4 Understanding Users

8/12/2019 4 Understanding Users

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Ridi [email protected]


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A need to understand users

Interacting with technology iscognitive

We need to take into accountcognitive processes involved

and cognitive limitations ofusers

We can provide knowledgeabout what users can andcannot be expected to do

Identify and explain thenature and causes of problemsusers encounter


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What goes on in the mind


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Attention

Selecting things to concentrateAllows us to focus on information that isrelevant to what we are doing

Involves audio and/or visual sensesFocussed and divided attention enables usto be selective in terms of the mass ofcompeting stimuli but limits our ability tokeep track of all eventsInformation at the interface should bestructured to capture users attention


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Activity: Find the price of a double room at the Holiday Inn in Bradley


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Activity: Find the price for a double room at the Quality Inn inColumbia


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Attention in Our Activity

Tullis (1987) found that the two screens producedquite different results1st screen - took an average of 5.5 seconds to search

2nd screen - took 3.2 seconds to search

Why, since both displays have the same density ofinformation (31%)?Spacing

In the 1st screen the information is bunched up together, making

it hard to searchIn the 2nd screen the characters are grouped into verticalcategories of information making it easier


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Design Implication for Atention

Make information salient when it needsattending to

Use techniques that make things stand out

like colour, ordering, spacing, underlining,sequencing and animation

Avoid cluttering the interface - follow the

google.com example of crisp, simple designAvoid using too much because the softwareallows it


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Over-use of graphics


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Sufficient of graphics


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Perception and recognition

How information is acquired from the worldand transformed into experiencesObvious implication is to designrepresentations that are readily perceivable,e.g.

Text should be legibleIcons should be easy to distinguish and read


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Is color contrast good? Find italian


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Are borders and white spacebetter? Find french


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Activity

Weller (2004) found people took less time tolocate items for information that was groupedusing a border (2nd screen) compared with using colorcontrast (1st screen)

Some argue that too much white space on webpages is detrimental to searchMakes it hard to find information

Do you agree?


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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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Design implications

Representations of information need to be designed to beperceptible and recognizableIcons and other graphical representations should enableusers to readily distinguish their meaningBordering and spacing are effective visual ways ofgrouping informationSounds should be audible and distinguishableSpeech output should enable users to distinguish betweenthe set of spoken words

Text should be legible and distinguishable from thebackground


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Memory

Involves first encoding and then retrievingknowledgeWe dont remember everything - involves

filtering and processing what is attended toContext is important in affecting our memory(i.e., where, when)Well known fact that we recognize things much

better than being able to recall thingsBetter at remembering images than wordsWhy interfaces are largely visual


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Processing in memory

Encoding is first stage of memorydetermines which information is attended to in the environmentand how it is interpreted

The more attention paid to something,And the more it is processed in terms of thinking about itand comparing it with other knowledge,The more likely it is to be remembered

e.g., when learning about HCI, it is much better to reflect uponit, carry out exercises, have discussions with others about it, andwrite notes than just passively read a book, listen to a lecture orwatch a video about it


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Context is important

Context affects the extent to which informationcan be subsequently retrievedSometimes it can be difficult for people to recallinformation that was encoded in a different

contexte.g., You are on a train and someone comes up to you and sayshello. You dont recognize him for a few moments but thenrealize it is one of your neighbors. You are only used to seeingyour neighbor in the hallway of your apartment block and seeinghim out of context makes him difficult to recognize initially


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Activity

Try to remember the dates of yourgrandparents birthdayTry to remember the cover of the last twoDVDs you bought or rented

Which was easiest? Why?People are very good at remembering visualcues about things

e.g., the colour of items, the location of objects and marks

on an objectThey find it more difficult to learn andremember arbitrary material

e.g., birthdays and phone numbers


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Recognition versus recall

Command-based interfaces require users to recallfrom memory a name from a possible set of 100sGUIs provide visually-based options that usersneed only browse through until they recognize

oneWeb browsers, MP3 players, etc., provide lists ofvisited URLs, song titles etc., that supportrecognition memory


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The problem with the classic 7 2

George Millers theory of how muchinformation people can rememberPeoples immediate memory capacity is verylimitedMany designers have been led to believe thatthis is useful finding for interaction design


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What some designers get up to

Present only 7 options on a menuDisplay only 7 icons on a tool barHave no more than 7 bullets in a list

Place only 7 items on a pull down menuPlace only 7 tabs on the top of a website page

But this is wrong? Why?


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Personal information management

Personal information management (PIM) is a growingproblem for most usersWho have vast numbers of documents, images, music files, videoclips, emails, attachments, bookmarks, etc.,Major problem is deciding where and how to save them all, then

remembering what they were called and where to find themagainNaming most common means of encoding themTrying to remember a name of a file created some time back canbe very difficult, especially when have 1000s and 1000sHow might such a process be facilitated taking into accountpeoples memory abilities?


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Is Apples Spotlight search tool any good?


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Design implications

Dont overload users memories with complicatedprocedures for carrying out tasksDesign interfaces that promote recognition ratherthan recall

Provide users with a variety of ways of encodingdigital information to help them rememberwhere they have stored them

e.g., categories, color, flagging, time stamping


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Mental models

Users develop an understanding of a system throughlearning and using it

Knowledge is often described as a mental modelHow to use the system (what to do next)What to do with unfamiliar systems or unexpected situations(how the system works)

People make inferences using mental models of how tocarry out tasks


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Mental models

Craik (1943) described mental models asinternal constructions of some aspect of theexternal world enabling predictions to be

madeInvolves unconscious and conscious processes,where images and analogies are activated

Deep versus shallow models (e.g. how todrive a car and how it works)


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Information processing

Conceptualizes human performance inmetaphorical terms of informationprocessing stages


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Model Human processor (Card et al, 1983)

Models the information processes of a userinteracting with a computerPredicts which cognitive processes are involvedwhen a user interacts with a computer

Enables calculations to be made of how long auser will take to carry out a task


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The human processor model


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Design implication

Provide external representations at theinterface that reduce memory load andfacilitate computational offloading

e.g. Informationvisualizations havebeen designed toallow people to makesense and rapiddecisions aboutmasses of data


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Distributed cognition

Concerned with the nature of cognitivephenomena across individuals, artifacts, andinternal and external representations (Hutchins,1995)

Describes these in terms of propagation acrossrepresentational stateInformation is transformed through differentmedia (computers, displays, paper, heads)


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How it differs from informationprocessing


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Whats involved

The distributed problem-solving that takes placeThe role of verbal and non-verbal behaviorThe various coordinating mechanisms that areused (e.g., rules, procedures)The communication that takes place as thecollaborative activity progressesHow knowledge is shared and accessed


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Key points

Cognition involves several processes including attention,memory, perception and learning

The way an interface is designed can greatly affect howwell users can perceive, attend, learn and remember howto do their tasks

Theoretical frameworks such as mental models andexternal cognition provide ways of understanding how andwhy people interact with products, which can lead tothinking about how to design better products

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4 Understanding Users