I'd say it is normal. Generally you wouldn't find equations describing some proposed model, instead you would find "equations" describing the statistical observ

I'd say it is normal. Generally you wouldn't find equations describing some proposed model, instead you would find "equations" describing the statistical observations. This paper, however, isn't empirical. It instead proposes a theoretical framework, based on the earlier studies. It argues (hopefully soundly) from the premises of the quoted studies to the conclusions it reaches. The point of the research isn't to present this is exactly how this behaves in mathematical terms, or even suggest a mathematical model for how it could work. Instead it presents a semi-formal description of how it could work, so someone can come up with an experiment trying to establish if it really does work that way. Once some evidence is obtained, you go from there to the more mathematical models. Its hard to formalise things especially in fields were you're far removed from the maths. So rather than spending a ton of time making a model that is probably fundamentally wrong, you make an approximation in informal language. Scientific discovery is in my mind is always a balancing act between verifying propositions (which don't really _mean_ anything) and sharing thoughts (which don't really _prove_ anything). In cognitive neuroscience semi-formal descriptions are great. In comp-sci, give me the equation already!