ABSTRACT
We can characterize the picture we begin to get of the development of behaviour as a series, or rather a web, of events, starting with innate programming instructions contained in the zygote, which straightaway begin to interact with the environment; this interaction may be discontinuous, in that periods of predominantly internal development alternate with periods of interaction, or sensitive periods. The interaction is enhanced by active exploration; it is steered by selective Sollwerte [ideal or template to which response is compared] of great variety; and stage by stage this process ramifies; level upon level of ever-increasing complexity is being incorporated into the programming.
