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HCI Principles
• Broader in scope than guidelines —^ “more
fundamental, widely applicable, and enduring”
• On the other hand,^ this greater generality results in
the need for more clarification, or individual interpretation by interaction designers
• The upshot is — before applying HCI principles,^ get to
know the context of your users and applications very well first
• Many HCI gurus offer^ “their take” on design principles
— frequently overlapping, with individual highlights
Principle: Know Thy User
• Corollary:^ if you think you know thy user,^ think again
• Diversity across multiple dimensions:^ age,^ gender,
physical and cognitive abilities, education, culture or ethnicity, training, motivation, goals, personality
• Two types of user knowledge:
- Interface — knowledge of the technology that “presents” the system image
- Domain — knowledge of the real-world activities that your user interface seeks to accomplish
User Proficiency Profiles
interface knowledge domain/task knowledge novice little to none; shallow little to none; shallow first-time little to none; shallow knowledgeable knowledgeable intermittent some, but not specific knowledgeable expert frequent expert expert
Accommodating Multiple
User Profiles
• Scope:^ are we designing for all profiles? (ideally yes)
Or just a subset? (implies vertical applications)
• Multi-layer ,^ level-structured ,^ or^ spiral^ interfaces
• Novices get^ “training wheels” — limited options,
but also fewer opportunities for error
• Increased proficiency enables increased functionality
• Multiple layers include both software and
documentation
• Not unlike progressing through a modern video game
Principle: “Golden Rules”
HCI gurus provide individual takes on the most important elements of good user interfaces. Here are Shneiderman’s Eight Golden Rules:
- Strive for consistency
- Cater to universal usability
- Offer informative feedback
- Design dialogs to yield closure
- Prevent errors
- Permit easy reversal of actions
- Support internal locus of control
- Reduce short-term memory load
Nielsen’s Take: Ten Usability
Heuristics
• Simple and natural dialog
• Speak the user’s language
• Minimize user memory load
• Consistency
• Feedback
• Clearly-marked exits
• Shortcuts
• Good error messages
• Prevent errors
• Help and documentation
Tognazzini’s Take: Sixteen
First Principles
Anticipation Defaults Human Interface Objects Protect the User’s Work Autonomy Efficiency of the User Latency Reduction Readability Color Blindness Explorable Interfaces Learnability — Limit Tradeoffs Track State Consistency Fitts’s Law Use of Metaphors Visible Navigation
Discerning Patterns in the
Rules
• Despite variations in phrasing and emphasis,^ certain
common themes emerge among these (and other) sets of golden rules — this should give you an idea for prioritization and generality
• One way to reason about these rules objectively is to
relate them to how they influence the five metrics of learnability, efficiency, memorability, errors, and subjective satisfaction
• It remains to be seen whether these rules will
converge into the “one, true HCI rulebook”
Principle: Integrating
Automation vs. Control
• Sanders and McCormick (1993) suggest that we play
to a human being’s strengths as opposed to a machine’s:
• Avoid routine,^ tedious,^ and error-prone tasks —
automation
• Focus on making decisions,^ dealing with the
unexpected, and planning for the future — control
• A corollary to control is^ predictability^ — we generally
don’t want the computer to “have a mind of its own”
• The FAA says it well:^ “improve system performance,
without reducing human involvement” and “train users when to question automation” (2003)
• Automation vs.^ control grows in significance as
anthropomorphic and adaptive user interfaces grow in popularity and sophistication
- (^) Microsoft’s Office Assistants (or sometimes, Microsoft Office itself)
- (^) Assorted “bots” and pseudo natural-language interfaces (online help, search engines)
- (^) “Trained” spam filters
- (^) Amazon and others’ “your store” or “your page” features
