. . . the most ubiquitous finding in developmental research is that infants show more adult- like performance as they grow older. 
The very fact that children grow up and become adults relates to the above sentence. The starting and the ending points of the child’s development are known to us. The main aim of the developmental theories is to find out the ‘paths’ that lead to the change from an infant to an adult. Thus in a way different theories ‘map’ out the regions between the infant and adult. For achieving this, every theory has some tools, processes, structures and concepts. Change and development in each of these parameters results in the overall development of the child. The parameters and the agents of development may be different in the different approaches. We consider each of the major developmental theories with respect to their parameters of development.
The broad outlines for the various developmental approaches presented here follow closely the section What Develops? at the end of each chapter in  unless otherwise indicated.
1 Piagetian Approach
The basic paradigm that the Piagetian approach envisages, is the stagewise development of the child and the associated psychological structures or schemes. The stages of child range from an infant at sensorimotor stage to an adolescent in formal operational stage. Associated with each stage is the characteristic structural change in schemes, regulations, functions, and various logico-mathematical structures. So the answer to the question ‘what develops’ according to Piaget would be that the schemes and structures associated with each stage develop, in accordance to characteristic for each stage. This development can be assessed through observations, interviews taken by the experimenter  pg. 72.
2 Information Processing Approach
In the information processing approach, the cognitive processing is the measure of development. The increase in cognitive processing means that it becomes efficient, well organized, and the content of information also increases, which results in the overall development. Children acquire ‘rules’, ‘strategies’, ‘scripts’ and more knowledge. The concept of memory is directly related to the cognitive processing, it determines the ‘speed’ of processing as well as the ‘output’. So the increase in the memory capacity results in the overall increase ‘quality’ as well as the ‘quantity’ of the cognitive processing. In case of the connectionist approach the strengthening of connections in terms of number and strengths over time, would represent the development of the particular path of connections related to the input.
3 Vygotskian Approach
In the Vygotskian approach the development of the child has a distinctly social character. Also the development is not just limited to the individual, but is much broader in the outlook; viz. a culture, a species, a child, a cognitive skill. The basic unit of development is the “active-child-in- cultural-context.” This unit is responsible for construction of different cognitive skills, including “system of meaning and its psychological tools.” The ideal end point in development of each culture is dependent of the goals of the particular culture. The goal of the culture is the basic driving force for the development of the child, and the interactions of the child with the society are responsible for this. The psychological tools or the higher mental functions are the parameters of the development of the child. A volitional control, conscious awareness of these higher mental functions represents a final step in the process of development  Chapters 5 and 6.
4 Psychoanalytic Approach
In the Freudian or the psycho-analytic approach three structures viz. the id, ego and the superego form the central basis of the theory. The id is the largest portion of the mind, is innate and is responsible for biological needs and desires. The id aims to satisfy the impulses without any delay. The ego which emerges in early infancy, is the conscious part of the personality and is responsible for the completion of id’s impulses in accordance with reality. The superego develops between 3 -6 years and incorporates the values of the society. The emergence, interaction and the struggle between these three structures form the basis of development.  pg. 14,  pg. 137.
5 Social Learning Theories
The learning theorists provide only a few universal behaviors as the act of learning itself depends on ‘what the environment has to offer.’ Since this theory accounts for development primarily as a quantitative change, one in which the learning episodes accumulate over time; the ability to skillfully learn what is observed or listened from the other people or by attending to symbolic characters or imitation in the society is developed in the children universally  pg. 201.
6 Ecological Theories
In the Gibson’s ecological theory child actively learns from experience and environment. The child learns to detect the structure, which specifies the information available to be perceived. Gibson has proposed four parameters for human behavior viz. agency, prospectivity, search for order, and flexibility. Agency “is the self in control, the quality of intentionality in behavior.” We see ourselves as distinct from the environment, and can be agent to cause the change in it. Thus with development our aspect towards this relationship changes. Prospectivity refers to the intentionality, planning and anticipation of the future. This is also seen to develop with the age. The search for order would involve the search for patterns, order and regularity in trying to make the sense of the environment. The aspect of flexibility comes into picture with the adaptation to the environment with whatever ‘skills’ one has. The affordances [“what an environment offers it provides for an organism; they are opportunities for action”] needed for working in another setting are obtained by changing the activities  pg. 360.
7 Modularity Nativism
The term modularity nativism refers to a set of approaches that postulate certain innate modules, structures or constraints, each specialized for a particular domain of cognition  pg 20. The modules are ‘pre-programmed’ to respond to specific sorts of information. These innate modules require a ‘trigger’ in form of little experiences, with appropriate content, to be activated. The different modules are posited to be relatively independent of each other, such that the development in one does not overflow into another. The developmental changes in thinking are caused by external factors such as maturation  pg. 427. This in turn implies that the infant mind is not very different from that of an adult.
8 Theory Theory
The theory theory approach is another domain specific approach to child development, which likens the children’s knowledge to a scientific theory  pg. 20. The children are capable of constructing intuitive, folk , everyday na ̈ıve “theories” for a particular domain  pg. 423. According to this theory the child has different theories for different domains. In the development process the children ‘test’ these intuitive theories, just like a scientists, in light of their experiences, thus they are like ‘little scientists’. So the answer to the question, What Develops? is that these intuitive na ̈ıve theories develop, with the experience of the children with the real world.
9 Dynamic Systems
The dynamic systems approach to child development addresses change over time in the complex holistic systems, especially self organizing ones  pg. 432. The term dynamic system most generally means “simply systems of elements that change over time.” In dynamic systems we have two basic themes for development  pg. 563:
- Development can only be understood as the the multiple, mutual, and continuous interaction of all the levels of the developing system, from the molecular to the cultural.
- Development can only be understood as nested processes that unfold over many time scales, from milliseconds to years.
One of the metaphors that is used to explain the dynamic systems approach is a mountain stream . The behavioral pattern are analogous to the eddies and the ripples of a mountain stream. In mountain stream metaphor “behavioral development is seen as an epigenetic process, that is truly constructed by its own history and system wide activity”  pg. 569. Thus development is seen as a process in which new behavioral patterns emerge because of interaction. 
 Aslin as quoted in  pg. 47.
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 Miller P. H., Theories of Developmental Psychology 2001, W.H. Freeman
 Thelen E., Smith L. B., “Dynamic Systems Theories” Chapter 10 in Handbook of Child Psychology : Vol. 1. Theoretical Models of Human Development 1998, Wiley
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