Key takeaways from ‘The design of everyday things’ by Don Norman

Sujin Park
6 min readSep 21, 2022


This book has been on my to-read list for a long time, and I finally decided to read this highly acclaimed book in the design community by Don Norman (frankly, it was a bit overwhelming to start given the small font and 368 pages, but once I started reading, it was a breeze). I’m not a designer but this book offered countless nuggets of wisdom that are directly applicable to do my job well as Product Manager. The book touches on critical tenets of good design (vs. bad) that warrants anyone to take away meaningful lessons regardless of their roles. I wanted to share several excerpts from the book that rung bell with me; I know I will come back to theses many times in my career when I need a little reminder of what constitutes great design.

We need to remove the word failure in our vocabulary, replacing it instead with learning experience. To fail is to learn: we learn more from our failures than from our successes. With success, sure, we are pleased, but we often have no idea why we succeeded. With failure, it is often possible to figure out why, to ensure that it will never happen again.

When something doesn’t work, it can be considered an interesting challenge, or perhaps just a positive learning experience.

[Design philosophy that every design of products / services must follow]

● Do not blame people when they fail to use your products properly.

● 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.

● Make it possible to correct problems directly from help and guidance messages. Allow people to continue with their task: Don’t impede progress — help make it smooth and continuous. Never make people start over.

● Assume that what people have done is partially correct, so if it is inappropriate, provide the guidance that allows them to correct the problem and be on their way.

● Think positively, for yourself and for the people you interact with.

Designs should strive to minimize the chance of inappropriate actions in the first place by using affordances, signifiers*, good mapping, and constraints to guide the actions.

*Signifiers: perceivable cues about the affordances — the actions that are possible for a person to take — with a designed object.

[Seven fundamental principles of design]

1. Discoverability: It is possible to determine what actions are possible and the current state of the device.

2. Feedback: There is full and continuous information about the results of actions and the current state of the products or service. After an action has been executed, it is easy to determine the new state.

3. Conceptual model: The design projects all the information needed to create a good conceptual model of the system, leading to understanding and a feeling of control. The conceptual model enhances both discoverability and evaluation of results.

4. Affordances: The proper affordances exist to make the desired actions possible.

5. Signifiers: Effective use of signifiers ensures discoverability and that the feedback is well communicated and intelligible.

6. Mappings: The relationship between controls and their actions follows the principles of good mapping, enhanced as much as possible through spatial layout and temporal contiguity.

7. Constraints: Providing physical, logical, semantic, and cultural constraints guide actions and eases interpretation.

Never criticize unless you have a better alternative.

[The five whys]

Root cause analysis is intended to determine the underlying cause of an incident, not the proximate cause. The Japanese have long followed a procedure for getting at root causes that they call the ‘Five Whys,’ originally developed by Sakichi Toyoda and used by the Toyota Motor Company as part of the Toyota Production System for improving quality. It means that when searching for the reason, even after you have found one, do not stop: ask why that was the case. And then ask why again. Keep asking until you have uncovered the true underlying causes. Does it take exactly five? No, but calling the procedure ‘Five Whys’ emphasize the need to keep going even after reason has been found.


If every decision had to be questioned, nothing would ever get done. But if decisions are not questioned, there will be major mistakes — rarely, but often of substantial penalty.


Rather than stigmatize those who admit to error, we should thank those who do so and encourage the reporting. We need to make it easier to report errors, for the goal is not to punish, but to determine how it occurred and change things so that it will not happen again… 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.

Designing for errors

· Understand the causes of error and design to minimize those causes.

· Do sensibility checks. Does the action pass the ‘common sense’ test?

· Make it possible to reverse actions — to ‘undo’ them — or make it harder to do what cannot be reversed.

· Make it easier for people to discover the errors that do occur and make them easier to correct it.

· Don’t treat the action as an error; rather, try to help the person complete the action properly. Think of the action as an approximation to what is desired.


The swiss cheese model for COVID-19

Reason’s Swiss cheese model of accidents: Unless the holes all line up perfectly, there will be no accident. This metaphor provides two lessons: First, do not try to find ‘the’ cause of an accident. Second, we can decrease accidents and make system more resilient by designing them to have extra precautions against error (more slices of cheese), less opportunities for slips, mistakes, or equipment failures (less holes), and very different mechanisms in the different subparts of the system (trying to ensure that the holes do not line up).

In a nutshell, the Swiss cheese metaphor suggests to…

· Add more slices of cheese.

· Reduce the number of holes (or make the existing holes smaller).

· Alert the human operators when several holes have lined up.

[Idea generation; brainstorming]

· Generate numerous ideas: It is dangerous to become fixated upon one or two ideas too early in the process.

· Be creative without regard for constraints: Avoid criticizing ideas whether your own or those of others. Even crazy ideas, often obviously wrong, can contain creative insights that can later be extracted and put to good use in the final idea selection. Avoid premature dismissal of ideas.

· Question everything: I am particularly fond of ‘stupid’ questions. A stupid question asks about things so fundamental that everyone assumes the answer is obvious. But when question is taken seriously, it often turns out to be profound: the obvious often is not obvious at all. What we assume to be obvious is simply the way things have always been done, but now that it is questioned, we don’t actually know the reasons. Quite often the solution to problems is discovered through stupid questions, through questioning the obvious.

[Featuritis: a deadly temptation]

Featuritis is highly infections. New products are invariably more complex, more powerful, and different in size than the first release of a product.

In her book Different, Harvard professor Youngme Moon argues that it is the attempt to match the competition that causes all products to be the same. When companies try to increase sales by matching every feature of their competitors, they end up hurting themselves. After all, when products from two companies match feature by feature, there is no longer any reason for a customer to prefer one over another.

The lesson is simple: don’t follow blindly; focus on strengths, not weaknesses. If the product has real strengths, it can afford to just be ‘good enough’ in the other areas.



Sujin Park

My long-term vision is to make a positive impact on society, and sharing my learnings via blogs is one of the endeavors to make my vision a reality.

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