Is COM objectoriented

1
Designing user interfaces
Lecture 5 Interaction styles
2
Interaction framework
O
Output
observation
presentation
articulation
performance
I
User (task)
System (core)
Input
3
Main interaction styles

• Menu selection
• Form fill-in
• Command language
• Natural language
• Direct manipulation

4
Menu selection

• Selection can be done by
• Cursor control keys, space bar (for short menus)
• Single letter or number selection codes
• Mouse (provide alternative method)
• Group menu choices
• Use vertical lists
• Create groups of logically similar items
• Form groups that cover all possibilities
• Make sure that items do not overlap
• Use familiar terminology

5
Simple menus
Single menu
Linear sequence
Tree structure
6
Examples single menus
Text
C\My Documentsdel junk All files in directory
will be deleted! Are you sure (Y/N)?

Iconic
7
Example text menu
UNIVERSITY OF BUCKINGHAM LIBRARY
MENU
Quick author/title search ..S In-depth
search....D Subject index
....I Help ....H Quit
....Q
Enter the appropriate letter __
8
Item presentation

• Ordering within groups
• Use natural order if suitable
• Time
• Numeric ordering
• Physical properties
• Otherwise
• Alphabetic
• Most frequently used items first
• Most important items first

9
Example multiple menus
Tabs
Extended menus
Pull down menus
Multiple selection menus
10
Guidelines for menus

• Make consistent use of
• Titles
• Item placement
• Instructions
• Error messages
• Status reports

11
Broad menu structure
Depth
Breadth
64 target items 4 choices per screen, three
levels 4 x 3
12
Deep menu structure
64 target items 2 choices per screen, six levels
2 x 6
Depth
Breadth
13
Acyclic network
14
Cyclic network
15
Why choose menu selection?

• Advantages
• Easy to learn and requires little memory
• Reduces keystrokes
• Structures decision making
• Easy error checking and reporting

• Disadvantages
• Slow and inefficient for frequent users
• Consumes screen space
• Navigation may be difficult with numerous choices
• Not suitable for data entry

16
Form fill-in

• Group related items by
• Semantic category
• Sequence of use
• Frequency of use
• Relative importance
• Separate logical groups by space, lines, colour,
  etc.
• Keep related items on the same screen

17
Example 1 form fill-in
Caption
Field
18
Caption and field design

• Distinguish captions from fields
• Place caption to left of a single field
• Place caption above a list of fields
• Break up long columns into groups
• Indicate number of character spaces available in
  a field
• Indicate when fields are optional
• Left-justify captions and fields

19
Prompts and instructions

• Place prompts to the right of fields or at bottom
  of screen
• Place instructions in a consistent location and
  make them visually distinct
• Use consistent terminology
• Navigation
• Position cursor in the default position
• Allow for movement between fields and within
  fields

20
Example 2 form fill-in
21
Input formats

• Use pop-up or pull down menus where user has to
  select from long list
• Provide defaults where possible
• Avoid case-sensitive formats where possible
• Error handling
• Allow character edits in fields
• Place cursor in field to be edited and highlight
  if possible

22
Why choose form fill-in?

• Advantages
• Easy to use and requires little memory
• Simplifies data entry
• Well-defined structure

• Disadvantages
• Requires typing skills and knowledge of valid
  inputs
• Consumes screen space
• Inflexible

23
Command language

• Semantics
• Complete set of functions
• Lexicon
• Command names or abbreviations
• Syntax
• Formats for command parameters and punctuation
• Interaction
• Structure of dialogue between user and computer

24
Examples command line
Command line interface
C\WINDOWS
Syntax
CHKDSK drivepathfilename /F /V
25
Guidelines for command language

• Choose words that easy to memorise
• Use consistent command formats
• Keep command strings short
• Provide online Help facility
• Use natural ordering sequence
• Place optional and/or least used items at the end
  of the command line
• Use defaults to reduce typing where possible
• Provide clear error messages

26
Why choose command language?

• Advantages
• Fast and efficient
• Appeals to 'power' users
• Flexible, user-controlled

• Disadvantages
• Difficult to learn and remember
• Requires typing skills
• Poor error handling

27
Natural language

• Use
• Subset of true natural language
• Consistent familiar terminology and simple brief
  grammatical forms
• Provide
• Co-operative response
• Optional clarification dialogue
• Visual clues to distinguish user input and system
  output
• Ways to view and edit dialogue history
• Instructions for navigation

28
Example natural language
http//www.franken.de/users/nicklas/das/projects/l
oqui/www_demo/LoquiDemo.html
29
Why choose natural language?

• Advantages
• Easy to learn and remember
• Powerful flexible and efficient
• Flexible, user-controlled

• Disadvantages
• Assumes knowledge of problem domain
• Requires clarification dialogues
• Requires typing skills
• Creates unrealistic expectations

30
Direct manipulation

• Users perform actions directly on visible objects
• Continuous representation of objects
• Physical actions or labelled button presses in
  place of command language
• Rapid incremental reversible operations with
  immediately visible results

31
Guidelines for direct manipulation

• Provide visual feedback for position, selection
  and movement
• Provide physical feedback for modes
• Provide an alternative interface for
  high-frequency expert users

32
Icons

• Choose a consistent scheme
• Design icons to be
• Concrete and familiar
• Visually and conceptually distinct
• Similar to other icons that belong to a set
• Avoid excessive detail
• Accompany by names
• Limit number of types
• Allow users to choose between iconic and textual
  display

33
Why choose direct manipulation?

• Advantages
• Presents task concepts visually
• Is easy to learn and remember
• Less error prone
• Encourages exploration
• Permits high subjective satisfaction

• Disadvantages
• Not self-explanatory
• Takes up more screen space
• May be hard to design and program
• May require graphics display, mouse, etc.

34
User psychology

• Attitude
• Readiness to respond to a psychological object
  with some degree of favour
• Positive, Neutral or Negative
• Motivation
• Internal state or condition that serves to
  activate or energise behaviour and give it
  direction
• High, Moderate or Low

35
User knowledge and experience (1)

• Typing skills
• Ranges from 135 wpm to 10 wpm
• High, Moderate or Low
• System experience
• Knowledge of the particular language or mode of
  interaction of a given system (e.g. use of
  special keys, codes for airlines)
• High, Moderate or Little
• Task experience
• Knowledge of the functions that the system is
  designed to help the user to perform (e.g.
  airline reservations)
• High, Moderate or Low

36
User knowledge and experience (2)

• Application experience
• Use of similar applications before (e.g. airline
  reservation systems)
• High, Moderate or Low
• Use of other systems
• Use of applications that are different from the
  one to be designed
• Frequent, Moderate or Infrequent
• Computer literacy
• Familiarity with use of hardware and jargon
  terms
• High, Moderate or Low

37
Job and task characteristics (1)

• Frequency of use
• How often? For how long?
• High, Moderate or Low
• Primary training
• Extensive programme, teach yourself, immediate
  use without training
• Formal, Some, Little or none
• System use
• Mandatory (required by job)
• Discretionary (choice of the user)

38
Job and task characteristics (2)

• Turnover rate
• How long does a user stay in that job?
• High, Moderate or Low
• Task importance
• How important is this task to the user?
• High, Moderate or Low
• Task structure
• Are the operations repetitive and predictable?
• Is there a lot of internal structure?
• High, Moderate or Low

39
Summary

• Describe five interaction styles
• Apply accepted guidelines
• Summarise advantages and disadvantages
• Choose a suitable style
• Further reading and revision
• Dix et al, Chap 3, pp115-139
• Mayhew, Chap 4, pp. 113-120, 144-170, Chap 5, pp.
  172-177, 183-214, Chap 7, pp. 228-233, 251-264,
  Chap 9, pp. 289-304, 316-330, Chap 10, pp.
  332-344, 359-363