Structural stage theory

Stage theories are based on the idea that elements in systems move through a pattern of distinct stages over time and that these stages can be described based on their distinguishing characteristics.

Piaget's theory of cognitive development

Piaget's theory goes through four stages: Sensorimotor: (birth to 2 years), Preoperations: (2 to 7 years), Concrete operations: (7 to 11 years), and Formal Operations: (11 to 16 years). Each stage has at least two substages, usually call early and fully. Also see Theory of cognitive development.

Underlying Assumptions

Each stage lays the foundation for the next.
Everyone goes through the stages in same order.
Each stage is qualitatively different. Meaning it is a change in nature, not just quantity
The child is an active learner. Basically they have to do it on their own, they can not be told.

Sensorimotor Stage (birth to 2 years)

A child comes into the world knowing almost nothing, but they have the potential that comes in the form of:

brain makeup
reflexes eg. sucking and visual orienting
innate tendencies to adapt to environment

Infants use these potentials to explore and gain an understanding about themselves and the environment. They have a lack of object permanence, which means they have little or no ability to conceive things as existing outside their immediate vicinity. For example: when you place a barrier, such as a piece of wood, in front of an object an infant will believe that the object is nonexistent.

Preoperational Stage (2 to 7 years)

Preoperational intelligence means the young child is capable of mental representations, but does not have a system for organising this thinking (intuitive rather than logical thought). The child is egocentric – which is they have problems distinguishing from their own perceptions and perceptions of others. A classic example is, a preoperational child will cover their eyes so they can not see someone and think that that person can not see them either.

The child also has rigid thinking, which involves the following:

Centration – a child will become completely fixed on one point, not allowing them to see the wider picture. For example, focusing only on the height of the container rather than both the height and width when determining what has the biggest volume.
State – can only concentrate on what something looks like at that time.
Appearance – focuses on how something appears rather than reality.
Lack of Reversibility – can not reverse the steps they have taken. Does not realize that one set of steps can be cancelled by another set of steps.
Lack of Conservation – realizing that something can have the same properties even if it appears differently.

Concrete Operations (7 to 11 years)

Intelligence is now both symbolic and logical.
Acquires ‘operations’ = a set of general rules and strategies.
The most critical part of operations is realising ‘reversibility’ = both physical and mental processes can be reversed and cancelled out by others.

The concrete operational child will overcome the aspects of rigidity apparent in a preoperational child. These are:

lack of reversibility
states
appearance
conservation

The tasks of concrete operations are:

Seriation – putting items (such as toys) in height order.
Classification – the difference between two similar items such as daisies and roses.
Conservation – realising something can have same properties, even if it appears differently.

It is important to realise that operations and conservations do not develop at the same time. They develop gradually and are not an ‘all or nothing’ phenomenon. For example, the first to develop is number conservation followed by mass conservation, area conservation, liquid conservation and finally solid volume conservation. Thinking is not abstract. It is limited to concrete phenomena and the child’s own past experiences.

Formal operations (11 to 16 years)

Child is capable of formulating hypotheses and then testing them against reality.
Thinking is abstract, that is a child/adolescent can formulate all the possible outcomes before beginning the problem. They are also capable of deductive reasoning.

Neo-Piagetian and Post-Piagetian Stage Theories

Juan Pascaual-Leone founded neoPiagetian stage theory when he pointed out to Piaget that all the half stages were stages also. Since that time there have been many stage theories proposed. Only the ones that cover at least infancy thought adulthood are mentioned here. These include Kurt W. Fischer's Skill Theory and Michael Commons and Francis Asbury Richards' Model of hierarchical complexity. There are now 15 stages, with 4 being added beyond Formal and one added between the beginning of preoperations and preoperations. Most stage sequences map onto one another. PostPiagetian stages are devoid of content and context and are therefore very powerful and general.