the interaction physical characteristics of interaction - PDF document

The Interaction • interaction models chapter 3 – translations between user and system • ergonomics the interaction – physical characteristics of interaction • interaction styles – the nature of user/ system dialog • context – social, organizational, motivational What is interaction? communication models of interaction user � system terms of interaction Norman model but is that all … ? interaction framework – see “language and action” in chapter 4 … Some terms of interaction Donald Norman’s model domain • Seven stages – the area of work under study e.g. graphic design – user establishes the goal goal – form ulates intention – what you want to achieve – specifies actions at interface e.g. create a solid red triangle – executes action task – how you go about doing it – perceives system state – ultim ately in term s of operations or actions – interprets system state e.g. … select fill tool, click over triangle – evaluates system state with respect to goal Note … – traditional interaction … • Norman’s model concentrates on user’s view – use of term s differs a lot especially task/ goal !!! of the interface 1

execution/evaluation loop execution/evaluation loop goal goal execution evaluation execution evaluation system system • user establishes the goal • user establishes the goal • formulates intention • formulates intention • specifies actions at interface • specifies actions at interface • executes action • executes action • perceives system state • perceives system state • interprets system state • interprets system state • evaluates system state with respect to goal • evaluates system state with respect to goal execution/evaluation loop execution/evaluation loop goal goal execution evaluation execution evaluation system system • user establishes the goal • user establishes the goal • formulates intention • formulates intention • specifies actions at interface • specifies actions at interface • executes action • executes action • perceives system state • perceives system state • interprets system state • interprets system state • evaluates system state with respect to goal • evaluates system state with respect to goal Using Norman’s model Human error - slips and mistakes Some systems are harder to use than others slip understand system and goal correct form ulation of action Gulf of Execution incorrect action user’s form ulation of actions � actions allowed by the system mistake may not even have right goal! Gulf of Evaluation user’s expectation of changed system state Fixing things? � slip – better interface design actual presentation of this state m istake – better understanding of system 2

Abowd and Beale framework Using Abowd & Beale’s model extension of Norm an… user intentions O � translated into actions at the interface their interaction fram ework has 4 parts � translated into alterations of system state – user output � reflected in the output display – input S U � interpreted by the user – system core task – output I input general framework for understanding interaction each has its own unique language – not restricted to electronic com puter system s interaction � translation between languages – identifies all m ajor com ponents involved in interaction – allows com parative assessm ent of system s problem s in interaction = problem s in translation – an abstraction Ergonomics • Study of the physical characteristics of interaction ergonomics • Also known as human factors – but this can also be used to m ean m uch of HCI! physical aspects of interfaces industrial interfaces • Ergonomics good at defining standards and guidelines for constraining the way we design certain aspects of system s Ergonomics - examples Industrial interfaces • arrangement of controls and displays Office interface vs. industrial interface? e.g. controls grouped according to function or frequency of use, or sequentially Context matters! • surrounding environment e.g. seating arrangem ents adaptable to cope with all office industrial sizes of user type of data textual numeric • health issues rate of change slow fast e.g. physical position, environm ental conditions (tem perature, hum idity), lighting, noise, environment clean dirty • use of colour e.g. use of red for warning, green for okay, … the oil soaked mouse! awareness of colour-blindness etc. 3

Glass interfaces ? Indirect manipulation • industrial interface: • office– direct m anipulation – traditional … dials and knobs – user interacts with artificial world system – now … screens and keypads • glass interface + cheaper, m ore flexible, • industrial – indirect m anipulation Vessel B Temp m ultiple representations, – user interacts precise values 0 100 200 with real world – not physically located, through interface plant interface loss of context, 113 • issues .. com plex interfaces immediat – feedback • m ay need both e feedbac multiple representations – delays k of same information instruments Common interaction styles • command line interface interaction styles • menus • natural language • question/ answer and query dialogue • form-fills and spreadsheets dialogue … computer and user • WIMP distinct styles of interaction • point and click • three–dimensional interfaces Command line interface Menus • Way of expressing instructions to the • Set of options displayed on the screen com puter directly • Options visible – function keys, single characters, short abbreviations, – less recall - easier to use whole words, or a com bination – rely on recognition so nam es should be m eaningful • Selection by: • suitable for repetitive tasks – num bers, letters, arrow keys, m ouse • better for expert users than novices – com bination (e.g. m ouse plus accelerators) • offers direct access to system functionality • Often options hierarchically grouped • command names/ abbreviations should be – sensible grouping is needed meaningful! • Restricted form of full WIMP system Typical example: the Unix system 4

Natural language Query interfaces • Fam iliar to user • Question/ answer interfaces – user led through interaction via series of questions • speech recognition or typed natural language – suitable for novice users but restricted functionality • Problem s – often used in inform ation system s – vague – am biguous • Query languages (e.g. SQL) – hard to do well! – used to retrieve inform ation from database • Solutions – requires understanding of database structure and – try to understand a subset language syntax, hence requires som e expertise – pick on key words Form-fills Spreadsheets • Prim arily for data entry or data retrieval • first spreadsheet VISICALC, followed by • Screen like paper form. Lotus 1-2-3 • Data put in relevant place MS Excel most common today • Requires • sophisticated variation of form-filling. – good design – grid of cells contain a value or a formula – obvious correction – formula can involve values of other cells facilities e.g. sum of all cells in this colum n – user can enter and alter data spreadsheet m aintains consistency WIMP Interface Point and click interfaces W indows • used in .. I cons – m ultim edia M enus – web browsers P ointers – hypertext … or windows, icons, m ice, and pull-down m enus! • just click something! – icons, text links or location on map • default style for majority of interactive com puter system s, especially PCs and desktop • minimal typing machines 5

Three dimensional interfaces • virtual reality elements of the wimp interface • ‘ordinary’ window systems – highlighting flat buttons … – visual affordance – indiscrim inate use click m e! just confusing! windows, icons, menus, pointers • 3D workspaces … or sculptured + + + – use for extra virtual space buttons, toolbars, – light and occlusion give depth palettes, dialog boxes – distance effects also see supplementary material on choosing wimp elements Windows Icons • Areas of the screen that behave as if they • small picture or image were independent • represents some object in the interface – can contain text or graphics – often a window or action – can be m oved or resized • windows can be closed down (iconised) – can overlap and obscure each other, or can be laid out next to one another (tiled) – small representation fi m any accessible windows • scrollbars • icons can be many and various – allow the user to m ove the contents of the window up and down or from side to side – highly stylized • title bars – realistic representations. – describe the nam e of the window Pointers Menus • important component • Choice of operations or services offered on the screen • Required option selected with pointer – WIMP style relies on pointing and selecting things • uses mouse, trackpad, joystick, trackball, File Edit Options Font cursor keys or keyboard shortcuts Typewriter Screen • wide variety of graphical images Times problem – take a lot of screen space solution – pop-up: m enu appears when needed 6