My definition of interaction requires an action and a response. There’s an understanding that if I affect or act on an object, something will happen. Good interaction means that I know what to do, and that I have an idea of what to expect. Interaction designers must create both sides, by understanding or fostering a goal so a user would know how to act, and providing a response. I say that I have an idea of what to expect, because if something completely different happens, the experience will feel broken. Surprises can also lead to good interactions, but this means my expectations were surpassed, not neglected.
As a UX designer I tend to think of interaction in relationship to completing a task. What are the steps I need to take? How will I know what to do next, and how will I know when I’m done? The UX designer must understand the user’s mental model. Mental models are like pre-programmed interactions based on past experiences. For example, I have a mental model of ordering food at a restaurant. If I am ordering take-out, I will look for the counter to order. I will expect to find a menu with food and prices. If I sit down to eat, I will expect someone to come take my order, bring me food, and eventually I will pay. There are other types of restaurants that follow different models, but there have to be clues to guide me. The more I go to a restaurant, the more automatic the behavior would become. If something different happened, it would be jarring. Again, the experience would feel broken.
Bret Victor points out in A Brief Rant On The Future Of Interaction Design that our interactions with technology are largely limited to “Pictures Under Glass”. That presents certain design challenges because the tactile feedback from physical objects is missing. UX has been borrowing from the physical world from a long time, making buttons look like something you could press, calling on metaphors such as shopping carts in e-commerce. Though the internet is inherently a form of publication, and is often no more interactive than a book or a brochure. Victor doesn’t implore us to make those 2D experiences better, but to pull away from the screen, and reclaim the physicality technology is currently missing. That is innovating for the future.