Quotes from Donald A. Norman

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.

The presence of an affordance is jointly determined by the qualities of the object and the abilities of the agent that is interacting. This relational definition of affordance gives considerable difficulty to many people. We are used to thinking that properties are associated with objects. But affordance is not a property. An affordance is a relationship. Whether an affordance exists depends upon the properties of both the object and the agent.

There seems to be a conspiracy, one calculated to destroy our sanity by overloading our memory. Many codes, such as postal codes and telephone numbers, exist primarily to make life easier for machines and their designers without any consideration of the burden placed upon people. Fortunately

Whenever you see hand-lettered signs pasted on doors, switches, or products, trying to explain how to work them, what to do and what not to do, you are also looking at poor design.

Make something too secure, and it becomes less secure.

Cognition and emotion are tightly intertwined, which means that the designers must design with both in mind.

Design research supports both diamonds of the design process. The first diamond, finding the right problem, requires a deep understanding of the true needs of people. Once the problem has been defined, finding an appropriate solution again requires deep understanding of the intended population, how those people perform their activities, their capabilities and prior experience, and what cultural issues might be impacted.

When I used to work for the local government organisation we HAD TO change our Passwords every three months. To ensure I could remember it, I used to write it on a Post-It note and stick it above my desk.

A brain in a negative emotional state provides focus: precisely what is needed to maintain attention on a task and finish it.

It seems natural for people to blame their own misfortunes on the environment. It seems equally natural to blame other people's misfortunes on their personalities. Just the opposite attribution, by the way, is made when things go well. When things go right, people credit their own abilities and intelligence. The onlookers do the reverse. When they see things go well for someone else, they sometimes credit the environment, or luck.

Violation of cultural conventions can completely disrupt an interaction.

Most industrial accidents are caused by human error: estimates range between 75 and 95 percent. How is it that so many people are so incompetent? Answer: They aren't. It's a design problem.

When things work, we are informed, comfortable, and effective. When things break, we may no longer be able to function. This dependence upon technology is very old, but every decade, the impact covers more and more activities.

First, most accidents do not have a single cause: there are usually multiple things that went wrong, multiple events that, had any one of them not occurred, would have prevented the accident.

With open-source software, inexpensive open-source 3-D printers, and even open-source education, we can transform the world.

Apple treated iPod as a service, not as an isolated product. They therefore worked diligently to ensure that all stages were handled seamlessly, resulting in an excellent customer experience.

La stessa tecnologia che semplifica la vita offrendo più funzioni in ciascun apparecchio la complica anche rendendo il dispositivo più difficile da imparare e da usare. Questo è il paradosso della tecnologia.

Three Levels of Processing: Visceral, Behavioral, and Reflective. Visceral and behavioral levels are subconscious and the home of basic emotions. The reflective level is where conscious thought and decision-making reside, as well as the highest level of emotions.

You are designing for people the way you would like them to be, not for the way they really are." When

Web sites count as services, and so the very same lessons apply. Some Web sites recognize repeat visitors, making useful suggestions, but in a nonintrusive way.

When a device as simple as a door has to come with an instruction manual—even a one-word manual—then it is a failure, poorly designed.