Critical Changing Period of Puberty

To explain the development of Imagination and Creativity in Childhood, Vygotsky put forward a curve constructed by Ribot which shows different components as well as stages of the development of imagination.

"The curve IM represents the course of development of the imagination during the first period. It rises sharply and then remains at the level achieved for a relatively long period of time. The dotted line RO represents the development of the intellect or reason. This development, as the figure shows, starts later and rises more slowly because it requires a greater accumulation of experience and more complex transformations of this experience. Only at point M do the two lines—development of the imagination and development of reason—coincide. " --- Vygotsky  Imagination and Creativity in Childhood

As Vygotsky argued, he didn't think children's' imagination is superior to adults due to the limited experiences and simple perceptions which are mainly based on a motor-tactile system. Only when they develop the visual mode of perceiving the world, an opposing principle of behavior compared with motor-tactile one, children start to cultivate more analytic processes of consciousness rather than merely allow physical action to dominate their processes of consciousness. 

Vygotsky also mentioned that during the period of adolescence, teenagers would encounter the inequilibrium of imagination due to their psychological conflict between subjectivity and objectivity. He explained this phenomenon by discussing why children quit drawing and start to employ writing to express themselves. 

"During this period the imagination undergoes a profound transformation: it changes from subjective to objective. “Physiologically the reason for this crisis is the formation of an adult body and adult brain; psychologically the reason is the antagonism between the purely subjective imagination and the objective rational processes, or, in other words, be- tween instability and stability of mind.” "---- Vygotsky  Imagination and Creativity in Childhood

Later on, he illustrated this psychological division in puberty of children by stating two different kinds of imagination: plastic(external, builds using elements borrowed from without) imagination and the emotional (internal, builds using elements taken from within) imagination. If I understand right, I consider the first one would be more objective and the second one more subjective. 

The great thing for the first period of children's imagination development is the very close association with emotions which also create lots of faith toward the product of their creative work. But merely relying on internal imagination couldn't give teenagers enough satisfaction when they enter a more social world.  

"Only by cultivating this mastery of the material can we ensure that children’s drawing is on the right developmental path for their age. We thus see the problem in all its complexity. It has two parts: on the one hand, we need to cultivate creative imagination; on the other hand, a special culture is needed for the process of embodying the images created by imagination. Only when both aspects are adequately developed, can children’s creativity develop properly and provide the child with what we have a right to expect from him. Another aspect, associated with drawing at this age is that children’s drawing is very closely associated with productive work or artistic production."  ---- Vygotsky  Imagination and Creativity in Childhood

I kind of understand this point that children need more tools and techniques as well as social-cultural environment for them to further develop creative imagination during the period of puberty. If not, their capability of imagination would probably go down even if their intellectual development could grow normally. But I'm still confused about the connection between motor-tactile, visual mode of perceiving the world as well as Children's sense of subjectivity, objectivity. Does that mean if children activate their visual mode of perception, they would experience more objectivity? From previous reading, it seems that the mechanism behind the action-based behavior and more verbal-based behaviors is different in their role of controlling and directing oneself. However, what's the role of imagination in this transformation? I'm thinking about the different psychological and physical differences behind those two stages of children's imagination development presented by the graph above.