Documents
Resources
Learning Center
Upload
Plans & pricing Sign in
Sign Out

HCI Lesson Direct Manipulation

VIEWS: 100 PAGES: 57

									                                                                           1

               Direct Manipulation Interfaces

   Positive acceptance of an application
      Mastery of the interface
      Competence in performing tasks
      Ease in learning originally and in assimilating advanced features
      Confidence in the capacity to retain mastery over time
      Enjoyment in using the interface
      Eagerness to show off interfaces to novices
      Desire to explore more powerful aspects
                                                                             2

               Direct Manipulation Interfaces

   Attributes of direct-manipulation interfaces
      Visibility of the objects and actions of interest
           • Example: Driving an automobile
      Rapid, reversible, incremental actions
      Replacement of types commands by a pointing action on the object of
       interest
      Example: Dragging a file to a trash can versus “rm file.doc”
           • What about: “rm file*.doc”?
           • What about “rm *.*” with no undo?
                                                                                                  3

               Direct Manipulation Interfaces

   Extensions of direct manipulation
      Virtual reality – users are in an immersed environment
           • Reality is blocked out via a head-mounted display
           • Hand gestures (via a data glove) allow users to point, select, grasp and navigate


      Augmented reality – user remains in normal surroundings, but adds a
       transparent overlay.
           • Examples – labeled buildings, hidden plumbing


      Tangible user interfaces – users manipulate physical objects
           • Example – putting several plastic blocks near each other to create an office floor
             plan
                                                                 4

              Direct Manipulation Interfaces

   Command-line versus display editors versus word processors
      The Tubeless Interface
                                                                          5

               Direct Manipulation Interfaces

   Command-line versus display editors versus word processors
      Single-line and Multi-line Editors (e.g., IBM MVS, VM, TSO, JCL)
                                                                                                                    6

                   Direct Manipulation Interfaces

   Command-line versus display editors versus word processors
        Single-line and Multi-line Editors versus WYSIWYG (what you see is what you get) editors (e.g.,
         Microsoft Word – early 1990s)
        Example: Three basic modes of vi

             •   Command mode (Telling the computer what to do: Low level commands, e.g., move the cursor
                 to the right one character)

                      Default when you enter vi.

                      Most letters, or short sequences of letters, that you type will be interpreted as commands

                      Pressing Esc when you're in command mode, your terminal will beep at you. This is a very
                       good way to tell when you're in command mode

             •   Insert mode (Entering the content)
                      Whatever you type is inserted in the file at the cursor position
                      Press Esc to end insert mode, and return to command mode.
             •   Line mode (Telling the computer what to: High level commands, e.g. Save)
                      To enter line mode from command mode, type a colon ( : )
                      Your cursor moves to the bottom of the screen, by a colon prompt.
                      Type a line mode command, then press Enter.
                                                                                                                      7

                  Direct Manipulation Interfaces

   Command-line versus display editors versus word processors
      Single-line and Multi-line Editors (e.g., vi)



        Starting vi and Saving Files
        Starting vi: vi filename (start editing filename, create it if necessary)
        Saving the file you're working on and/or leaving vi: :wq (write the file to disk and quit)
        Quit without saving any changes: :q!
        :w! newfile (write all lines from the entire current file into the file 'newfile', overwriting any existing
        newfile)
        :n,m w! newfile (write the lines from n to m, inclusive, into the file newfile, overwriting any existing
        newfile)
                                                                                                        8

                   Direct Manipulation Interfaces

   Command-line versus display editors versus word processors
      Single-line and Multi-line Editors

          Type         To Move To
          h            one space to the left (also try left arrow)
          j            one line down (also try down arrow)
          k            one line up (also try up arrow)
          l            one space to the right (also try right arrow)
          $            end of current line
          ^            beginning of current line
          Enter        beginning first word on the next line
          G            end of file
          :n           line n; use :0 to move the beginning of the file
          w            beginning of next word; 5w moves to the beginning of the 5th word to the right
          e            end of next word
          b            beginning of previous word
          Ctrl-b       one page up
          Ctrl-f       one page down
          %            the matching (, ), [, ], {, or }
                       (Press % with your cursor on one of these characters to move your cursor its
                       mate.)
                                                                                                 9

                  Direct Manipulation Interfaces

   Command-line versus display editors versus word processors
      Single-line and Multi-line Editors
              • Searching for text

          Type            To
          /string         search down for string
          ?string         search up for string
          n               repeat last search from present position

              • Inserting text

          Type            To
          a               append starting right of cursor
          A               append at the end of the current line
          i               insert starting left of cursor
          I               insert at beginning of the current line
          o               open line below cursor, then enter insert mode
          O               open line above cursor, then enter insert mode
          :r newfile      add the contents of the file newfile starting below the current line
                                                                                                       10

                 Direct Manipulation Interfaces

   Command-line versus display editors versus word processors
      Single-line and Multi-line Editors
           • Deleting text

          Type   To
          x      delete single character; 5x deletes 5 characters
          dw     delete word; 5dw deletes 5 words
          dd     delete line; 5dd deletes 5 rows
          cw     delete word, leaves you in insert mode (i.e. change word)
          cc     change line -- delete line and start insert mode
          s      change character -- delete character and start insert mode
          D      delete from cursor to end of line
          C      change from cursor to end of line -- delete and start insert mode
          u      undo last change
          U      undo all changes to current line
          J      join current line with line that follows (press Enter in insert mode to split line)
                                                                                           11

                   Direct Manipulation Interfaces

   Command-line versus display editors versus word processors
      Single-line and Multi-line Editors
           • Cutting and Pasting

          Type     To
          xp       transpose two characters (two commands, x followed by p)
          yy       yank (i.e. copy) one line into a general buffer (5yy to yank 5 lines)
          "ayy     yank into the buffer named a
          P        put the general buffer back before the current line
          "aP      put from buffer a before current line
          p        put the general buffer back after the current line
          "ap      put from buffer a after the current line

           • Miscellaneous Commands

          Type      To
          Ctrl-g    show line number of current line
          Ctrl-l    redraw the entire display
                                                                                   12

               Direct Manipulation Interfaces

   Command-line versus display editors versus word processors
      Early 1980s – Text editing was done with line-oriented command languages
      Nroff/troff: Unix based word processor
                         .nf = no-fill, you use for graphs or
                         text that you don't want spaces to
                         be ignored


                       .ce # = centers by the # of sentences you enter




              .ti # = .ti indents but only for one line, so if you have one
              sentence that needs to be indented 8 spaces but the rest of
              the page is indented 3 you can use .ti 8 for that single
              sentence




             .fi = fill-in, extra space will be ignored and text that is entered
             like this, the fill-in command will continue until you enter a .nf
             command and vice-versa



             .in # = # is the number of spaces you want the text indented,
             this command will be in place until you put in a new .in
             command...if you want something to not be indented you put in
             .in 0
                                               13

              Direct Manipulation Interfaces

   Command-line editors
      Who would use these interfaces?
      Why?
                                                                                14

              Direct Manipulation Interfaces

   Command-line editors
      Who would use these interfaces?
      Why?
          • Mastery of the interface
          • Competence in performing tasks
          • Ease in learning originally and in assimilating advanced features
          • Confidence in the capacity to retain mastery over time
          • Enjoyment in using the interface
          • Eagerness to show off interfaces to novices
          • Desire to explore more powerful aspects
                                               15

              Direct Manipulation Interfaces

   Command-line editors
      Who would use these interfaces?
      Why?
          • BETTER THAN A TYPEWRITER

          • BETTER THAN A SLIDE RULE

          • BETTER THAN A CALCULATOR
                                                                                              16

                 Direct Manipulation Interfaces

   Advantages of WYSIWYG Editors
        Users see a full page of text

             • 20 to 60 lines provides a context for each sentence
        The document is seen as it will appear when printed

            • Eliminating the clutter of formatting commands
        Cursor action is visible
            • Indicates where to focus attention and apply action
        Cursor motion is natural

            • Arrow keys or mouse provide natural physical mechanisms for moving the cursor
        Labeled icons make frequent actions rapid

            • Toolbar for frequent actions
        Immediate display of the results of an action

            • Example: Clicking a button to center text provides immediate result
        Rapid response and display

            • Full page of text in a fraction of a second
        Easily reversible actions
             • Example: Undo, backspace
                                                                                17

               Direct Manipulation Interfaces

   Technology advancements evolving from word processing
      Integration of graphics, spreadsheets, animations, photographs, etc.
      Desktop publishing software
      Presentation software
      Hypermedia environments and the World Wide Web (hyperlinks to
       documents)
      Improved macro facilities (e.g., construct, save and edit sequences of
       frequently used actions)
      Spell checkers and thesauri
      Grammar checkers
           • Use of passive voice
           • Excessive use of certain words
           • Lack of parallel construction
      Document assemblers
           • Contracts
           • Wills
                                                                     18

               Direct Manipulation Interfaces

   Spreadsheets
      1979 – VisiCalc from a Harvard Business School student
      254 rows and 63 columns
      Functions within a cell as it relates to other cells
      Simulation of an accountants spreadsheet
      Lotus 1-2-3 dominated the market in the 1980s
      Today Excel dominates
           • Graphics displays
           • Multiple windows
           • Statistical routines
           • Database access (e.g., Price List to Service Catalog)
                                                                                               19

               Direct Manipulation Interfaces

   Spatial Data Management
      Geographic applications – Nicholas Negroponte at MIT
      Display of the world and able to zoom in on the Pacific Ocean to see markers
       for convoys of military ship
      Joystick input
      Google Earth
      ArcView – ESRI
           • Map-related information database for Law Enforcement
           • Select type of information to display (roads, population, rainfall, topography,
             political boundaries
                                                                                    20

               Direct Manipulation Interfaces

   Video Games
      The most exciting, well-engineered, commercially successful application of
       direct-manipulation concepts?
      Pong
      Pacman
      40 million Nintendo game players reside across 70% of those American
       households that include 8 to 12 year olds
      Field of action is visual and compelling
      Button presses, joystick motions and knob rotations produce rapid response
       on the screen
      No syntax to remember
      Error messages are rare – the results of the action are obvious and easily
       reversed
      Often there is continuous display of the score (competition between others
       and the player themselves)
           • Positive reinforcement that encourages mastery
                                                                21

               Direct Manipulation Interfaces

   Video Games
      Educational Video Games – direct manipulation
           • SimCity – education on urban planning




           • The Sims – stronger attraction to women then men
                                                                               22

            Direct Manipulation Interfaces

 Video Games
    Computer Role Playing Games (CRPGs)
        • Players assume the role of a fictional character
        • Activity takes place in a fictional world
        • User’s control many of their character's actions
        • Myst
    Massively Multiplayer On-Line Role Playing Games (MMORPGs)
        • A large number of players interact with one another in a virtual
          world
        • Interaction is in a persistent world
             – hosted by the game's publisher
             – continues to evolve while the player is away from the game
        • Worldwide MMORPGs revenues exceeded half a billion dollars in 2005
        • World of Warcraft
                                                                                 23

               Direct Manipulation Interfaces

   Video Games versus Business Applications
      Game players
           • Engaged in competition with a system or other players
           • Seek entertainment and focus on challenge
           • May prefer random events
      Application users
           • Prefer a strong internal locus of control
           • Focus on their tasks and may resent too many playful distractions
           • Do not prefer random events
                                                                                          24

               Direct Manipulation Interfaces

   Computer-aided Design
      Automobiles, electronic circuitry, aircraft, mechanical engineering
      Structural engineering, floorplans, interiors, landscaping, plumbing, electrical
       installation, etc.
      When the design is complete, the program can provide information regarding:
           • Current
           • Voltage drops
           • Fabrication costs
           • Manufacturing problems
                                                                                                25

              Direct Manipulation Interfaces

   Computer – aided Manufacturing and Process Control
      Honeywell’s Experion Process Knowledge System
          • Provides the manager of a oil refinery or power utility plant with a colorized
            schematic of the plant
          • Can indicate with a red line a sensor value that is out of range
          • With a single click the operator can get a more detailed view of the troubling
            component
          • A second click can provide more detailed information the sensor, or reset a value
            or circuit
          • Basic strategy: eliminate the need for complex commands that the operator might
            only need to recall during a once-a-year emergency
                                                   26

             Direct Manipulation Interfaces

 Direct Manipulation in Office Automation
    Xerox Star
       • Sophisticated Text Formatting
       • Graphics
       • Multiple Fonts
       • High Resolution
       • Cursor Based Interface
    Apple Lisa
       • Precursor to the Macintosh
       • Hardware and software designs supported
           – Pull-down menus
           – Multi-window manipulation
           – Editing of graphics and text
           – Dragging of icons
                                                             27

             Direct Manipulation Interfaces

 Direct Manipulation in Office Automation
    MS-DOS Commands vs. Macintosh Direct Manipulation
       • Tasks: Creating, copying, renaming, erasing files
       • After training and practice, average task times:
            – MS-DOS is 5.8 minutes
            – Macintosh is 4.8 minutes
       • After training and practice, average errors:
            – MS-DOS is 2.0
            – Macintosh is 0.8
                                                                                          28

              Direct Manipulation Interfaces

 Continuing evolution of direct manipulation
     Quicken
     Home Automation
        • Direct manipulation on a floor plan of:
             – Burglar alarms
             – Heat sensors
             – Smoke detectors
             – Opening/closing curtains or screens
             – Air conditioning and heating
             – Audio/video speakers or screens
                  » E.g., users can route sound from a MP3 player located in the living
                    room to the kitchen by dragging the MP3 icon into the kitchen
     Virtual Worlds
        • Travel through the human body
        • Ride an electron cloud as it spins around a nucleus
                                                                                          29

              Direct Manipulation Interfaces

 Continuing evolution of direct manipulation
     Problems with direct manipulation
        • Spatial or visual representation are not necessarily an improvement over text
             – Especially for blind or visually impaired users
        • Direct manipulation designs may consume considerable screen space
             – May result in scrolling or multiple actions
        • Users must learn the meanings of visual representations
             – Icon interpretation
        • For experienced typists, taking a hand off the keyboard to move a mouse may
          take more time then typing the relevant command
        • Users may not share the same understanding of the metaphor, analogy, or
          conceptual model with the designer (testing is required)
        • Browser based applications limit direct manipulation (e.g., drag & drop)
             – Require Dynamic HTML, Java or Flash
                                                                                 30

             Direct Manipulation Interfaces

 Advantages of direct manipulation
    Continuous representation of the objects and actions of interest with
     meaningful visual metaphors
    Physical actions or presses of labeled buttons, instead of complex syntax
    Rapid, incremental, reversible actions whose effects on the objects of
     interest are visible immediately
                                                                                           31

             Direct Manipulation Interfaces

 Advantages of direct manipulation
    Design systems with the following benefits
       • Novices can learn basic functionality quickly
       • Experts can work rapidly to carry out a wide range of tasks, even defining new
         functions and features
       • Knowledgeable intermittent users can retain operational concepts
       • Error messages are rarely needed
       • Users can immediately see whether their actions are furthering their goals, and
         if the actions are counterproductive, they can change the direction of their
         activity
       • Users experience less anxiety because the interface is comprehensible and
         because actions are easily reversed
       • Users gain confidence and mastery because they are the initiators of action,
         they feel in control, and they predict the interface’s responses
                                                                                      32

             Direct Manipulation Interfaces

 The OAI Model and Direct Manipulation
    The object of interest is displayed so that interface actions are close to the
     high-level task domain
    Little need for mental decomposition of tasks into multiple interface
     commands with complex syntactic forms (e.g., vi: go to line, go to word,
     go to character)
    Each action produces a comprehensible result in the task domain that is
     visible in the interface immediately
    The closeness of the task domain to the interface domain reduces
     operator problem-solving load and stress
    Compared to textual descriptors, visual representations of objects may be
     more natural and closer to human innate capabilities
       • Action and visual skills emerged well before language in human evolution
                                                                                       33

             Direct Manipulation Interfaces

 Visual Thinking and Icons
    Semiotics – the study of signs and symbols
    Icon – an image, picture or symbol representing a concept
       • In computer systems usually less than one inch square (64x64 pixels)
       • Smaller icons are often integrated with a window border or toolbar
    Task dependency
       • When working on a visual task (e.g., painting program), icons may be useful
       • When working on a text-based task, it may be better to stay text based
    Icons with words (or mouse-overs) are useful
                                                                                    34

             Direct Manipulation Interfaces

 Icon related guidelines
    Represent the object or action in a familiar and recognizable manner
    Limit the number of different icons
    Make the icon standout from its background
    3-d icons can be visually distracting
    Ensure that a single selected icon is clearly visible when surrounded by
     unselected icons
    Make each icon distinctive from every other icon
    Ensure harmoniousness of each icon as a member of a family of icons
    Design the movement animation (e.g., grayed-out ghost image on a drag)
    Detail information
       • Larger shadowing for a larger file
       • Color to show the age of a document
       • Animation to show how much of a file has printed (document icon absorbed
         progressively into the printer icon)
    Explore use of combination of icons
                                                                               35

             Direct Manipulation Interfaces

 Direct Manipulation Programming
    Example: programming a radio to a set of stations by pressing/holding a
     channel selection button
    Phone Services
                                                                       36

             Direct Manipulation Interfaces

 Direct Manipulation Programming
    Programming in the User Interface
       • Sufficient computational generality
            – Conditionals (if, then, else)
            – Iteration (repeat/while)
       • Access to appropriate data structures and operators
            – File structures for directories
            – Addition, subtraction, etc.
       • Ease in programming
            – By specification or by demonstration (Flash animation)
            – Argument passing
       • Simplicity in invocation and assignment of arguments
       • Low risk
            – High probability of bug free programs
            – Halt and resume
                                                                               37

             Direct Manipulation Interfaces

 Direct Manipulation Programming
    Viscosity – the difficulty of making changes to a program
    Progressive evaluation – the capacity for execution of partial programs
                                                                                      38

              Direct Manipulation Interfaces

 3-Dimensional Interfaces
    Some applications are designed as 2-D to be simpler than real-world
     systems
       • Constrain movement
       • Limit interface actions
       • Ensure visibility of interface objects
    Enhanced 3D may be better than 3D
       • Flying through objects
       • Multiple simultaneous views of objects
       • X-ray vision
       • Shrink/expand objects
       • Group/ungroup components
       • Going back in time
    Less than successful 3D interfaces
       • Air-traffic control
       • Showing altitude by perspective drawing only adds clutter when compared to
         an overview from directly above
                                                                            39

             Direct Manipulation Interfaces

 Second Life
    Multi-user environment where users interact
    Users can choose avatars (fantasy images, desirable characteristics)
                                                                  40

             Direct Manipulation Interfaces

 Relationship to:
    Personality Theory
    Social Psychology
    Spatial Cognition
 Applicable to business meetings, community discussion groups,
  political forums?
    Blaxxun envision
                                              41

             Direct Manipulation Interfaces

 3D Desktops and Workplaces
    Microsoft’s Task Gallery
    Intel’s Grand Canyon
    Xerox PARC’s Information Visualizer
    No successful products yet
                                                                                       42

              Direct Manipulation Interfaces

 Tips for effective 3D interfaces
     Use occlusion, shadows, perspective and other 3D techniques carefully
     Minimize the number of navigation steps for users to accomplish their
      tasks
     Keep text readable (better rendering, good contrast with background, an
      no more than 30-degree tilt)
     Avoid unnecessary visual clutter, distraction, contrast shifts and reflections
     Simplify user movement (keep movements planar, avoid surprises like
      going through walls)
     Organize groups of items in aligned structures to allow rapid visual search
     Enable users to construct visual groups to support spatial recall (e.g.,
      placing items in corners)
                                                                                 43

              Direct Manipulation Interfaces

 Guidelines for inclusion of 3D features
     Provide users overviews so they can see the big picture
     Allow teleportation (rapid context shifts by selecting destination in an
      overview)
     Offer x-ray vision
     Provide history keeping (recording, undoing, replaying, editing)
     Permit rich user actions on objects (save, copy, annotate, share, send)
     Give users control over explanatory text (pop-up, floating, screen tips)
     Offer tools to select, mark and measure
     Implement dynamic queries to rapidly filter out unneeded items
     Enable landmarks to show themselves even at a distance
     Allow multiple coordinated views (users can be in more than one place at
      a time)
                                                                              44

             Direct Manipulation Interfaces

 Teleoperation
    Derived from direct manipulation and process control
    Physical processes taking place in a remote location
       • Clean-up in a nuclear reactor
    Need adequate feedback in sufficient time to permit effective decision
     making
       • Manufacturing
       • Medicine (consultation, radiology)
       • Military operations (drones)
    Home automation
       • Answering machines
       • Security systems
       • Energy control
       • Appliances
                                                                                       45

             Direct Manipulation Interfaces

 Design to accommodate teleoperation issues
    Slow response times and time delays
       • Transmission delay (time for command to reach the microscope)
       • Operation delay (time until the microscope responds)
    Incomplete feedback
       • The microscope can transmit its current position, but operates so slowly it
         cannot indicate the exact current position
    Unanticipated interferences
       • The slide is accidentally moved by a person at the local site
    May be better for the user to specify a destination (rather than a motion)
     and wait until the action is completed
                                              46

             Direct Manipulation Interfaces

 Telemedicine
    Remote examination
    Remote surgery
    Telepathology
       • Magnification
       • Focus
       • Illumination
       • Position
                                                                            47

              Direct Manipulation Interfaces

 Virtual and Augmented Reality
    “Being in” as opposed to “Looking at”
    Architectural applications
       • Wall-sized image to give perspective
       • Animation to simulate movement (left to right)
       • Treadmill to simulate walking toward, walk through doors, stairs
       • Replace projector with a head-mounted display
    Some applications are better when “looked at”
       • Air-traffic control
       • To surgeons want to “Be in” the patients body?
    Training using virtual reality
       • Fifth Dimension Technologies www.5DT.com
                                                                                             48

             Direct Manipulation Interfaces

 Virtual and Augmented Reality
    The CAVE (National Center for Supercomputing Applications)
    An immersive virtual reality facility designed for the exploration of and
     interaction with spatially engaging environments.
    The stereoscopic capabilities, coupled with its uniquely immersive design,
     enable scientists and researchers to interact with their data
       • An atmospheric scientist can actually "climb inside" of a hurricane and visualize
         its complex and chaotic elements from any angle or visual perspective
       • A biological researcher, examining a tightly coiled strand of DNA, can virtually
         "unravel" this strand and manipulate it in an environment that preserves the
         critical depth information of the data.
                                                                                                        49

               Direct Manipulation Interfaces

 Artificial Reality
     VideoPlace – Myron Krueger
        • Surround the user with an artificial reality which responded to their movements and
          actions.
        • The users were able to visually see the results of their actions on screen, through the use
          of colored silhouettes.
        • The users had a sense of presence while interacting with onscreen objects and other
          users.
        • The sense of presence was enough that users pulled away when their silhouettes
          intersected with those of other users.
                                                                     50

              Direct Manipulation Interfaces

 Applications of virtual environments
     Phobia treatment
        • Acrophobia
     Pain Control
        • Immersive environments provide distractions for patients
     Interior Design
        • OAI model
            – Click, drag, enlarge objects
            – Room painting tool
                                                                    51

              Direct Manipulation Interfaces

 Augmented Reality
    See the real world with an overlay of additional information
       • See wires or plumbing behind walls
       • Tourist glasses – label buildings in a historic town
       • Molecular biology
                                                                                         52

             Direct Manipulation Interfaces

 Virtual environments dependent on integration of multiple technologies
    Visual Display
       • Normal Display
           – 12 to 17 inches diagonally at a normal viewing distance of 70 cm subtends
             a visual angle of about 5-degrees
       • Large Screen
           – 17 to 30 inches can cover 20 to 30-degrees
       • Head Mounted Displays
           – 100 degrees horizontally and 60-degrees vertically
           – Head motion produces new images so users perceive 360-degrees
           – Displays must approach 100-millisecond delay in presenting images to
             approach real time
                                                                                        53

             Direct Manipulation Interfaces

 Virtual environments dependent on integration of multiple technologies
    Head-position sensing
       • Head-mounted displays can provide differing views depending on head position




    Hand-position sensing
       • DataGlove
                                                                                           54

              Direct Manipulation Interfaces

 Virtual environments dependent on integration of multiple technologies
    Force feedback and haptics
       • Hand-operated remote-control devices for performing chemistry experiments or
         for handling nuclear materials
       • Gives users a sense of grasp
    Sound input and output
       • Training of Army tank crews while using realistic sounds of battle resulted in:
            – Elevated heart rates, more rapid breathing, and increased perspiration
       • Speech recognition for initiating actions and making menu selection
            – Keyboard and mouse use is restricted
    Other sensations
       • Tilting and vibration of flight simulators
    Collaborative and competitive virtual environments
       • Two people at remote sites working together while seeing each others actions
         and the object of interest
                                                                      55

               Direct Manipulation Interfaces

 Definition, benefits, and drawbacks of direct manipulation
     Definition
        • Visual representation (metaphor) of the “world of action”
        • Objects are always shown
        • Rapid, incremental, and reversible actions
        • Replacement of typing with pointing/selecting
        • Immediate visibility of results of actions
     Benefits over commands
        • Less syntax reduces error rates
        • Errors are more preventable
        • Faster learning and higher retention
        • Encourages exploration
                                                                                    56

              Direct Manipulation Interfaces

 Definition, benefits, and drawbacks of direct manipulation
     Concerns
        • Increased system resources (possibly)
        • Some actions may be cumbersome (e.g., form fillin forcing use of mouse)
        • History and other tracing may be difficult
        • Visually impaired users may have more difficulty
                                                                      57

              Direct Manipulation Interfaces

 Piaget’s Four Stages of Development
    Sensorimotor (birth to 2 years)
    Preoperational (2 to 7 years)
    Concrete operational (7 to 11 years)
       • Physical actions on an object are comprehensible
       • Children acquire the concept of conservation or invariance
       • Direct manipulation brings activity to this stage
    Formal operational (begins at 11 years)
       • Symbol manipulation to represent actions on objects

								
To top