ABSTRACT
In this chapter I will continue to describe, in developmental terms, how children move from constructing objectcentred descriptions to those which show view-specific information. The move from one approach to another is not explained by recourse to a theory which proposes that one or other approach is available as an option from the early infancy. According to this idea, what develops are not the ‘resources’, but merely the ‘resourcefulness’ of the child in being able to select from one or other mode (Costall, 1995). We have seen that the use of one or other mode is an ecological issue; and that modes develop in accordance with ecological requirements. As Alan Costall has argued, the construction of depth on the picture plane requires a developmental explanation, and this is what I will offer now.
