1. Human Computer Interaction
Design Issues

2. What is Human Computer Interaction ?
Definition 1 - A discipline concerned with the design, evaluation and implementation of interactive computing systems for human use and the study of major phenomena surrounding them.
Definition 2 - The study of people, computer technology, the ways these influence each other and how we can make this computer technology more usable by people.

3. categories of interface
Command Line
Menu-driven
Prompted User Interface
Graphical User Interface

4. Command Line

5. Menu-driven

6. HCI Prompted User Interface Graphical User Interface
Video timer programmer
ATM, auto banking machine
Graphical User Interface
Windows
Mac
XWindows

7. HCI Interface model Domain model
Presentation to the user.
The interface
Domain model
The actual “content” or “subject matter”
One domain model can have several interface models

8. HCI Issues I/O devices Cognitive characteristics of user
Background of the users
Tasks
Types of interface available

9. Separation of domain and interface model
copy c:mywork.txt a:
underlying operating system commands, interrupt service routines, process management
Windows...

10. Design for users Importance of good user centered design
Contribution of other academic disciplines
psychology
sociology
linguistics
others

11. Good interface development
Low level issues
User needs analysis
What tasks will be performed
Where will the system be used
Leads to usability index...

12. Norman’s Design Principles
Affordance
Feedback
Visibility

13. Interface metaphors Representations of recognisable objects
Users experience of reality

14. Direct manipulation Interact with the object of interest
(with a representation…)
no need to remember textual descriptions of items
easy to learn, very usable and often well liked
good feedback, affordance and visibility
allows the creation of interface metaphors which lead to an intuitive interface

15. Characteristics of DM elements should be visible
operations should be straightforward (rapid) and reversible
“small” operation incrementally causes “big” effects
no need to revert to command language

16. User Needs Analysis Task Person (partially blind)
Situation(environment or application)

17. Visualisation
Translate large mental load into comprehensible visual image
Improvements in sound and other technologies… preferred term
perceptualisation

18. Perceptualisation (Perceptual User Interface)
Definition - Perceptual interfaces are ones in which the computer is given the ability to sense and produce analogs of the human senses, such as allowing computers a sense of touch and force feedback.

19. Accessibility (A category of usability
Definition2 - Removal of barriers that prevent people with disabilities from participating in substantial life activities,ie Information technology.
Definition2 - Enables successful access to information and encourages the use of information technology.eg. Partially blind persons

20. Design for Access & Average user
Accessibility is usability which allows the user to effectively & efficiently work on a system.
Eg. Design of the talking book, led to the tape being created.