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How do designers improve their products to work around flaws in human logic? If anything is to be learned from behavioral economics, it is that how people should behave is not how they do behave.

In The Design of Everyday Things, Don Norman argues that designers must accept this fact. Norman teaches the top frameworks behind this "human-centered" design system, the three most important areas of design, and why designers must consider additional principles besides logic, such as psychology, cognitive science, and art, to design excellent products that work better across any industry.

Top 20 insights

  1. Two of the most important features of good design are discoverability and understanding. Discoverability: Is it possible to figure out what actions are possible and how to perform them? Understanding: What does it all mean? How is the product supposed to be used? What do all the different controls and settings mean?
  2. Discoverability comprises five fundamental psychological concepts: 1) Affordances (a chair affords support, so in turn it affords the ability to sit); 2) Signifiers (a flat panel on a door signifies one should push); 3) Constraints (imposed limitations on design that can come in four types: physical; cultural; semantic; and logical); 4) Mappings (ordered switches on the wall might specify which switch is for which light); 5) Feedback (the communicating of an action).
  3. "Today, I realize that design presents a fascinating interplay of technology and psychology, that the designers must understand both. Engineers still tend to believe in logic. … 'Why are people having problems?' they wonder. 'You are being too logical,' I say. 'You are designing for people the way you would like them to be, not for the way they really are.'"
  4. The seven stages of action comprise one stage for goals, three stages for execution, and three stages for evaluation: 1) Goal (form the goal); 2) Plan (the action); 3) Specify (an action sequence); 4) Perform (the action sequence); 5) Perceive (the state of the world); 6) Interpret (the perception); 7) Compare (the outcome with the goal). This is a simplified breakdown but offers a useful framework to guide design.
  5. "When people use something, they face two gulfs: the Gulf of Execution, where they try to figure out how it operates, and the Gulf of Evaluation, where they try to figure out what happened. The role of the designer is to help people bridge the two gulfs. … The gulf [of Evaluation] is small when the device provides information about its state in a form that is easy to get, is easy to interpret, and matches the way the person thinks about the system."
  6. Norman recommends 'root cause analysis' to define one's goals and subgoals, with the aim to discover the root cause of an action. If someone reads until it gets dark, their goal becomes to turn a light on. But this is really a subgoal to read; reading is a subgoal for learning; learning is a subgoal for application, and so on. Conduct this kind of root cause analysis and major innovations may follow — in design or elsewhere: constantly ask why — what is the real goal?
  7. A useful framework for root cause analysis is what Norman calls the 'Five Whys'. Originally used by Sakichi Toyoda and the Toyota Motor Company to improve quality (a company renowned for its quality-control), it simply asked 'why' repeatedly. It might not always consist of five questions, but it is framed as such to encourage one to ask the question repeatedly. "Why did it go wrong?" Human error. "Why was there human error?" He was tired. "Why was he tired while operating dangerous machinery?" And so on.
  8. "Harvard Business School marketing professor Theodore Levitt once pointed out, 'People don't want to buy a quarter-inch drill. They want a quarter-inch hole!' Levitt's example of a drill is only partially correct, however. … Once you realise that they don't really want the drill, you realize that perhaps they don't really want the hole, either: they want to install their bookshelves. Why not develop methods that don't require holes? Or perhaps books that don't require bookshelves."
  9. The seven stages of action—a useful framework for designers to use: 1) What do I want to accomplish? 2) What are the alternative action sequences? 3) What action can I do now? 4) How do I do it? 5) What happened? 6) What does it mean? 7) Is this okay? Have I accomplished my goal? "This puts the burden on the designer to ensure that at each stage, the product provides the information required to answer the question."
  10. There are two types of knowledge that people use on a day-to-day basis: knowledge of—referred to by psychologists as declarative knowledge (remember to stop at red traffic lights)—and knowledge how—also known as procedural knowledge (skills to be a musician). One need not recall exactly what a coin looks like to pay for things; knowledge that it is a coin is enough.
  11. Why did millions of Americans confuse the Susan B. Anthony dollar coin with the pre-existing quarter, yet nobody confused the new $20 bill with the identically sized $1 bill? Because all notes in America are the same size, so Americans subconsciously determined that size was not a factor by which to differentiate notes. Coins, on the other hand, are frequently differentiated by size. "Consider this an example of design principles interact with the messy practicalities of the real world," Norman writes. "What appears good in principle can sometimes fail when introduced to the world."
  12. There are two types of memory that have different implications for design. First, short-term or working (STM) memory is important for designers to consider because it is not reliable; it is too flimsy and leaves the mind quickly, especially if there are distractions (a good example of this in poor practice is electronic medical-records systems that automatically log nurses out, which forces them to write vital information down on their hands before it is lost).
  13. The other—long-term memory (LTM)—can create natural mappings for product users; for example, if a motorcyclist forgets how to signal a left turn (whether to push or pull a switch), they might recall that when they turn right, the left handlebar moves forward. Their LTM has given them a frame of reference to remember how to use a product. Designers should consider this principle to guide natural mappings.
  14. Approximations can be important tools for one to use when they design things. For example, an approximation of STM might be: "There are five memory slots in short-term memory. Each time a new item is added it takes up a slot, which knocks out whatever was there beforehand." Is it precisely true? No. But it serves a useful function. Use such approximations to help yourself.
  15. There are four kinds of constraints: physical, which use properties of the physical world to suggest action; cultural, which are based on cultural norms, because "each culture has a set of allowable actions for social situations"; semantic, which rely on the meaning of a given situation to control the set of possible actions; and logical, which use good-old logic, usually through the advantage of logical relationships between "the spatial or functional layout of components and the things that they affect or are affected by."
  16. "When a device as simple as a door has to have a sign to tell you whether to pull, push, or slide, then it is a failure, poorly designed."
  17. "If all else fails, standardize. … If all makers of faucets could agree on a standard set of motions to control amount and temperature … then we could all learn the standards once, and forever afterward use the knowledge for every new faucet we encountered. If you can't put knowledge on the device (that is, knowledge in the world), then develop a cultural constraint: standardize what has to be kept in the head."
  18. Toyota has long been known for its manufacturing excellence. Its method to minimize error is based in part on the philosophy of jidoka—roughly translated to 'automation with a human touch'. At the Toyota Production System, workers are expected to report any error, which often means entire assembly lines must be halted. This is in contrast to many cultures which emphasize efficiency and economic maximization; social pressures often prevent people from the report of errors. At Toyota, when an error is noticed, a special cord called an andon stops the assembly line and alerts the expert crew. Toyota also punishes non-reporting of error. This is an example of how products and systems can be designed to ensure safer, more effective work environments.
  19. The temptation in business is to continually add new features to an already great product. A company will make something that works, but eventually, the market becomes saturated: everybody now owns the product. Competitors release similar products with more features. Hence what Norman calls 'featuritis'. "Good design requires designers to step back from competitive pressure and ensure that the entire product is consistent, coherent, and understandable. This stance requires the leadership of the company to withstand the marketing forces that beg to add this feature or that, each thought to be essential for some market segment."
  20. There are two kinds of innovation, according to Norman: radical and incremental. Each has its utility, and no one is more valuable than the other. Incremental innovation is the slow, steady changes made to the automobile over the course of 100 years. This is more appropriate than radical innovation in some cases. Radical innovation on the other hand is "what many people seek, for it is the big, spectacular form of change," Norman writes. "But most radical ideas fail, and even those that succeed can take decades." Not every change has to be radical.


Ever asked, "How the hell does my thermostat actually work, and why on God's green earth must it be so confusing?" Everyday things are often designed poorly. Designers often go for style over substance — beauty over utility. Companies add needless features to products to increase sales but do nothing for a product's design. Commuters shouldn't have to perform tai chi to operate train station taps.

In The Design of Everyday Things, Donald A. Norman offers a desperately needed perspective on design. The book emphasizes the need for human-centered design and draws on various subjects from psychology to art and offers useful frameworks for designers to make things with the user in mind — warts and all.

The psychopathology of everyday things

Ever approached a door and did not know how to use it? Should you push or pull? Slide or rotate? Wave? So has Donald A. Norman. So much so that such doors are now known as Norman Doors. Don Norman is an engineer by trade and by nature. He sees the world as many engineers do: logically.

Norman has a friend that became stuck between two sets of doors because their hinges were not visible and he could not figure out how to pass through. The building's entrance "probably won a design prize," Norman writes sarcastically. But because it causes confusion, it is designed poorly.

For simple designs, like those for a door or kettle, manual instructions to "push" or "pull" should not be necessary. Good design should indicate action by itself. Make a pillar visible so that it's clear which side of a door is attached to a hinge. When simple things are overly complex, Norman writes, "the whole purpose of the design is lost."

The three key areas of design

Norman focuses on three areas that fall under the category of design:

  1. Industrial design: Industrial designers tend to focus on form and material. Industrial design is the professional service to create and develop concepts and specifications that optimize the function, value, and appearance of products and systems for the mutual benefit of the user and manufacturer.
  2. Interaction design: Interaction designers focus on understandability and usability. The design is based on how people interact with technology. The goal is to enhance people's understanding of what can be done, what is happening, and what has occurred. It draws on principles of psychology, design, art, and emotion to ensure a positive user experience.
  3. Experience design: Experience designers emphasize the emotional impact of a given design. Under this method, the quality and enjoyment of the total experience are considered across products, processes, services, events, and environments.

The five principles of good design

Discoverability is a crucial stage of user experience and comprises five fundamental psychological concepts:

1. Affordances

The relationship between an object's properties and the capabilities of the agent that interacts with it—ergo, a chair affords support, so in turn, it affords the ability to sit on it. An affordance only exists if the agent can interact appropriately; for example, if a child is not strong enough to lift a stool, the stool does not afford lifting. Affordance is relative. To be effective, affordances and anti-affordances have to be discoverable.

2. Signifiers

Signifiers are the components that signal affordance. A flat panel on a door signifies the need to push it open. Affordances determine what actions are possible. Signifiers communicate where the action should take place. "When external signifiers—signs—have to be added to something as simple as a door, it indicates bad design."

3. Constraints

There are four kinds of constraints. Physical, which use properties of the physical world to suggest action; cultural, which are based on cultural norms, because "each culture has a set of allowable actions for social situations"; semantic, which rely on the meaning of a given situation to control the set of possible actions; and logical, which use good-old logic to take advantage of the logical relationships between "the spatial or functional layout of components and the things that they affect or are affected by."

4. Mapping

Mappings indicate the relationship between two sets of things. For example, if there are rows of spotlights in a ceiling, a series of switches on the wall might specify which switch is for which light, depending on their order. This would constitute mapping: the switches are mapped according to the lights. Another example might be a car steering wheel: when it turns right, the top of the steering wheel moves right along with the car itself. The car uses spatial correspondence to make use of the car simple and obvious.

5. Feedback

Feedback in design is crucial and should be immediate. It is the communication of an action. If a cyclist is at a red traffic light that stays red for longer than expected, perhaps it has not registered the cyclist's presence, because their vehicle is smaller than a car. The system lacks feedback.

6. Conceptual models

There is a sixth principle of good design: the conceptual model of the system. Simply, this is an explanation of how something works. Files and folders in one's computer are not files or folders; they are conceptual models of those objects because humans are used to how these objects perform a similar function in real life. This is a useful conceptual model.

"We bridge the Gulf of Execution [where a user tries to figure out how a thing operates] with signifiers, constraints, mappings, and a conceptual model. We bridge the Gulf of Evaluation [where a user tries to figure out what happened] through the use of feedback and a conceptual model."

When something goes wrong, like when information stored on the cloud goes missing, the conceptual model must offer a solution or it is limited in its quality. Files might appear accessible to users but be untouchable. "Simplified models are valuable only as long as the assumptions that support them hold true."

The psychology of everyday actions

"Emotion is highly underrated," Norman writes. "In fact, the emotional system is a powerful information processing system that works in tandem with cognition. Cognition attempts to make sense of the world: emotion assigns value. It is the emotional system that determines whether a situation is safe or threatening, whether something that happens is good or bad, desirable or not. Cognition provides understanding: emotion provides value judgments." Perhaps more reason for engineers to soften their hard-logic-based approach: people are emotional creatures and must be accepted as such.

Relatedly, Norman suggests designers consider three levels of processing: 1. visceral, or automatic responses, behavioral, or well-learned actions triggered by situations, and reflective, or conscious opinion in hindsight. Design must take place at all levels. Bad designs can induce frustration and anger; good designs can induce pride, enjoyment, and calm.

Find meaning in failure

Norman recommends designers change their perception of failure—that they incorporate more positive psychology into their work. When one designs something new, they should do not worry about failure. What's more:

  1. Do not blame others for their inability to use your design.
  2. Take people's difficulties as signifiers of where the product can be improved.
  3. Eliminate all error messages from electronic or computer systems; instead, provide help and guidance.
  4. Make it possible to correct problems directly from help and guidance messages; don't impede users' tasks, and don't make them start over.
  5. Assume what someone has done is partially correct; provide guidance that allows them to correct the problem and move on.
  6. Think positively for yourself and the people you interact with.

Knowledge in the head and in the world

"A friend kindly let me borrow his car, an older, classic Saab. Just before I was about to leave, I found a note waiting for me: 'I should have mentioned that to get the key out of the ignition, the car needs to be in reverse.' The car needs to be in reverse! If I hadn't seen the note, I never could have figured that out. There was no visible cue in the car: the knowledge needed for this trick had to reside in the head. If the driver lacks that knowledge, the key stays in the ignition forever." Norman uses this as a warning: designers must make it obvious what must be done to use the things they design.

There are two types of knowledge that people use on a day-to-day basis: knowledge of—referred to by psychologists as declarative knowledge (remember to stop at red traffic lights)—and knowledge how—also known as procedural knowledge (knowledge of how to play a musical instrument). One need not recall exactly what a coin looks like to pay for things; knowledge that it is a coin is enough.

Use the world to remember stuff

How does a pilot remember so much? They are given myriad complex instructions before they take flight. The answer is that they don't. They do not leave the unreliable short-term or working memory responsible for such important decisions. There is too much to remember to do. Therefore, pilots take advantage of their plane's equipment to 'remember' important information. This is the design implication: for the risk of failure to be mitigated, designers must consider the limitations of human memory.

'Prospective memory' denotes the task to remember to do something in the future. For this, one needs a reminder of it. A reminder is made up of two main components: a signal and a message. A signal lets one know something needs to be remembered; a message informs one what the thing to be remembered actually is.

Activity-centered design

Given that spatial mapping of switches (such as light switches) is not always appropriate, activity-centered controls are sometimes a nice solution. For example, many auditoriums have activity-based switches; a switch might be labeled 'lecture', which when pressed activates the correct balance of light (nearer the back of the hall) and darkness (near a projector or screen, so it's easier for the audience to see the presentation).

Sound in design

Norman writes of the importance of sound used in design to offer positive or negative feedback. Think of the tinny sound heard when a car door fails to close properly. Then, compare that to the satisfying catch sound when it closes correctly.

For blind people, the lack of sound that comes from new electric vehicles is a problem. The ability to listen out for a car's revs is often how blind people know whether it is safe to cross a road. Because of this, sounds are now added to electric vehicles to make them safer.

Skeuomorphic design can help

Skeuomorphic is the name given to something new to resemble something old, like early plastics that resembled wood. Skeuomorphic designs can be useful conceptual models that aid learning; recall the example of 'folders' and 'files' in your computer's hard drive. This makes it easy for users to know what's happened.

Human error? No, bad design

If a person fails to understand their home thermostat, who is at fault, the technology, or the person? Norman believes it is often the technology.

Technologies that people must use each day should not be as complex as they often are. Rather than blame ourselves, we ought to expect more of our everyday things.

Most industrial accidents—between 75% and 95%—are caused by human error. Norman thus poses the question: How is it that people are so incompetent? His answer: they aren't. It is a design problem.

"We design equipment that requires people to be fully alert and attentive for hours or to remember archaic procedures even if they are only used infrequently, sometimes only once in a lifetime. We put people in boring environments with nothing to do for hours on end, until suddenly they must respond quickly and accurately. Or we subject them to complex, high-workload environments, where they are continually interrupted while having to do multiple tasks simultaneously. Then we wonder why there is a failure."

Understanding why there is an error

Errors occur for many reasons: people are asked to be alert for hours on end, they must multitask, they must operate machinery that makes it difficult to resume operation after distraction (despite the very human inclination to be distracted by things), and so on. But for Norman, perhaps worst of all is people's attitudes towards error.

"If the system lets you make an error, it is badly designed. And if the system induces you to make the error, then it is really badly designed. When I turn on the wrong stove burner, it is not due to my lack of knowledge: it is due to poor mapping between controls and burners. Teaching me the relationship will not stop the error from recurring: redesigning the stove will."

Two types of errors: slips and mistakes

There are two types of errors: slips and mistakes. A slip occurs when someone intends to do one action but does something else. There are two kinds of slips: action-based, like when someone pours milk into coffee and then puts the coffee cup back in the refrigerator; and memory-lapse, like when someone forgets to turn the gas off after cooking.

A mistake occurs when the wrong goal is established in the first place. There are three kinds of mistakes: rule-based, like when the right diagnosis is made but the wrong course of action is planned; knowledge-based, like when a problem is misdiagnosed because of erroneous or incomplete knowledge; and memory-lapse, when stages of goals, plans, or evaluation are forgotten.

The swiss-cheese model of how errors lead to accidents

British researcher James Reason first likened error to Swiss cheese. He argued that when systems go badly wrong, like when a nuclear power plant explodes, multiple things must go wrong and thus align in a grim cocktail of error. Think of holes in different pieces of Swiss cheese that line up so that a single straight line could pass through each of them. Norman says this is why most analyses of error are doomed to fail: stakeholders usually stop their investigation when they find one thing that went wrong. However, the answer is to be found further ahead, as catastrophes are usually caused by multiple things that go wrong rather than only one.

Design thinking

Design thinking asks designers to solve a problem only if they are certain it is the right problem to solve. One should scrutinize an issue to the high heavens before they attempt to solve it. This is how design thinking works.

"Design thinking has become the hallmark of the modern design firm," Norman writes. There are two key types of design thinking: the double-diamond diverge-converge model of design and human-centered design. There are two stages of this model: problem and solution, which are, for simplicity's sake, the two phases of design. Each stage involves divergence and convergence.

To use the 'problem' stage as an example, one must first diverge the approach and consider various possibilities to determine what the real problem is. Then, they must converge when they feel the right problem has been identified. Divergence is to consider possibilities; convergence is to decide the next course of action. This divergence/convergence occurs at both the problem and solution phases.

Human-centered design

Human-centered design actually takes place within the double-diamond model. Human-centered design refers to how exactly problems and solutions are discovered. It is, according to Norman: "The process of ensuring that people's needs are met, that the resulting product is understandable and usable, that it accomplishes the desired tasks, and that the experience of use is positive and enjoyable." There are four different activities of the human-centered design process.

  1. Observation — this form of design research involves simply observations of people as they use products and behave as they normally would. The goal is to understand the nature of a problem
  2. Idea generation — creativity is critical at this stage. Norman recommends to generate a lot of ideas, create without regard for constraints, and question everything
  3. Prototype — the only way to really know if an idea is reasonable is to test it. Build a quick prototype or mock-up of each potential solution
  4. Test — gather a person or group of people as closely resemblant to the target demographic as possible to test the thing you have designed. Norman recommends to study five people individually; then, when those tests have been analyzed, study five more people individually, and so on

Activity-centered design

When one develops products that are to be used by people all over the world, like refrigerators, cameras and computers, activity-centered design is an accent method to human-centered design. Here, it is important to "let the conceptual model of the product be built around the conceptual model of the activity."

For example, the core components of cars are pretty much identical in every country. So, when the goal is to design more effective and efficient cars, designers should consider the principles of how to drive. A heads-up displays mean that critical instrument and navigation information are displayed in the space in front of the driver so they don't have to take their eyes off the road to see it; automatic functionality mean that there is no need for the clutch pedal; and so on.


We often take standardized technology for granted. Clocks are standardized, but if you change the image of a clock from the one most people know, it becomes much more difficult to read. Even if the new clock is more logical, the further it deviates from the standardized version, the more difficult it is for humans to read.

Sometimes the goal is to deliberately make things difficult

But not everything should be made easy to use. If something ought to be inaccessible or difficult, it should be designed that way. Think of a high-security safe. If the safe is difficult to operate but was designed that way, under the principles of good design it is designed well. It all depends on the object's purpose.