![16
Standards
Set by national or international bodies to ensure compliance by a large
community of designers.
Standards require sound underlying theory and slowly changing technology
Hardware standards more common than software
High authority and low level of detail
Example [of standards] - ISO 9241 "Ergonomic Requirements for Office Work
with Visual Display Terminals (VDT)
09/28/2024 Design Rules](https://image.slidesharecdn.com/chapter6-240928114357-8c36294e/85/Chapter-6-pptx-human-computer-interaction-16-320.jpg)
Chapter 6.pptx human computer interaction
- 2. 2 Outline Principles to support usability Standards Guidelines Golden rules and heuristics 09/28/2024 Design Rules
- 3. 09/28/2024 Design Rules 3 Design rules Helps to increase the usability of the system/product Design rules should be used early in the lifecycle Direction for design Classified Based on the rule’s authority and generality Vary in their level of abstraction Used to apply the theory in practice Essential characteristics of good design are often summarized through ‗golden rules‗ or heuristics
- 4. 4 Types of design rules 1. Principles Abstract design rules Low authority and high generality Principles are derived from knowledge of the psychological, computational and sociological aspects of the problem domains Are largely independent of the technology They depend to a much greater extent on a deeper understanding of the human element in the interaction. They can therefore be applied widely but are not so useful for specific design advice. e.g. interface should be easy to navigate 09/28/2024 Design Rules
- 5. 5 Cont… 2. Standards Specific design rules High authority and limited application Measurable e.g. use color RGB #1010D0 on home links 3. Guidelines Lower authority More general application Advice on how to achieve principles More technology oriented e.g. use color to highlight links 09/28/2024 Design Rules
- 6. 6 Principles to support usability usability Learnability Flexibility Robustness 09/28/2024 Design Rules
- 7. 7 Principles to support 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 09/28/2024 Design Rules
- 8. Principles to support usability • Robustness: the level of support provided the user in determining successful achievement and assessment of goal-directed behavior.
- 9. 9 Principles of learnability Predictability Determining effect of future actions based on past interaction history Operation visibility - user actions should be matched by a response Synthesizability Ability of the user to assess the effect of past operations on the current state When an operation changes some aspect of the internal state, it is important that the change is seen by the user Immediate vs. eventual honesty 09/28/2024 Design Rules
- 10. 10 Principles of learnability (con…) Familiarity How prior knowledge applies to new system Guess ability; affordance Generalizability Support for the user to extend knowledge of specific interaction within and across applications to other similar situations Consistency Likeness in input/output behaviour arising from similar situations or task objectives 09/28/2024 Design Rules
- 11. 11 Principles of flexibility Dialogue initiative Who controls dialogue flow system vs. user pre-emptiveness user pre-emptive dialog allows the user to offer any input action at any time for maximum flexibility. system-driven interaction hold back flexibility whereas a user-driven interaction favors it. modal dialog boxes are system pre-emptive direct manipulation is user pre-emptive Minimize system pre-emptive dialogue and maximize user pre-emptive dialogue 09/28/2024 Design Rules
- 12. 12 Principles of flexibility Multithreading Ability of system to support user interaction for more than one task at a time Task migratability Passing responsibility for task execution between user and system Example Spell-checking 09/28/2024 Design Rules
- 13. 13 Principles of flexibility… Substitutivity Allowing equivalent values of input and output to be substituted for each other Representation multiplicity; equal opportunity Example values in input fractions/decimals, values in output both digital and analog. Customizability Modifiability of the user interface by user (adaptability) or system (adaptivity) Adaptability refers to the user’s ability to adjust the form of input and output Adaptivity is automatic customization of the user interface by the system. 09/28/2024 Design Rules
- 14. 14 Principles of robustness Observability ability of user to evaluate the internal state of the system from its perceivable representation at the interface. brows ability; defaults; reachability; persistence; Recoverability ability of user to take corrective action once an error has been recognized reachability; forward/backward recovery; commensurate effort 09/28/2024 Design Rules
- 15. 15 Principles of robustness (ctd) Responsiveness It measures the rate of communication between the system and the user Short durations and instantaneous response times are desirable. Response time stability covers the invariance of the duration for identical or similar computational resources. Task conformance Degree to which system services support all of the tasks the user wishes to perform Task completeness addresses the coverage issue and Task adequacy addresses the user’s understanding of the tasks 09/28/2024 Design Rules
- 16. 16 Standards Set by national or international bodies to ensure compliance by a large community of designers. Standards require sound underlying theory and slowly changing technology Hardware standards more common than software High authority and low level of detail Example [of standards] - ISO 9241 "Ergonomic Requirements for Office Work with Visual Display Terminals (VDT) 09/28/2024 Design Rules
- 17. 17 Guidelines More suggestive and general Many textbooks and reports full of guidelines Abstract guidelines (principles) applicable during early life cycle activities Detailed guidelines (style guides) applicable during later life cycle activities Understanding justification for guidelines aids in resolving conflicts 09/28/2024 Design Rules
- 18. 18 Golden rules and heuristics A number of advocates of user-centered design have presented sets of ‘golden rules’ or heuristics Useful check list for good design Better design using these than using nothing! Different collections e.g. Shneiderman’s 8 Golden Rules Norman’s 7 Principles Nielsen’s 10 Heuristics 09/28/2024 Design Rules
- 19. 19 Shneiderman’s 8 Golden Rules 1. Strive for consistency • Consistent sequences of actions should be required in similar situations 2. Enable frequent users to use shortcuts • Abbreviations, function keys, hidden commands, and macro facilities 3. Offer informative feedback • For every operator action, there should be some system feedback 09/28/2024 Design Rules
- 20. 20 Rules Cont. 4. Design dialogs to yield closure Gives the operators the satisfaction of accomplishment, Help the user know when they have completed a task. An indication that the way is clear to prepare for the next group of actions. 5. Offer error prevention and simple error handling The system should be able to detect the error and offer simple, comprehensible mechanisms for handling the error. 09/28/2024 Design Rules
- 21. 21 Rules Cont. 6. Permit easy reversal of actions Relieves anxiety Encourages exploration of new options E.g undo 7. Support internal locus of control Design the system to make users the initiators of actions rather than the responders The user is in control of the system, which responds to his actions. 8. Reduce short-term memory load By keeping displays simple, consolidating multiple page displays and providing time for learning action sequences. 09/28/2024
- 22. 22 Norman’s 7 Principles 1. Use both knowledge in the world and knowledge in the head. • Provide the necessary knowledge within the environment 2. Simplify the structure of tasks. 3. Make things visible: bridge the gulfs of Execution and Evaluation. • The more visible functions are, the more likely users will be able to know what to do next 4. Get the mappings right. • User actions should map clearly onto system events 09/28/2024 Design Rules
- 23. 23 Norman’s 7 Principles Cont. 5. Exploit the power of constraints, both natural and artificial. • Determining ways of restricting the kind of user interaction that can take place at a given moment. 6. Design for error • Anticipate the errors the user could make and design recovery into the system 7. When all else fails, standardize • If there are no natural mappings then arbitrary mappings should be standardized so that users only have to learn them once 09/28/2024 Design Rules
- 24. 24 Nielsen’s 10 Heuristics 09/28/2024 Design Rules 1. Visibility of system status 2. Match between system and the real world 3. User control and freedom 4. Consistency and standards 5. Error prevention 6. Recognition rather than recall 7. Flexibility and efficiency of use 8. Aesthetic and minimalist design 9. Help users recognize, diagnose and recover from errors 10.Help and documentation
- 25. 25 HCI design patterns An approach to reusing knowledge about successful design solutions A pattern is an invariant solution to a recurrent problem within a specific context. Patterns address the problems that designers face by providing a ‘solution statement’ Example HCI pattern ‘go back to a safe place’ Patterns do not exist in isolation but are linked to other patterns in languages which enable complete designs to be generated 09/28/2024 Design Rules
- 26. 26 HCI patterns Cont. Characteristics of patterns Capture design practice not theory Capture the essential common properties of good examples of design They tell to the designer what needs to be done and why Represent design knowledge at varying levels: social, organisational, conceptual, detailed Express values about what is humane in interface design. Are intuitive and readable and can be used for communication between all stakeholders A pattern language should be generative and assist in the development of complete designs. 09/28/2024 Design Rules