CDFR 2000 Ch 5
CDFR 2000 Ch 5 CDFR 2000
Popular in Child Development I: Prenatal through Middle Childhood
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This 10 page Class Notes was uploaded by AmberNicole on Wednesday October 5, 2016. The Class Notes belongs to CDFR 2000 at East Carolina University taught by Dr. Archana Hegde in Fall 2016. Since its upload, it has received 3 views. For similar materials see Child Development I: Prenatal through Middle Childhood in Child Development and Family Relations at East Carolina University.
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Date Created: 10/05/16
Changes in body proportions Cephalocaudal trend o Latin for "head to tail" o During the prenatal period, the head develops more rapidly than the lower part of the body Proximodistal trend o Growth proceeds, literally, from "near to far" - from the center of the body outward Individual and group differences Growth norms o Height and weight averages for children her age Children of the same age differ in rate of physical growth Best estimate of a child's physical maturity is skeletal age, a measure of bone development Brain Development Two vantage points of brain growth o The microscopic level of individual brain cells o The larger level of the cerebral cortex, the most complex brain structure and the one responsible for highly developed intelligence of our species Development of neurons Neurons o Nerve cells o Store and transmit information o Between them are tiny gaps, or synapses, where fibers from different neurons come close together but do not touch o Neurons send messages to one another by releasing chemicals called neurotransmitters, which cross the synapse o As neurons form connections, stimulation becomes vital to their survival o Neurons that are seldom stimulated soon lose their synapses, in a process called synaptic pruning that returns neurons not needed at the moment to an uncommitted state so they can support future development o Glial cells, which are responsible for myelination, the coating of neural fibers with an insulating fatty sheath (called myelin) that improves the efficiency of message transfer Measuring of brain functioning Electroencephalogram (EEG) o Electrodes embedded in a head cap record electrical brain wave activity in the brain's outer layers- the cerebral cortex o Researchers use an advanced tool called a geodesic sensor net (GSN) to hold interconnected electrodes (up to 128 for infants and 256 for children and adults) in place through a cap that adjusts to each person's head shape, yielding improved brain wave detection Event related potentials (ERPs) o Using the EEG, the frequency and amplitude of brain waves in response to particular stimuli (such as a picture, music, or speech) are recorded in the cerebral cortex o Enables identification of general regions of stimulus induced activity Functional magnetic resonance imaging (fMRI) o While the person lies inside a tunnel shaped apparatus that creates a magnetic field, a scanner magnetically detects increased blood flow and oxygen metabolism in areas of the brain as the individual processes particular stimuli o The scanner typically records images every 1 to 4 seconds; these are combined into a computerized moving picture of activity anywhere in the brain (not just its outer layers) o Not appropriate for children younger than age 5 to 6, who cannot remain still during testing Positron emission tomography (PET) o After injection or inhalation of a radioactive substance, the person lies on an apparatus with a scanner that emits fine streams of X-rays, which detect increased blood flow and oxygen metabolism in areas of the brain as the person processes particular stimuli o As with fMRI, the result is a computerized image of activity anywhere in the brain o Not appropriate for children younger than age 5 to 6 Near infrared spectroscopy (NIRS) o Using thin, flexible optical fibers attached to the scalp through a head cap, infrared (invisible) light is beamed at the brain; its absorption by areas of the cerebral cortex varies with changes in blood flow and oxygen metabolism as the individual processes particular stimuli o The result is a computerized moving picture of active areas in the cerebral cortex o Unlike fMRI and PET, NIRS is appropriate for infants and young children, who can move within limited range during testing Development of the cerebral cortex The cerebral cortex surrounds the rest of the brain, resembling half of a shelled walnut It is the largest brain structure- accounting for 85% of the brain's weight and containing the greatest number of neurons and synapses Regions of the cortex The cortical regions with the most extended period of development are the frontal lobes The prefrontal cortex, lying in front of areas controlling body movement, is responsible for thought- in particular, consciousness, inhibition of impulses, integration of information, and use of memory, reasoning, planning, and problem solving strategies Lateralization and plasticity of the cerebral cortex The cerebral cortex has two hemispheres, or sides, that differ in their functions and the specialization of two hemispheres is called lateralization Brain plasticity o A highly plastic cerebral cortex, in which many areas are not yet committed to specific functions, has a high capacity for learning o And if a part of the cortex is damaged, other parts can take over the tasks it would have handled o The eyes are an exception Messages from the right half of each retina go to the hemisphere; messages from the left half of each retina go to the left hemisphere. Thus, visual information from both eyes is received by both hemispheres Human evidence: victims of deprived early environments Compared with agemates adopted shortly after birth, these children showed extreme stress reactivity, as indicated by high concentrations of the stress hormone cortisol in their saliva – a physiological response linked to persistent illness, delayed physical growth, and learning and behavior problems, including deficits in attention and control of anger and other impulses After sitting on their mother's lap and playing an enjoyable game, preschoolers adopted, on average, at age one and a half years form Romanian orphanages had abnormally low urine levels of oxytocin – a hormone released by the brain that evokes calmness and contentment in the presence of familiar, trusted people Appropriate stimulation Experience – expectant brain growth, refers to the young brain's rapidly developing organization, which depends on ordinary experiences – opportunities to explore the environment, interact with people, and hear language and other sounds Experience-dependent brain growth occurs throughout our lives o It consists of additional growth and the refinement of established brain structures as a result of specific learning experiences that vary widely across individuals and cultures Changing states of arousal Not until the middle of the first year is the secretion of melatonin, a hormone within the brain that promotes drowsiness, much greater at night than during the day Heredity, nutrition, relative freedom from disease, and emotional well-being all affect early physical growth Heredity o As long as negative environmental influences such as poor nutrition or illness are not severe, children and adolescents typically show catch up growth – a return to a genetically determined growth path – once conditions improve o Genetic makeup also affects body weight: the weights of adopted children correlate more strongly with those of their biological than of their adoptive parents Nutrition o Nutrition is especially crucial for development in the first two years because the baby's brain and body are growing so rapidly o Pound for pound, an infant's energy needs are at least twice those of an adult o 25% caloric intake goes to growth Reasons to breastfeed Provides the correct balance of fat and protein o Compared with the milk of other mammals, human milk is higher in fat and lower in protein o This balance, as well as the unique proteins and fats contained in human milk, is ideal for a rapidly myelinating nervous system Ensures nutritional completeness o A mother who breastfeeds need not add other foods to her infant's diet until the baby is 6 months old o The milks of all mammals are low in iron, but the iron contained in the breast milk is much more easily absorbed by the baby's system o Consequently, bottle fed infants need iron fortified formula Helps ensure healthy physical growth o One year old breastfed babies are leaner (have a higher percentage of muscle to fat), a growth pattern that persists through the preschool years and that is associated with a reduction in later overweight and obesity Protects against many diseases o Breastfeeding transfers antibodies and other infection fighting agents from mother to baby and enhances functioning of the immune system o Compared with bottle fed infants, breastfed babies have far fewer allergic reactions and respiratory and intestinal illness symptoms o Breastfeeding in the first four months (especially when exclusive) is linked to lower blood cholesterol levels in adulthood and, thereby, may help prevent cardiovascular disease Protects against faulty jaw development and tooth decay o Sucking the mother's nipple instead of an artificial nipple helps avoid malocclusion, a condition in which the upper and lower jaws do not meet properly o It also protects against tooth deccay due to sweet liquid remaining in the mouths of infants who fall asleep while sucking on a bottle Ensures digestibility o Because breastfed babies have a different kind of bacteria growing in their intestines than do bottle fed infants, they rarely suffer from constipation or other gastrointestinal problems Smooths the transition to solid foods o Breastfed infants accept new solid foods more easily than do bottle fed infants, perhaps because of their greater experience with a variety of flavors, which pass from the paternal diet into the mother's milk Malnutrition Marasmus o Wasted condition of the body caused by a diet low in all essential nutrients o It usually appears in the first year of life when a baby's mother is too malnourished to produce enough breast milk and bottle feeding is also inadequate Kwashiorkor o Caused by an unbalanced diet very low in protein o The disease usually strikes after weaning, between 1 and 3 years of age Emotional well being Growth faltering is a term applied to infants whose weight, height, and head circumference are substantially below age related growth norms and who are withdrawn and apathetic In as many as half such as, a disturbed parent-infant relationship contributes to this failure to grow normally Learning capacities Learning refers to changes in behavior as the result of experience Classical conditioning Classical conditioning possible in young infants o In this form of learning, a neutral stimulus is paired with a stimulus that leads to a reflex response o Once the baby's nervous system makes the connection between the two stimuli, the neutral stimulus produces the behavior by itself Before learning takes place, an unconditioned stimulus (UCS) must consistently produce a reflex, or unconditioned, response (UCR) To produce learning, a neutral stimulus that does not lead to the reflex is presented just before, or at about the same time as, the UCS. Carolyn stroked Caitlin's forehead as each nursing period began. The stroking (neutral stimulus) was paired with the taste of milk (UCS) If learning has occurred, the neutral stimulus alone produces a response similar to the reflexive response. The neutral stimulus is then called a conditioned stimulus (CS), and the response it elicits is called a conditioned response (CR) If the CS is presented alone enough times, without being paired with the UCS, the CR will no longer occur, an outcome called extinction Operant conditioning In operant conditioning, infants act, or operate, on the environment, and stimuli that follow their behavior change the probability that the behavior will occur again o A stimulus that increases the occurrence of a response is called a reinforcer o Removing a desirable stimulus or presenting an unpleasant one to decrease the occurrence of a response is called punishment Habituation Habituation refers to a gradual reduction in the strength of a response due to repetitive stimulation A new stimulus – a change in the environment – causes responsiveness to return to a high level, an increase called recovery Recovery to a new stimulus, or novelty preference, assesses infants' recent memory Like adults, infants shift from a novelty preference to a familiarity preference as more time intervenes between habituation and test phases in research By focusing on that shift, researchers can also use habituation to assess remote memory, or memory for stimuli to which infants were exposed weeks or months earlier Imitation Imitation is copying the behavior of another person Scientists have identified specialized cells in motor areas of the cerebral cortex in primates – called mirror neurons – that may underlie early imitative capacities Mirror neurons fire identically when a primate hears or sees an action and when it carries out that action on its own The sequence of motor development Gross motor development refers to control over actions that help infants get around in the environment, such as crawling, standing, and walking Fine motor development has to do with smaller movements, such as reaching and grasping Presents the age range during which most babies accomplish each skill, indicating large individual differences in rate of motor progress A baby who is a late reacher will not necessarily be a late crawler or walker Dynamic systems perspective helps us understand how motor development takes place Motor skills as dynamic systems Dynamic systems theory of motor development is the mastery of motor skills that involves acquiring increasingly complex systems of action When motor skills work as a system, separate abilities blend together, each cooperating with others to produce more effective ways of exploring and controlling the environment Each new skill is a joint product of the following factors o Central nervous system development o The body's movement capacities o The goals the child has in mind o Environmental supports for the skill Rather than being hardwired into the nervous system, motor behaviors are softly assembled form multiple components, allowing for different paths to the same motor skill Fine motor development: reaching and grasping Newborns also make poorly coordinated swipes, called prereaching Development of reaching and grasping Proprioception is our sense of movement and location in space, arising from stimuli in the body Ulnar grasp is a clumsy motion in which the young infant's fingers close against the palm Infants use the thumb and index finger in a well coordinated pincer grasp Perceptual development Sensation suggests a fairly passive process in which the baby's receptors detect when exposed to stimulation Perception is active in the fact that we organize and interpret what we see Speech perception Brain imaging evidence reveals that in young infants, discrimination of speech sounds activates both auditory and motor areas in the cerebral cortex Tuning in to familiar speech, faces, and music: a sensitive period for culture specific learning Perceptual narrowing effect is perceptual sensitivity that becomes increasingly attuned with age to information most often encountered Analyzing the speech stream They have an impressive statistical learning capacity by analyzing the speech stream for patterns – repeatedly occurring sequences of sounds – they acquire a stock of speech structures for which they will later learn meanings, long before they start to talk around age 12 months Vision Visual acuity is fineness of discrimination and increases steadily throughout the first year, reaching 20/80 by 6 months and in adult level of about 20/20 by 4 years Depth perception Depth perception is the ability to judge the distance of objects from one another and from ourselves Motion is the first depth cue to which infants are sensitive Babies 3 to 4 weeks old blink their eyes defensively when an object moves toward their face as though it is going to hit Binocular depth cues arise because our two eyes have slightly different views of the visual field the brain blends these two images, resulting in perception of depth Beginning at 3 to 4 months and strengthening between 5 and 7 months, babies display sensitivity to pictorial depth cues – the ones artists often use to make a painting look three dimensional Pattern perception A general principle, called contrast sensitivity, explains early pattern preferences Contrast refers to the difference in the amount of light between adjacent regions in a pattern If babies are sensitive to (can detect) the contrast in two or more patterns, they prefer the one with more contrast Combining Pattern Elements Like adults, 3-4 month year olds engage in boundary extension: When re- exposed to a photograph of a natural scene, they remember it as extending beyond its original boundaries Face perception Infants tendency to search for structure in a patterned stimulus applies to face perception Newborns prefer to look at photos and simplified drawings of faces with features arranged naturally (upright) rather than unnaturally (upside down or sideways) Size and shape constancy Size constancy is the perception of an object's size as the same, despite changes in the size of its retinal image Perception of an object's shape as stable, despite changes in the shape projected on the retina, is called shape constancy Intermodal perception Our world provides rich, continuous intermodal stimulation – simultaneous input form more than one modality, or sensory system In intermodal perception, we make sense of these running streams of light, sound, tactile, odor, and taste information, perceiving them as integrated wholes Amodal sensory properties are information that is not specific to a single modality but that overlaps two or more sensory systems Because communication is often intermodal (simultaneously verbal, visual, and tactile), infants receive much support from other senses in acquiring language Understanding perceptual development Differentiation theory – infants actively search for invariant features of the environment – those that remain stable – in a constantly changing perceptual world Affordances are the action possibilities that a situation offers an organism with certain motor capabilities
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