David W Parker - Developer

books

Book: The Design of Everyday Things

published on
  • Read: April-May 2012
  • Rating: 8.0/10

The Design of Everyday Things (DOET) by Donald Norman is a classic book on, well, design. It wasn’t exactly what I was expecting, and I think it was different in a good way. The book pertains mostly to what people would think of as “usability” rather than “design,” especially for those of us working with software, where we think of design as rounded corners, and other aesthetics like that. This book doesn’t mention that stuff at all. Rather, it discusses what makes a good design and how a good design solves problems for those using the everyday object. I really think that the original name of the book, The Psychology of Everyday Things (POET), is an excellent name for the book. All said, I’d highly recommend this book.

My Notes

Topics:

  1. It’s not your fault
  2. Design Principles
    • Conceptual Models
    • Feedback
    • Constraints
    • Affordances
  3. The Power of Observations

One of the most important principles of design: visibility

Natural signals = natural design

When simple things need pictures, labels, or instructions, the design has failed

When an action has no apparent result, you may conclude that the action was ineffective

Principles of Design for Understanding and Usability (Conceptual Models)

  1. Provide a good conceptual model
    • Allows us to predict the effects of our actions
    • Three mental models: Design model (designer), User’s model (user), and System image (system)
    • People form mental models through experience, training, and instruction
    • When the system image is incoherent or inappropriate, as in the case of the refrigerator, then the user cannot easily use the device
  2. Make things visible
    • Whenever the number of possible actions exceeds the number of controls, there is apt to be difficulty

Principle of Mapping

Mapping is a technical term meaning the relationship between two things, in this case beteen the controls and their movements and the results in the world

  • Additive dimensions: add more to show incremental increases
  • Substitutive dimensions: substitute one value for another to make a change

Principle of Feedback

Feedback– sending back to the user information about what action has actually been done, what result has been accomplished– is a well known concept in the science of control and information theory

The paradox of technology should never bee used as an excuse for poor design

Psychology of Everyday Actions

Falsely blaming yourself: if a design is faulty and the task appears simple or trivial, then people blame themselves

“If an error is possible, someone will make it. The designer must assume that all possible errors will occur and design so as to minimize the chance of the error in the first place, or its effects once it gets made. Errors should be easy to detect, they should have minimal consequences, and, if possible, their effects should be reversible.”

In general, it has been found that people attribute their own problems to the environment, those of other people to their personalities

When things go right, people credit their own forceful personalities and intelligence

To get something done:

  1. start with a goal that is to be achieved
  2. do something to the world; take action to move yourself or manipulate someone or something
  3. finally, check to see that your goal was made

4 things to consider:

  1. the goal
  2. what is done to the world
  3. the world itself
  4. the check of the world

An intention is a specific action taken to get to the goal

Seven stages of action: one for goals, three for execution, three for evaluation

  1. Forming the goal
  2. Forming the intention
  3. Specifying an action
  4. Executing the action
  5. Perceiving the state of the world
  6. Interpreting the state of the world
  7. Evaluating the outcome

Knowledge in the Head and in the World

Precise behavior can emerge from imprecise knowledge for four reasons 1. Information is in the world 2. Great precision is not required 3. Natural constraints are present 4. Cultural constraints are present

Information is in the World

Whenever information needed to do a task is readily available in the world, the need for us to learn it diminishes

  • Knowledge of: declarative knowledge. Facts and rules
  • Knowledge how: procedural knowledge. Enables people to perform music, play tennis, etc - best taught by demonstration and best learned through practice

Memory is knowledge in the Head

People use their memories and how they retrieve information:

  1. Memory for arbitrary things
  2. Memory for meaningful relationships
  3. Memory through explanation

Memory is also knowledge in the World

Reminders - to do something in the world, at a later time or date

  • Two aspects of a reminder: signal and message
  • The ideal reminder has to have both components

Test products before you buy them!

  • think stove burners, and if they must include labels and reminders, then they may have a faulty design, as there isn’t a natural mapping
  • Often the purchaser is not the user

Tradeoff between Knowledge in the World and in the Head

  • Retreivability
    • World: whenever visible or audible
    • Head: not readily retrievable. Requires memory search or reminding
  • Learning
    • World: learning not required. Interpretation substitutes for learning. How easy it is to interpret information in the world depends upon how well it exploits natural mappings and constraints
    • Head: requires learning, which can be considerable. Learning is made easier if there is meaning or structure to the material.
  • Efficiency of use
    • World: tends to be slowed up by need to find and interpret the external information
    • Head: can be very efficient
  • Ease of use at first encounter
    • World: high
    • Head: low
  • Aesthetics
    • World: can be unaesthetic and inelegant, especially if there is a need to maintain a lot of information. This can lead to clutter. In the end, aesthetic appeal depends upon the skill of the designer
    • Head: nothing need be visible, which gives more freedom to the designer, which in turn can lead to better aesthetics

Knowing what to do

Problems occur whenever there is more than one possibility

Types of constraints: * Physical * Example: most keys * Semantic * Rely upon the meaning of the situation to control set of possibly actions * Cultural * Example: Red lights and Green lights * Logical * Think natural mappings

Visibility and Feedback

  1. Visibility: make the relevant parts visible
  2. Feedback: give each action an immediate and obvious effect

To Err is Human

Categories of errors: slips and mistakes

  • Slip = automatic behavior
  • Mistakes = conscious deliberation

  • Mosty everyday errors are slips
  • Slips show up most frequently in skilled behavior
  • Slips result from a lack of attention

Types of slips:

  1. Capture errors - frequently done activity suddenly takes change instead of (captures) the one intended
  2. Description errors - intended action has much in common with the others that are possible (correct action on wrong object)
  3. Data-driven errors - automatic actions are data-driven
  4. Associative activation errors - you think something that ought not to be said and then you said it (Freudian slips)
  5. Loss-of-activition errors - simply forgetting to do something
  6. Mode errors - when devices have different modes of operation

Asking for confirmation cannot catch all slips

Mistakes result from the choice of inappropriate goals

Structure of tasks:

  • Wide and deep - most games (chess)
  • Shallow - menu of an ice cream store
  • Narrow - cookbook recipe

What is not an everyday activity? Those with wide and deep structures

Error is often thought of as something to be avoided or something done by unskilled or unmotivated people. But everyone makes errors

Forcing functions:

  • Interlock - force operations to take place in proper sequence
  • Lockins - keeps an operation active, preventing someone from prematurely stopping it
  • Lockouts - prevents someone from entering a place that is dangerous, or prevents an event from occurring

A design philosophy

  • Put the required knowledge in the world. Don’t require all the knowledge to be in the head. Yet do allow for more efficient operation when the user has learned the operations, has gotten the knowledge in the head
  • Use the power of natural and artificial constraints: physical, logical, semantic, and cultural. Use forcing functions and natural mappings
  • Narrow the gulfs of execution and evaluation. Make things visible, both for execution and evaluation. On the execution side, make the options readily available. On the evaluation side, make the results of each action apparent. Make it possible to determine the system state readily, easily, and accurately, and in a form consistent with the person’s goals, intentions, and expectations

The design challenge

Forces that work against evolutionary design

  • Demands of time
  • Curse of individuality

Donald Norman uses EMACS! … and he mentions that Dvorak keyboard layout is superior… I must be doing something right.

Designers are not typical users

There is no such thing as the average person

The ability of conscious attention is limited: focus on one thing and you reduce your attention to others

Two deadly temptations for the designer:

  1. Creeping featurism
    • Tendency to add to the number of features that a device can do, often extending the number beyond all reason
    • With each additional feature compes extra complexity
  2. Worshipping of false images
    • Most expensive does not mean best for the job

One important method to make systems easier to learn and to use is to make them explorable, to encourage the user to experiment and learn the possibilities through active exploration

Exploration

  • In each state of the system, the user must readily see and be able to do the allowable actions
  • The effect of each action must be both visible and easy to interpret
  • Actions should be without cost

User Centered Design

Design should:

  • Make it easy to determine what actions are possible at any moment
  • Make things visible, including the conceptual model of the system, the alternativee actions, and the results of actions
  • Make it easy to evaluate the current state of the system
  • Follow natural mappings between intentions and the required actions; between actions and the resulting effect; and between the information that is visible and the interpretation of the system state

Seven Principles for Transforming Difficult Tasks into Simple Ones

  1. Use both knowledge in the world and knowledge in the head
  2. Simplify the structure of tasks
  3. Make things visible: bridge the gulfs of execution and evaluation
  4. Get the mappings right
  5. Exploit the power of constraints, both natural and artificial
  6. Design for error
  7. When all else fails, standardize

Questions? E-mail me: this domain AT gmail DOT com