Psychology Development Prenatal Development, Infancy & Childhood
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Prenatal Development
Development happens quickly during the prenatal period, which is the time between conception and birth. This period is generally divided into three stages: the germinal stage, the embryonic stage, and the fetal stage.
Stage 1: The Germinal StageThe two-week period after conception is called the germinal stage. Conception occurs when a sperm cell combines with an egg cell to form a zygote. About thirty-six hours after conception, the zygote begins to divide quickly. The resulting ball of cells moves along the mother’s fallopian tube to the uterus.
Around seven days after conception, the ball of cells starts to become embedded in the wall of the uterus. This process is called implantation and takes about a week to complete. If implantation fails, as is quite common, the pregnancy terminates. One key feature of the germinal stage is the formation of a tissue called the placenta. The placenta has two important functions:
- Passing oxygen and nutrients from the mother’s blood into the embryo or fetus
- Removing waste materials from the embryo or fetus
Stage 2: The Embryonic StageThe embryonic stage lasts from the end of the germinal stage to two months after conception. The developing ball of cells is now called an embryo. In this stage, all the major organs form, and the embryo becomes very fragile. The biggest dangers are teratogens, which are agents such as viruses, drugs, or radiation that can cause deformities in an embryo or fetus. At the end of the embryonic period, the embryo is only about an inch long.
Stage 3: The Fetal StageThe last stage of prenatal development is the fetal stage, which lasts from two months after conception until birth. About one month into this stage, the sex organs of the fetus begin to form. The fetus quickly grows as bones and muscles form, and it begins to move inside the uterus. Organ systems develop further and start to function. During the last three months, the brain increases rapidly in size, an insulating layer of fat forms under the skin, and the respiratory and digestive systems start to work independently.
Fetal Viability
Around twenty-two to twenty-six weeks after conception, the fetus reaches the age of viability, after which it has some chance of surviving out-side the womb if it is born prematurely. The chances of a premature baby’s survival increase significantly with each additional week it remains in the mother’s uterus.
Adverse Factors Affecting Fetal Development
Although the womb provides protection, the fetus remains indirectly connected to the outside world through its mother. Several factors that are linked to the mother can harm the fetus:
- Poor nutrition
- Use of alcohol
- Smoking
- Use of certain prescription or over-the-counter drugs
- Use of recreational drugs such as cocaine, sedatives, and narcotics
- X-rays and other kinds of radiation
- Ingested toxins, such as lead
- Illnesses such as AIDS, German measles, syphilis, cholera, smallpox, mumps, or severe flu
Fetal Alcohol Syndrome
Mothers who drink heavily during pregnancy may have babies with fetal alcohol syndrome. Babies with this syndrome may have problems such as small head size, heart defects, irritability, hyperactivity, mental retardation, or slowed motor development. Fetal alcohol syndrome is incurable.
Infancy and Childhood
Babies come into the world with many innate abilities, or abilities that are present from birth. At birth, they possess motor reflexes such as the sucking reflex and the grasping reflex. Newborns can also hear, smell, touch, taste, and see, and these sensory abilities develop quickly.
Motor Development
Motor development also progresses quickly. Motor development is the increasing coordination of muscles that makes physical movements possible. Developmental norms tell us the median age at which babies develop specific behaviors and abilities. Babies often deviate a fair amount from these norms.
Researchers used to think motor skill development could be explained mostly by maturation, genetically programmed growth and development. According to this view, babies learn to sit up, pull themselves to a standing position, and walk at particular ages because they are hard-wired that way. However, recent research suggests that motor development isn’t just a passive process. Although maturation plays a large role, babies also actively develop motor skills by moving around and exploring their environments. Both maturation and experience influence motor development.
It’s Not All Maturation
Maturation plays a much greater role in the development of early motor skills, such as crawling and walking, than in development of later motor skills, such as juggling or playing basketball. The development of later motor skills depends on genetic predisposition, exposure to good teachers, and social factors.
Cultural differences also affect how quickly motor skills develop, although the timing and sequence of early motor skill development remains similar across all cultures.
Example: In cultures where babies receive early training in sitting up, standing, and walking, they develop these skills earlier. Conversely, in other cultures, mothers carry babies most of the time, and babies develop these skills later.
Temperament
Some babies have fussy personalities, while others have chirpy or quiet natures. These differences result from temperament, the kind of personality features babies are born with. Researchers generally agree that temperament depends more on biological factors than on environment. In the 1970s, Alexander Thomas and Stella Chess, two researchers who study temperament, described three basic types of temperament: easy, slow to warm up, and difficult. In their research, 40 percent of the children were easy, 15 percent were slow to warm up, and 10 percent were difficult. The remaining 35 percent of the children displayed a mixture of these temperaments:
- Easy children tend to be happy and adapt easily to change. They have regular sleeping and eating patterns and don’t upset easily.
- Slow-to-warm-up children tend to be less cheerful and less adaptable than easy children. They are cautious about new experiences. Their sleeping and eating patterns are less regular than those of easy children.
- Difficult children tend to be glum and irritable, and they dislike change. Their eating and sleeping patterns are irregular.
Attachment
Attachment is the close bond between infants and their caregivers. Researchers used to think that infants attach to people who feed them and keep them warm. However, researchers Margaret and Harry Harlow showed that attachment could not occur without contact comfort. Contact comfort is comfort derived from physical closeness with a caregiver.
The Harlows’ Baby Monkeys
The Harlows raised orphaned baby rhesus monkeys and studied their behavior. In place of its real mother, each baby monkey had two substitute or surrogate mothers. One “mother” had a head attached to a wire frame, warming lights, and a feeding bottle. The other “mother” had the same construction except that foam rubber and terry cloth covered its wire frame. The Harlows found that although both mothers provided milk and warmth, the baby monkeys greatly preferred the cloth mother. They clung to the cloth mother even between feedings and went to it for comfort when they felt afraid.
Responsive Mothering
Psychologist Mary Ainsworth and her colleagues found that attachment happens through a complex set of interactions between mothers and infants. The infants of sensitive, responsive mothers have stronger attachments than the infants of insensitive mothers or mothers who respond inconsistently to their infants’ needs. However, an infant’s temperament also plays a role in attachment. Difficult infants who fuss, refuse to eat, and sleep irregularly tax their mothers, which makes it hard for the mothers to be properly responsive.
Attachment Styles
Ainsworth devised an experiment called the Strange Situation in order to study attachment behavior. She asked each mother in the sample to bring her infant to an unfamiliar room that contained various toys. After the mother and infant had spent some time in the room, a stranger entered the room and tried to play with the infant. A short while later, the mother left the room, leaving the infant with the stranger. Then the mother returned to the room, and the stranger left. A little later, the mother left the room again, briefly leaving the infant alone. Finally, the mother returned to the room.
Based on her observations of infants’ behavior in the Strange Situation, Ainsworth described three types of attachment patterns:
- Secure attachment: Most infants in the sample had a secure attachment to their mothers. These infants expressed unhappiness when their mothers left but still played with the stranger. When their mothers returned, the infants looked happy. The infants displayed greater attachment to their mothers than to the stranger.
- Anxious-ambivalent attachment: Some infants showed a type of insecure attachment called an anxious-ambivalent attachment. These infants became upset when their mothers left but resisted contact with their mothers when they returned.
- Avoidant attachment: Other infants showed a type of insecure attachment called an avoidant attachment. These infants didn’t seem upset when their mothers left and avoided their mothers when they returned. Researchers did not see a significant difference in the way these infants treated their mothers and the stranger.
Culture and Attachment Style
Culture can influence attachment style because different cultures have different child-rearing practices. Ainsworth’s research in the United States showed that most of her white, middle-class sample of infants had a secure attachment to their mothers. However, in Germany, where parents encourage independence from an early age, a much higher proportion of infants display an avoidant attachment, according to Ainsworth’s classification. In Japan, where infants rarely separate from their mothers, the avoidant style is nonexistent, although a higher proportion of anxious-ambivalent attachments occurred than in the United States.
Separation Anxiety
Whether they are securely attached or not, most babies do experience separation anxiety. Separation anxiety is the emotional distress infants show when they separate from people to whom they are attached. Separation anxiety typically begins at about six to eight months of age and reaches peak intensity when an infant is about fourteen to eighteen months old.
Day Care
Controversy surrounds the question of whether or not to place children in day care. Some research has suggested that babies have a greater chance of developing insecure attachments if a nonparental figure cares for them for more than twenty hours per week. However, most of the evidence suggests that day care doesn’t create poor attachment. Studies have even shown that day care can have positive effects on social development.
Gender Development
Sex isn’t the same as gender. Sex refers to a biological distinction between males and females. An example of sex difference is the timing of puberty. Because of biological processes, girls’ sexual organs mature before those of boys. Gender refers to a learned distinction between masculinity and femininity. An example of gender difference is girls’ and boys’ attitudes toward dolls. Very early on, American society teaches boys that playing with dolls is considered a girlish thing to do. Gender stereotypes are societal beliefs about the characteristics of males and females.
Gender Differences
Some gender differences exist, although certainly not as many as stereotypes suggest. For example, starting in preschool, gender differences arise in play behavior. Boys prefer playing with boys and girls with girls. Boys prefer to play with boyish toys like trucks and girls with girlish toys like dolls. Different people give different answers for why this is so:
- Researchers who emphasize biological differences between the sexes say that these preferences arise from biological factors such as genetics and evolution, prenatal hormones, or brain structure.
- Researchers who focus on cognitive development believe that these preferences exist because boys and girls develop different gender schemas or mental models about gender.
- Researchers who study learning think that environment produces these preferences. They point out that almost from the moment of birth, girls and boys receive different treatment. Gender preferences, these researchers say, simply reflect what society teaches children about gender.
