HumanComputer Interaction

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Human-Computer Interaction

• Information Systems

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Methods covered

• For information artefacts
• Cognitive Dimensions (CD)
• For social navigation
• Distributed Information Spaces (DIS)
• Concept-based Analysis for Surface and Structural
  Misfits (CASSM)
• ERMIA

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Cognitive Dimensions

• Thomas Green

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What do they work on?

• The cognitive dimensions approach applies to
  information artefacts.
• Information artefacts are the tools we use to
  store, manipulate, and display information.
• They can be interactive, such as word-processors,
  graphics packages, mobile telephones, radios,
  telephones, central heating control systems,
  software environments, VCRs, ....
• Or non-interactive, such as tables, graphs, music
  notation, programming languages, etc.
• Other methods in HCI are solely aimed at
  interactive devices, such as editors and the
  like. The focus of those approaches is on the
  process of interaction. Therefore, they do not
  work well on non-interactive artefacts.

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What does it deliver?

• The CDs approach avoids any kind of simplified
  bug hunting or overall difficulty measure.
• Instead, the information artefact is evaluated
  along 13 different dimensions, each of which is
  cognitively relevant, giving a profile.
• The profile determines the suitability for
  various tasks. The dimensions are not
  intrinsically good or bad. Different types of
  user activity are best supported by different
  profiles.

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The nature of IA

• Designing a garden is not like designing a
  bridge. Garden design is very aesthetic, and part
  of the job is exploring the options, changing
  ones mind, feeling ones way to a new vision.
  Bridge design is less inspirational and very much
  more safety-critical. These are different types
  of user activity, and they are likely to be
  supported by different kinds of software or
  drafting tools.
• It would be nonsense to claim that all
  information artefacts should satisfy some single
  set of criteria. Four main classes of activity
  can be distinguished there is a preferred
  profile for each type of activity.

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Four types of activity for IA

• Incrementation adding a new card to a cardfile
  adding a formula to a spreadsheet
• Transcription copying book details to an index
  card converting a formula into spreadsheet terms
  
• Modification changing the index terms in a
  library catalogue changing the layout of a
  spreadsheet modifying the spreadsheet to compute
  a different problem
• Exploratory design typographic design sketching
  programming on the fly (hacking)

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The structure of IA

• The following concepts can be used to model the
  structure of information artefacts
• Notation
• Environment
• Medium
• Layer
• Sub-devices

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The structure of IA the environment

• Text written with a word-processor is easy to
  modify text written with a pen and paper is much
  harder to modify. These are different
  environments.

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The structure of IA the notation

• Inserting a new paragraph into a novel is much
  easier than inserting a new page into a very
  formal document with numbered paragraphs and
  manifold cross-references. These are different
  information structures, or notations.

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The structure of IA layers

• Consider a slightly more complicated example,
  building a program. There are two layers.
• In one layer, the notation is the programming
  language, the environment is the editor, and the
  medium is the computer memory, which is
  persistent, since the program is built up there.
• The other layer is the editing layer. Here, the
  notation is keystrokes and mouse actions, the
  environment is the keypad, and the medium is
  transient the notation is translated into
  editor actions, such as selecting a word or
  deleting a character in the program.

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The structure of IA sub-devices

• A sub-device is a part of the main system that
  can treated separately because it has different
  notation, environment, and medium.
• The simplest sub-device might be a pad of paper,
  considered as part of an information system whose
  main components are software. Its function might
  be to record notes about the main information
  structure

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Some Cognitive Dimensions

• Viscosity resistance to change
• Hidden dependencies important links between
  entities are not visible
• Premature commitment constraints on the order of
  doing things
• Abstraction types and availability of
  abstraction mechanisms
• Secondary notation extra information in means
  other than formal syntax
• Visibility ability to view components easily

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Cognitive Dimensions viscosity

• Resistance to change the cost of making small
  changes.
• Viscosity has two types
• Repetition viscosity Manually changing US
  spelling to UK spelling throughout a long
  document
• Knock-On viscosity inserting a new figure into a
  document creates a need to update all later
  figure
• numbers, plus their cross-references within the
  text also the list of figures and the index

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Cognitive Dimensions Hidden Dependency

• A hidden dependency is a relationship between two
  components such that one of them is dependent on
  the other, but that the dependency is not fully
  visible.
• Example HTML links if your page is linked to
  someone elses, e.g. the HCI 98 site, how will
  you know if and when that page is moved, changed,
  or deleted?

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Cognitive Dimensions Premature Commitment

• Definition Constraints on the order of doing
  things force the user to make a decision before
  the proper information is available.
• Example The amateur sign-writer at work

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Cognitive Dimensions Abstraction

• Definition An abstraction is a class of
  entities, or a grouping of elements to be treated
  as one entity, either to lower the viscosity or
  to make the notation more like the users
  conceptual structure.
• Example macros in software systems e.g. styles
  in word processing.
• An important characteristic of abstraction is
  that it changes the notation. Almost invariably,
  the notation is changed by expansion a new term
  is added.

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Cognitive Dimensions Secondary Notation

• Definition Extra information carried by other
  means than the official syntax. The formal
  notation can sometimes be supplemented with
  informal additions which have no official
  meaning, but which can be used to convey extra
  information to readers.
• Example Indentation in programs
• Indentation or pretty-printing is an essential
  part of a programming language, but it has no
  meaning to the compiler in most cases it is a
  form of secondary notation. Exactly the same
  pretty-printing idea is used to help make
  telephone numbers easier to read, although
  interestingly enough, conventions differ from
  country to country in Britain we split numbers
  into threes and fours, but in France they split
  them into two-digit groups.

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CD relevance to activity types
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Distributed Information Spaces

• David Benyon and others

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Social navigation

• Users move around websites as they would in open
  physical spaces e.g. town centre.
• Such navigation is characterised by
• looking for cues to find their way around
• avoiding remembering and planning, but make use
  of information immediately available information
  scent
• develop a mental model as they repeatedly go
  through certain paths information ecology
• Minmize the cost of digging out for information
• Make use of the experience of other users.

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Distributed Information Spaces

• This involves users moving around rather than
  browse through a window
• Which means that information artefacts have to be
  distributed around such space
• Information artefacts in this case may not be
  sufficient, hence other support is usually
  provided
• Devices through which users take action
• Agents to perform tasks on behalf of the user

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Distributed Information Spaces

• The IADA tools that support DIS would usually be
  clustered in activity areas
• Each activity area would normally be equipped
  with an appropriate set of IADA tools to support
  the user through such activity
• The architecture of the DIS would also support
  users movements as they navigate through a
  particular path.

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Representation of DIS
Information Artefact
Device
Agent
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Formal modelling of IA IDSERMIA

• The Entity Relationship method has been adapted
  for the modelling of information artefacts, hence
  the acronym ERMIA.
• Three elements are used for this modelling

Entity
Attribute
Relationship
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• Concept-based Analysis
• for
• Surface and Structural Misfits
• (CASSM)

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The U-S-T Diagram revisited
User
Interface
Conceptual Model
System
Task
Conceptual Gap
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The U-S-T Diagram revisited
User
Interface
Conceptual Model
System
Task
Interface
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The U-S-T Diagram revisited
User
Interface
Conceptual Model
System
Task
Interface
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CASSM user-interface-system dependency values.
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Types of difficulties that interface objects may
present

• Disguised represented, but hard to interpret
• Delayed represented, but not available to the
  user until some time later in the interaction
• Hidden represented, but the user has to perform
  an explicit action to reveal the state of the
  entity or attribute
• Undiscoverable represented only to the user who
  has good system knowledge, but unlikely to be
  discovered by most users.

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combinations of User-Interface-System
possibilities

• P-P-P No difficulties good fit between user
  and system.
• P-P-A This is an unlikely combination, unless
  the analyst chooses to encode interface objects
  that only affect the display but not the
  underlying system representation in this way.
  Such a combination is unlikely to cause user
  difficulties.
• P-D-P This combination is likely to cause some
  user difficulties, depending on the exact reason
  why the interface representation causes
  difficulties.
• P-D-A Like present-present-absent, this is an
  unlikely combination, and it is up to the analyst
  to consider why they have encoded a concept in
  this way and what the likely difficulties might
  be.
• P-A-P The lack of interface representation would
  mean that users need to manipulate system
  concepts indirectly, which is likely to cause
  serious difficulties.
• P-A-A This is a common situation and is one of
  the three first-level cases. It causes
  difficulties.
• D-P-P In this case, the user may be forced to be
  explicit about some concept that they would
  naturally not mention. These are only problematic
  if the user is required to set or change values,
  not if the user only views pre-set system
  settings.

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combinations of User-Interface-System
possibilities

• D-P-A This is another unlikely combination, and
  is generally unlikely to cause user difficulties.
• D-D-P This combination is likely to cause user
  difficulties, depending on the exact reason why
  the interface representation causes difficulties.
  In this case the user is probably required to
  make explicit some information they would not
  normally work directly with.
• D-D-A Like present-present-absent, this is an
  unlikely combination, and it is up to the analyst
  to consider why they have encoded a concept in
  this way and what the likely difficulties might
  be.
• D-A-P The lack of interface representation would
  mean that users need to manipulate system
  concepts indirectly, which is likely to cause
  serious difficulties.
• D-A-A This is another unlikely combination. If
  it occurs, the analyst should consider the
  consequences.
• A-P-P As discussed above, these are concepts
  that the user has to learn however, they are
  clearly represented at the interface.

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combinations of User-Interface-System
possibilities

• A-P-A This is an unlikely combination, unless
  the analyst chooses to encode interface objects
  that affect only the display but not the
  underlying system representation. These will be
  interface objects that are (presumably) easy to
  learn and only affect surface aspects of the
  interaction, and are therefore unlikely to cause
  great difficulties.
• A-D-P This combination is likely to cause user
  difficulties these are important system concepts
  that are poorly represented at the interface in
  some way, but that the user has to learn to work
  with.
• A-D-A This is such an unlikely combination that
  it is equivalent to being absent from all three
  situations, which should never arise.
• A-A-P This is a source of user difficulties
  something the user has to learn about if they are
  to work effectively with the system, but which
  cannot be accessed or manipulated through the
  interface.

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CASSM Analyses of the London Underground Ticket
Vending Machines (TVMs)
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CASSM Analyses of the London Underground Ticket
Vending Machines (TVMs)
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CASSM Analyses of the London Underground Ticket
Vending Machines (TVMs)
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Distributed Information space(DIS)
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Representation of DIS
Information Artefact
Device
Agent
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• Use the notation on the previous slide to develop
  a conceptualisation of the DIS of a major
  shopping centre in town
• Divide the space into appropriate areas of
  activities to reflect the type of support that
  should be made available to a typical user
  (visitors to the shopping centre)