Cognitive development refers to how people understand the world through genetic and learned factors. Jean Piaget believed children progress through distinct stages of intellectual development in a gradual process. He proposed that intellect grows through assimilation, incorporating new experiences into existing understanding, and accommodation, modifying existing understanding to fit new information. Piaget identified four main stages of cognitive development: sensory motor, preoperational, concrete operational, and formal operational.

1. COGNITIVE DEVELOPMENT
 refers to how a person perceives, thinks, and gains an
understanding of his/her world through the interaction and
influence of genetic and learned factors
 Jean Piaget believed that all children pass through a series
of distinct stages in intellectual development. As a child
moves to a new stage, his/her thinking is qualitatively
different from that of the previous stage. He saw this
progression from one stage to the other as a continuous
and gradual process
 He was convinced that intellect grows through processes
he called assimilation and accommodation

2.  Assimilation – using existing patterns in new situations, for
example, an infant that has been sucking on a nipple is suddenly
presented with a pacifier and starts sucking on it. Since a pacifier is
similar to a nipple, the infant can adjust the way his mouth fits
around the pacifier, in other words, the infant assimilates the pacifier,
a new object, to an existing schema
 Not every object infants encounter can be assimilated to an existing
schema. When an infant encounters a blanket, for instance, she
may try to suck on it. However, because the qualities of a blanket
are so unlike the qualities of a nipple or thumb, she is unable to
assimilate the blanket as an object to suck on
 Accomodation – when existing ideas are modified to fit new
requirements, that is, she will modify the she sucks, perhaps by
choosing a corner of the blanket and suck on that, using
approximately but not exactly the same schema as when sucking on
a nipple

3. I. SENSORY MOTOR STAGE (BIRTH – 2 YRS)
# Intellectual level is nonverbal
# Looking, grasping, and other actions
# Emergence of object permanence – concept that objects
continue to exist even when they are hidden from view
# By about age 11/2, a child begins to actively pursue
disappearing objects and by age 2, a child can anticipate the
movement of an object behind a screen
II. PREOPERATIONAL STAGE (2 – 7 YRS)
- Develop an ability to think symbolically and to use language
- Childs thinking makes little or no use of reasoning and logic
- Child is egocentric – thought that is self-centered and fails to
consider the viewpoints of others
- Children do not understand certain rules of operation, such as
irreversibility and centration

4. - Irreversibility – the inability to mentally reverse a sequence of
events or logical operations e.g. 2 x 3 = 6 but when asked
3 x 2 = ?
- Centration – the tendency to focus, or center, on only one
aspect of a situation and ignore other important aspects of the
situation e.g. center only on the height of the beaker
III. CONCRETE OPERATIONAL STAGE (7 – 11 YRS)
- Mastery of the concept of conservation – concept that the
volume of matter remains unchanged when the shape of
objects changes e.g. they understand that pouring liquid from
a tall glass into a shallow dish does not reduce the amount of
liquid
- During concrete operational stage, children can perform
operation but only on images of tangible “concrete” objects

5. IV. FORMAL OPERATIONAL STAGE (11 – 15 YRS)
- Child’s thinking is applied to abstract concepts
- Becomes capable of hypothetical thinking
- Is capable of deductive reasoning
- Capable of systematic formulation and testing of concepts
- Individuals can perform abstract reasoning necessary to
comprehend algebra, psychology, physics and philosophy
- The ability to think in formal operational stage also allows the
thinker to explore his own values and beliefs and compares
them to those of their parents, friends and teachers
- Individuals often fail to differentiate between what others are
thinking and their own thoughts, this is known as adolescent
egocentrism – the belief that one is the focus of others’
thoughts and attention