Hi Mike, I thought I might get such a response. I have to admit that what you have highlighted is true in certain contexts, but you have to remember that as alluded to in ISO 13091 (click here)
, when identifying or manipulating curved objects such as a watch case, or the example more commonly used - a coin - both the shape of the edge and
its position on the on the skin is signaled to the central nervous system. That adds an order of magnitude to the processing requirements, so to speak, of the old grey matter. Unfortunately, or at least to my knowledge, there are no studies on the precision with which humans can discriminate such curved edges.
If that were not enough, you should also remember that edge sensitivity of cutaneous mechanoreceptors changes with the curvature of an edge (Wheat & Goodwin, 2001). Why is this important? Well, unless the curvature both on the y- and z-planes are identical between the Journe and Lange cases (which I doubt, considering the Journe has a "Directoire" edge vs. Lange's flat & brushed edge) then enhanced mechanoreceptor responses cannot, in themselves, provide information about the shape of an edge. Spherical curvature is reflected by two orthogonal changes in curvature, instead of a single change in curvature, e.g. in edges. You can see now how curved edges present a challenge because, as you may have guessed, the number of afferents activated during the detection process will be relatively small compared to the spatial precision required.
Why am I bringing this up you ask? Well, the original claim was that you "could feel the difference in Lange's better finish". How are we to know that the "better" feeling didn't come from a more pleasing curvature rather than "finish" (whatever that means, I'm assuming smoothness of the metal). You would need either 1) identical cases, or 2) a flat surface produced by both manufacturers to be tested. However, in the case of the latter, this would only prove the superiority in producing a flat finish, and may or may not (more likely not) translate over to case manufacturing. If "finish" is being used in a broader sense, then I can argue that it's subjective enough to not have the ability of being used in absolute statements. A very simple counter argument could be that "I ran my fingers around each watch and I felt the difference in Journe's better finish". An even simpler argument is "No, you can't". In the end, it seems, even with bionic fingers it comes down to personal preference.