Tognazzini wrote a magazine column with all the downsides: overly funny, non-academic, etc. I think Tog meant something like selecting commands from a menu vs using a command line across a range of applications. Anyway, studies like that must be somewhere in Proceedings of CHI, I guess. (Just checked bibliography in "Tog on interface", but nothing seemed to match. Found a comparison of different types of menus, but that's different. But also relevant: I guess most people would say using pop-up menu right at the mouse cursor will be faster than a fixed one at the top of the screen, yet the experiment shows the opposite.)
Mousing implies things are visible and you merely point to them. Keyboard implies things are non-visible and you recall commands from memory. These two must have a principal difference. Many animals use tools: inanimate objects lying around that can be employed for some gain. Yet no animal makes a tool. Making a tool is different from using it because to make a tool one must foresee the need for it. And this implies a mental model of the world and the future, i.e. a very big change compared to simply using a suitable object on the spot. (The simplest "making" could be just carrying an object when there is no immediate need for it, e.g. a sufficiently long distance. Looks very simple and I myself do not know if any animals exhibit such behavior, it seems to be on the fence. It would be telling if they don't.)
I think the difference between mousing and keying is about as big as of using a tool and making a tool. Of course, if we use the same app all day long, then its keys become motor movements, but this skill remains confined to the app.
Mousing implies things are visible and you merely point to them. Keyboard implies things are non-visible and you recall commands from memory. These two must have a principal difference. Many animals use tools: inanimate objects lying around that can be employed for some gain. Yet no animal makes a tool. Making a tool is different from using it because to make a tool one must foresee the need for it. And this implies a mental model of the world and the future, i.e. a very big change compared to simply using a suitable object on the spot. (The simplest "making" could be just carrying an object when there is no immediate need for it, e.g. a sufficiently long distance. Looks very simple and I myself do not know if any animals exhibit such behavior, it seems to be on the fence. It would be telling if they don't.)
I think the difference between mousing and keying is about as big as of using a tool and making a tool. Of course, if we use the same app all day long, then its keys become motor movements, but this skill remains confined to the app.