Reflections on geometry and navigation

The geometric arrangement of surfaces in an environment plays an important role in navigation in vertebrate animals. In this line of research, an animal is typically disoriented and then presented the task of relocating a previously encountered goal. Aside from the geometric shape of the enclosure, other non-geometric (featural) cues are typically available, including colours of walls, objects serving as landmarks, or smells. Animals use both geometric and featural cues, but mammals sometimes rely solely on geometric cues. This has led to views that the processing of geometric information is modular, being the work of a geometric module. Recent work has started to address just what geometric properties are encoded. These current issues are commented on in this paper, and a tentative picture is drawn that both global and local geometry, each in limited ways, are used for navigation. A view of modularity is also presented in which spatial information is stored together (in non-modular fashion), but some computational processes are modular and operate on limited kinds of information.