Cognitive Aspects of UIDesign

Lecture 2

May 16, 2006

As hard as computers may be tounderstand, humans are harder!

Still, there are properties of humanlearning and performance that we can

focus on

Ergonomics

• er·go·nom·ics ("&r-g&-'nä-miks)

“…an applied science concerned withdesigning and arranging things peopleuse so that the people and thingsinteract most efficiently and safely…”

AKA human engineering

Cognetics: Ergonomics for theBrain

AKA cognitive engineering

• The study of human mental abilities,their limitations, and the applicationof this in design.

“Use a machine or tool in accord with itsstrengths and limitations and it will do agood job for you”

“Design a UI in accord with the abilitiesand foibles of humankind, and you willhelp the user to not only get the jobdone but also be a happier, moreproductive person”

What is Cognition?

• Facility for human-like processing ofinformation– Mental functions, processes, states of

intelligent entities

• More widely…– The act of knowing

– Social sense (emergent development ofknowledge and concepts)

Cognition as Computation

• Computational-RepresentationalUnderstanding/Theory of Mind

“Thinking can best be understood in termsof representational structures in the mind,and the computational procedures thatoperate on them”

The mind as a computer..?

Program

Data Structures +

Algorithms

= Running Program

Mind

Mental Representation +

Computational Procedures

= Thinking

What does cognition entail?

PerceivingThinking

RememberingLearning

Understandingand interacting

with others

PlanningImaginingPaintingWriting

Making decisionsSolving problems

Daydreaming

Specific Processes

• Attention

• Perception and recognition

• Memory

• Learning

• Reading, speaking, listening

• Problem solving, planning, reasoning,decision making

Attention

• Selective concentration– “Locus of attention”

• Involves senses

• Not always voluntary

• Cannot focus on more than one thing

Goals of attention

• Matching what we want with theinformation that is available

• Information presentation– Influences ability to attend to information

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Code

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Design Implications: Attention

• Make information salient

• Don’t overload the user

• K · I · S · S

Perception

• Acquiring and transforming informationinto experiences– Via sense organs

– Experiences of objects, events, sounds,tastes

• Perceptions do not automaticallybecome memories– Cannot assume that a user will therefore

remember

Design implications

• Information should be readily perceivedin the manner intended

• Combining media must be done socarefully– Lip syncing

Memory

• Recalling information so that we maybehave appropriately– E.g. face recognition, conversation

recollection

• Filtering process– We cannot remember everything

– Not perfect, sadly

The Memory Process

• Encoding– Determining what is attended to and how

interpreted

– More attention paid & more processing -->more likely to be remembered

• E.g. “Active learning”

• Context of encoding– Imagine running into someone “out of

context”

• We are better recognizers than recallers

Activity

Try to remember the dates of all thebirthdays of the members of your familyand close friends.

Next, try to recall the cover of the lastDVD or CD you bought

• What memory strategies do you use?

Design Considerations

• Don’t force your user to rememberarbitrary information– GUIs versus text-based design

– Web page bookmarks

– Many others

• File management

File Management

• We create huge numbers of files

• How do we make sure we can find themagain?

• Problem of information retrieval

Information Retrieval

• Two processes:

Recall-directed scanning

Use memory to get as close as possible

Recognition-based scanningRecall is insufficient, must look directly for file

Imagine trying to find a particular website

Information Retrieval

• Use processes together to facilitate filetracking

• Use memory to get as close as possible

• Then switch to recognition-basedpresentation

• Natural language processing can help

Design Implications

• Don’t overload user’s memories

• Promote recognition not recall– E.g. icons, menus, consistency

• Provide users with a variety of encodingmethods– OS X’s colour bars, e.g.

– Flagging

Learning

How to use a computer-based application

versus

Using a computer-based application to learn

Techniques for Learning

• Learning by doing

• “Training wheels”– Restrict options for novices

– Make learning tractable

Learning Styles• Concrete

– Prefer information visualization– Seek direct relationship with knowledge

• E.g. practical applications

• Canonical– Prefer abstract symbol manipulation– Separate learner and information

• Also– Visual versus auditory versus active

Design Implications

• Encourage exploration– Dynalinking

• Offer variety– Different representations of the same

process or concept

• Constrain and guide the learner

Reading, speaking, listening

• Meaning constant across 3 modes• Some considerations

– Can re-read written information– Reading can be faster– Listening is “easier”– Written language is more constrained by

grammar– People have different abilities and

preferences

Examples of applications

• Interactive books/pages for learning foreignlanguages

• Speech recognition

• Speech generation

• Natural language systems

• Other input devices for assisting people withvarious disabilities– E.g. auditory and tactile interfaces for the blind

Design Implications

• Spoken menus and instructions shouldbe short

• Accentuate intonation and cadence inartificial voices

• Provide opportunities to adjust visualpresentation– E.g. enlarging text without disrupting

information presentation

Problem solving, planning,reasoning, decision making

• Reflective cognition– What to do, options and consequences– Involve conscious aspects; interaction with

others; artifacts (e.g. maps)

• Comparing different sources ofinformation– E.g. choosing a search engine or web

page

Level of Experience

• Affects reflective cognition– Novices may make assumptions or work

by “trial and error”

– Experts know optimal strategies• Consider an expert chess player

Design Implications

• Provide “levels” of information– Available to users who want more

Building Habits

• What is a habit?

• Essential to higher life forms– Imagine driving; typing; walking

• Persistent use of an interface willdevelop habits– Must take advantage of this

– Ensure user habits smooth the flow of theirwork

Do you agree or disagree?

The ideal interface reduces userinvolvement to benign habituation.

Habit == automatic tasks

• Allows us to perform more than oneactivity at a time

• Automaticity prevents/reduces taskinterference– The more predictable/automatic a task, the

less it interferes with other tasks

• Can simulate simultaneity by switching

Points to consider

• Many problems with current UI are dueto the failure to embrace human habits– E.g. too many options shift attention from

task to choice of method

• Habits are very hard to break– Must ensure we build good ones

• No amount of training can prevent habitformation

Inevitability of habits

• Consider notion of “confirming beforeyou delete”– If errors are rare, will develop habit of

typing “Y”

• Any confirmation step that elicits a fixedresponse soon becomes useless

What do you think?

Can you brainstorm other confirmationtechniques that minimize errors due tohabitual response?

How will the user feel about your method?

Locus of Attention• Roger Penrose:

– “A characteristic feature of consciousthough…is its ‘oneness’ -- as opposed to agreat many independent activities going onat once”

• Evidence in studies asking users tomonitor a “demanding stream ofinformation”– Will miss alternative streams of

information, even presented to samesensory organ

Absorption

• The more intense the focus, the harderto shift the locus

• Can be essential to productivity

• Consider– Reading a book; video games; thinking

deeply

– Can be deadly -- e.g. 1972 plane crashwhile trying to change a bulb

Design Implications• Assume user is absorbed

– E.g. cursor changes do not always work

• User’s response can be proportional tothe degree of absorption– A user is most likely to miss a response

when it is most important

• If a UI is too stressful– The user focuses on the computer and not

his task– Can miss helpful aids when stressed about

unexpected computer behaviour

Design Implications

• Exploit the single locus of attention– Takes human about 10 seconds to switch

contexts from one task to another

• E.g. Canon CAT– Stored bit by bit image of screen

– Placed on screen when user restarted

– Appeared to “instant” start

• E.g. Card shuffling noise

Activity

• You can design interfaces so that errormessages are not necessary.– Discuss.

– How might this work? Do you think this ispossible?

Mental Models

• The user’s knowledge of how to use asystem and how the system works– Internal constructions of some aspect of

the external world

– Can be conscious or unconscious

• Use model to make inferences aboutinteraction

Mental Models

• Incorrect models are common

• Consider these two dilemmas– Coming home on a winter day

– Making pizza when you are starving

• Other examples– Crosswalks

– Frozen cursor

Mental Models & UI

• Mental models of interactive devices areoften poor

• Behaviour is often verystrange/unpredictable

• When models fail, users becomefrustrated

How can we facilitate bettermodels?

• Education– Tradeoff -- not everyone wants/has time to learn

• Design more transparent interfaces– Provide user feedback

– Intuitive interface

– Clear instructions

– Online tutorials

– Context sensitive guidelines when users are stuck

– Metaphor and analogy

Recap

• What is cognition?

• Various aspects of cognition– What are they?

– How can the impact UI design?