Chapter 6. Interface Design Basics

We can engage with digital products only through some sort of interface. We can't (yet) connect to digital devices through a cable directly from our brains to their microprocessors. For now, we need some intermediary to communicate between us and our digital devices: an interface.

Interface design is so closely tied to interaction design that many believe they are the same thing, which isn't exactly true. Interface design is only the experienced representation of the interaction design, not the interaction design itself. The interface is only what people see, hear, or feel, and while it is immensely important, it is only a part of interaction design.

Interfaces are a bit like icebergs. The part that can be seen is really just the tip; what's below the surface, what isn't seen, is the main part of the interaction design: the design decisions that the designer has made and the technical underpinnings that makes the interface a reality. An interface is where the interaction designer's choices about how people can engage with a product and how that product should respond are realized. In other words, the interface is where the invisible functionality of a product is made visible and can be accessed and used.

This is not to say that interaction designers should ignore or downplay the interface. Not at all. If an interface doesn't display the attributes of good interaction design as described in Chapter 3trustworthy, appropriate, smart, responsive, clever, ludic, and pleasurableusers aren't going to engage with it. All the time the interaction designer spent crafting rich functionality will be for naught if the interface is poor.

In the past, form closely followed function. A hammer looks the way it does because its shape is optimal for driving in nails. With digital devices, however, form doesn't necessarily follow function. Objects on a screen can have any shape and can potentially serve any purpose. For example, an unlabeled button sitting in the middle of a Web page could look like an elephant, a tea cup, or even like, well, a button, and clicking it could open another Web page, start an animation, play music, close the browser window, or do a variety of other things. When working with digital devices, the interaction designer has a lot more fluidity and ambiguity to account for.

Remember too that interaction designers also design services, where the interface typically consists of physical spaces, products, and people (see Chapter 8).