Developmental Psychology
What Is Developmental Psychology?
Developmental psychology is a branch of psychology which studies the growth and maturation of a person over time.
This includes things such as physical, cognitive and social changes, and how each of these affects us during the different stages of our life.
Child psychology is a subset of developmental psychology, and focuses on the stages of life from birth to the beginning of adolescence (around age 12-13).
Adolescent psychology is also a subset of developmental psychology, and is concerned with development during early adolescence to our late teenage years of life (13-19).
The reason why developmental psychology is such an important area of study, is because all adults are products of their childhood and the things they experienced during that childhood.
Therefore by studying infants, children and teenagers developmental psychology can help us to gain a better understanding of the adult mind.
In addition to this, developmental psychology also studies the changes that occur during adulthood, which subsequently allows to us understand the various factors that affect our behaviour from birth to death.
Biological Development
Whilst much of our behaviour comes as a result of the things we learn and experience in life, what underlines the type of behaviour we display is our biology, or more specifically, our genetics.
For example, if a fertilised egg contains two X chromosomes (XX), then the resulting individual will be born a female.
Should however that egg contain an X and a Y chromosome (XY), then that individual will be born a male.
So right from the very start of life our biology plays a hugely significant role in the type of behaviour we will display throughout our entire life.
If you are born a female, then you may like the colour the pink and enjoy playing with dolls. If you are born a male, then you may like the colour blue and enjoy playing with toy cars or action men.
Of course I am stereotyping the sexes here, but this is only done to demonstrate how a small difference in our biology (our chromosomal patterns) can result in us behaving in one way or another.
Trisomy 21
Another example of how biology can affect our behaviour at the chromosomal level, can be found with people who suffer from Down’s syndrome.
These individuals are born with a chromosomal abnormality called trisomy 21, which results in three chromosomes instead of the usual pair. The effect of this is mental retardation, poor health and a shortened lifespan.
This view of biology playing a significant role in development was something which was held by Sigmund Freud, who is quoted as saying “Biology is destiny”.
Whether or not biology is our ultimate destiny is open to debate, because as is shown with feral children, even though our genetics may give us the potential to achieve something, it is the environment which determines whether or not we will realise that potential.
Sperm, Ovum & Chromosomes
Life begins when a sperm (spermatozoon) provided by the father, unites with an egg (ovum) provided by the mother.
Both the sperm and egg contain twenty-three single chromosomes, and when the ovum is fertilised these chromosomes combine to form twenty-three pairs of chromosomes.
Through the process of mitosis, these chromosomal pairs in the fertilised egg are replicated into daughter cells which each contain the same number of chromosomes as the original egg.
These daughter cells then continue to divide, eventually producing billions of cells.
Each chromosome contains a series of genes, which are ultimately responsible for the various characteristics we develop when we are born and then display throughout our life.
For example, one person may have a gene that gives them blonde hair, whilst another person may have a gene that gives them brown hair.
These genes (and their resulting characteristics) are inherited from both the mother and father. They are therefore passed on from generation to generation through the process of sexual reproduction.
Conception & Birth
There are four stages associated with conception and birth :
1 - Zygote
A zygote is a fertilised egg (formed when the sperm and ovum unite).
This stage lasts for about one week, and is characterised by the division of one single cell into a large group of cells.
2 - Embryo
After the zygote has been formed its cells continue to divide and replicate, forming a structure known as the embryo. This occurs from weeks one to seven.
During this stage the cells begin to differentiate (become specialised) and form three distinct embryonic layers.
The Ectoderm
Ectoderm basically means outside skin, and will eventually become the sense organs, skin and nervous system.
The Mesoderm
Mesoderm basically means middle skin, and will eventually become the heart, bones, connective tissue and muscles.
The Endoderm
Endoderm basically means inside skin, and will eventually become the inner lining of the stomach, intestines and lungs.
3 - Foetus
From weeks seven to birth the embryo becomes the foetus, during which the cells of the foetus continue to divide and become more specialised.
During this period cells such as brain cells, skin cells and hair cells are formed, and later the body will start to form as the head and limbs begin to appear.
The foetal stage typically lasts for around seven months, which makes the time from conception to birth around nine months.
4 - Neonate
Neo means “new” and nate means “birth”. A neonate is therefore a newborn, something most people simply refer to as a baby.
Technically a baby is an infant, which is a neonate that has gained weight after birth and can neither walk nor talk.
Developmental Psychology Summary
• Developmental psychology is the study of the changes that occur throughout a person’s lifetime and how those changes affect them.
• Child psychology is the study of the development of children.
• Adolescent psychology is the study of the development of adults.
• Biology plays a big role in determining the type of behaviour we display throughout our life.
• The environment can help or hinder our biological potential.
• A zygote is a fertilised egg.
• The embryo undergoes a process of differentiation to form three distinct embryonic layers; the ectoderm, the mesoderm and the endoderm.
• The foetus begins to develop specialised cells, and starts to take on the appearance of a human body.
• A neonate is a new born.
