First Principles of Interaction Design
Foundational interaction design principles from Apple's first human interface designer, covering everything from anticipation to visible navigation.
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Anticipation
Bring users all the information and tools they need for each step. Predict what they’ll want next rather than making them search for it.
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Autonomy
Give users control over their environment while maintaining sensible boundaries. People feel most comfortable when they can explore without hazard.
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Color Blindness
Never use colour as the only means of conveying information. Roughly 10% of men have some form of colour blindness.
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Consistency
Maintain consistency at multiple levels—platform, application, and within features. But break consistency deliberately when it aids understanding.
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Defaults
Choose intelligent defaults that serve most users. Make them easy to change and use clear language to explain what restoration options actually do.
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Efficiency of the User
Optimise for human productivity, not machine efficiency. People cost far more than computers, so save their time first.
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Explorable Interfaces
Let users move freely backward and forward through workflows. Clear, visible navigation encourages people to complete tasks.
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Fitts' Law
Target acquisition time depends on distance and size. Make important controls large and position them near screen edges where the cursor stops naturally.
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Human Interface Objects
Create objects that behave consistently and can be manipulated directly. Users should be able to predict how objects will respond.
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Latency Reduction
Reduce actual wait times and make unavoidable delays feel shorter. Acknowledge input immediately and show progress indicators.
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Learnability
Balance learnability with usability for experienced users. The ideal interface works well for both novices and experts.
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Metaphors
Use metaphors that help users understand new concepts through familiar ones. But don’t let the metaphor limit what the software can do.
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Protect Users' Work
Ensure users never lose their work through system failure, their own error, or misunderstanding. Save continuously and enable recovery.
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Readability
Text must be readable. Use high contrast, appropriate sizes, and avoid visual tricks that sacrifice legibility for style.
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Track State
Remember where users are and what they’ve done. Restore their context when they return rather than forcing them to start over.