Interaction Styles

1
Interaction Styles
2
Overview

• To frame our discussion, consider
• What are the major interaction styles of
  human-computer interaction in use today?
• On what dimensions could we compare and contrast
  these styles?
• Is usability attainable in system development?

3
Outline

• History
• Command
• Menu
• Direct Manipulation
• Which Interaction Style is best?
• Measurable Goals
• Principles in Designing for Usability

4
(No Transcript)
5
Meaning

• the user is an idiot for using the package.
• any user can use the package effectively.
• the designer is an idiot for designing the user
  interaction in this way.

6
History

• Different terms have been used to describe the
  communication between the user and the computer
  (software). As richer styles of communication
  have become commonplace interaction styles has
  become the term of choice.

7
Command Line

• Early applications were command-driven. Users
  were expert, knowledgeable and not afraid of
  computers. They could be expected to overcome any
  obstacles by sheer perseverance.

8
Command Line

• Commands provide a way of expressing instructions
  to the computer directly. Communication between
  user and computer is purely textual.

9
Command Line

• Commands can take the form of function keys,
  single characters, short abbreviations, whole
  words, or combination of the first two. An issue
  with command interface is the number of
  keystrokes required to complete a command.

10
Command Line

• Commands must be remembered.
• There is a difference between remembered when we
  consider recall and recognition. These are two
  distinct memory processes.

11
Concerns

• Care must be taken in choosing the commands for
  the system.
• Mnemonics are often suggested as a way to support
  recall. CTRL-c copy, CTRL-s save

12
Form Fill-in

• Form fill-in was designed for clerical workers
  with little experience with computers, to enable
  them to carry out repetitive data entry tasks.
  These interfaces mimicked paper forms with the
  aim of retaining the characteristics of data
  entry in the paper medium.

13
Form Fill-in

• Navigation from one data entry area to another
  was designed to allow clerks to move the
  insertion point without looking at the screen.
• Relied heavily on users expertise in keyboarding.

14
(No Transcript)
15
Menu

• A list of options are presented to the user and
  the appropriate decision is selected by typing
  some code or selection the option required.
• Menus do not require the user to remember the
  item they want, they only need to recognize it.

16

• Choose the option desired
• 1 input data manually
• 2 input data from data file
• 3 perform simple analysis
• 4 perform detailed analysis
• 5 other options
• Select Option ?

17
Pull-Down Menu
18
Hierarchical
19
Concerns

• 1. Naming of items on the option list
• 2. Depth versus breadth
• 3. Categorizing options
• 4. Time to selection (Fitts Law)

20
Direct Manipulation

• WIMP
• Direct manipulation systems are characterized by
  icons representing objects. These objects can be
  acted upon directly by the user using a pointing
  device.

21
Direct Manipulation

• The choice of icons to represent objects of
  interest to the user is important.
• If representations are well-chosen then the
  learning curve is steep owing to the user's
  familiarity with the objects and intended
  actions.

22
Concerns

• 1. The degree of match between the designer's
  choice of representation and the user's
  understanding.
• 2. Choice of metaphors to support the user's
  activity.
• 3. Explicit attention to places and ways the
  instantiated and "real" objects differ.
• 4. Cultural bias of representation choices.

23
Which is Best?
24
Measurable Goals

• 1. Time to learn -
• How long does it take for typical members of the
  users community to learn how to use the commands
  relevant to a set of tasks?
• 2. Speed of performance -
• How long does it take to carry out the benchmark
  set of tasks?
• 3. Rate of errors -
• How many and what kinds of errors are made in
  carrying out the set of tasks?
• 4. Retention over time -
• How well do users maintain their knowledge after
  set period of time? (perhaps related to frequency
  of use)

25
Principles in Designing for Usability

• Early Focus on Users and Tasks
• Empirical Measurement
• Iterative Design