One of the most important roles in product development is the role of interaction designer. An interaction designer designs how the users will interact with the product and conceptualize the tasks they perform. He decides whether, for example, the user interface will be command driven, object oriented (clicking on objects then specifying what to do with them), or wizard based. The interaction designer decides the individual steps in the use cases.
Every company has one or more people that play the interaction designer role. Usually, those people have little or no expertise in interaction design. Sadly, they typically don't even realize how unqualified they are.
Let's see who typically plays the role at companies.
- Engineer. An engineer is an expert on building what is designed. Yes, an engineer may know how to design the internal structure of the hardware or software, but such skills don't guarantee any expertise in interaction design.
- SME. A subject matter expert is an expert on the concepts in the domain. What about such expertise entails any knowledge of what it takes to maximize a product's usability? In fact, SMEs often have a skewed perception of usability, as they are expert users, not typical users.
- UI designer. User interface designers know how to lay out a screen. They know the best place to put the buttons, what size font to use, whether to use a drop-down menu or a list, and how to make it all look sharp. But interaction and sequencing is a different matter.
- Product manager. A properly-cast product manager is an expert on the problems, users, and buyers in the market. Understanding users is important, even essential, but it doesn't by itself entail any expertise in designing a product to be usable to them. A product manager frames the usability metrics, but doesn't necessarily know how to achieve them.
It's certainly possible that a person playing one of these roles just happens to possess user interaction design skills. And in a healthy, productive organization, some people are flexible and play multiple roles. But realize that, to the extent people playing these roles are qualified user interaction designers, it is a coincidence.