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Understanding users

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Overview

• What is cognition?

• What are users good and bad at?

• Mental models

• External cognition

• Using this understanding to informsystem design

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Why do we need to understandusers?

• Interacting with technology is cognitive

• We need to take into account cognitive rocessesinvolved and cognitive limitations of users

• We can rovide knowledge about what users canand cannot be exected to do

• Identify and exlain the nature and causes of

roblems users encounter• !uly theories" modelling tools" guidance and

methods that can lead to the design of betterinteractive roducts

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#$ %ringing cognitive

sychology knowledge to &'I

 

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'ore cognitive rocesses

• (ttention

• )ercetion and recognition

• Memory

• *eading" seaking and listening

• )roblem+solving" lanning" reasoning and

decision+making" learning• &ere we focus on attention" ercetion ,

recognition" , memory

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(ttention

• !electing things to concentrate on from themass around us" at a oint in time

• -ocussed and undivided attention enables us

to be selective in terms of the mass ofcometing ossibilities available

• It involves auditory and.or visual senses

• Information at the interface should be

structured to cature users/ attention" e$g$ useercetual boundaries 0windows1" colour"sound and flashing lights

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2esign imlications for

attention• Make information salient when it needs

attending to

• Use techni3ues that make things stand out likecolour" ordering" sacing" underlining"se3uencing and animation

• (void cluttering the interface + follow the

google$com examle of cris" simle design

• (void using too much because the softwareallows it

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(n examle of over+use of

grahicsOur Situation

S t a t e t h e b a d n e w s

B e c l e a r , d o n ’ t t r y t o o b s c u r e t h es i t u a t i o n

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)ercetion and recognition

• &ow information is ac3uired from theworld and transformed into exeriences

• Obvious imlication is to designreresentations that are readilyerceivable" e$g$

4 5ext should be legible

4 Icons should be easy to distinguish andread

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Which is easiest to read and

why?

What is the time?

What is the time?

What is the time?

What is the time?

What is the time?

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Memory

• Involves recalling various kinds of knowledge thatallows us to act aroriately

• We don/t remember everything + involves filteringand rocessing

• 'ontext is imortant in affecting our memory

• We recogni6e things much better than being able torecall things

4 5he rise of the 7UI over command+based interfaces

• %etter at remembering images than words4 5he use of icons rather than names

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5he roblem with the classic

 89±:/ 

• 7eorge Miller/s theory of how muchinformation eole can remember

• )eole/s immediate memory caacity is verylimited

• Many designers have been led to believe that

this is useful finding for interaction design

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What some designers get u to;

• )resent only 9 otions on a menu

• 2islay only 9 icons on a tool bar

• &ave no more than 9 bullets in a list

• )lace only 9 items on a ull down menu

• )lace only 9 tabs on the to of a websiteage

4 %ut this is wrong? Why?

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Why?

• Inaroriate alication of the theory

• )eole can scan lists of bullets" tabs" menuitems till they see the one they want

• 5hey don/t have to recall them from memoryhaving only briefly heard or seen them

• !ometimes a small number of items is good

design

• %ut it deends on task and available otions

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More aroriate alication of

memory research• -ile management and retrieval is a real

roblem to most users

• *esearch on information retrieval can beusefully alied

• Memory involves : rocesses

4 recall+directed and recognition+based scanning

• -ile management systems should be designedto otimi6e both kinds of memory rocesses

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-ile management

• -acilitate existing memory strategiesand try to assist users when they getstuck

• &el users encode files in richer ways

4 )rovide them with ways of saving files usingcolour" flagging" image" flexible text" time

staming" etc

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Mental models

• Users develo an understanding of asystem through learning , using it

• <nowledge is often described as a mentalmodel

4 &ow to use the system 0what to do next1

4 What to do with unfamiliar or unexected

situations 0how the system works1• )eole make inferences using mental

models of how to carry out tasks

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Mental models

• 'raik 0#=>1 described mental modelsas internal constructions of some asectof the external world enabling

redictions to be made• Involves unconscious and conscious

rocesses

• 2ee versus shallow models 0e$g$ howto drive a car and how it works1

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Everyday reasoning , mentalmodels

0a1 @ou arrive home starving hungry$ @ou look in thefridge and find all that is left is an halve cookedfood$ @ou have an electric oven$ 2o you warm itu to 9A degrees first and then ut it in 0as

secified by the instructions1 or turn the oven uhigher to try to warm it u 3uicker?

0b1 @ou are going for an interview and almost late$

@ou decided to take the elevator instead of thestairs to get to the office on time for the interview$&ow many time will you ress the elevator button

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&eating u a room or oven thatis thermostat+controlled

• Many eole have erroneous mentalmodels$

• Why?4 7eneral theory" where 8more is more/

rincile is generalised to different settings0e$g$ (ccelerator edal" gas cooker" ta"

radio volume1

4 5hermostats based on model of on+offswitch model

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External cognition

• 'oncerned with exlaining how weinteract with external reresentations0e$g$ mas" notes" diagrams1

• What are the cognitive benefits andwhat rocesses involved

• &ow they extend our cognition

• What comuter+based reresentationscan we develo to hel even more?

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Externali6ing to reducememory load

• 2iaries" reminders" calendars" notes" shoing lists"to+do lists + written to remind us of what to do

• External reresentationsB4 *emind us that we need to do something 0e$g$ to buy

something for valentine/s day1

4 *emind us of what to do 0e$g$ buy a card1

4 *emind us when to do something 0e$g$ send a card by acertain date1

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'omutational offloading

• When a tool is used in conunction with anexternal reresentation to carry out acomutation 0e$g$ en and aer1

• 5ry doing the sum below 0a1 in your head"0b1 on a iece of aer and c1 with acalculator$ 4 :> x >AF G??

• Which is easiest and why?

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(nnotation and cognitivetracing

• (nnotation involves modifying existingreresentations through making marks

4 e$g$ crossing off" ticking" underlining

• 'ognitive tracing involves externallymaniulating items into different orders

or structures4 e$g$ laying scrabble" laying cards

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2esign imlication

• )rovide external reresentations at theinterface that reduce memory load andfacilitate comutational offloading

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Informing design based on our

understanding of users• &ow can we use knowledge about users

to inform system design?

• )rovide guidance and tools4 2esign rinciles and concets

4 2esign rules

• )rovide analytic tools

4 Methods for evaluating usability

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Mental models , system

design• (ssumtion is that if you can understand how

eole develo mental models then can hel them

develo more aroriate mental models ofsystem functionality

• -or examle" a design rincile is to try to makesystems transarent so eole can understandthem better and know what to do

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<ey oints

• 'ognition involves many rocesses includingattention" memory" ercetion and learning

• 5he way an interface is designed can greatly affecthow well users can erceive" attend" learn andremember how to do their tasks

• 5he concetual framework of 8mental models/ and 8external cognition/ rovide ways of understandinghow and why eole interact with roducts" whichcan lead to thinking about how to design betterroducts

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ExerciseB (5Ms

• Write down how an (5M works4 &ow much money are you allowed to take out?

4 What denominations?

4 If you went to another machine and tried the same what

would haen?

4 What information is on the stri on your card? &ow isthis used?

4 What haens if you enter the wrong number?

4 Why are there auses between the stes of atransaction? What haens if you try to tye duringthem?

4 Why does the card stay inside the machine?

4 2o you count the money? Why?

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&ow did you fare?

• @our mental model4 &ow accurate?

4 &ow similar?

4 &ow shallow?