Perceived affordances help people figure out what actions are possible without the need for labels or instructions. I call the signaling component of affordances signifiers.

The seven-stage model of the action cycle can be a valuable design tool, for it provides a basic checklist of questions to ask. In general, each stage of action requires its own special design strategies and, in turn, provides its own opportunity for disaster. Figure 2.7 summarizes the questions: 1. What do I want to accomplish? 2. What are the

Gibsonian psychology,

Our strengths are in our flexibility and creativity, in coming up with solutions to novel problems. We are creative and imaginative, not mechanical and precise. Machines require precision and accuracy; people don’t. And we are particularly bad at providing precise and accurate inputs. So why are we always required to do so? Why do we put the

How do we form an appropriate conceptual model for the devices we interact with? We cannot talk to the designer, so we rely upon whatever information is available to us: what the device looks like, what we know from using similar things in the past, what was told to us in the sales literature, by salespeople and advertisements, by articles we may

People are innately disposed to look for causes of events, to form explanations and stories. That is one reason storytelling is such a persuasive medium.

Feedback must be immediate: even a delay of a tenth of a second can be disconcerting. If the delay is too long, people often give up, going off to do other activities.

(Put “Norman doors” into your favorite search engine—be sure to include the quote marks: it makes for fascinating reading.)

The information that helps answer questions of execution (doing) is feedforward. The information that aids in understanding what has happened is feedback.