2) the iconicity can be too neat and obvious, hiding the more general content of the concept (one of my students reported a difficulty with the full concept of 'triangle', because the sign outlines a neat equilateral one in space, and so the student had difficulty thinking of an oblique triangle). Even if not as obvious as in this case, this problem too is common for all languages, on the interface between our languages for general use and the terminologies, or languages for special use (Picht and Draskau 1985; Myking 1998).

 Triangle NSL

 Different triangles