HCI(Human Computer Interaction) and Usability are becoming core concepts of the system development process to improve and enhance system facilities and to satisfy user needs and necessities.
- HCI assists designers and analysts to identify the needs of texts, fonts, layout, graphics, color, etc.
- While Usability ensures system the system is efficient, effective, safe, easy to learn, easy to remember, easy to evaluate, and provides job satisfaction to users.
- ISO 9421 defines usability as effectiveness, efficiency, and satisfaction with which users accomplish tasks.
Usability
Principles of Usability:
- Learnability: The ease with which new users can begin effective interaction and achieve maximal performance
- Flexibility: The multiplicity of ways the user and system exchange information
- Robustness: The level of support provided to the user in determining achievement and assessment of goal-directed behavior
Principles to Support USABILITY
1. Principles of Learnability:
- Predictability: It determines the effects of future action based on past interaction history.
- Synthesizability: It determines the effects of past operations on current states. eg.- move file
- Familiarity: New users can get familiar with the functionality and interaction style of the application.
- Consistency: It means through the resultant behavior of the system. Every time system gives the same result on the same set of inputs.
- Generalizability: It requires specific knowledge of the same domain knowledge. eg.- Cut, Copy, etc.
2. Principles of Flexibility:
- Dialog initiative: All the dialogs are done by a simple request and response system.
- Multithreading: Single set of code on input can be used by several processes at different stages of execution.
- Task Migratability: Transfer the execution of the task from the system to the user and decide who is better. eg.- Spell Checker
- Substitutivity: It allows equivalent values of input and output to be substituted with each other. eg.- Percentages and Grades
- Customizability: It supports the modifiability of the user interface by a user (adaptability) or system (adaptivity).
3. Principles of Robustness:
- Observability: The user should be able to evaluate the internal features of a system and give proper feedback.
- Responsiveness: Real system feedbacks on the user’s action.
- Recoverability: To fix and solve errors and get the correct actions.
- Task Conformance: The system supports all the requirements of the user and how the user interacts with them.