono$ics also touc#es #u$an

psyc#oloy and syste$ constraints4

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Arrane$ent of controls and

displays

-or safety&critical applications t#e setsof controls and parts of t#e displays#ould be rouped loically to allow

rapid access by t#e user suc# as plantcontrol% a(iation and air trac control4

,o$e e5a$ples of roupin control is.

-unctional control ,e3uential control

-re3uency control

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T#e p#ysical en(iron$ent of t#e

interaction

)#ere will t#e syste$ be used*

By w#o$ will it be used*

)ill users be sittin% standin or$o(in about*

Are t#ere any p#ysically c#allenedusers*

E(eryone s#ould be able to seecritical displays

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Healt# issues

P#ysical position

Te$perature

Li#tin Noise

Ti$e

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T#e use of color

display s#ould be as distinct as possible

Blue s#ould not be used to display criticalinfor$ation4

If color is used as an indicator it s#ould notbe t#e only cue

Red $ay be used to indicate e$erency andalar$s0 reen% nor$al acti(ity0 and yellow%

standby and supportin function4 Re$e$ber t#at color con(entions are

culturally deter$ined4

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Some bad interface examples