Aside from improved and updated examples, the most important addition to this chapter is a section on culture, which is of special importance to my discussion of “natural mappings.” What seems natural in one culture may not be in another. The section examines the way different cultures view time—the discussion might sur- prise you.
Few substantive changes. Better examples. The elaboration of forc- ing functions into two kinds: lock-in and lockout. And a section on destination control elevators, illustrating how change can be extremely disconcerting, even to professionals, even if the change is for the better.
This chapter is completely new. I discuss two views of human- centered design: the British Design Council’s double-diamond model and the traditional HCD iteration of observation, ide- ation, prototyping, and testing. The first diamond is the diver- gence, followed by convergence, of possibilities to determine the appropriate problem. The second diamond is a divergence- convergence to determine an appropriate solution. I introduce activity-centered design as a more appropriate variant of human- centered design in many circumstances. These sections cover the theory.
The chapter then takes a radical shift in position, starting with a section entitled “What I Just Told You? It Doesn’t Really Work That Way.” Here is where I introduce Norman’s Law: The day the prod- uct team is announced, it is behind schedule and over its budget.
I discuss challenges of design within a company, where sched- ules, budgets, and the competing requirements of the different divisions all provide severe constraints upon what can be accom- plished. Readers from industry have told me that they welcome these sections, which capture the real pressures upon them.
The chapter concludes with a discussion of the role of standards (modified from a similar discussion in the earlier edition), plus some more general design guidelines.
Great designers produce pleasurable experiences. Experience: note the word. Engineers tend not to like it; it is too subjective. But when I ask them about their favorite automobile or test equipment, they will smile delightedly as they discuss the fit and finish, the sensa- tion of power during acceleration, their ease of control while shift- ing or steering, or the wonderful feel of the knobs and switches on the instrument. Those are experiences.
Experience is critical, for it determines how fondly people re- member their interactions. Was the overall experience positive, or was it frustrating and confusing? When our home technology be- haves in an uninterpretable fashion we can become confused, frus- trated, and even angry—all strong negative emotions. When there is understanding it can lead to a feeling of control, of mastery, and of satisfaction or even pride—all strong positive emotions. Cog- nition and emotion are tightly intertwined, which means that the designers must design with both in mind.
When we interact with a product, we need to figure out how to work it. This means discovering what it does, how it works, and what operations are possible: discoverability. Discoverability re- sults from appropriate application of five fundamental psycholog- ical concepts covered in the next few chapters: affordances, signifiers, constraints, mappings, and feedback. But there is a sixth principle, perhaps most important of all: the conceptual model of the system. It is the conceptual model that provides true understanding. So I now turn to these fundamental principles, starting with affor- dances, signifiers, mappings, and feedback, then moving to con- ceptual models. Constraints are covered in Chapters 3 and 4.