Cognitive development refers to the development of a child in terms of information processing, conceptual resources, perceptual skill and language learning. Jean Piaget (Figure 2) was the main force in discussing cognitive development, developing a theory of four stages that all children go through as they grow and develop. Two of these stages, the preoperational and concrete operational, will be discussed here.
The brain grows and matures rapidly during early childhood, faster than any other organ in a child's body. Once nerve cells in the brain are in place, they form synapses. These synapses release neurotransmitters, which are chemical signals that help the brain communicate. Synapses evolve rapidly, and in doing so, some synapses will die off to make room for new or more important ones. If a neuron is not being used by the brain, it goes through a process known as synaptic pruning - the removal of unnecessary neurons to make room for necessary ones. Glial cells, which account for half of the brain mass in early childhood, are responsible for a process known as myelination. This process improves message transfer between synapses and assists in brain development. The connection between neighboring neurons (made smoother through myelination) allows for advanced brain function, such as action planning and the integration of sensory information from the environment. The developing brain will grow from 30 percent of its adult weight at birth to 70 percent by age 2 - due to synaptic pruning, myelination and a child's environmental experiences.
Piaget's Childhood Stages
Piaget's preoperational and concrete operational define the development of childhood. During these stages, growth and development occur to assist the child in further development. According to Piaget, each stage of development incorporates previous knowledge; that is, a child needs to go through an earlier stage in order to fully develop in a later stage.
Preoperational development allows a child to increase his or her mental representation of objects, generally through make-believe play. Piaget states that language is the most flexible means of mental representation, but that children do not yet have the capability to solely use language as a means of representation. Rather, children perform actions as a means to master language and symbolic thought. Sociodramatic play, in which children play with others and create elaborate plots and characters, culminates in the understanding of representational thought and activity. However, children in this stage still struggle to understand dual representation - the idea that an object can be both an object and a symbol. Much thought during the preoperational phase is also egocentric - focused only on the child's point of view.
During the concrete operational phase, a major turning point in cognition occurs - the appearance of more logical and organized thought. Several key thinking processes emerge during this phase - reversibility, seriation, and transitive inference. Reversibility is the capacity to go through a series of steps and mentally reverse them, ending up back at the beginning. Seriation is the ability to order items by a quantitative dimension, such as height or weight. Transitive inference is a relational concept in which children can understand how objects related to one another. For example, if a dog is a mammal, and a Boxer is a dog, than a Boxer must also be a mammal.
In terms of behavior during the concrete operational stage, children develop more capacity for learning, and most are excited to learn new things by undergoing formal schooling. In fact, the school experience seems to enhance the stages of Piaget's cognitive developmental theory.