This is outstanding theoretical work, resembling a handbook chapter more than the usual journal article, and unlikely to be read just once. It is a worthy sequel to the seminal 1969 paper that introduced the Additive-Factor Method (AFM), and presents a taxonomy of methods for inferring mental modules within which AFM can be regarded as a special case. The paper complements and extends his recent chapter titled 'Discovering mental processing stages' (Sternberg, 1998). Written with the admirable clarity and conciseness that we have come to expect from this author, it goes without saying that I consider the paper highly appropriate as a contribution to the special issue in honor of Andries Sanders. . . . Case 2 includes the AFM, but multiplicative combination rules are also considered, and intriguing examples demonstrate novel applications of the method to response probability, response rate, reaction time, and ERPs. In my opinion, the systematic exposition and analysis of Case 1 methods is even more important and may turn out to advance cognitive neuroscience as much as the AFM has advanced cognitive psychology.
I feel that this is an extremely useful piece of work. The author reconciles [sic] one of the most important issues of cognitive psychology, namely, the decomposition of a complex system into meaningful parts. Readers will greatly appreciate that the author brings together various methodological approaches on this topic, because these are presently scattered across the literature. It is very useful to see them evaluated and contrasted within a single framework. Thus the limitations and possibilities of each approach becomes apparent. The thoroughness of the theoretical analysis is exemplary. I strongly recommend to publish this paper in Acta Psychologica after a minor revision.