My rating: 4 of 5 stars
An excellent book about how to design usable products. It’s philosophical but backed by plenty of examples (text and images) of good and bad design, including buildings, appliances, and technology. It’s interesting and well-written. I read the 1988 edition, so most of the tech references are dated, but the design principles still apply.
OptimWise designs websites for small businesses, so I found this very practical. I liked Norman’s emphasis on simplicity, intuitiveness, and designing for error.
I was amused by the Norman’s predictions of future tech. He mentions the portable computer, digital calendar, and “central computer system” (Internet), among others. As a web designer, I smiled when I read that, “the next step in writing technology is already visible on the horizon: hypertext.”
This book was recommended to me about 5 years ago, and I’ve heard about it several times since. I finally decided to read it because it was listed in A Comprehensive Reading List for and by Designers.
Here’s a summary straight from the book:
- Make it easy to determine what actions are possible at any moment (make use of constraints).
- Make things visible, including the conceptual model of the system, the alternative actions, and the results of actions.
- Make it easy to evaluate the current state of the system.
- Follow natural mappings between intentions and the required actions; between actions and the resulting effect; and between the information that is visible and the interpretation of the system state.
In other words, make sure that (1) the user can figure out what to do, and (2) the user can tell what is going on.
Seven Principles for Transforming Difficult Tasks into Simple Ones
- Use both knowledge in the world and knowledge in the head.
- Simplify the structure of tasks.
- Make things visible: bridge the gulfs of Execution and Evaluation.
- Get the mappings right.
- Exploit the power of constraints, both natural and artificial.
- Design for error.
- When all else fails, standardize.
Here are my notes on the rest of the book. Quotes are straight from the book.
“Bad design cannot be patched up with labels, instructions manuals, or training courses.”
“But appearances are only part of the story: usability and understandability are more important, for if a product can’t be used easily and safely, how valuable is its attractiveness?”
The Psychopathology of Everyday Things
Things can have “vestigial” features: features that hang on for generations because customers don’t complain about them, even though they’re not beneficial. Since designers can justify the presence of almost any feature, the vestigial features persist and complicate interfaces.
“The paradox of technology: added functionality generally comes along at the price of added complexity.”
“Whenever the number of functions and required operations exceeds the number of controls, the design becomes arbitrary, unnatural, and complicated.”
The Psychology of Everyday Actions
“If an error is possible, someone will make it. The designer must assume that all possible errors will occur and design so as to minimize the chance of the error in the first place, or its effects once it gets made. Errors should be easy to detect, they should have minimal consequences, and, if possible, their effects should be reversible.”
Knowledge in the Head and in the World
“Usability is not often thought of as a criterion during the purchasing process. Moreover, unless you actually test a number of units in a realistic environment doing typical tasks, you are not likely to notice the ease or difficulty of use. If you just look at something, it appears straightforward enough, and the array of wonderful features seems to be a virtue. You may not realize that you won’t be able to figure out how to use those features. I urge you to test products before you buy them.”
To Err Is Human
Prompts that ask the user to confirm that they want to delete something are ill-timed, because the user just “initiated the action and is still fully content with the choice.” They are unlikely to catch an error, because they’re confirming the action, not the filename. “It would be more appropriate to eliminate irreversible actions … Then the user would have time for reconsideration and recovery.”
“When you build an error-tolerant mechanism, people come to rely upon it, so it had better be reliable.”
What the designer should do:
- Understand the causes of error and design to minimize those causes.
- Make it possible to reverse actions – to undo them – or make it harder to do what cannot be reversed.
- Make it easier to discover the errors that do occur, and make them easier to correct.
- Change the attitude toward errors. Think of an object’s user as attempting to do a task, getting there by imperfect approximations. Don’t think of the user as making errors; think of the actions as approximations of what is desired.
The Design Challenge
“If you don’t know any keyboard, there is little difference in typing speed among a qwerty keyboard, an alphabetic keyboard, and even a random arrangement of keys. If you know even a little of the qwerty, that is enough to make it better than the others.”
“The Dvorak keyboard … is easier to learn and allows for about 10 percent faster typing.”
“Once a satisfactory product has been achieved, further change may be counterproductive, especially if the product is successful. You have to know when to stop.”
“If everyday design were ruled by aesthetics, life might be more pleasing to the eye but less comfortable; if ruled by usability, it might be more comfortable but uglier. If cost or ease of manufacture dominated, products might not be attractive, functional, or durable. Clearly, each consideration has its place. Trouble occurs when one dominates all the others.”
“But with extra features comes extra complexity. Each new feature adds yet another control, or display, or button, or instruction. Complexity probably increases as the square of the features.”
One way to treat “featurism” is modularization: “create separate functional modules, each with a limited set of controls, each specialized for some different aspect of the task.”
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