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The Design of Everyday Things Book Summary – Donald Norman

What you will learn from reading The Design of Everyday Things Summary:

– How we think through every decision we make in life.

– The two most important aspects of good design.

– How to design for error. 

The Design of Everyday Things Book Summary:

 The complete guide to human centered design. The design of everyday things  distills the principles of good design from legendary designer Donald Norman. The book makes it easy to understand the difference between good and bad design and what to do about it. Read on if you want to appreciate how the world of design impacts your life everyday.


Two most important aspects of design are discoverability and understanding:

Discoverability – Is it possible to even figure out what actions are possible and where and how to perform there? 

Understanding – How is it supposed to be used? What does it mean?  


Different types of design: 

Industrial design – preference for form and material 

Interactive design (software) – understandability and usability 

Experience design – emotional impact (restaurant) 

Human centred design – Putting human needs, capabilities and behaviours first.  

Primary research through observation as people are generally unaware of their needs. Avoid specifying the problem but iterate approximations till you can after a time. Saves false confidence. 


Discoverability has 5 psychological concepts:

Affordances –are the possible interactions between people and the environment. Some affordances are perceivable, others are not. They are relationships not properties. Perceived affordances often act as signifiers but they can be ambiguous. 

Key distinction – Affordances determine what actions are possible. Signifiers communicate where the action should take place.  

Signifiers – signal things, in particular what actions are possible and how they should be done. Signifiers must be perceivable else they fail to function. Remember – People are scanning for clues, as a designer you need to provide these clues. 

Constraints – providing physical, logical, semantic and cultural constraints guides actions and eases interpretation. 

Mappings – Mapping controls to function, principle of pressing up goes up etc.. 

Feedback – communication of the results of an action (the more immediate the better). Poor feedback can be worse then no feedback as it is uninformative, distracting and anxiety provoking.  

Feedback should also be prioritised. Also important signals of results should be attention capturing.  

And the overall conceptual model which ties it all together (true understanding) – mental models of understanding how a product works. A good conceptual model is valuable in providing understanding and predicting how things will behave. 

Without a good model we operate by rote, blindly and don’t appreciate why or what effects to expect. When a novel situation happens we can gain a deeper understanding of what is going on.  


The psychology of everyday actions

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 see below: 

The role of the designer is to help people bridge the two gulfs. We bridge the Gulf of Execution through the use of signifiers, constraints, mappings, and a conceptual model. We bridge the Gulf of Evaluation through the use of feedback and a conceptual model. 




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) 




We can do many actions, repeatedly cycling through the stages while being blissfully unaware that we are doing so. It is only when we come across something new or reach some impasse, some problem that disrupts the normal flow of activity, that conscious attention is required.


Design must take place at all levels:

Understanding of conceptual model allows a positive feeling (accomplishment) thus facilitation of creating a accurate conceptual model is key. This itself explains why people don’t like change it shows loss of control. (Think order and chaos, chaos causes anxiety and this is why people oppose change, it challenges their deep seated mental models.) 



Semantics is the study of meaning. Semantic constraints are those that rely upon the meaning of the situation to control the set of possible actions.

Semantic constraints rely upon our knowledge of the situation and of the world. Such knowledge can be a powerful and important clue. But just as cultural constraints can change with time, so, too, can semantic ones.

Cultural constraints – If you can’t put the knowledge on the device (that is, knowledge in the world), then develop a cultural constraint: standardise what has to be kept in the head. 

Legacy Constraints – (the legacy problem) Too many devices use the existing standard-that is the legacy. If the symmetrical cylindrical battery were changed, there would also have to be a major change in a huge number of products. The new batteries would not work in older equipment, nor the old batteries in new equipment.

People invariably object and complain whenever a new approach is introduced into an existing array of products and systems. Conventions are violated: new learning is required. The merits of the new system are irrelevant: it is the change that is upsetting. The destination control elevator is only one of many such examples. The metric system provides a powerful example of the difficulties in changing people’s conventions.


Designing for error:

In mistakes a person makes a poor decision, misclassifies a situation or fails to take all relevant factors into account. Many mistakes arise from the vagaries of human thought often because people tend to rely upon remembered experiences rather than on more systematic analysis. 

In rule-based and knowledge based situations the most serious mistakes occur when the situation is misdiagnosed. 

With mis-diagnosis of the problem comes misinterpretation of the environment as well as the faulty comparisons of the current state with expectations. These mistakes can be difficult to correct especially if you continue to search for solutions to the wrong problem. 


Steps for reducing error:

Understand the causes of error and design to minimise these causes 

Do sensibility checks (does this make sense) 

Make it possible to reverse actions (undo) or make it hard to do what cannot be reversed

Make it easy for people to discover the error and make them easier to correct

Don’t treat the action as an error, help the person complete the action properly. 

Confirmation or error messages 

Swiss cheese metaphor of error. 

-Reduce number of holes (make holes smaller) 

-Alert operator when several holes line-up 

-Add more slices of cheese 

Remember – There is never a single cause, therefore, investigations should be long.  

We need to think about all the interacting factors that lead to human error and then to accidents, then devise ways to make the systems as a whole more reliable. 

Sometimes people really are at fault with drugs, fatigue etc… 

Resilience engineering is a paradigm for safety management that focuses on how to help people cope with complexity under pressure to achieve success. A resilient organisation treats safety as a core value not a commodity that can be counted. One measure of resilience is therefore the ability to create a foresight, before failure or harm occurs. 

Paradox of automation is that over reliance will lead to cataclysmic failure, failure would be systematic and larger. 


Competition, design and innovation:

Competition copying of features leads to little differentiation. Better strategy for companies is to concentrate on areas where they are stronger and strengthen them even more. If product has real strengths it can afford to be just good enough in other areas. 

Technology changes the way we do things however fundamental needs remain unchanged. (What is the job to be done?) 

Think of things that don’t change such as social interaction, communication, sports, music, entertainment and education etc… these needs will remain the same even if they get satisfied in radically different ways. 

Note that a superior solution would be to solve the fundamental need-solving the root need. After all, we don’t really care about keys and locks: what we need is some way of ensuring that only authorized people can get access to whatever is being locked. Instead of redoing the shapes of physical keys, make them irrelevant. Once this is recognized, a whole set of solutions present themselves: combination locks that do not require keys, or keyless locks that can be operated only by authorized people.

Most innovation is done as an incremental enhancement of existing products. What about radical ideas, ones that introduce new product categories to the marketplace? These come about by reconsidering the goals, and always asking what the real goal is: what is called the root cause analysis. 

It doesn’t matter how many people buy a product if they are going to dislike it when they start using it.