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Conceptual Model

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A description of the proposed system in terms of a set of ... Quicken: 'CheckBook' 6. Alternative Conceptual Models. A better way? 7. Types of Conceptual Models ... – PowerPoint PPT presentation

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Title: Conceptual Model


1
Conceptual Model
  • Mr. John Kelleher

2
Conceptual Model
  • A description of the proposed system in terms of
    a set of integrated ideas and concepts about what
    it should do, behave and look like, that will be
    understandable by the users in the manner
    intended.


3
Conceptual Models Run-Throughs
  • How many windows in your house?

Carelmans Tandem Convergent Bicycle (Model for
Fiancés)Carelmans Coffee Pot for
MasochistsJacques Carelman, Catalog of
Unfindable Objects, Balland.
4
People form Conceptual Models to
  • Predict future (or infer invisible) events.
  • Find causes for observed events.
  • Determine appropriate actions to cause desired
    changes.
  • Serve as mnemonic devices for remembering
    relations and events.
  • Provide a means of understanding an analogous
    device.
  • Allow them to apply heuristic problem-solving
    strategies designed to overcome information
    processing limitations.
  • However, often incomplete and vague
  • Home thermostat

5
Key aspects to design of a conceptual model
(1/2)
  • Decide what user will be doing when carrying out
    their tasks his interaction mode
  • searching for information? recording events?
  • E.g. Jeff Hawkins PDA (Palm Pilot)
  • E.g. Buchenau and Suri (2000) Defibrillator
  • E.g. Third Age Suit at ICE, Loughborough Univ.
  • This prompts the choice of interaction style
  • E.g. PDA (pen interface), command line interface,
    speech input, HUD (Head-Up Display)

6
Key aspects to design of a conceptual model
(2/2)
  • Actual concrete solutions thought through
  • behavior of the interface
  • look and feel
  • particular interaction styles
  • Content metaphors
  • desktop
  • paper document
  • notebook with tabs
  • score sheet , stage with actors (Director)
  • accounting ledger (spreadsheet)
  • stereo (for all media players)
  • phone keypad
  • calculator
  • Web "Shopping Carts"
  • Quicken "CheckBook"

7
Alternative Conceptual Models
  • A better way?

8
Types of Conceptual Models
  • Structural model
  • explains what the system does independent of use
    (its a system-centered model).
  • User has internalized structure of how the item
    works
  • Internalized declarative knowledge
  • Explanation of the underlying mechanism
  • Functional model
  • explains what the system does to assist a users
    task (its a user-centered model)
  • Internalized procedural knowledge
  • Developed from past knowledge and experience in a
    similar domain (calculator)

9
Which model?
10
Incomplete model
11
Implications for HCI
  • Users conceptual models are usually vague and
    incomplete
  • just a piece of the puzzle
  • The Interface should match the understanding the
    user already has
  • Contrast with earlier HCI advice, where the
    users must grow the appropriate mental model of
    the application
  • Users prefer simple models
  • simple and working solution (even it is not
    completely correct)
  • Occams Razor
  • Threshold of Indignation

12
(No Transcript)
13
Refrigerator
freezer
fresh food
  • Problem freezer too cold, but fresh food just
    right

14
Refrigerator Controls
  • Problem freezer too cold, but fresh food just
    right
  • What is your conceptual model?

How do you adjust the controls? Answer keep the
numerical setting unchanged. Change the
alphabetic setting, C -gt B
15
Most Likely Conceptual Model
  • i.e., independent controls

16
Correct Conceptual Model
Thermostat (Location Unknown)
Control A
Freezer
Valve
Cooling Unit
Cold Air
Fresh Food
Control B
  • Now can you fix the problem?
  • One control for two functions Problem!

17
How design is received
  • Developers of systems construct their mental
    models of how the system should function. This is
    called the design model.
  • Users develop their own mental models of how
    their tasks should be accomplished, users model.
  • After contact with a system, users build up a
    system image.

18
Design Model Users Model
?
Users Model
Design Model
System Image
  • Users gets model from experience usage
  • through system image
  • What if design user models dont match?

19
But designers often do not intend that image
  • Designers and the majority of users have never
    met.
  • The user of the system starts off with goals
    expressed in psychological terms. The system,
    however, presents its current state in physical
    terms.
  • Thats how gulfs have been created. Thus there is
    often a discrepancy.

20
Three problems emerge
  • Mapping problems - which controls the temperature
    in the refrigerator and which one for the
    freezer? not directly intuitive
  • Ease of control - it is often required to
    manipulate several physical variables at the same
    time for a simple user goal, like maintaining
    total rate constant while increasing the
    temperature.
  • Evaluation requires prompt feedback

21
Two Guidelines for Design
  • 1. Provide a good conceptual model
  • allows user to predict the effects of our actions
  • Problem
  • designers conceptual model communicated to user
    through system image appearance, written
    instructions, system behaviour through
    interaction, transfer, idioms and stereotypes
  • if system image does not make model clear and
    consistent, user will develop wrong conceptual
    model

22
Two Guidelines for Design (contd.)
  • 2. Make things visible
  • relations between users intentions, required
    actions, and results are
  • sensible
  • non arbitrary
  • meaningful
  • Visible affordances, mappings, and constraints
  • Use visible cultural idioms
  • Reminds person of what can be done and how to do
    it

23
Good Design
  • Scissors
  • Affordances holes for something to be inserted
  • Constraints big hole for several fingers, small
    hole for thumb
  • Mapping between holes and fingers suggested and
    constrained by appearance
  • Positive transfer and cultural idioms learned
    when young constant mechanism
  • Conceptual model implications clear of how the
    operating parts work

24
Bad Design
1200
  • Digital Watch
  • Affordances four push buttons to push, but not
    clear what they will do
  • Constraints and mapping unknown no visible
    relation between buttons, possible actions and
    end result
  • Transfer of training little relation to analog
    watches
  • Cultural idiom somewhat standardized core
    controls and functions but still highly variable
  • Conceptual model must be taught

25
Interface Metaphors
  • Definition of Metaphor
  • application of name or descriptive term to an
    object to which it is not literally applicable
  • Purpose
  • leverages our knowledge of familiar, concrete
    objects/experiences to understand abstract
    computer and task concepts
  • Metaphor is basic to human language for a similar
    reason it allows us to talk about knew or
    abstract things by drawing on familiar
    experience
  • Time is like a line we move on
  • We can go forward and look back
  • We can push a meeting back
  • Love is like a journey(also like a fall)

A presentation tool is like a slide projector
26
Metaphor
  • Since functional models draw on past experience
    and not everyone has computer experience, its
    useful to draw on the real world.
  • Hence the desktop metaphor
  • Directories are like folders
  • Files are like sheets of paper
  • Windows are like ?
  • Menus are like menus
  • Deleting is like putting in the trash
  • Running an application program is like opening
    the doc.
  • Copy to buffer and restore is like
    cut-and-paste...

27
Interface Metaphors
  • Use metaphors that matches user's conceptual task
  • desktop for office workers
  • paintbrush for artists
  • layers for animators
  • ledger for accountants
  • search engine for surfers
  • timeline for video editors
  • scrollbar, toolbar, portal
  • even Bluetooth!

28
Uses of metaphors
  • as a way of conceptualising a particular
    interaction style, e.g. using the system as a
    tool
  • as a conceptual model that is instantiated as
    part of an interface, e.g., the desktop metaphor
  • as a way of describing computers, e.g., the
    Internet highway
  • names for describing specific operations e.g.,
    cut and paste commands for deleting and
    copying objects
  • as a part of the training material aimed at
    helping learning, e.g., comparing a word
    processor with a typewriter.

29
Opposition to interface metaphors (1/3)
  • Overly literal interpretation
  • Unnecessary fidelity
  • Metaphors meant to support under-standing of new
    domain
  • Break the rules
  • Bin on desktop
  • Too constraining
  • E.g. finding a deeply nested file or moving a
    file to another folder
  • Conflicts with design principles
  • Fidelity with metaphor compromises design
    principles
  • E.g. violating consistency principle with Mac bin

30
Opposition to interface metaphors (2/3)
?
  • Not being able to understand the system
    functionality beyond the metaphor
  • Metaphor acts as straight-jacket to users vision
  • Overly literal translation of existing bad
    designs
  • Calculator (a) replicatespoor design elements
    of real calculators

31
Opposition to interface metaphors (3/3)
  • Limits the designers imagination in conjuring up
    new paradigms and models
  • Always looking backwards
  • Microsoft Windows Media Player vs. WinAmp
  • Gentner Nielsen (1996) Superbook

32
Interaction Paradigms
?
  • A particular philosophy about interaction design
  • Can inform novel conceptual models
  • Beyond GUI
  • Ubiquitous computing
  • Pervasive computing
  • Wearable computing

33
Metaphors Strengths Difficulties
  • Strengths
  • Gives a way for people to understand a new
    concept quickly given what they know.
  • Helps to provide good choices for visual and
    audio elements, as well as terminology.
  • Difficulties
  • The metaphor may create expectations that are
    false along with the true ones
  • Can I shred this file instead of putting in the
    trash can?
  • Our understanding is functional rather than
    structural. That means understanding is
    relative to how we do things.

34
Evaluating suggested metaphors
?
  • How much structure does the metaphor provide?
  • Organises the disparate features
  • How much of the metaphor is relevant to the
    problem? How inadequate is the metaphor?
  • Is the interface metaphor easy to represent?
  • Will your audience understand the metaphor?
  • How extensible is the metaphor?
  • Consider these questions in light of a shared
    calendar system.

35
The Metaphor of Direct Manipulation
  • Direct Manipulation
  • the feeling of working directly on the task
  • An interface that behaves as though the
    interaction was with a real-world object rather
    than with an abstract system
  • Central ideas
  • visibility of the objects of interest
  • rapid, reversible, incremental actions
  • manipulation by pointing and moving
  • immediate and continuous display of results
  • Almost always based on a metaphor
  • mapped onto some facet of the real world task
    semantics)

36
Object-Action vs Action-Object
  • Select object, then do action
  • interface emphasizes 'nouns' (visible objects)
    rather than 'verbs' (actions)
  • Advantages
  • closer to real world
  • modeless interaction
  • actions always within context of object
  • inappropriate ones can be hidden
  • generic commands
  • the same type of action can be performed on the
    object
  • eg drag n drop

37
Resources
  • Chapter 2Understanding and conceptualising
    interaction
  • Chapter 8Prototyping and Construction
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