The heart of interaction design

Interaction design is a difficult thing to define because it encompasses a lot of fields. It can be the design of a software application or the design of a website. It can be the design of a physical product, especially one with controls, an interface.

The common thread is of course the design of how people interact with things. In particular, things that can be controlled with some form of interface. And the common thread in all these types of things is the button.

Physical products have all kinds of controls: buttons, knobs, toggle switches, sliders, wheels (really big knobs), levers. Onscreen products also have their own controls: buttons, checkboxes, radio buttons, text fields, links, sliders and more. But only the button really transcends both the physical and onscreen worlds.

Industrial design is purely physical. Web and software design are purely digital. But designing digital products crosses this boundary, requiring the skills of both disciplines. Responsibilities intersect at the button. The industrial designer is responsible for the form, shape, look, and feel of the product. The interaction designer (or someone with one of the many similar/related titles) is responsible for how it works and what happens onscreen. But they overlap at the buttons. They must collaborate on how many buttons (or other controls) will exist and where they are placed on the product. The interaction designer then continues with what the buttons do. The industrial designer continues with their look and feel.

But the button concerns everybody and therefore lies right at the heart of all the disciplines that comprise interaction design. What else do washing machines and websites have in common?