7 Design Rules

8/2/2019 7 Design Rules

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Design RulesDesign RulesDesign RulesDesign Rules

Human Computer InteractionHuman Computer Interaction

--Dix, Finlay,Dix, Finlay, AbowdAbowd, Beatle, Beatle- -

Vu,Vu, ThiThi Hong NhanHong Nhan( [email protected] )( [email protected] )

Faculty of Information TechnologyFaculty of Information Technology

Vietnam National University, HanoiVietnam National University, Hanoi

(( Lecture NotesLecture Notes ))
mailto:[email protected]:[email protected]:[email protected]:[email protected]


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Introduction

Principles to support usability

Learnability

Flexibility

OutlineOutlineOutlineOutline

20122012--0202--0909 Design RulesDesign Rules PagePage 22

Robustness

Standards

Guidelines

Golden rules & heuristics

HCI patterns


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Types of design rulesTypes of design rulesTypes of design rulesTypes of design rules

PrinciplesAbstract design rules

Low authority (Tnh tin c y th p)

High generality (Tnh khi qut cao)

Standards

Specific design rules

High authority

Limited application

GuidelinesLow authority

More general application



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Principles to support usabilityPrinciples to support usabilityPrinciples to support usabilityPrinciples to support usability

Learnability ( Tnh h c c)

The ease with which new users can begin effective interaction and

achieve maximal performance

Flexibilit Tnh linh n

Refer to the multiplicity of ways the user and system exchange

information

Robustness( Tnh v ng ch c)The level of support provided to the user in determining successful

achievement and assessment of goal-directed behavior



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Determining the result of the

future interaction based on the

users knowledge of the

interaction history


LearnabilityLearnability: Predictability: PredictabilityLearnabilityLearnability: Predictability: Predictability


E.g., to open a file, a window will

appear

and allow us to choose the file

If the files name is wrongly

typed, a message will be popped

up


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Assess the effect of past actions on the current stateWhen an operation changes some aspect of the internal state , its important that

the change is seen by the user

The principle of honesty (tnh chn th c )


LearnabilityLearnability: synthesizability: synthesizabilityLearnabilityLearnability: synthesizability: synthesizability


of such change

Immediate vs. eventual honestyE.g., compare moving a file from one directory to another

in a command language system , have to remember the destination directory &

ask to see the contents of the directoryTo verify the file has been moved eventual honesty

in a visual desktop interface , an icon of file is dragged to the destination folder

where it remains visible immediate honesty


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LearnabilityLearnability: familiarity: familiarityLearnabilityLearnability: familiarity: familiarity

Tnh quen thu cThe extend to which a users knowledge and experience in other

real-world or computer-based domains can be applied when

interactin with a new s stemnew s stem


E.g., when word processor was introduced,

the analog between word processor and typewriter was intended to

make the new technology more immediately accessible to those whohad little experience with the former but a lot of experience with the later


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LearnabilityLearnability (cont.)(cont.)LearnabilityLearnability (cont.)(cont.)

generalizability ( Tnh khi qut)

Extend users knowledge of specific interaction behaviors to situations

that are similar but previously unencountered

Can occur within a single application & across a variety of applications


E.g., in multi-windowing systems, cut/copy/paste operations are

attempted to provide to all applications in the same way

Consistency (Tnh nh t qun)

Likeness in input/output behavior arising from similar situations or

similar task objectives


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FlexibilityFlexibilityFlexibilityFlexibility

Dialogue initiative (Ch ng h i tho i)

Consider which partner(user/system) has the initiative in the

conversation

The system can initiate all dialogs , in which case the user simply


responds to request for information

E.g., a modal dialog box prohibits the user from interacting with the

system in a way that doesnt direct input to the box

Alternatively, the user may be entirely free to initiate any action towards

the system

System-driven interaction hinders flexibility, whereas user-driven

interaction favors it


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Flexibility (contd)Flexibility (contd)Flexibility (contd)Flexibility (contd)

Multi-threading ( a tuy n o n )Ability of the system to support more than one task at a time

Thread is a part of a dialoga part of a dialog that relates to a given task

multi-threading allows simultaneous communication of information pertaining to

separate tasks


E.g., in a windowing system, each window represent a different taskText editing in one window, file management in another, email in another

A multi-modal (a phu ng th c) dialog allows for concurrent multi-threading

Youre editing a program when a beep indicates that a new email has arrived

The audible beep has interleaved with your requests from the keyboard to

perform edits


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Flexibility: TaskFlexibility: Task migratabilitymigratabilityFlexibility: TaskFlexibility: Task migratabilitymigratability

Kh nng chuy n giao gi a cc nhim v

Concerns the transfer of control for execution of tasks between

user and system


. ., - ,

against its own list of acceptable spellings (based on an equipped

dictionary)

But its not desirable, because most computerized dictionaries donthandle proper names correctly, nor can distinguish correct and

unintentional duplicates of words

In those cases, the task is handled over to the user


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Flexibility:Flexibility: substitutivitysubstitutivityFlexibility:Flexibility: substitutivitysubstitutivity

Tnh thay th c

Require the equivalent values can be substituted for each others

E.g., the form of an input expression to determine the margin for a

letter


You may want to enter the value in either inches or centimeters

Or you may want to input the value explicitly (say 1.5 inches)

Substituitivity contributes towards the flexibility

by allowing the user to choose whichever form best suits the needs of

the moment

Minimize user errors and cognitive effort


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Flexibility: customizabilityFlexibility: customizabilityFlexibility: customizabilityFlexibility: customizability

Tnh ty bi nIs the modification of the user interface by the user or system

We are concerned with the automatic modification that the system

would make based on its knowledge of the user


User-initiated vs. system-initiated modification ( adaptability vs.

adaptivity )Adaptability refers to the users ability to adjust the form of input and

output , is restricted to the surface of the interfaceUser allowed to adjust the position of soft buttons on the screen or redefine

command names

Adaptivity is automatic customization of the user interface by the system Decision for adaption based on user expertise or observed repetition of certain task

sequences


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RobustnessRobustnessRobustnessRobustness

observabilityability of the user to evaluate the internal state of the system from its perceivablerepresentation at the interface

Recoverability

Ability to reach a desired goal after recognition of some error in a previous


Forward error recovery : accept the current state

Backward: return to a prior state before proceeding

ResponsivenessMeasure the rate of communication between the system and user

Response time is the duration of time needed by the system to express the state

changes to the user

Short durations and instantaneous response times are desirable


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Robustness: task conformanceRobustness: task conformanceRobustness: task conformanceRobustness: task conformance

Tnh thch nghi v i nhi m v

Degree to which system services support all of the users tasks


Task completeness address the coverage issue

Its desirable that the system services be suitably general so that the

user can define new tasksnew tasks


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Set by national or international bodies to ensure compliance by a

large community of designers

Standards require sound underlying theory & slowly changing

technology

StandardsStandardsStandardsStandards


Hardware standards more common than software

high authority, low level of detail

ISO 9241 defines usability as effectiveness(h u d ng), efficiency,

and satisfaction with which users accomplish tasks


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Kim ch namMore suggestive and general (khuyn rn v khi qut)

Many textbooks and reports full of guidelines

Abstract uidelines rinci les a licable durin earl life c cle

GuidelinesGuidelinesGuidelinesGuidelines


activities

Detailed guidelines applicable during later life cycle activities

Understanding justification( l l ) for guidelines aids in resolving

conflicts


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Golden rules & heuristicsGolden rules & heuristicsGolden rules & heuristicsGolden rules & heuristics

broad brush design rules (Lu t thi t k ch i r ng)

Used as useful check list for good design

Different collections, e.g.,

Schneidermans 8 golden rules

Normas 7 principles



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SchneidermansSchneidermans 8 golden rules8 golden rulesSchneidermansSchneidermans 8 golden rules8 golden rules


1. Strive for consistency (Tnh nh t qun)

2. Enable frequent users to use shortcuts

3. Offer informative feedback


4. Design dialogs to yield closure

5. Offer error prevention and simple error handling

6. Permit easy reversal of actions (cho php quay l i hnh ng c )

7. Support internal locus of control (h tr v tr i u khi n bn trong

8. Reduce short-term memory load


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Normas 7 principlesNormas 7 principlesNormas 7 principlesNormas 7 principles


1. Use both knowledge in the real world and knowledge in the head

2. Simplify the structure of tasks

3. Make things visible: bridge the gulfs of Execution and Evaluation


4. Get the mappings right

5. Exploit the power of constraints, both natural and artificial

6. Design for error

7. When all else fails, standardize


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HCI patternsHCI patternsHCI patternsHCI patterns

An approach to capturing and reusing the knowledge of what made

a system (or paradigm) successful

A pattern is a variant solution to a recurrent problem within a specific

context

Patterns dont exist in isolation but are linked to other patterns in

languages which enable complete design to be generated



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HCI patterns (contd)HCI patterns (contd)HCI patterns (contd)HCI patterns (contd)

Features of patterns & patterns languages

Capture design practice & embody knowledge about successful

solutions

Capture essential common properties of good design ey on t te t e es gner ow to o somet ng u w a nee s to e

done and why

Represent design knowledge at varying levels , ranging from social and

organizational issues through conceptual design to detailed design

Intuitive and readable can be used for communication between all

stakeholders



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SummarySummarySummarySummary

Have seen how design rules can be used to provide direction for the

design process

The most abstract design rules are principles

Which represent generic knowledge about good design practice

Patterns

capture design practice

and attempt to provide a generative structure to support the design

process


7 Design Rules

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