1. Introduction to Design Rules 1.1. Types of Design Rules
   • Principles
   • Standard
   • Guidelines 1.2. Usability Principles
   • Learnability
   • Flexibility
   • Robustness
   • Synthesizability
   • Predictability
2. Design Guidelines 2.1. Shneiderman’s 8 Golden Rules 2.2. Nielsen’s 10 Heuristics 2.3. Norman’s 7 Principles 2.4. HCI design patterns

Design Rules

Designing for Maximum Usability

• Goal of Interaction Design: Focuses on achieving maximum usability.

Principles of Usability

• General Understanding: Abstract design rules with low authority and high generality.

Standards and Guidelines

• Direction for Design: Provides guidance for design.

Design Patterns

• Capture and Reuse Design Knowledge: Involves documenting and applying reusable design solutions.

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Types of Design Rules

• Principles:
  • Abstract design rules with low authority and high generality.
• Standards:
  • Specific design rules with high authority but limited application.
• Guidelines:
  • Lower authority with more general application.

Increasing Authority

Increasing Generality

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Usability Principles

• Learnability: Ease with which new users can begin effective interaction and achieve maximal performance.
• Flexibility: Multiplicity of ways the user and system exchange information.
• Robustness:
  • Assessing the effect of past actions.
  • Immediate vs. eventual honesty.
• Synthesizability:
  • Determining the effect of future actions based on past interaction history.
  • Operation visibility.
• Predictability: Assessing the effect of past actions.

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Difference Between Windows 7 and Windows 8

• Comparing the learnability of the two designs.

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Learnability

• Familiarity:
  • How prior knowledge applies to the new system.
  • Guessability; affordance.
• Generalizability:
  • Extending specific interaction knowledge to new situations.
• Consistency:
  • Likeness in input/output behavior arising from similar situations or task objectives.

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Generalizability Example

• Users are familiar with the toolbar in Microsoft PowerPoint, and the same knowledge applies in Adobe Photoshop toolbar.

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Familiarity Example

• A recycle bin is a familiar item in the real world, and the recycle bin icon immediately suggests its function, indicating a collection of items. Similar to a folder for documents.

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Consistency Example

• The design of Apple’s products is consistent across devices/platforms, providing the same look and feel for iPhone, iPad, MacBook, or Mac PC.

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Dialogue Initiative

• Freedom from system-imposed constraints on input dialogues.
• System vs. user preemptiveness.

Customizability

• Modifiability of the user interface by the user or system (adaptability or adaptivity).

Multithreading

• Ability of the system to support user interaction for more than one task at a time.
• Concurrent vs. interleaving; multimodality.

Substitutivity

• Allowing equivalent values of input and output to be substituted for each other.
• Representation multiplicity; equal opportunity.

Migratability

• Passing responsibility for task execution between user and system.
• Examples include automated spell checkers, grammar checkers, etc.

Flexibility

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Dialogue Initiative Example

• Freedom from system-imposed constraints on input dialogues.

Customizability Example

• Users can choose the appearance of the toolbar according to their preference.

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Multithreading Examples

• Multithreading in Mozilla.
• Multithreading in Windows.
• Task migratability in a BMI Calculator.

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Robustness

• Responsiveness:
  • How the user perceives the rate of communication with the system.
• Stability:
  • Task conformance.
  • Degree to which system services support all of the user’s tasks.
  • Task completeness; task adequacy.

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Using Design Rules

• Design rules suggest how to increase usability.
• They differ in generality and authority.

Increasing Authority

Increasing Generality

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Standards

• Set by national or international bodies to ensure compliance by a large community of designers.
• Require sound underlying theory and slowly changing technology.
• Hardware standards are more common than software.
• High authority and low level of detail.
• ISO 9241 defines usability as effectiveness, efficiency, and satisfaction with which users accomplish tasks.

Guidelines

Abstract Guidelines (Principles) Applicable During Early Life Cycle Activities

1. More Suggestive and General Approach
   • Design principles that are broad and offer general guidance.
2. Understanding Justification for Guidelines
   • Acknowledging the rationale behind guidelines aids in resolving conflicts.

Detailed Guidelines (Style Guides) Applicable During Later Life Cycle Activities

1. Golden Rules and Heuristics
   • “Broad brush” design rules for better design.
   • Useful checklists for good design.
   • Different collections include Nielsen’s 10 Heuristics, Shneiderman’s 8 Golden Rules, and Norman’s 7 Principles.

Shneiderman’s 8 Golden Rules

1. Strive for Consistency (Rule 1)
   • Emphasizes maintaining uniformity in design.
2. Enable Frequent Users to Use Shortcuts (Rule 2)
   • Facilitate efficiency by providing shortcuts for experienced users.
3. Offer Informative Feedback (Rule 3)
   • Ensure the system communicates effectively with users.
4. Dialog Design for Closure (Rule 4)
   • Design dialogs to give users a sense of completion.
5. Error Prevention and Handling (Rules 5 and 6)
   • Provide measures to prevent errors and allow easy reversal of actions.
6. Support Internal Locus of Control (Rule 7)
   • Empower users by allowing them to feel in control.
7. Reduce Short-term Memory Load (Rule 8)
   • Minimize the cognitive load on users.

Norman’s 7 Principles

1. Use Both Knowledge in the World and Knowledge in the Head (Principle 1)
   • Leverage external and internal knowledge for design.
2. Simplify the Structure of Tasks (Principle 2)
   • Streamline task complexity for user understanding.
3. Make Things Visible (Principle 3)
   • Enhance visibility to bridge the gaps of execution and evaluation.
4. Get the Mappings Right (Principle 4)
   • Ensure accurate mapping between actions and results.
5. Exploit the Power of Constraints (Principle 5)
   • Utilize constraints, both natural and artificial, to guide user interactions.
6. Design for Error (Principle 6)
   • Incorporate design elements that minimize errors.
7. Standardize When All Else Fails (Principle 7)
   • Standardization as a fallback when other design strategies fail.

UI Design Patterns

1. UI Design Patterns Overview
   • An approach to reusing knowledge about successful design solutions.
2. Characteristics of Patterns
   • Capture design practice, not just theory.
   • Represent design knowledge at various levels: social, organizational, conceptual, detailed.
   • Embody values and contribute to humane interface design.

UI Design Patterns Examples

1. Examples of UI Design Patterns
   • Password strength meter.
   • Alternate row colors.
   • Breadcrumb navigation.

Summary

Principles for usability

• repeatable design for usability relies on maximizing benefit of one good design by abstracting out the general properties which can direct purposeful design
• The success of designing for usability requires both creative insight (new paradigms) and purposeful principled practice

Using design rules

• standards and guidelines to direct design activity