ABSTRACT
A number of neurobiological models of visual development have been put forward over the past twenty years. One popular idea is that of two visual systems: a primitive, evolutionarily older subcortical system controls orienting responses which define crudely ‘where' an object is located and triggers foveation, while newer cortical mechanisms define ‘what' is actually in the foveated area. Using this idea, Bronson (1974) suggested that newborn vision is totally subcortically controlled with the cortex starting to mature at around 2 months postnatally. Atkinson (1984) put forward a modified model in which the newborn visual system is largely subcortically controlled, with executive control of vision being taken over by a number of cortical modules postnatally. These cortical modules can be thought of as a number of cortical streams, each specifically processing particular types of visual information and each becoming operational at different ages.
