人機(jī)界面第二章

?

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Wesleyisan

imprintofDesigning

the

User

Interface:Strategies

for

Effective

Human-ComputerInteractionFifth

EditionBen

Shneiderman

&

Catherine

Plaisantin

collaboration

withMaxine

S.

Cohen

and

Steven

M.

JacobsCHAPTER

2:Guidelines,

Principles,

and

TheoriesGuidelines?

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reserved.2-2Shared

languageBest

practicesCriticsToo

specific,

incomplete,

hard

to

apply,

andsometimes

wrongProponentsEncapsulate

experienceNavigating

the

interface?

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Sample

of

the

National

Cancer

Institutesguidelines:Standardize

task

sequencesEnsure

that

embedded

links

are

descriptiveUse

unique

and

descriptive

headingsUse

check

boxes

for

binary

choicesDevelop

pages

that

will

print

properlyUse

thumbnailimagestopreview

largerimagesAccessibility

guidelines?

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rights

reserved.2-4

Provide

a

text

equivalent

for

every

nontextelement

For

any

time-based

multimediapresentation

synchronize

equivalentalternatives

Information

conveyed

with

color

shouldalso

be

conveyed

without

it

Title

each

frame

to

facilitate

identificatiand

navigationOrganizing

the

display?

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reserved.2-5

Smith

and

Mosier

(1986)

offer

five

high-level

goalsConsistency

of

data

displayEfficient

information

assimilation

by

the

userMinimal

memory

load

on

the

userCompatibility

of

data

display

with

data

entryFlexibility

for

user

control

of

data

displayGetting

the

user’s

attention?

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of

fontsInverse

videoBlinkingColorAudioFacilitating

data

entry?

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rights

reserved.2-7Consistency

of

data-entry

transactionsMinimal

input

actions

by

userMinimal

memory

loadonusers

Compatibility

of

data

entry

with

datadisplayFlexibility

for

user

control

of

data

entryPrinciples?

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More

fundamental,

widely

applicable,

andenduring

than

guidelinesNeed

more

clarificationFundamental

principlesDetermine

user’s

skill

levelsIdentify

the

tasksFive

primary

interaction

stylesEight

golden

rules

of

interface

designPrevent

errorsAutomation

and

human

controlDetermine

user’s

skill

levels?

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rights

reserved.2-9“Know

the

user”

Age,

gender,

physical

and

cognitiveabilities,

education,

cultural

or

ethnicbackground,

training,

motivation,

goals

andpersonalityDesign

goals

based

on

skill

levelNovice

or

first-time

usersKnowledgeable

intermittent

usersExpert

frequent

usersMulti-layer

designsIdentify

the

tasks

Task

Analysis

usually

involve

longhoursobserving

and

interviewing

usersDecomposition

of

high

level

tasksRelative

task

frequencies2-10?

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rights

reserved.Choose

an

interaction

style

DirectManipulationMenu

selectionForm

fillin

CommandlanguageNatural

language2-11?

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of

Directness2-12?

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8

golden

rules

of

interface

design?

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rights

reserved.2-13Strive

for

consistencyCater

to

universal

usabilityOffer

informative

feedbackDesign

dialogs

to

yield

closurePrevent

errorsPermit

easy

reversal

of

actionsSupport

internal

locus

of

controlReduce

short

term

memory

loadPrevent

errors?

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Make

error

messages

specific,

positive

in

tone,and

constructiveMistakes

and

slips

(Norman,

1983)Correct

actionsGray

out

inappropriate

actionsSelection

rather

than

freestyle

typingAutomatic

completionComplete

sequencesSingle

abstract

commandsMacros

and

subroutines?

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rights

reserved.Automation

and

human

control2-15Automation

andhuman

control

(cont.)?

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reserved.2-16Successful

integration:–

Users

can

avoid:Routine,

tedious,

and

error

prone

tasksUsers

can

concentrate

on:

Making

critical

decisions,

coping

withunexpected

situations,

and

planning

futureactionsAutomation

andhuman

control

(cont.)?

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Supervisory

control

needed

to

dealwith

real

world

open

systems

E.g.

air-traffic

controllers

with

lowfrequency,

but

high

consequences

offailure

FAA:

design

should

place

the

user

incontrol

and

automate

only

to

improvesystem

performance,

without

reducinghuman

involvementAutomation

andhuman

control

(cont.)?

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for

autonomous

agents–

knows

user"s

likes

and

dislikesmakes

proper

inferencesresponds

to

novel

situationsperforms

competently

with

little

guidance

Tool

like

interfaces

versus

autonomousagents

Aviators

representing

human

users,

notcomputers,

more

successfulAutomation

andhuman

control

(cont.)?

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modeling

for

adaptive

interfaces–

keeps

track

of

user

performanceadapts

behavior

to

suit

user"s

needsallows

for

automatically

adapting

system

response

time,

length

of

messages,

density

of

feedback,content

of

menus,

order

of

menu

items,

type

of

feedback,content

of

help

screenscan

be

problematicsystem

may

make

surprising

changesuser

must

pause

to

see

what

has

happeneduser

may

not

be

able

topredict

next

changeinterpretwhat

has

happenedrestore

system

to

previous

stateAutomation

andhuman

control

(cont.)?

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rights

reserved.2-20Alternative

to

agents:–

user

control,

responsibility,accomplishmentexpand

use

of

control

panelsstyle

sheets

for

word

processorsspecification

boxes

of

query

facilitiesinformation-visualization

toolsAutomation

andhuman

control

(concluded)Features

to

aid

in

universalaccessAbove:

Mac

OS

X

system

preferencesettingsRight:

Windows

Vista

Control

Panel?

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the

specifics

of

guidelines

Principles

are

used

to

developtheories

Descriptions/explanatory

orpredictiveMotor

task,

perceptual,

or

cognitiveExplanatory

andpredictive

theories?

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theories:–

Observing

behaviorDescribing

activityConceiving

of

designsComparinghigh-level

concepts

of

two

designsTrainingPredictive

theories:Enable

designers

to

compare

proposeddesigns

for

execution

time

or

error

ratesPerceptual,

Cognitive,&

Motor

tasks?

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Perceptual

or

Cognitive

subtaskstheoriesPredicting

reading

times

for

free

text,lists,

or

formatted

displays

Motor-task

performance

timestheories:Predicting

keystroking

or

pointing

timesTaxonomy(explanatory

theory)?

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on

a

complex

set

of

phenomenaFacilitate

useful

comparisonsOrganize

a

topic

for

newcomersGuide

designersIndicate

opportunities

for

novel

productConceptual,

semantic,

syntactic,

andlexical

model?

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and

van

Dam

four-level

approachConceptual

level:User"s

mental

model

of

the

interactive

systemSemantic

level:Describes

the

meanings

conveyedbythe

user"s

command

input

and

bythe

computer"s

output

displaySyntactic

level:Defines

how

the

units

(words)

that

convey

semantics

are

assembledinto

a

complete

sentence

that

instructs

the

computer

to

perform

acertain

taskLexical

level:Deals

with

device

dependencies

and

with

the

precise

mechanisms

bywhich

auser

specifies

the

syntaxApproach

is

convenient

for

designersTop-down

nature

is

easy

to

explainMatches

the

software

architectureAllows

for

useful

modularityduring

designStages

of

action

models?

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seven

stages

of

actionForming

the

goalForming

the

intentionSpecifying

the

actionExecuting

the

actionPerceiving

the

system

stateInterpreting

the

system

stateEvaluating

the

outcomeNorman"s

contributionsContext

of

cycles

of

action

and

evaluation.Gulf

of

execution:

Mismatch

between

the

user"s

intentionsand

the

allowable

actionsGulf

of

evaluation:

Mismatch

between

the

system"srepresentation

and

the

users"

expectationsStages

of

action

models

(cont.)?

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principles

of

good

designState

and

the

action

alternatives

should

be

visibleShould

be

a

good

conceptual

model

with

a

consistentsystem

imageInterface

should

include

good

mappings

that

reveal

therelationships

between

stagesUser

should

receive

continuous

feedbackFour

critical

points

where

user

failures

can

occurUsers

can

form

an

inadequate

goalMightnot

find

the

correct

interface

object

because

of

anincomprehensible

label

or

iconMaynot

know

how

to

specify

or

execute

a

desired

actionMay

receiveinappropriateor

misleading

feedback?

2010

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rights

reserved.Consistency

through

grammarsConsistent

user

interface

goalDefinition

is

elusive

-

multiple

levels

sometimes

inconflictSometimes

advantageous

to

be

inconsistent.ConsistentInconsistent

AInconsistent

Bdelete/insert

characterdelete/insert

worddelete/insert

linedelete/insert

character

delete/insert

characterremove/bring

worddestroy/create

lineremove/insert

worddelete/insert

linedelete/insertparagraphdelete/insert

paragraph

kill/birth

paragraph2-29Consistency

throughgrammars

(cont.)?

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action

verbsTake

longer

to

learnCause

more

errorsSlow

down

usersHarder

for

users

to

rememberThe

disappearance

of

syntax?

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Users

must

maintain

a

profusion

of

device-dependent

details

in

their

human

memory.Which

action

erases

a

characterWhich

action

inserts

a

new

line

after

the

third

line

of

atext

fileWhich

abbreviations

are

permissibleWhich

of

thenumberedfunction

keys

produces

theprevious

screen.The

disappearanceof

syntax

(cont.)?

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Learning,

use,

and

retention

of

this

knowledge

ishampered

by

two

problemsDetails

vary

across

systems

in

an

unpredictablemannerGreatly

reduces

the

effectiveness

of

paired-associatelearning

Syntactic

knowledge

conveyed

by

example

andrep