Interaction and Complexity

One aspect of interaction that keeps emerging is related to complexity. A lot of people complain that interacting with systems and devices today is too complex. As a natural reaction to that, a lot of designers argue for simplicity as an important design principle. But what is complexity when it comes to interaction and why does it appear? In our recent book "Things that keep us busy -- the elements of interaction" we spend two chapters on interaction complexity and the related notion of control.

We do this by examining what interaction complexity is and what causes it. This leads to a theory (or model) of interaction complexity that consists of four different types of complexity. This is what we write (on p 85).

"We will identify and define four main loci of complexity of an artifact or system (see figure 5.1), all with respect to its designed purpose:

      1. internal complexity

      2. external complexity

      3. interaction complexity

      4. mediated complexity

These four loci should not be thought of as different measures or types

of complexity; they represent a rough division into the main (more or less abstract) locations where complexity is residing in varying degrees, and manifesting itself in various ways."

and figure 5.1 lays out how these different forms of complexity relate to each other.

After having worked with this model for quite some time, I find it quite useful and it helps to understand many aspects of interactivity and its relation to complexity. One of the major consequences of the model is that it indicates (strongly) that there is no easy "fix". To design for simplicity does not have any optimal solutions, every design decision about how to handle (or where to put complexity) leads to serious trade-offs that are inevitable.

This is why I believe that understanding this model can help and prepare every interaction designer to better approach the design of any interactive system and device.