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University of Guelph
Family Relations and Human Development
FRHD 1020
Susan Chuang

Human Development 1 Chapter 4: Infancy Growth and Change in Infancy Changes in Height and Weight  Babies grow at a faster rate in their first year than at any later time of life.  Birth weight doubles by the time the infant is 5 months old, and triples by the end of the first year, to about 10 kilos on average.  At 6 months, a well-nourished baby looks on the plump side, but by year 1, the child lose much of their baby fat, and the trend toward a lower ratio of fat to body weight continues until puberty.  Growth in height in the first year is uneven, occurring in spurts rather than steadily.  Cephalocaudal principle: principle of biological development that growth tends to begin at the top, with the head, and then proceeds downward to the rest of the body.  Proximodistal principle: principle of biological development that growth proceeds from the middle of the body outward. Teeth and Teething.  Teething: period of discomfort and pain experienced by infants as their new teeth break through their gums  There are several signs that a baby has begun teething, even if a tooth has not yet broken through.  Parents might notice more drooling, more coughing, and perhaps a rash around the mouth. Babies also often seize the opportunity for something to bite when teething.  They also tend to become irritable.  Some may be reluctant to breast or bottle feed because the suction created from feeding adds to their discomfort. Brain Development  Neurotransmitter: chemical that enables neurons to communicate across synapses.  Axon: part of a neuron that transmits electric impulses and releases neurotransmitters.  Dendrites: part of the neuron that receives neurotransmitters.  The number of neurons in the brain drops by age 2 to about one-half what it was at birth.  Overproduction/exuberance: burst in the production of dendritic connections between neurons.  At birth the neurons have few interconnections, but by age 2 each neuron is connected to hundreds or even thousands of other cells.  Myelination: process of growth od the myelin sheath around the axon of a neuron. Myelination is active in the early years of life but continues at a slower rate until about age 30.  Synaptic pruning: Process in brain development in which dendritic connections that are used become str9onger and faster and those that are unused whither away. Brain Specialization  The brain is divided into 2 major regions: the hindbrain, midbrain, and forebrain.  The hindbrain and midbrain mature earliest and perform the basic biological functions necessary to life.  The forebrain is divided into 2 main parts, the limbic system and the cerebral cortex.  The structures of the limbic system include the hypothalamus, the thalamus and the hippocampus.  The hypothalamus plays a role in monitoring and regulating our basic animal functions, including thirst, hunger, body temperature, sexual desire, and hormonal levels.  The Thalamus acts as a receiving and transfer center for sensory information from the body to the rest of the brain.  The hippocampus is crucial to memory.  Cerebral cortex: outer portion of the brain, containing four regions with distinct functions  Lateralization: specialization of functions in the 2 hemispheres of the brain The plasticity of the Infant Brain  Plasticity degree to which development can be influenced by environmental circumstances.  High plasticity of the Infant brain makes it adaptable but also vulnerable Sleeping Changes  Two important issues of sleep infancy are the risk of dying during sleep and the issue of whom infants should sleep with. For both issues, there are important cultural variations. Sudden Infant Death Syndrome (SIDS)  Sudden infant death syndrome (SIDS): death within the first year of life due to unknown reasons, with no apparent illness or disorder  Although deaths from SIDS have no clear cause, there are several factors known to put infants at risk including: o Sleeping stomach down instead of flat on the back o Low birth weight and low Apgar scores o Having a mother who smoked during pregnancy, or being around smoke during infancy o Soft bedding, sleeping in an overheated room, or wearing two or more layers of clothing during sleep. Human Development 3 Chapter 4: Infancy  Our theory is that babies’ vulnerability to SIDS at 2-4 months old reflects the transition from reflex behaviour to international behaviour.  One thing that is certain is that sleeping on the back instead of the stomach makes an enormous difference in lowering the risk of SIDS Cosleeping: Who sleeps with whom?  Cosleeping: cultural practice in which infants and sometimes older children sleep with one or both parents.  Custom complex: distinctive cultural pattern of behaviour that reflects underlying cultural beliefs.  Parents in an individualistic culture may fear that cosleeping will make infants and children too dependent.  However, children who cosleep with their parents in infancy are actually more self-reliant.  SIDS is almost unknown in cultures where cosleeping is the norm. In the United States, where most parents do not cosleep, rates of SIDS are amoung the highest in the world.  There appears to be some reasons for this pattern o Most parents and infants in cosleeping cultures sleep on relatively hard surfaces such as a mat, on the floor, or a futon, thus avoiding the soft bedding that is sometimes implicated in SIDS. o Infants who cosleep breast-feed more often and longer than infants who do not, and these frequent episodes of arousal in the course of the night make SIDS less likely o Cosleeping mothers tend to lay their infants on their backs to make the mother’s breast more easily accessible for breast feeding. Infant Health Nutritional Needs Introduction of solid foods.  Cultures vary widely in when they introduce solid foods to infants, ranging from those that introduce it after just a few weeks of life to those that wait until the second half of the first year.  At 4-5 months, infants still have a gag reflex that causes them to spit out any solid item that enters their mouths.  In the West, paediatricians generally recommend introducing solid food during the fifth or sixth month of life. Malnutrition in Infancy.  Malnutrition in infancy is usually due to the mother is so ill or malnourished herself that she is unable to produce an adequate supply of breast milk. OR, she may have a disease that can be communicated through breast milk, such as tuberculosis or HIV, and she has been advised not to breast-feed.  Marasmus: disease in which the body wastes away from lack of nutrients. Infant Mortality Causes and prevention of infant mortality  It takes place during the first month of life and is usually due to sever birth defects or low birth weight, or is an indirect consequence of the death of the mother during childbirth.  Diseases are another major cause of infant mortality worldwide.  The number one source of infant mortality beyond the first month but within the first year is diarrhea  Oral rehydration therapy (ORT): treatment for infant diarrhea that involves drinking a solution of salt and glucose mixed with clean water.  Although millions of infants wordwide die yearly from lack of adequate mutation and medical care, in the past half century many diseases that formerly killed infants and young children have been reduced or even eliminated due to vaccines that provide immuniation.  Typically, children receive vaccinations for these diseases in the first or second year of life. However, there is a great deal of variability worldwide in how likely children are to be vaccinated.  Although rumours have circulated that some vaccinations may actually cause harm to children, for example by triggering autism, scientific studies have found no basis for these claims. Cultural Beliefs and Practices to Protect Infants  Historically, parents had no immunizations or other medical care for their infants, but they often went to great lengths to try and protect their babies from death.  Although they knew nothing about the physiological causes of illness and had no effective medical remedies, they attempted to devise practices that would allow their infants to avoid harm.  Today, in cultures where medical remedies for infant illness are scarce, parents often resort to magical practices intended to protect their babies from disease and death  The Fulani people of West Africa believe that a sharp knife should always be kept near the baby to ward off the witches and evil spirits that may try to take its soul.  Finally, the Ifalaluk of Micronesia believe that neonates should be covered with cloths in the weeks after birth to encourage sweating which they believe helps babies grow properly. Baby on the Move: Motor and Sensory Development. Motor Development  Gross motor development: Development of motor abilities including balance and posture as well as whole-body movements such as crawling. Human Development 5 Chapter 4: Infancy  Fine motor development: development of motor abilities involving finely tuned movements of the hands such as grasping and manipulated Gross Motor Development Milestones of Gross Motor Development in Infancy Milestone Average age Age range* Holding head up 6 weeks 3 weeks-4 months unsupported Rolling over 4 ½ months 2-7 months Sitting without support 7 months 5-9months Crawling 7 months 5-11 months Standing 11 months 5-12 months Walking with support 11 ½ months 7-12 months (cruising) Walking 12 months 9-17 months  How much infants’ gross motor development is ontogenetic—meaning that it takes place due to an inborn, genetically based, individual timetable—and how much of it is due to the experience of learning? As with most aspects of development, both genetics and environment are involved.  Most developmental psychologists view gross motor development in infancy as a combination of the genetic timetable, the maturation of the brain, support and assistance from adults for developing the skill, and the child’s own efforts to practice the skill.  Looking at infant gross motor development across cultures provides a vivid picture of how genetic and environments interact.  Even after they learn to crawl at about 6 months old and walk at about one year old, infants in traditional cultures are restricted in their exercise of these new motor skills.  Some cultures actively promot infants’ grow motor development.  Infants in cultures where they are strapped to the mother’s back or swaddled learn to crawl and walk at about the same ages as infants in cultures that neither bind their infants nor make special efforts to support gross motor development.  Infants in cultures where gross motor development is actively stimulated may develop slightly earlier than in cultures where parents make no special effort. Fine Motor Development  Opposable thumb: position of the thumb apart from the fingers, unique to humans, that makes possible fine motor movements.  The principal milestones of fine motor development in fancy are reaching and grasping. Oddly, infants are better at reaching during the first month of life than they are at 2 months of age.  Neonates will extend their arms awkwardly toward an interesting object, an action called prereaching, although it is more like a swipe or a swing than a well-coordinated reach.  At about 3 months, reaching reappears, but in a more coordinated and accurate wat than in the neonate.  Grasping is also a neonatal reflex and this means it is not under intentional control. Like reaching, grasping becomes smoother and more accurate furing the first year, as infants learn to adjust the positions of their fingers and thumbs even before their hand reaches the object, and to adjust further once they grasp the object, in response to its size, shape and weight.  At the same time as infants’ abilities for reaching and grasping are advancing, they are learning to coordinate the two.  Learning to coordinate reaching and grasping is the basis of further development of fine motor skills, and an essential part of human motor functioning.  By 9-12 months, infants learn the “pincer grasp” that allows them to hold a small object between their thumb and forefinger. Depth Perception  Depth perception: ability to discern the relative distance of objects in the environment.  Binocular vision: Ability to discern the relative distance of objects in the environment.  Depth perception becomes especially important once babies become mobile.  This was the first demonstrated in a classis experiment by Eleanor Gibson and James Walk. o They made a glass covered table with a checkered pattern was just below the surface whereas on the other half of it was about two feet below, giving the appearance of a visual cliff in the middle of the table. o The infants in the study were happy to crawl around on the shallow side of the cliff, but most would not cross over to the deep side, even when their mothers stood on the other side of it and beckoned them encouragingly. This showed that they have learned death perception. Intermodal Perception  Intermodal perception: integration and coordination of information from the various senses.  Even neonates possess a rudimentary form of this ability. When we hear a sound they look in the direction it came from, indicating coordination of auditory and visual responses.  The early development of intermodal perception helps infants learn about their physical and social world. Human Development 7 Chapter 4: Infancy SECTION 2: Cognitive Development Piaget’s Theory of Cognitive Development.  Mental structure: in Piaget’s theory of cognitive development, the cognitive systems that organize thinking into coherent patterns so that all thinking takes place on the same level of cognitive functioning.  Cognitive-developmental approach: Focus on how cognitive abilities change with age in stage sequence of development, pioneered by Piaget and since taken up by other researchers. What Drives Cognitive Development?  Maturation: concept that an innate, biologically based program is the driving force behind development.  Along with maturation, Piaget emphasized that cognitive development is driven by the child’s efforts to understand and influence the surrounding environment  Schemes: Cognitive structures for processing, organizing, and interpreting information.  The two processes involved in the use of schemes are assimilation and accommodation.  Assimilation: altering new information to fit an existing scheme  Accomodation: changing a scheme to adapt to new information. Ages Stage Characteristics 0-2 Sensorimotor Capable of coordinating the activities of the senses with motor activities 2-7 Preoperational Capable of symbolic representation, such as in language, but with limited ability to use mental operations 7-11 Concrete operational Capable of using mental operations, but only in concrete, immediate experience; difficulty thinking hypothetically. 11-15 and up Formal Operations Capable of thinking logically and abstractly; capable of formulating hypotheses and testing them systematically; thinking is more complex; and can think about
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