The Design of Everyday Things
by Donald A. Norman

Paperback (reprint), 288pp
Publisher: Basic Books
Pub. Date: August 2002
ISBN-13: 9780465067107

B&N online price: $15.25
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FROM THE PUBLISHER

First business discovered quality as a key competitive edge; next came service. Now, Donald A. Norman reveals how smart design is the new competitive frontier. The Design of Everyday Things is a powerful primer on how and why some products satisfy customers while others only frustrate them.

SYNOPSIS

The Psychology of Everyday Action

There are seven stages of action -- one for goals, three for execution, and three for evaluation.

* Forming the goal
* Forming the intention
* Specifying an action
* Executing the action
* Perceiving the state of the world
* Interpreting the state of the world
* Evaluating the outcome

These relate to the following principles of good design:

* Visibility: By looking, the user can tell the state of the device and the alternatives for action.
* A good conceptual model: The designer provides a good conceptual model for the user, with consistency in the presentation of operations and results and a coherent, consistent system image.
* Good mappings: It is possible to determine the relationships between actions and results, between the controls and their effects, and between the system state and what is visible.
* Feedback: The user receives full and continuous feedback about the results of actions

Knowledge in the Head and in the World

Not all knowledge required for precise behavior has to be in the head. It can be distributed--partly in the head, partly in the world, and partly in the constraints of the world. Precise behavior can emerge from imprecise knowledge for four reasons.

* Information is in the world.
* Great precision is not required
* Natural constraints are present
* Cultural constraints are present

When knowledge is maintained in the head, it can be enhanced in two ways: through providing meaningful relationships (that is, when the rules make sense in the context of other things we know), or through explanation (when we understand the underlying model).

The Trade-off Between Knowledge in the World and in the Head

Retrievability

* Knowledge in the world: Retrievable whenever visible or audible
* Knowledge in the head: Not readily retrievable. Requires memory search or reminding

Learning

* Knowledge in the world: Learning not required.
* Interpretation substitutes for learning: How easy it is to interpret information in the world depends upon how well it exploits natural mappings and constraints.
* Knowledge in the head: Requires learning, which can be considerable. Learning is made easier if there is meaning of structure to the material (or if there is a good mental model.

Efficiency of Use

* Knowledge in the world: Tends to be slowed up by the need to find and interpret the external information
* Knowledge in the head: Can be very efficient.

Ease of Use at First Encounter

* Knowledge in the world: High
* Knowledge in the head: Low

Aesthetics

* Knowledge in the world: Can be unaesthetic and inelegant, especially if there is a need to maintain a lot of information. This can lead to clutter. In the end, aesthetic appeal depends upon the skill of the designer.
* Knowledge in the head: Nothing need be visible, which gives more freedom to the designer, which in turn can lead to better aesthetics.

Knowing What to Do

When we encounter a novel object, how can we tell what to do with it? Either we have dealt with something similar in the past and transfer old knowledge to the new object, or we obtain instruction. In these cases, the information we need is in the head. Another approach is to use information in the world, particularly if the design of the new object has presented us with information that can be interpreted.

Using Constraints

* Physical constraints: Physical limitations constrain possible operations. Physical constraints are made more effective and useful if they are easy to see and interpret, for then the set of actions is restricted before anything has been done.
* Semantic constraints: Semantic constraints rely upon the meaning of the situation to control the set of possible actions. They rely upon our knowledge of the situation and the world.
* Cultural constraints: Some constraints rely upon accepted cultural conventions, even if they do not affect the physical or semantic operation of the device.
* Logical constraints: Natural mappings work by providing logical constraints.

Visibility and Feedback

Make relevant parts visible and give each action an immediate and obvious effect. Some suggestions include making visible the invisible and using sound for feedback.

To Err is Human

Types of Slips

* Capture errors: The capture error appears whenever two different action sequences have their initial stages in common, with one sequence being unfamiliar and the other being well practiced.
* Description errors: Description errors usually result in performing the correction action on the wrong object.
* Data-Driven errors: Automatic actions are data-driven -- triggered by the arrival of the sensory data. But sometimes data-drive activities can intrude into an ongoing action sequence, causing behavior that was not intended.
* Associative activation errors: If external data can sometimes trigger actions, so, too, can internal thoughts and associations. Loss of activation errors: One of the more common slips is simply forgetting to do something.
* Mode errors: Mode errors occur when devices have different modes of operation, and the action appropriate for one mode has different meanings in other modes.

Detecting Slips

In all situations I have examined, the error correction mechanism seems to start at the lowest possible level and slowly works its way higher. Whether this is universally true I do not know, but the hypothesis warrants further examination.

The Design Challenge

Much good design evolves: the design is tested, problem areas are discovered and modified, and then it is continually retested and remodified until time, energy, and resources run out. This natural design process is characteristic of products built by craftspeople, especially folk objects. With handmade objects such as rugs, pottery, hand tools, or furniture, each new object can be modified slightly from the previous one, eliminating small problems, making small improvements, or testing new ideas. over time, this process results in functional, aesthetically pleasing objects.

The technical term for this is hill-climbing, analogous to climbing a hill in the dark. Move your foot in one direction. If it is downhill, try another direction. If the direction is uphill, take one step. Keep doing this until you have reached a point where all steps would be downhill; then you are at the top of the hill.

Why Designers Go Astray

* Putting aesthetics first
* Designers are not typical users
* The designers clients may not be users
* Creeping featurism: There are two paths to treating featurism.
* One is avoidance, or at the least, great restraint. The second path is organization. Organize, modularize, use the strategy of divide and conquer. Suppose we take each set of features and hide them away in separate locations, perhaps with dividing barriers between sets.
* The worshipping of false images

Two Modes of Computer Usage

Most computer systems offer command mode, third-person interactions. To use the computer, you type commands to it, using a special command language that you have to learn. Some computer systems offer direct manipulation, first-person interactions. Both forms of interaction are needed. Third-person interaction is well suited for situations in which the job is laborious or repetitive, as well as those in which you can trust the system to do the job for you properly. But if the job is critical, novel, or ill-specified, or if you do not yet know exactly what is to be done, the you need direct, first-person interaction.

User-Centered Design

Seven principles for transforming difficult tasks into simple ones:

1) Use both knowledge in the world and knowledge in the head.
2) Simply the structure of tasks.
3) Make things visible: bridge the gulfs of Execution and Evaluation.
4) Get the mappings right.
5) Exploit the power of constraints, both natural and artificial.
6) Design for error.
7) When all else fails, standardize.

ANNOTATION

This book is part polemic, part science, part serious and part fun. It examines the effect of poor design and equipment failure on human behavior. Intended for a general audience, it covers user-centered design, the psychopathology of everyday things and the psychology of everyday actions.

BIOGRAPHY

Donald A. Norman has been an executive at Hewlett-Packard and a Vice President and Apple Fellow at Apple Computer, where he headed the Apple Research Laboratories. He is Professor Emeritus of Cognitive Science at the University of California at San Diego and the author of many books, including the classic The Design of Everyday Things, Things That Make Us Smart and The Invisible Computer.