Summary of "The Design of Everyday Things | Chapter 3 - Knowledge in the Head and in the World | Don Norman"
Summary of The Design of Everyday Things | Chapter 3 - Knowledge in the Head and in the World by Don Norman
Main Ideas and Concepts
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Knowledge in the Head vs. Knowledge in the World Knowledge needed to use objects and systems can reside either internally (in the user’s memory) or externally (in the environment). Neither knowledge in the head nor knowledge in the world alone is sufficient; effective behavior results from combining both. Knowledge in the world reduces memory load by providing cues, reminders, and constraints.
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Types of Knowledge
- Declarative knowledge: Facts and rules (e.g., traffic rules, how to remove a car key). Easy to teach and write down but not always followed or accurate.
- Procedural knowledge: Skills and how-to knowledge (e.g., playing tennis, typing). Difficult to verbalize and best learned by practice.
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Memory and Its Role in Design Human memory is limited and imperfect.
- Short-term (working) memory (STM): Holds a small amount of information (3-7 items) temporarily; easily disrupted by distractions.
- Long-term memory (LTM): Stores knowledge more permanently but retrieval is reconstructive, prone to errors and biases. Designers should minimize memory load by providing external cues and structuring information.
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Constraints and Cultural Conventions Physical constraints (shape, size, mechanics) and cultural conventions (rules, norms) limit possible actions, aiding memory and reducing errors. These constraints act as knowledge in the world or knowledge in the head.
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Natural Mappings and Signifiers Natural mappings link controls to their effects in an intuitive way (e.g., spatial arrangement of stove controls matching burners). Poor mappings cause confusion and errors. Signifiers (visible cues) are essential for discoverability and proper use.
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Approximate Models and Simplifications People use simplified mental models and approximations rather than precise, complex calculations or memories. Approximate answers (e.g., rough temperature conversions) are often sufficient for everyday tasks. Designers should aim for “good enough” solutions that reduce cognitive load.
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Memory Aids and Externalizing Knowledge Writing things down, using calendars, notes, alarms, and digital reminders offload memory demands. Reminders must have both a signal (cue to remember) and a message (what to remember). Over-reliance on memory can lead to errors; external knowledge aids performance.
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Trade-offs Between Knowledge in the Head and Knowledge in the World Knowledge in the head is efficient but requires learning and retention. Knowledge in the world requires no learning but depends on the physical presence and visibility of cues. Effective design balances these two sources.
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Memory in Groups and Technology
- Transactive memory: Groups share knowledge, each member remembers different parts.
- Cyber mind: Technology acts as an external memory aid (e.g., smartphones, internet). Dependence on technology increases, improving performance but creating vulnerabilities if technology fails.
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Cultural Differences in Design and Interpretation Natural mappings and metaphors may differ by culture (e.g., direction of time, button layouts). Designers must consider cultural conventions and perspectives to avoid confusion.
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Security and Memory Passwords and codes are difficult to remember, leading to insecure practices like writing them down. Security systems often fail to account for human memory limitations. Multi-factor authentication (something you have + something you know) is more secure but complex.
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Examples and Case Studies - Confusion caused by similar-looking coins in the US, UK, and France due to insufficiently distinct external cues. - Pilots managing complex, rapid instructions by offloading memory to notes and equipment settings. - Motorcycle turn signal confusion resolved by creating a meaningful mental model aligned with handlebar movement. - Stove controls poorly mapped to burners, leading to frequent user errors.
Methodologies, Instructions, and Design Guidelines
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Combining Knowledge Sources Design should integrate knowledge in the head and knowledge in the world to reduce user errors and cognitive load.
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Use Natural Mappings Arrange controls spatially and logically to match the objects or functions they control. Avoid arbitrary or inconsistent layouts.
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Provide Clear Signifiers Make controls and their states visible and understandable without requiring prior knowledge.
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Externalize Memory Encourage users to write down or store critical information externally. Use reminders that combine both signal and message components. Design systems to retain important information on display rather than disappearing quickly.
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Design for Approximate Use Accept that users rely on approximate models and estimates. Provide tools (calculators, digital aids) for precision when needed.
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Account for Cultural Differences Be aware of differing cultural metaphors and conventions in design (e.g., directionality, symbols).
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Minimize Memory Load Limit the number of items users must remember at once. Chunk information meaningfully. Use multiple sensory modalities (visual, auditory, haptic) to reduce interference in working memory.
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Security Design Recognize human limitations in memorizing passwords. Favor multi-factor authentication over complex password requirements alone.
Speakers and Sources Featured
- Don Norman – Author and main speaker presenting the concepts.
- Psychologists referenced:
- Ray Nickerson and Marilyn Adams (memory for coins)
- David Rubin and Wanda Wallace (memory and rhyme constraints)
- Albert Bates Lord (oral tradition of epic poetry)
- Daniel Wagner (transactive memory)
- Ken Paller (memory and sleep)
- Historical and literary references:
- Arabian Nights (Ali Baba story)
- Alfred North Whitehead (quote on automation of skills)
- Real-world examples and anecdotes:
- Pilots and air traffic control communication
- Stove control design issues
- Coin confusion in US, UK, and France
- Motorcycle turn signal example (Professor Yukata Sake)
- Security professionals and password practices
- Contemporary references:
- Google security meeting anecdote
- Online forums and Wikipedia discussions on coins and security
This chapter emphasizes the interplay between internal knowledge and external cues, the limitations of human memory, and the importance of designing everyday objects and systems that support users by balancing these knowledge sources effectively.
Category
Educational
