Metaphors for Human-Computer Interaction - Stony Brook 隐喻作为人机交互-石溪

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1、Metaphors and Styles of Human-Computer Interaction The psychology of metaphorsLike affordances,having a metaphor can tell you how you might use something.Unlike affordances(which are direct),metaphors are indirect(require more inferences)The psychology of metaphorsa metaphor provides a lot of inform

2、ation it enables the transfer of skillsgood metaphors provide natural mappingsmetaphors are not taken literallythey can highlight underlying assumptionsmetaphors are not symmetricalthey can be violatedThe psychology of metaphorsmetaphors can be mixed(e.g.,windows and desktops)metaphors can be mislea

3、ding(putting a disk in the trash)some things dont seem to have any obvious metaphor(ex:UNDO)one metaphor is better than another if it leads to more correct predictions about a systems behavior.Popular metaphors for computerscomputer as vast library (Memex,1945)computer as giant calculator(ENIAC,40s-

4、50s)computer as intelligent assistant(Licklider,1957)computer as sketchpad(Sutherland,1962)computer as tool or typewriter(Engelbart,1963)computer as human pretender(Weizenbaum,60s)computer as network(Taylor,1968)computer as book(portable)(Kay,Xerox PARC)computer as desktop/windows(Xerox PARC,70s)wit

5、h objectscomputers for the rest of us(Apple,1984)More or less successful metaphorstext editing as using a typewritervoice mail as answering machine or mailbox data as files(in folders or directories),represented as icons on desktop/in windowsdeleting a file as throwing it in the trashapplications as

6、 tools(sometimes w/icons)programming as building objectsprogramming as directing actors on a stageapplications as agentsMetaphors often suggest styles of interactionSome styles of interaction:Commands(&queries,keyboard shortcuts)Menus(and W.I.M.P.interfaces)Direct manipulationConversation(often w/sp

7、eech or natural language)BrowsingForms and spreadsheetsImmersive environmentsMetaphors often suggest styles of interactionSome styles of interaction:Commands(&queries,keyboard shortcuts)Typing in choices to a vending machineTelling a dog to go fetchInteracting with VMS,DOS,Unix,or protocols such as

8、Telnet,ftp,etc.Programming your VCR to record a TV showCommand interface advantagesDomain-specific languageSimilar to scripting languageThe user tells the system what to doe.g.tell the time,copy a file,save a fileThe user is in control(takes the initiative)Very common conceptual model for operating

9、a device(little or no intelligence in the device)Main benefits:Powerful(especially for experts and frequent users)Supports fast and efficient interactionGood for repetitive kinds of actionsExample:Copy command(DOS)Copies files from one location to another.The destination defaults to the current dire

10、ctory.copy file1 destinationIf multiple files are to be copied,the destination must be a directory,or an error will result.copy file1 file2 file3 destinationFiles may be copied to devices.To send file to printer:copy file lpt1To display file on screen(console):(alternatively:type file)copy file con

11、No feedback given after one of these commands;just a prompt Equivalent Unix command:cpCommand interface drawbacksThe user needs to know exactly where the information is and how its organizedThe user needs to know command syntaxNo tolerance whatsoever for errorsCan be cryptic,especially if little fee

12、dback is givenAnother example:SQL queriesWhich companies sell everything FabCo sells?(List companies such that there does not exist an item sold by FabCo that they do not sell.)“Which companies sell everything FabCo sells?select distinct X.namefrom suppliers Xwhere 0=(select count(*)from suppliers Y

13、where Y.name=“FabCoand 0=(select count(*)from suppliers Zwhere Z.name=X.nameand Z.item=Y.item)“Which companies sell everything FabCo sells?There must be an easier way!(Schneiderman,1986)“Since computers can display information 1000 times faster than people can enter commands,it seems advantageous to

14、 use the computer to display large amounts of information and allow novice and intermittent users simply to choose among the items.Styles of interactionCommands(&queries,keyboard shortcuts)Menus(and W.I.M.P.interfaces)Direct manipulationConversation(often w/speech or natural language)BrowsingForms a

15、nd spreadsheetsImmersive environmentsMenusUsers are given predetermined choicesAre often part of aWIMP interface(point&click)Windows and window managersIconsMenusPointing devicesMenusenforce a hierarchy on the users goalsrepresent well-trodden paths-you can do only what the designer envisionedYou ca

16、nnot filter and combine the world in novel waysDecisions in menu designWhat is the task hierarchy?How to order or group items?How to trade off depth vs.breadth?What labels to choose?Whether to include shortcuts?Menu types(not mutually exclusive)PermanentPull-downFall-downPop-upBinary ExtendedMultipl

17、e selectionRadio buttonsEmbedded Styles of interactionCommands(&queries,keyboard shortcuts)Menus(and W.I.M.P.interfaces)Direct manipulationConversation(often w/speech or natural language)BrowsingForms and spreadsheetsImmersive environmentsDirect Manipulation InterfacesRepresentations behave as if th

18、ey were the objects they represent.This reduces the distance between users and their goals.What You See Is What You Get(WYSIWYG)(Hutchins,Hollan,&Norman,1986)Direct manipulationInvented by Ivan Sutherland(Sketchpad,60s)Term was coined by Ben Shneiderman(1983)Theory developed by Hutchins,Hollan,&Norm

19、anInvolves dragging,selecting,opening,closing and zooming actions on virtual objects Exploits users knowledge of how objects behave in the physical world(various metaphors)Consistent with“what you see is what you get(WYSIWYG)Features of direct manipulationcontinuous representation of the objects of

20、interestFeatures of direct manipulationcontinuous representation of the objects of interestphysical actions,not complex syntaxExample:copying a file to a diskette:copy file.txt to b:file.txt versusdragging a file icon to a diskette icon(move vs.copy confusion)Features of direct manipulationcontinuou

21、s representation of the objects of interestphysical actions,not complex syntaxrapid,incremental,reversible operations with immediate visual feedbackFeatures of direct manipulationcontinuous representation of the objects of interestphysical actions,not complex syntaxrapid,incremental,reversible opera

22、tions with immediate visual feedbackeasy to learn,easy to remembercan operate upon output representation and use it as input back to the systemDirect Manipulation(semantic distance)Gulf of ExecutionGulf of Evaluation(articulatory distance)SystemUsers GoalsWhat do Ido now?What does that mean?Hutchins

23、,Hollan,&NormanWhy are DM interfaces enjoyable?Novices can learn the basic functionality quicklyExperienced users can work extremely rapidly to carry out a wide range of tasks,even defining new functions Intermittent users can retain operational concepts over timeError messages are rarely encountere

24、dUsers can immediately see if their actions are furthering their goals and if not,do something elseUsers experience less anxietyUsers gain confidence and mastery and feel in controlSome problems with D.M.Sometimes:information overload or screen clutterNot all tasks can be represented by objectsits h

25、ard to represent abstract thingsDM must function in the“here and“nowicons can be just as cryptic as words(the Vocabulary Problem:stay tuned)With DM,user is responsible for doing everything;but some tasks are better achieved by delegating!e.g.spell checkingrepetitive actions are tedious!Moving a mous

26、e around the screen can be slower than pressing function keys to do same actionsSome DM metaphors are taken too literallyDebate about styles of interactionDirect Manipulation (tool metaphors)v.Conversation (agent metaphors)(Schneiderman,1986)“People are different from computers,and human-human inter

27、action is not necessarily an appropriate model for human operation of computers.Since computers can display information 1000 times faster than people can enter commands,it seems advantageous to use the computer to display large amounts of information and allow novice and intermittent users simply to

28、 choose among the items.(Schneiderman,1986)“People are different from computers,and human-human interaction is not necessarily an appropriate model for human operation of computers.Since computers can display information 1000 times faster than people can enter commands,it seems advantageous to use t

29、he computer to display large amounts of information and allow novice and intermittent users simply to choose among the items.But what about:“Which companies sell everything FabCo sells?Styles of interactionCommands(&queries,keyboard shortcuts)Menus(and W.I.M.P.interfaces)Direct manipulationConversat

30、ion(often w/speech or natural language)BrowsingForms and spreadsheetsImmersive environmentsDialogue systemsMay take initiativeUnderlying metaphor is having a conversation with another personRanges from simple voice recognition systems to more complex natural language dialoguesExamples include dialog

31、s about timetables,search engines,advice-giving systems,help systemsMay(or may not)consist of anthropomorphic agents who converse with you or are part of an interface,e.g.Microsofts Bob and ClippyAgentsA metaphor for an“intelligent process that takes some initiative and perform tasks on the users be

32、halfThe user delegates responsibility to the agent.This feels very different from direct manipulation!Agents can be amplifiers or alternatively,prosthetics (2 distinct metaphors for agents)Tasks for Agents(Laurel;Maes)DelegationInformation retrieval-Web“botsSorting,organizing,filteringCoaching,tutor

33、ing,providing helpRemindingProgramming,doing repetitive thingsAdvisingEntertainingNavigationAgents(anthropomorphic or not)The most obvious metaphor for an interactive system that seems intelligent or takes initiative may be a human-like character.(But note:agents can be non-anthropomorphic as well a

34、 form can take initiative and act“intelligent by filling in the right values automatically.)What agent interfaces have you used?Food for thought:To what extent is dialog with a person similar to interacting with a computer?(Shneiderman:not at all!)(Others:If the system can take the initiative and ac

35、t“intelligently,then conversation is a good metaphor for interacting with an agent.)Should representations ever be anthopomorphic?CON:Ben ShneidermanSherry TurkelJoseph Weizenbaum(Eliza)PRO:Brenda LaurelI say:It depends on the situation!Drawbacks of delegation“Intelligent interfaces can be unpredict

36、able.How do you come to“trust your agent?Are anthropomorphic interfaces honest?There may be problems with anthropomorphizing an interface(Shneidermans arguments)Theater and stage metaphors(Brenda Laurel;Laura Gould)Interfaces are like theater-we suspend disbelief.Claim:Anthropomorphizing an interfac

37、e is not a problem:People arent so easily fooled.(This contrasts w/Shneidermans claims.)(What do you think?)InitiativeSome kinds of human conversations are scripted-who takes the initiative is relatively fixed.In other kinds of conversation,neither person takes all the initiative.Ideally,initiative

38、should be flexible.Human-Computer DialogWhat can go wrong?A dialog can be under-determined.when the user is mystified aboutwhat to do next and is forced to take the initiative.(a blank screen,cryptic commands)(Harold Thimbleby)Human-Computer Dialog(cont.)A dialog can be over-determinedwhen a system

39、is authoritarian and takes too much initiative.(unnatural constraints)Advantages:reduces the consequences of errorswhat the user does is predictableDialog DesignAvoid under-determined dialogs by providing help and by reducing options.Avoid over-determined dialogs by letting users undertake tasks in

40、flexible orders.Dont force them to do unnecessary things.Support alternative styles of interaction whenever possibleDifferent users are different!Interfaces that take the initiative are better for novices.Interfaces that let the user take the initiative are better for experts.An interface is over-or

41、 under-determined with respect to a particular user.Direct manipulation and menu interfaces are sometimes(not always)over-determined.Command languages and natural language are sometimes(not always)under-determined.Pros&cons of conversational style of interactionDialogue allows users,especially novic

42、es and technophobes,to interact with the system in a way that is familiar.makes them feel comfortable,at ease,not scaredMisunderstandings arise when the system fails to parse what the user says.Sometimes interfaces pretend to use natural language,which can lead to problems.e.g.child types into a sea

43、rch engine,that uses natural language the question:“How many legs does a centipede have?and the system responds:M acintosh PICTim age form atis not supportedStyles of interactionCommands(&queries,keyboard shortcuts)Menus(and W.I.M.P.interfaces)Direct manipulationConversation(often w/speech or natura

44、l language)BrowsingForms and spreadsheetsImmersive environmentsExploring and browsingSimilar to how people browse information with existing media(e.g.newspapers,magazines,libraries,pamphlets)Information is structured to allow flexibility in way user is able to search for informatione.g.multimedia,we

45、bBrowsers,hypertext,links Forms and spreadsheetsForms can vary from over-determined(enforcing a fixed order)to quite flexible(allowing user initiative)Spreadsheets are extremely flexible,allowing“user programming.They can sometimes be underdeterminedImmersive environmentsVirtual reality(stay tuned)O

46、ften mimic real life(representations are highly literal;go well beyond metaphors)Different styles of interacting lend themselves to very different metaphorsCommandstyping commands via keyboard;function key shortcutsMenusselecting from pre-determined choicesDirect manipulation acting on objects and i

47、nteracting with virtual objectsConversational dialogue systemsinteracting with the system as if having a conversationExploring,browsing,&foraging for informationfinding out and learning thingsbrowsers(different from menus)Choose the right interaction style and the right metaphorUnderstand how the sy

48、stem works.(use the system yourself)(ask engineers)Figure out what problems users have.(watch them use similar systems)(create prototypes and watch users)Generate metaphors and examine their properties.Ask these Qs:Does the metaphor have enough structure?Is the structure relevant to the application

49、or problem?(or is it superficial?)Is the metaphor easy to represent?Concrete enough?Will the users“get it?Can it be extended?Is the metaphor misleading?Annoying?Does the metaphor fit with the style of interaction?Problems with interface metaphors Sometimes they break conventional and cultural rulese

50、.g.recycle bin placed on desktopCan overly constrain designers in the way they conceptualize a problem spaceMay conflict with principles of good designForces users to understand the system in terms of the metaphorDesigners can inadvertently use bad existing designs and transfer the bad parts into the new designsLimits designers imagination in coming up with new conceptual models