This book discusses the design of everyday things from the perspective of psychology. It mainly includes 5 parts:
The features of good design and poor design
Well-designed objects are easy to interpret and understand. They contain visible clues to their operation. On the contrary, poorly-designed objects can be difficult and frustrating to use. They provide no clues- or sometimes false clues. They trap the user and thwart the normal process of interpretation and understanding.
The principle of interaction design
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. Affordances provide strong clues to the operations of things. 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 needed.
Norman explains that by signifiers he understands “any mark or sound, any perceivable indicator that communicates appropriate behaviour to a person.” . "Signifiers specify how people discover those possibilities: signifiers are signs, perceptible signals of what can be done. Signifiers are of far more importance to designers than are affordances." .
Constraints are the limits to an interaction or an interface. Some are really obvious and physical, for example the screen size on a phone. Others are more nuanced, like a single, continuous page website having an image peeking onto the main page. It is logical for the user to scroll down to see the next image, and thus the rest of the website.
Mapping is the relationship between control and effect. The idea is that with good design, the controls to something will closely resemble what they affect.
A great example of mapping is the vertical scroll bar. It tells you where you are in a page, and as you drag it down, the page moves down at the same rate; control and effect are closely mapped.
Every action needs a reaction. So well-designed objects should send back to the user information about what action has actually been done, like a sound, a moving dial, a spinning rainbow wheel, that the user’s action caused something.
"Sometimes things cannot be made visible. Enter sound: Sound can provide information available in no other way. Sound can tell us that things are working properly or that they need maintenance or repair. It can even save us from accidents"
6.A good conceptual model
it allows users to predict the effects of their actions. Without a good model, users operate by rote, blindly; they do operations as they were told to do those, they can’t fully appreciate why, what effects to expect, or what to do if things go wrong.
People falsely blaming themselves
Badly designed objects lead to taught helplessness. No wonder people feel guilty when they have trouble using objects, especially when they perceive (even if incorrectly) that nobody else is having the same problems.
How to prevent misoperation by design
1.Put the required knowledge in the world. Do not require all the knowledge to be in the head. Yet do allow for more efficient operation when the user has learned the operations, has gotten the knowledge in the head.
2.Use the power of natural and artificial constraints: Physical constraints, Semantic constraints, Cultural constraints, Logical constraints
3.Narrow the gulfs of execution and evaluation side, make the results of each action apparent. Make it possible to determine the system state readily, easily and accurately, and in a form consistent with the person’s goals, intentions and expectations.
Execution side: Forming the goal, Forming the intention, Specifying an action
Evaluation side: Executing the action, Perceiving the state of the world, Interpreting the state of the world, Evaluating the outcome
The paradox of technology
Technology offers the potential to make life easier and more enjoyable; each new technology provides increased benefit. At the same time, added complexities arise to increase our difficulty and frustration. The development of a technology tends to follow a U-shaped curve of complexity: starting high, dropping to a low, comfortable level; then climbing again. New kinds of devices are complex and difficult to use. As technicians become more competent and an industry matures, devices become simpler, more reliable and more powerful. But then, after the industry has stabilized, newcomers figure out how to add increased power and capability, but always at the expense of added complexity and sometimes decreased reliability.
The mindset of human-cantered design
Observation — Creation — Prototype — Test