modelling rich interaction sensor-based systems statusevent - PDF document

Modelling Rich Interaction • status–event analysis chapter 18 • rich environments in task analysis modelling rich interaction • sensor-based systems status–event analysis rich set of phenomena events status • events – things that happen input keypress m ouse position • e.g. alarm bell, beeps, keystrokes output beep display • status – things that are internal interrupt document state • e.g. screen display, watch face, mouse position external time t emperature • unifying framework – system ( formal analysis) – user (psychology & heuristics) Most notations only deal with subset of these • time behaviour – detect delays, select feedback • transferable phenomena e.g.STNs: event-in/ event-out e.g. polling – active agent discovers status change • � m ay need awkward work-arounds rich set of behaviour Properties of events � actions: • status change event – state change at (user initiated) event – the passing of a tim e � status change events: • actual and perceived events – e.g. stock drops below re-order level – usually som e gap � interstitial behaviour: • polling – between actions – e.g. dragging an icon – glance at watch face – status change becom es perceived event standard notations: • granularity � usually, � sometimes, � never! – birthday – days – appointm ent – m inutes 1

Design implications Naïve psychology • Predict where the user is looking • actual/ perceived lag… m atches application tim escale? – m ouse – when positioning – insertion point – interm ittently when typing – screen – if you're lucky • too slow – response to event too late • Immediate events e.g., power plant em ergency – audible bell – when in room (and hearing) – peripheral vision – m ovem ent or large change • too fast • Closure – interrupt m ore im m ediate task – lose attention (inc. m ouse) e.g., stock level low – concurrent activity email delivery email delivery (ctd) mailbox file mailtool screen user time status agent status agent mailbox file mailtool screen user time • m ail has arrived! status agent status agent mail arrives event mailtool • timeline at each level notices change icon event event mail arrives user notices event mailtool event notices change icon event event • Perceived event in minutes – not guaranteed user alternative timescale notices explicit examination – hours/ days event audible bell – seconds but want minutes – guaranteed screen button widget Screen-button – HIT Delete Delete Delete Delete screen button often m issed, … but, error not noticed the quick brown the quick brown the quick brown the quick brown quick quick quick quick a com m on widget, a com m on error: Why? Closure mistake likely – concurrent action not noticed – semantic feedback missed Solution widget feedback for application event Delete Delete Delete Delete a perceived event for the user N.B. an expert slip – testing doesn't help the quick brown the brown fox the quick brown the quick brown quick quick quick 2

Screen button – MISS HIT or a MISS? HIT CLICK identical screen feedback semantic feedback only MI SS closure � eye moves elsewhere Delete Delete Delete Delete one solution add simulated click the quick brown the quick brown the quick brown the quick brown quick quick quick quick the problem • task models rich contexts – form al description bringing • situatedness them – unique contexts together? • ethnography – rich ecologies ConcurTaskTrees (CTT) collaboration Paterno et al. CNUCE, Pisa • already in several notations – e.g. CTT, GTA book holiday abstract task user task • add artefacts too ? >> computer task holiday idea make booking user and computer cooperative task >> || >> email advert decide destination book flights choose hotel book hotel ( customer :) ( travel agent:) ( customer :) ( travel agent:) 3

Groupware Task Analysis information GTA pre-planned cognitive model – conceptual fram ework, tools, elicitation techniques goal � action Used_by rich m odel of task world Subrole Object Contains Role situated action rich ontology Is environment � action Responsible – human roles for Event Triggers Uses Plays collaboration Performed_by – physical and Performed_by Agent Task electronic objects Has Goal Subtask Triggers Subgoal control control • open loop control • open loop control – no feedback – no feedback – fragile – fragile • closed loop control – uses feedback – robust feedback control control environment environment system system actions actions adding information adding information (ctd) inform ation required when – subtask involves input ( or output) – some kind of choice (how to know what to do) 0. pour tea – subtask repeated ( but iterations unspecified) how many Plan 0: cups? sources of inform ation 1 then 2 i. part of existing task (e.g. phone number entered) when kettle boils 3 then 4 ii. user remembers it (e.g. recall number after directory enquiry) iii. on device display ( e.g. PDA address book, then dial) 1. 2. 3. 4. boil get out make pot iv. in the environment pour tea kettle cups of tea • pre-existing ( e.g. phone directory) • created in task (e.g. write number down on paper) GUI easy ( lots of space) m obile/ PDA need to think 4

triggers triggers process – what happens and order process – what happens and order triggers – when and why first thing in the holding post at coffee time morning get post from bring post get post from bring post open post open post pigeon hole to desk pigeon hole to desk common triggers artefacts • immediate • ethnographic studies – straight after previous task • as shared representation • tem poral • as focus of activity – at a particular tim e • sporadic • act as triggers, information sources, etc. – when som eone thinks of it! • external event – when som ething happens, e.g. phone call • environmental cue – som ething prom pts action … artefacts placeholders where are you? • knowing where you are in a process 1. controller 2. controller 3. pilot 4. pilot 5. choose new tell pilot new confirm new ascend to new flight – like a program counter flight level flight level flight level new level level achieved • coding: – m em ory – explicit (e.g. to do list) – in artefacts 5

step 1. choose new flight level step 3. flight level confirmed 1. controller 2. controller 3. pilot 4. pilot 5. 1. controller 2. controller 3. pilot 4. pilot 5. choose new tell pilot new confirm new ascend to new flight choose new tell pilot new confirm new ascend to new flight flight level flight level flight level new level level achieved flight level flight level flight level new level level achieved tracing placeholders step 5. new flight level acheived a form of inform ation, m ay be … 1. controller 2. controller 3. pilot 4. pilot 5. choose new tell pilot new confirm new ascend to new flight – in people’s heads flight level flight level flight level new level level achieved • remembering what to do next – explicitly in the environm ent • to-do lists, planning charts, flight strips, workflow – im plicitly in the environm ent • location and disposition of artefacts electronic environments … papers tidy or skewed – fewer affordances for artefacts letter open or closed – danger for careless design! car courtesy lights • turn on low intention and – when doors unlocked/ open sensor-based interaction • turned off – after tim e period – when engine turned on driver's purpose is to get into the car incidentally the lights come on 6

Pepys MediaCup • Xerox Cambridge (RIP) • cup has sensors – heat, m ovem ent, pressure • active badges • broadcasts state (IR) • automatic diaries • used for awareness – user is m oving, drinking, … Allan's purpose to visit Paul’s office Han's purpose to drink coffee incidentally diary entry created incidentally colleagues are aware shopping cart onCue • goods in shopping cart analysed • ‘intelligent’ toolbar – e.g. Amazon books – appropriate intelligence • used to build knowledge about books • make it good when it works – people who like X also like Y • don’t make it hard of it doesn’t • used to give you suggestions • analyses clipboard contents – “you might like to look at … ”, “special offer … ” • suggests things to do with it my purpose to buy a book user's purpose to copy text elsewhere incidentally shown related titles incidentally alternative things to do the intentional spectrum fluidity intentional intentional press light switch co- option users explicitly use behaviour e.g. open door for lights expected expected walk into room expecting lights to switch on com prehension users notice, form model walk into room … unbeknown to you then rely on behaviour incidental incidental … air conditioning increases 7