Modes of Representation
During the course of a child's development there are changes in the way that it represents (i.e. stores and retrieves) information that is perceived through the senses. A small infant is limited to the actions that it can make upon the world surrounding it, when it first learns to separate the world into "me" and "not me", discovering its body schema. From then on its learning consists of developing and revising that schema as it performs more operations on the outside world and learns from the effects that result.
It is hard to imagine how a baby thinks. It cannot yet think in pictures of objects because it has not really discovered what objects are yet, or what properties they have, in a real enough way to picture them. Instead it remembers things as a kind of "muscle memory" (in the sensori-motor kinesthetic system) using an internal representation of the "feel" of things to code the information.
A baby remembers things as a kind of "muscle memory" using an internal representation of the "feel" of things to code the information.
Before 4 or 5 years of age traumatic memories and their accompanying considerations and decisions that affect future behavior are not available to recall in the way that an adult recalls, like a full-perceptic movie, but rather in terms of emotional body-centered feelings of needs and wants or fears and pains, although there will be an element of auditory or visual imagery particularly accompanying poignant moments. There will be hardly any visual representation of the first eighteen months, before the individual starts to walk and talk.
Between 4 and 8 years of age the predominant representation has become auditory, with memories featuring received commands. During this period the child develops realistic internal imaging of the world around him, so that by 7 or 8 years of age a concrete visual mode of representation has become the predominant way of thinking about and remembering experience.
Pretty soon though, the child's world widens further still, until it includes information that isn't easily represented using pictures. Try imaging a concept like "freedom" or "fairness". When this happens the child becomes more likely to use symbolic representation, including inner speech, using words as formalised symbols that "stand for" the concepts. At this point the child's own decisions and intentions may be expressed as inner speech, whereas before they were "felt" intentions.