"The Design of Everyday Things" by Don Norman

• Good design is actually a lot harder to notice than poor design, in part because good designs fit our needs so well that the design is invisible, service us without drawing attention to itself. Bad design, on the other hand, screams out its inadequacies, making itself very noticeable.
• Emotion is so important that I wrote an entire book, Emotional Design, about the role it plays in design.
• Two of the most important characteristics of good design are discoverability and understanding.
• Many products defy understanding simply because they have too many functions and controls.
• The problem with the designs of most engineers is that they are too logical.
• We have to accept human behavior the way it is, not the way we would wish it to be.
• We are designing things for people, so we needed to understand both technology and people.
• Even experts make errors. So we must design our machines on the assumption that people will make errors.
• Experience is critical, for it determines how fondly people remember their interactions.
• An affordance is a relationship between the properties of an object and the capabilities of the agent that determine just how the object could possibly be used.
• To be effective, affordances and anti-affordances have to be discoverable--perceivable.
• Visible affordances provide strong clues to the operations of things.
• Affordances determine what actions are possible. Signifiers communicate where the action should take place.
• The relationship between a control and its results is easier to learn where there is an understandable mapping between the controls, the actions, and the intended result.
• Natural mapping, by which I mean taking advantage of spatial analogies, leads to immediate understanding.
• Feedback--communicating the results of an action--is a well known concept from the science of control and information theory.
• Feedback must be immediate: even a delay of a tenth of a second can be disconcerting.
• Poor feedback can be worse than no feedback at all, because it is distracting, information, and in many cases irritating and anxiety-provoking.
• A conceptual model is an explanation, usually highly simplified, of how something works. It doesn’t have to be complete or even accurate as long as it is useful.
• Simplified models are valuable only as long as the assumptions that support them hold true.
• No matter how brilliant the product, if people cannot use it, it will receive poor reviews.
• Good conceptual models are the key to understandable, enjoyable products: good communication is the key to good conceptual models.
• It doesn’t matter how good a product is if, in the end, nobody uses it.
• Seven stages of action: one for goals, three for execution, and three for evaluation.
• goal (form the goal)
• plan (the action)
• specify (an action sequence)
• perform (the action sequence)
• perceive (the state of the world)
• interpret (the perception)
• compare (the outcome with the goal)
• Most innovation is done as an incremental enhancement of existing products.
• Most of human behavior is a result of subconscious processes.
• Cognition and emotional cannot be separated. Cognitive thoughts lead to emotions: emotions drive cognitive thoughts.
• We need to remove the word failure from our vocabulary, replacing it instead with learning experience.
• To fail is to learn: we learn more from our failures than from our successes.
• Take people’s difficulties as signifiers of where the product can be improved.
• Eliminate all error messages from electronic or computer systems. Instead, provide help and guidance.
• The idea that a person is at fault when something goes wrong is deeply entrenched in society.
• Human error usually is a result of poor design: it should be called system error. Humans are continually; it is an intrinsic part of our nature. System design should take this into account.
• Don’t criticize unless you can do better.
• Whenever knowledge needed to do a task is readily available in the world, the need for us to learn it diminishes.
• We learn to discriminate among things by looking for distinguishing features.
• Some things can only be solved by massive cultural changes, which probably means they will never be solved.
• Make something too secure, and it becomes less secure.
• Science deal in truth, practice deals with approximations. Practitioners don’t need truth: they need results relatively quickly that, although inaccurate, are “good enough” for the purpose to which they will be applied.
• The unaided mind is surprisingly limited. It is things that make us smart. Take advantage of them.
• Natural mappings are those where the relationship between the controls and the object to be controlled.
• The lack of clear communication among the people and organizations constructing parts of a system is perhaps the most common cause of complicated, confusing designs.
• A useable design starts with careful observations of how the tasks being supported are actually performed, followed by a design process that results in a good fit to the actual ways the tasks get performed.
• Forcing functions are a form of physical constraint: situations in which the actions are constrained so that failure at one stage presents the next step from happening.
• An interlock forces operations to take place in proper sequence.
• A lock-in keeps an operation active, preventing someone from prematurely stopping it.
• Where's a lock-in keeps someone in a space or prevents an action until the desired operations have been done, a lockout prevents someone from entering a space that is dangerous, or prevents an event from occurring.
• Violations of convention can be very disturbing.
• People invariably object and complain whenever a new approach is introduced into an existing array of products and systems.
• Skeuomorphic is the technical term for incorporating old, familiar ideas into new technologies, even though they no longer play a functional role.
• We should treat all failures in the same way: find the fundamental causes and redesign the system so that these can no longer lead to problems.
• Error occurs for many reasons. The most common is in the nature of the tasks and procedures that require people to behave in unnatural ways--staying alert for hours at a time, providing precise, accurate control specifications, all the while multi tasking, doing several things at once, and subjected to multiple interfering activities.
• Interruptions are a common reason for error, not helped by designers and procedures that assume full, dedicated attention yet that do not make it easy to resume operations after an interruption.
• Root cause analysis is the name of the game: investigate the accident until the single, underlying cause is found.
• Most accidents do not have a single cause: there are usually multiple things that went wrong, multiple events that, had any of them not occurred, would have prevented the accident.
• Root cause analysis is intended to determine the underlying cause of an incident, not the proximate cause.
• The tendency to stop seeking reasons as soon as a human error has been found is widespread.
• When people err, change the system so that type of error will be reduced or eliminated. When complete elimination is not possible, redesign to reduce the impact.
• A slip occurs when a person intends to do one action and ends up doing something else. With a slip, the action performed is not the same as the action that was intended.
• There are two major classes of slips: action-based and memory-lapse. In action-based slips, the wrong action is performed. In lapses, memory fails, so the intended action is not done or its result not evaluated.
• A mistake occurs when the wrong goals is established or the wrong plan is formed.
• Checklists are powerful tools, proven to increase the accuracy of behavior and to reduce error, particularly slips and memory lapses. They are especially important in situations with multiple, complex requirements, and even more so where there are interruptions.
• It is always better to have two people do checklists together as a team: one to read the instruction, the other to execute it.
• Printed checklists have on major flaw: they force the steps to follow a sequential ordering, even where this is not necessary or even possible.
• In general, it is bad design to impose a sequential structure to task execution unless the task itself requires it. This is one of rht e major benefits of electronic checklists: they can keep track of skipped items and can ensure that the list will not be marked as complete until all items have been done.
• Most major accidents are preceded by warning signs: equipment malfunction or unusual events.
• Hindsight makes events seem obvious and predictable. Foresight is difficult. During an incident, there are never clear clues.
• It is relatively easy to design for the situation where everything goes well, where people use the device in the way that was intended, and no unforeseen events occur. The tricky part is to design for when things go wrong.
• It should not be possible for one simple error to cause widespread damage.
• Doing two tasks at once takes longer than the sum of the times it would take to do each alone.
• One of my rules in consulting is simple: never solve the problem I am asked to solve. Why such a counterintuitive rule? Because, invariably, the problem I am asked to solve is not the real, fundamental, root problem. It is usually a symptom.
• The secret to success is to understand what the real problem is.
• It is all too easy to see only the surface problems and never dig deeper to address the real issues.
• A brilliant solution to the wrong problem can be worse than no solution at all; solve the correct problem.
• Good designers never start by trying to solve the problem given to them: they start by trying to understand what the real issues are.
• The two phases of design--finding the right problem and meeting human needs and capabilities--give rise to two phases of the design process. The first phase is to find the right problem, the second is to find the right solution.
• There are four different activities in the human-centered design process:
• observation
• idea generation
• prototyping
• testing
• The only way to really know whether an idea is reasonable is to test it. Build a quick prototype or mockup of each potential solution.
• [When testing] study five people individually. Then, study the results, refine them, and do another iteration, testing five different people. Five is usually enough to give major findings.
• If you really want to test many more people, it is far more effective to do one test of five, use the results to improve the system, and then keep iterating the test-design cycle until you have tested the desired number of people. This gives multiple iterations of improvement, rather than just one.
• If everything works perfectly, little is learned. Learning occurs when there are difficulties.
• The hardest part of the development of complex products is management: organizing and communicating and synchronizing the many different people, groups, and departmental divisions that are required to make it happen.
• There is no such thing as the average person. This poses a particular problem for the designer, who usually must come up with a single design for everyone.
• Standardization provides a major breakthrough in usability.
• Most things are intended to be easy to use, but aren’t. But some things are deliberately difficult to use--and ought to be.
• Featuritis is an insidious disease, difficult to eradicate, impossible to vaccinate against.
• Creeping featurism is the tendency to add to the number of features of a product, often extending the number beyond all reason. There is no way that a product can remain useable and understandable by the time it has all of those special-purpose features that have been added in over time.
• If the product has real strengths, it can afford to just be “good enough” in the other areas.
• Technology changes the way we do things, but the fundamental needs remain unchanged.
• Because the fundamental psychology of human being will remain unchanged, the design rules in this book will still apply.
• Technology changes rapidly, but people and culture change slowly. Change is, therefore, simultaneously rapid and slow. It can take months to go from invention to product, but the decade-sometimes many decade--for the product to get accepted.
• In the world of products, original ideas are the easy part. Actually producing the disease as a successful product is what is hard.
• Tradition and custom coupled with the large number of people already used to an existing scheme makes change difficult or even impossible. This is the legacy problem once again: the heavy momentum of legacy inhibits change.
• Once a standard is in place, the vested interests of existing practice impede change, even where the change would be an improvement.
• There are two major forms of product innovation: one follows a natural , slow evolutionary process; the other is achieved through radical new development.
• In general, people tend to think of innovation as being radical, major changes, where's the most common and powerful form of it is actually small and incremental.
• Being first does not guarantee success.
• Radical innovation changes lives and industries. Incremental innovation make things better. We need both.
• What industries are ready for radical innovation? Try education, transportation, medicine, and housing, all of which are overdue for major transformation.
• Technology changes rapidly, people and culture change slowly.
• Fundamental needs will also stay the same, even if they get satisfied in radically different ways.
• Technology, people, and cultures: all will change.
• Reliance on technology is a benefit to humanity. With technology, the brain gets neither better nor worse. Instead, it is the task that changes. Human plus machine is more powerful than either human or machine alone.
• Our technologies may change, but the fundamental principles of interaction are permanent.