"The power of observation: If I have been successful, this book will change the way you see the world. You will never look at a door or light switch the same way again. You will become an acute observer of people, of objects, and of the way they interact. In fact, if there is one single most important part of the book it is this: learn to watch, learn to observe. Observe yourself. Observe others. As the famous baseball player Yogi Berra said, "You can observe a lot by watching." Problem is, you have to know how to watch.
Before you picked up this book, had you seen a hapless user, whether an unknown person or even yourself, you would have been apt to blame the person. Now you will find yourself critiquing the design. Better yet, you will find yourself explaining how to fix the problem."
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The Design of Everyday Things, 2002 edition, by Donald A. Norman, Preface to the 2002 Edition, page xii