This is an excellent book for those who aspire to do good work in the field of design, engineering, architecture, consumer products, or anything creative. After reading the book, you will have an enhanced appreciation for everyday things around you - things as trivial as a toaster, refrigerator, and pen. You will learn what separates a good product from a bad one. Dan Norman, the author is a renowned cognitive scientist and usability expert. He worked as a user experience architect at Apple, and popularized the term "user-centered-design".
Notes from the book:
Far too many items in the world are designed, constructed, and foisted upon us with no understanding for how they will be used. Three key things stand out of the book:
- Not the user's fault: If people are having trouble with your product, its not their fault - it's the fault of design
- Design Principles: Don't criticize something unless you can offer a solution.
- Feedback: The user must be able to see the effect of his action. If he presses something, let him know through the design interface.
- Constraints: The surest way to make something easy to use, with few errors, is to make it impossible to do otherwise. e.g. Battery of memory cards go only one way in properly designed products
- Affordances: A good designer makes sure that appropriate actions are perceptible and inappropriate ones invisible.
- The power of observation: The path to be a good designer, starts by learning to watch, and learning to observe. Yogi Berra said "You can observe a lot by watching". Problem is you have to know how to watch.
Design is intended to be used by people, so the needs and requirements ought to be driving the entire development process. One of the most important principles of design in visibility. Think about the times you pushed on the doors that need to be pulled, or slide down the side. The correct parts must be visible, and they must convey the right message.
Affordance refers to the perceived and actual properties of the thing, primarily those fundamental properties that determine just how the thing could possibly be used. Plates are for pushing. Knobs are for turning. Slots are for inserting things into. Balls are for throwing or bouncing. When affordances are taken advantage of, the user knows what to do just by looking: no picture, label, or instruction is required. When simple things need pictures, labels, or instuctions, the design has failed. The two holes in a scissors are cleverly designed. One is meant for thumb, and another one for several fingers. You can't go wrong.
To make sure your design is inline with how people do things, you can ask yourself 7 questions. How easily can one:
- Determine the function of the device?
- Tell what actions are possible?
- Tell if the system is in the desired state?
- Determine mapping from intention to physical movement?
- Determine mapping from system state to interpretation?
- Perform an action?
- Tell what state the system is in?
Well designed products have good mappings, natural relationships, between the controls and the things controlled. Single controls often have single functions. There is good feedback. The system is understandable. Whenever, the number of possible actions exceeds the number of controls, there is apt to be difficulty. When the number of controls equals the number of functions, each control can be specialized, each can be labeled.
To err is human. Users will take unintended actions, therefore it is better to plan for it. There are six types of errors:
- Capture errors: Frequently done activity takes charge instead of the one intended, e.g. You get in your car on Sunday morning to get breakfast, and find yourself driving to office.
- Description Errors: Intended action has much in possible with others that are possible. e.g. Long rows of identical switches. Intend to flip one, instead flip a similar looking one.
- Data-driven Errors: Triggered by the arrival of sensor data.
- Associative Activation Errors: Your office phone rings, and you say "Come on, in" at it.
- Loss-of-activation errors: Simply forgetting to do something. You walk all the way to the kitchen, open the refrigerator, but wonder why you opened it.
- Mode errors: Occur when devices have different modes of operation. e.g. you press the button on the watch to pause the stop-watch, but you accidentally hit the reset button.
The best way to address these errors, is to brainstorm early in the design phase for every possible scenario that can go wrong with product usage. For each scenario, either place constraints to avoid that option, or notify user with immediate feedback, so he can detect the error.
The paradox of technology and importance of design - It usually takes five or six attempts to get a product right. This may be acceptable in an established product, but if an newly introduced product doesn't catch on in the first two or three times, it is dead.