Biological Aspects of Development: From Fertilized Egg to Infant
Unit 7. Developmental Psychology: How Children Become Adults
A familiar proverb states, “As the twig is bent, so grows the tree/'' Meant to apply as a metaphor to the raising of children, this saying contains within it an entire justification for the study of developmental psychology. Every adult was once a child., and the adult was shaped and formed by experiences during childhood. Psychologists as far apart in many of their assumptions and conclusions as Sigmund Freud and John Watson subscribed to the general view that in order to understand adult behavior it is necessary to study child behavior.
The contemporary approach to developmental psychology expands the concept of development well past childhood and adolescence. There are also developmental stages associated with adulthood.
Developmental psychology is the study of the growth and maturation of the individual over an extended span of time. Child psychology is a subset of developmental psychology. It concerns itself primarily with the study of the individual from birth to the beginning of adolescence (usually around the age of twelve or thirteen). Adolescent psychology is also a subset of developmental psychology. It concerns itself primarily with the study of the individual from the beginning of adolescence to its end (usually around the age of eighteen). Sometimes child psychology refers loosely to both child and adolescent psychology.
Biological Aspects of Development: From Fertilized Egg to Infant
Freud said. '‘“Biology is destiny."' Although Freud is usually thought of as a psychologist, not a biologist, his early academic love was the study of biology. He was trained as a biologist before he became a medical doctor. Freud’s statement recognizes that, although learning and experience shape behavior, much of our behavior is based on a foundation of genetic givens. For example, if a fertilized egg contains an XX chromosome pattern, the individual will become a female.
If the fertilized egg contains an XY pattern, the individual will become a male.
The fact that one is a female or a male will be an important determining actor in countless behaviors from birth to death. For a second example, let’s say that a fertilized egg contains three chromosomes where normally there is a twentyfirst pair of chromosomes. This is a chromosomal anomaly known as trisomy 21. The individual will suffer from Down’s syndrome, a pattern characterized by mental retardation and poor health. Freud’s view that biology is destiny has much to recommend it. (A chromosomal anomaly is an abnormal chromosome pattern.)
The individual begins when a given sperm and a given ovum unite. Provided by the father, the sperm, or more completely spermatozoon, is a highly mobile cell with a tail. Provided by the mother, the ovum is a single egg cell. Both the sperm and the ovum contain twenty-three single chromosomes. When the egg is fertilized, there will be twenty-three pairs of chromosomes. Meiosis is the process that reduces pairs of chromosomes to the individual chromosomes found in either the sperm or the ovum. Mitosis, on the other hand, is the process that allows a cell to reproduce itself. This process starts with twenty-three pairs of chromosomes, and all twenty-three pairs are replicated. It is mitosis that makes possible the growth of the individual from one cell, the fertilized egg. to billions of cells.
A chromosome is a rodlike structure that contains genes. A chromosome is so named because it is capable of picking up a dye, making the structure visible under a microscope. Cbromo refers to color, and soma refers to body. Thus a chromosome is a “colored body.”
A gene is the basic unit of heredity. It is made up of strands of deoxyribonucleic acid (DNA), a complex organic molecule with the unique ability to replicate itself. It is the genes that do all of the active work associated with hereditary influence. The relationship of a chromosome to a group of genes is similar to the relationship of a ship to its crew. The chromosome is the ship. The genes are the members of the crew.
There are four stages associated with conception and birth: (1) zygote. (2) embryo. (3) fetus, and (4) neonate. When a sperm and an ovum unite to form a fertilized egg. the new being is called a zygote. The stage of the zygote lasts for one week. During this stage the zygote develops rapidly from a single cell to a large group of cells. A zygote may be imagined as a ball of cells without differentiation.
From one week to seven weeks, the new being is called an embryo. As the cells continue to divide and replicate themselves, some differentiation begins to take place. Three basic embryonic layers emerge: (1) ectoderm, (2) mesoderm, and (3) endoderm. The ectoderm is the outer layer of cells, and it will become the sense organs, skin, and nervous system. The mesoderm is the middle layer of cells, and it will become the heart, bones, and muscles. The endoderm is the internal layer of cells, and it will become the stomach, intestines, and lungs.
From seven weeks to birth, the new being is called a fetus. Fetal development is rich and complex. The cells continue to divide, and they become specialized in their structures and functions. Brain cells (neurons), skin cells, hair cells, fat cells, and many other kinds of cells form. The head, limbs, fingers and toes, and other features of the body appear. In the typical case, the stage of the fetus lasts a little over seven months, making the total time from conception to birth about nine months.
At birth the new being is called a neonate. 2\го means “new."' And hsu means “birth." Thus the word Htonsiг simply means “newborn."' If the neonate loses weight after birth, then he or she is not referred to as an infant until birth weight has been regained. The word infant is from Latin roots meaning “without speech.”
Freud’s Theory of Psychosexual Development: From the Oral to the Genital Stage
The infant is on the threshold of continuing biological and psychological development. Freud'-s theory of development has been highly influential. First proposed about eighty years ago, it has had a large impact on the way in which both psychologists and parents have thought about sexual development in children. It has also influenced child-rearing practices.
According to Freud, there are five stages in psychosexual development. Psychosexual development refers to the development of a sexual identity, attitudes
toward sexual behavior, and emotional reactions to sexual stimuli. Sexual development, in Freud'-s view, is much more than biological. Identity, attitudes, and emotional reactions are psychological in nature. That is why Freud used the term psycbostxualinstead of simply sixual to refer to the kind of development he wanted to study.
The five stages of psychosexual development are: (1) oral, (2) anal, (3) phallic,
(4) latency, and (5) genital. In order to appreciate Freud’s theory, it is necessary to introduce a concept he employed called libido. Libido is thought of as psychosexual energy, and Freud hypothesized that it is invested in different zones of the body during the various stages of psychosexual development. These zones, or areas, of the body are called the erogenous zones, and they are associated with sexual pleasure. The principal erogenous zones are the oral, anal, and genital areas of the body.
The latency stage lasts for about six years. It begins at age six or seven and ends at age twelve or thirteen. In effect, it ends when puberty begins. The libido has migrated from the oral to the anal to the phallic zone. Now it goes underground and becomes, to surface appearance, dormant. The libido goes under- psychological conflict. Freud suggested that the child has a certain amount of dawning sexual desire and tends to make the parent of the opposite sex the focus of this desire. However, due to moral development, guilt sets in and the libido goes into hiding.
It is repressed to an unconscious level.
The emotional conflict associated with the child's forbidden wish to seek sexual expression with a parent is called the Oedipus complex. Freud was inspiredto coin this term from his familiarity with the Greek tragedy Oedipus ILr.v (i.e.,
“Oedipus, the King’ll written by the dramatist Sophocles around 400 B.C. In the
play, Oedipus inadvertendy kills his own father and unknowingly marries his own
mother. Writing in German in Austria, Freud used the term Oedipus complex to
refer to either males or females. Later authors, writing in the United States, sometimes
use the term Oedipus complex to refer to males and Electra complex to
refer to females. (Electra is also a Greek play. Written by the dramatist Euripides,
also around 400 B.C., it bears some resemblance to Oedipus Rsx)
The genital stage begins at twelve or thirteen and continues throughout adulthood. With puberty, biological maturation can no longer be denied. The repression lifts and the individual becomes intensely conscious of sexual interest.
Libido makes a final shift from the phallus to a more general interest in the opposite sex. In normal development, the individual transfers sexual interest away from the parent and toward potential partners who are not members of the family.
Freud’s outline suggests that much can go wrong with sexual development.
There can be too much excitation and arousal associated with one of the stages. Or, conversely, there can be too much inhibition, punishment, or emotional injury associated with one of the stages. Freud indicated that either too much excitation or too much inhibition can induce a fixation of libido, meaning the libido is to some extent “stuck''' in one particular erogenous zone. According to Freud, such fixations may play a role in various problems and maladaptive behaviors, including overeating, constipation, pedophilia, exhibitionism, fetishism, and sexual dysfunctions.
Freud‘‘s theory is, as are all theories, a set of concepts, not a set of facts. Freud’s theory has received its share of criticism. For example, research suggests that although self-stimulation of the phallus is relatively common in children, it is not, as Freud thought, a behavior pattern demonstrated by almost all children. The psychoanalyst Karen Homey, one of Freud’s advocates, rejected the biological sexuality of the Oedipus complex. Instead, Homey suggested that, for example, a male child is often jealous of the position of power and importance the father has with the mother. The male child has a forbidden wish to take the father’s place, not so much as a sexual rival, but as a psychological one.