Jawaharlal Nehru Technological University Hyderabad B.Tech IV HUMAN COMPUTER INTERACTION Previous Question Paper (February/March - 2022 - R15)

General principles of user interface design provide a framework for creating usable, efficient, and satisfying systems. Key principles include:

• Consistency: Interfaces should follow consistent rules for terminology, layout, and interaction patterns throughout the application to reduce the user's cognitive load.
• Visibility of System Status: The system should always keep users informed about what is happening through appropriate feedback within a reasonable time.
• Match between System and Real World: The design should use language, concepts, and conventions familiar to the user rather than system-oriented jargon.
• User Control and Freedom: Users often perform actions by mistake and need a clearly marked emergency exit to undo or redo actions.
• Error Prevention: A design that prevents a problem from occurring in the first place is better than good error messages.
• Recognition rather than Recall: Minimize the user's memory load by making objects, actions, and options visible.
• Flexibility and Efficiency of Use: Accelerators, unseen by the novice user, may often speed up the interaction for the expert user.
• Aesthetic and Minimalist Design: Dialogues should not contain information that is irrelevant or rarely needed.

Manipulation styles in GUIs define how users interact with digital objects to achieve tasks.

Direct Manipulation: This style allows users to interact directly with objects on the screen as if they were physical objects. Key characteristics include continuous representation of objects, physical actions instead of complex syntax, and rapid, incremental, reversible operations. Examples include dragging a file icon into a folder or resizing a window by dragging its corner. It provides immediate visual feedback, making the interface intuitive and reducing the need for memorizing commands.

Indirect Manipulation: This style involves interacting with objects through an intermediary, such as a menu, a dialog box, or a command line. The user does not interact with the object itself but rather provides instructions to the system to perform an action on that object. Examples include selecting 'Move' from a context menu to relocate a file or using a 'Properties' dialog box to change settings. While less intuitive than direct manipulation, indirect manipulation is often more powerful for complex tasks where precise control or batch processing is required.