The Design of Everyday Things March 7, 2011Posted by Darren Kwong in Uncategorized.
The Design of Everyday Things by Don Norman
Review by Darren Kwong, MS – Mechanical Engineering 2011
In the book originally titled The Psychology of Everyday Things, Don Norman discusses user-centered design principles through a set of examples that demonstrate good and bad design in terms of usability. After reading the book, one should see the world with a new mindset where fault is attributed to design, not the user: “If I am having trouble using something, it’s not my fault–it is probably poorly designed.” There are numerous examples of things that may be aesthetically pleasing or full of features, but problematic to use (like a door that should be pushed but looks like it could be pulled). For a designer, this has strong implications on the factors to consider when designing something. Let’s delve into some of the ideas presented in this book.
Affordances describe what actions are possible or perceived to be possible with an object. For example, the handle on the door above affords a pulling motion. Another example used in the book is a pair of scissors. It has holes for fingers to be placed in, and blades for cutting. This ties into the principle of visibility. What can be done with an object should be visible to the user, and what shouldn’t be doable should be hidden. I definitely agree with these principles, and have experienced issues relating to them myself. Consider, for example, the new MacBook trackpad:
With its slightly recessed appearance, it does not afford clicking. The trackpad itself looks like a large surface for manipulating the cursor, and I would not have known that it is a depressible button.
In addition to knowing what actions are possible, it is important to get feedback on the state of a system. Being able to see or hear the effects of your actions allows you to confirm what you have done. One example that comes to mind is the lack of feedback from push buttons for crosswalks. Without indication of the button-press being registered, people tend to keep pressing them over and over. In other systems, feedback can be used to prevent errors. My friend wrote a timer program that displayed a set of instructions and allowed the user to time the task. The timer needed to be in focus to function properly, but it was easy to forget to bring it back into focus when switching between programs. On several occasions, a user would think that he started the timer and find out too late that it was out of focus.
The idea is simple: constrain the user’s set of possible actions such that the chance of error is removed or minimized. For the timer program example, I proposed to mask the instructions when the timer was out of focus. This constrains the user from reading the instructions when the timer is out of focus. The timer must be brought back into focus to get the instructions. Masking the instructions also provides feedback on the state of the system.
A conceptual model or mental model is a model of how something works, and it often affects the way a user interacts with an object. Norman discusses the bridge between the design model of a system and the user’s model of it. A person who thinks that pressing a crosswalk button more times will make the light change faster has a flawed mental model. Perhaps a better feedback mechanism should be used to indicate the effect of pressing the button, which would show that additional presses have no effect.
Things are easier to use when there is a natural mapping between form and function. Norman presents a good example of natural mapping in a Mercedes Benz power seat control. The controls are arranged like a car seat, and adjusting it results in the same change in the actual seat.
When I initially read through these principles, I was hesitant to accept the principles as ones to be followed to the letter. They were good principles to have in mind, but not to be constrained by. My idea of user-centered design was to design for the intended user. For example, a DSLR camera might be daunting to someone who has never used one before, but the feature set is desirable, and a learning curve is to be expected. Norman presented a similar example where he thought a bus driver would have trouble learning a large array of bus controls, but the bus driver said that everything was where it should be and it was no problem at all. What may seem unusable by one group of persons might be perfect for another. Though these issues were not immediately addressed, the last chapter of the book discussed them and even mentioned that the principles could be reversed if it would meet the desired effect.
Usability is a very important aspect of design that makes the difference between a happy user and a frustrated one. This is a great book to open the eyes of designers and place attention to the flaws of things we use every day. Everyone can relate to at least one of the examples presented in the book. The issues and principles provided are hard to deny. What are some experiences you’ve had?