I recently finished “The Design of Everyday Things”. I found Norman’s perspective on inanimate objects eye-opening. But, I did find the book dense and if I have one criticism- it’s that the book isn’t designed to guide you towards becoming a better designer. “The Design of Everyday Things” is a psychological treatise that is loosely organized with lots of examples. So what I have tried to do in this post is breakdown the key points and rearrange them a bit, so that it reads more like a manual for better design. If you haven’t read the book, you can buy it here.
“Design must convey the essence of a device’s operation; the way it works; the possible actions that can be taken; and, through feedback, just what it is doing at any particular moment. Design is really an act of communication, which means having a deep understanding of the person with whom the designer is communicating.”
“Each time a new technology comes along, new designers make the same horrible mistakes as their predecessors. Technologists are not noted for learning from the errors of the past. They look forward, not behind, so they repeat the same problems over and over again. Today’s wireless devices are appalling.”
“Whenever the number of possible actions exceeds the number of controls, there is apt to be difficulty.”
How People Do Things – The 7 Steps
1) Forming the goal
2) Forming the intention
3) Specifying an action
4) Executing the action
5) Perceiving the state of the world
6) Interpreting the state of the world
7) Evaluating the outcome
Repeat back to #1 based on what has happened as a result of actions
The point of understanding How People Do Things is to avoid the Gulfs of Execution and Evaluation when designing products.
A Gulf of Execution arises when there is a difference between the intentions and the allowable actions provided by a system. For example, if you want to open the sunroof, but there are no buttons to be found that might allow you to open the sunroof. Alternatively, a long sequence of actions may be required that are unintelligible to you, so you just don’t open the sunroof.
A Gulf of Evaluation arises when a great amount of effort is required to interpret the physical state of a system and/or determine how well expectations and intentions have been met. A good example of this is a CD player where it is impossible to tell whether there is a CD in the player or not. In addition, a system that provides no feedback – i.e. you click a button and nothing happens affirmative or negative – resulting in a Gulf of Evaluation.
Building on these concepts, you can ask yourself 7 questions to make sure your design is inline with How People Do Things:
1) How easily can one determine the function of the device?
2) How easily can one tell what actions are possible?
3) How easily can one tell if the system is in the desired state?
4) How easily can one determine mapping from intention to physical movement?
5) How easily can one determine mapping from system state to interpretation?
6) How easily can one perform an action?
7) How easily can one tell what state the system is in?
The 3 foundations to good design serve to answer these seven questions:
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.
What Knowledge Does Your User Have?
Common and instinctive visual knowledge is easily retrievable and visible/audible. There is no learning required and ease of use at first encounter is high. Challenges are that the user may need to try to interpret the design since information is not communicated explicitly. In addition, the design may not be aesthetically pleasing given a common need to maintain a lot of information.
Remembered or learned knowledge makes for efficient use and minimalist design. However, it requires learning to use, particularly before initial use.
How Does the User Know What to Do?
Placing constraints makes it easier for the user to know what to do
Allowing the user too many different ways to use a device by not constraining the controls/functionality is a common cause of poor design.
Make the invisible, visible
Have a good display
Use sound to enhance visibility
How Do You Keep the User From Making Errors?
Errors come in two different flavors- 1) slips result from automatic behavior and 2) mistakes result from conscious deliberations
Common slip errors
- Capture error – a frequently done activity is swapped with another frequently done activity
- Description error – the intended action has much in common with others that are possible
- Data-Driven error – data-driven activities can intrude into an ongoing action sequence causing unintended behavior
- Associate Activation error – internal thought triggers incorrect action – Freudian slip
- Loss-of-activation error – forgetting to do something
- Mode error – when a device has different modes of operation, and the action appropriate for one mode has different meanings in other modes
You need feedback loops in place for the user to detect that there has been a slip!