Human Computer Interaction Design Issues

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.

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

Command Line

Menu-driven

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

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

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

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

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

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

Norman’s Design Principles Affordance Feedback Visibility

Interface metaphors Representations of recognisable objects Users experience of reality

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

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

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

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

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.

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

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.