Design rules: Principles to support usability, Standards and guidelines

Notes

Study Notes

HCI Notes: Design Rules and Principles

Design Rules and Usability Principles

Guidelines for creating effective, efficient, and satisfactory interactive systems.

1. Foundational Usability Principles

Usability principles are abstract design rules derived from theory or experience, intended to be broad and application-independent. They serve as guidance for designers and evaluation criteria for experts.

Example: Shneiderman's Golden Rules

  • **Strive for Consistency:** In terminology, prompts, and sequencing of actions.
  • **Seek Universal Usability:** Cater to diverse users (novice, expert, disabled).
  • **Offer Informative Feedback:** For every user action, feedback must be provided.
  • **Design Dialogs to Yield Closure:** Sequences of actions should have a clear beginning, middle, and end.
  • **Permit Easy Reversal of Actions:** Support "Undo" for single actions or groups of actions.
  • **Reduce Short-Term Memory Load:** Make objects, actions, and options visible.

Example: Nielsen's 10 Heuristics

(See Usability Engineering Notes for full list)

  • Visibility of System Status
  • Match Between System and Real World
  • User Control and Freedom
  • Error Prevention
  • Recognition Rather than Recall

2. Standards (Mandatory Design Rules)

Standards are strict rules set by national or international bodies (e.g., ISO, ANSI) or regulatory agencies. They must be followed to ensure compliance, safety, and compatibility.

ISO Standards (International Organization for Standardization)

  • **ISO 9241:** A comprehensive set of standards covering the ergonomics of human-system interaction.
  • **ISO 9241-11 (Usability Definition):** Defines usability in terms of effectiveness, efficiency, and satisfaction.
  • **ISO 9241-210:** Covers the human-centred design process for interactive systems (UCD process).

Regulatory and Accessibility Standards

  • **WCAG (Web Content Accessibility Guidelines):** Internationally recognized standards for making web content accessible to people with disabilities.
  • **Industry Standards:** Rules governing medical devices, aviation software, etc., where safety is paramount.

3. Guidelines (Specific, Flexible Advice)

Guidelines are low-level, specific recommendations for design derived from principles. They are platform-specific and provide practical advice, but can be broken if necessary for a superior design.

Platform-Specific Examples

  • **Apple Human Interface Guidelines (HIG):** Specifies how iOS and macOS apps should look and behave (e.g., button sizes, navigational patterns).
  • **Google Material Design:** Provides rules for layout, color, motion, and interaction for Android and web applications.

Scope and Utility

  • **Coverage:** Cover minute details like error message wording, preferred input controls, and minimum tap targets.
  • **Flexibility:** Since they are low-level, designers often have to select or prioritize conflicting guidelines based on the specific context of use.

4. Design Rule Hierarchy

Design rules exist on a spectrum from the abstract and general (Principles) to the concrete and mandatory (Standards).

Level Nature Binding Force
Standards (Highest) Specific, Formal, Regulatory Mandatory (Compliance Required)
Principles (Medium) General, Abstract, Theory-based Strong Recommendation (Heuristics)
Guidelines (Lowest) Specific, Contextual, Detailed Advice Flexible Advice (Can be broken if justified)

Navigation

Iterative desig... Back to Module golden rules an...