On the neurology of perception

The neurological base of biological space and of spatial perception is discussed. The nervous system is viewed as a system controlling behaviour. Movements as elements of behaviour are guided movements: goal-directed, programmed and ordered in space. Perceptual space is derived from directional properties of behaviour. The sense organs are not 'doors of perception', transparent to the alleged properties of the environment. Rather they are used in a centrifugal sense--outward from the organism. They are instrumental in updating a 'map' of the outside world and of the organisms as part of that world. The map is, in essence, a projection of the organism's own behaviour modified by the regularities, constraints and supports encountered in the world. The role of the periphery varies from moment to moment with the organisational level of behaviour. Thus, the sensomotor system is operated for updating the map and also for calibrating movements. At a peripheral level it helps to level out irregularities encountered in the execution of simple movements. All these functions may take place at the same time. Taken together, these considerations serve as an explanation of the fact that we are able to determine the spatial properties of objects although the shape as such is not presented to the sensory surface of the body, nor are the various scanpaths of our exploratory movements a replica of the geometrical properties of the object.