Theorizing about how people perform any cognitive information-processing task typically takes the form of proposing a modular model of the cognitive system that people use to accomplish that task. Some of these models are stage models; many are not. In particular, models in which the passage of information from one module to another is cascaded rather than discrete are currently very popular, but these by definition are not stage models. The additive factor method as described by Sternberg (2011) is designed specifically for working with stage models. How useful is it for theorists whose models are not stage models? The goal of the additive factor method is the verification or discovery of the parts (modules) of cognitive systems. That is also the goal of the method of cognitive neuropsychology. I concur with Sternberg's view that these are complementary methods that can inform each other.