PSY 221_CHAPTER 4 SLIDES.ppt (1).pptx

Developmental Psychology I Fall 2015 Chapter 4 • Physical Development in Infancy and Toddlerhood • The First Two Years of Life Body Growth o The first two years; the most remarkable & busiest time of development. o Rapid changes;  Body & brain  Learning  Motor skills  Perceptual capacities....

Developmental Psychology I Fall 2015 Chapter 4 • Physical Development in Infancy and Toddlerhood • The First Two Years of Life Body Growth o The first two years; the most remarkable & busiest time of development. o Rapid changes;  Body & brain  Learning  Motor skills  Perceptual capacities. HEIGHT: o By the end of 1st year  81.28 cm - Gain 50% in height o By 2 years  91.44 cm. -75% greater in height WEIGHT: o By 5 months  6.8 kg. o At 1 year  10 kg. o At 2 years  13.6 kg. o Grow in spurts; parents describe their babies as irritable & very hungry on the day before spurt. o Around the middle of the first year- gain “baby fat” until about 9 months, then get slimmer o Muscle tissue increases very slowly; strenght & coordination limited. Body Growth  Individual and Group Differences o Male/Female:  Girls slightly shorter, lighter than boys o Ethnic:  African-American > American> Asian o Physical Maturity:  Being heavier or higher does not say anything about physical maturity  The best estimate of a child’s physical maturity is Skeletal Age: It is determined by X-raying the long bones of the body to see the extent to which soft, pliable cartilage (kıkırdak) has hardened into bone  Girls  Greater physical maturity than boys. (May Contribute to greater resitance to harmful environmental influences) Body Growth Changes in Body Proportions • Two growth patterns: • 1) Cephalocaudal Trend: Head to tail  During the prenatal period; head develops more rapidly than the lower part of the body o By age 2  the head: 1/5 & the legs: 1/2 • 2) Proximodistal: “Near to far”; from the center to the outward o Extremities grow later than head, chest, & trunk o Hands & feet: The last.  Brain Development 1)Development of Neurons o The o human brain; consists of 100-200 billion neurons Neurons are nerve cells that store and transmit information o In prenatal period- neurons are produced in the embryo’s neural tube o Then, migrate to form the brain o Once they are in place; they differantiate; form dendrites & axons & synapses o Neurons that are seldom stimulated soon lose their synapses, in a process called synaptic pruning  that returns neurons nor needed at the moment to an uncommitted state so that they can support future development o In all, about 40 percent of synapses are pruned during childhood and adolesecence to reach the adult level o If few neurons are produced after the prenatal period, what causes the dramatic increase in brain size during the first two years? o About half of the brain’s volume consists of 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. o Gains in neural fibers and myelination  Responsible for the extraordinary gain in overall size of the brain Major Milestones of Brain Development  Methods for Measuring Brain Functioning  Electroencephalogram (EEG): measures electrical activity in the brain’s outer layers celebral cortex.  Event-related potentials (ERPs): 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 multiple areas of the cerebral cortex. Enables identification of general regions of stimulus-induced activity.  Functional magnetic resonance imaging (fMRI): Detailed, three dimensional computerized pictures of the entire brain & active areas.  Detects changes in blood flow & oxygen by  Methods for Measuring Brain Functioning  Positron emission tomography (PET): A radiactive glucose molecule is injected & increased blood flow and oxygen metabolism in areas of the brain as the person processes certain stimuli are detected.  Not appropriate for children younger than age 5 to 6.  Near-infrared spectroscopy (NIRS) / Nearinfrared optical topography (NIROT): Most suitable technique for infants and young children.  Optical fibers attached to the scalp using a head cap.  fMRI and NIROT 2) Development of the Cerebral Cortex o Cerebral cortex is the largest brain structure, accounting for 85 percent of the brain’s weight. o The order in which cortical regions develop corresponds to the order in which various capacities emerge in the infant & growing child. o Auditory cortex, visiual cortex, motor cortex & somatosensory cortex develops rapidly. o Language areas (Wernicke’s & Broca’s) active from late infancy through the preschool years. o Development of Frontal Lobes (The Prefrontal Cortex) - takes more time to develop  Consciousness, inhibition of impulses, planning, problem solving, & personality o From age 2-months on, the prefrontal lobes functions more effectively. o BUT, it undergoes especially rapid myelination and formation and pruning of synapses during the preschool and school 2) Development of the Cerebral Cortex  Lateralization of Cerebral Cortex: o Brain has 2 hemispheres (Right &Left) o Some tasks are mostly performed by the left hemisphere; some are mostly performed by right hemisphere. Left Hemisphere  Sensory information and control of right side of body  Verbal abilities Right Hemisphere  Sensory information and control of left side of body  Spatial abilities (e.g.,  Positive emotion (e.g., joy) judging distances, reading maps, and recognizing  Sequential, analytical (piece-bygeometric shapes) piece) processing  Negative emotion (e.g., o Two hemispheres communicatedistress) & work together, doing so more effectively with the age. Holistic, integrative o At birth, the hemispheres haveprocessing already begun to specialize. o Newborns show greater activity in the left hemisphere while listening to speech sounds or positive arousal and greater activity in the right hemisphere while responding to nonspeech sounds and to stimuli that evoke negative emotion  Brain Plasticity: o Researchers study brain lateralization to learn more about brain plasticity  A highly plastic cerebral cortex, in which many areas are not yet committed to specific functions, has a high capacity for learning. o If a part of the cortex is damaged, other parts can take over the tasks. o Once the hemispheres letaralized; recovery may not be easy o In & young children, parts of brain are not yet orinfants impossible. specialized. (So; recover better from brain injury) o During the first two years- brain is the most plastic. o Older children, even adults, have some plasticity. Sensitive Periods in Brain Development : o Early, extreme sensory deprivation results in permenant brain damage & loss of functions (verify the existence of sensitive periods!!) o Animal studies  if a 1- month of kitten deprived of light for only 3-4 days; these areas of the brain degenerate. o When the kitten is kept in dark during the 4th week- the damage is severe & permanent. o The quality of early environment affects the overall brain growth. o Studies focusing on children who are victims of deprived early environments reveal some parallels with the animal studies. E.g., Romanian children; institutionalized for more than the first 6 months  serious intellectual deficits. Also, serious mental health problems (inanttention, overactivity, & unruly beh.s) Evidence of Sensitive Periods o Appropriate stimulation is required for adequate brain development. o Environments that overwhelm the children with expectations beyond their capacities also interfere with the brain’s potential. How the appropriate stimulation characterized? TWO TYPES OF BRAIN DEVELOPMENT: 1. Experience-expectant brain growth: Ordinary experiences “expected” for the brain to grow normally. E.g.: Opport.s to see & touch objects, hear sounds. 2. Experience-dependent brain growth: Additional growth and refinement of established brain structures as a result of specific learning experiences that vary widely across individuals and cultures. E.g.: Practicing violin or piano. o For the first five or six years  No evidence for sensitive Changing States of Arousal o Rapid brain growth also means that organization of sleep & wakefulness changes substantially during 2 years, and fussiness and crying also decline. o Sleep needs decline from 18 to 12 hours a day by age 2. o Sleep-wake pattern, now increasingly conforms to night-day schedule (6-9 months take 2 daytime naps; by 18 months; need 1 day-time nap; between ages 3 and 5, napping subsides) o At the middle of 1st year (around 6 months) - Melatonin; a hormone that promotes drowsiness is secreted much greater at night than during the day  So, forcing younger babies to sleep early through offering an evening feeding may be problematic. Changing States of Arousal o These changing arousal patterns are due to brain development, BUT they are also affected by cultural beliefs and practices and individual parents’ needs. E.g., Dutch versus American parents. o Cosleeping; Greatly practised in collectivist cultures (establishing parent-child bond). Although some critics recommend that infants should be moved to their own room by 3 months of age; studies show that;  Cosleeping babies are breast-fed three times more.   May help protection of infant death syndrome Develop no emotional problems. Influences on Early Growth o Physical growth results from the complex interplay btw. both genetic & environmental factors:  Heredity  Nutrition (breast vs. bottlefeeding) Malnutrition Emotional well-being Influences on Early Growth  Heredity: o Heredity is important in physical growth. • (identical twins- are much alike in body size) o When diet & health are adequate, height & rate of physical growth largely determined by heredity. o If the negative environmental conditions (malnutrition & illness) are not severe - children show catch up growth (a return to genetically influenced path) once the conditions improve. • (Yet, heart, internal organs & brain may still suffer) oBody weight also affected by heredity. o The weights of adopted children correlate more strongly with those of biological parents. Influences on Early Growth  Nutrition: o Because the baby’s brain & body grows so rapidly; nutrition is especially crucial for the first 2 years. • Breast Feeding vs. Bottle Feeding: o Breast Feeding (Mother’s Milk)- right kind of food. o Breast-fed babies in poverty-stricken regions are less likely to be malnourished & more likely to survive the first year of life. o WHO- recommends breastfeeding until 2 years with solid foods added at 6 months.     Benefits of Breastfeeding Correct fat-protein balance Disease protection  Better jaw and tooth development Nutritionally complete  Easier transition to solid food More digestible Better growth Influences on Early Growth  Malnutrition: o In developing countries & war-torn areas (limited resources) malnutrition is widespread. o 1/3 of the world’s chidren suffer from malnutrition before age 5. o Marasmus; wasted condition of the body caused by a diet low in all nutrients. o Appears in the 1st year of life when a baby’s mother is too malnourished to produce enough milk & bottle-feeding is also inadequate. o Baby-starves; become painfully thin & in danger of dying. Influences on Early Growth  Malnutrition: o Kwashiorkor; caused by an unbalanced diet very low in protein. The disease strikes btw. 1-3 years of age. o Child’s body breaks down its own protein reverses; whıch causes the swelling, hair to fall out, belly to enlarge. o Children who survive these forms of malnutrition; grow to be smaller in all body dimensions, lasting damage to brain, heart, liver & internal organs. o When their diets improve; they tend to gain excessive weight. o Malnutrition distrupt appetite control centers ın the braın; when the food becomes plentiful child overeats. Influences on Early Growth  Malnutrition: Types  Marasmus  Kwashiorkor  Food insecurity Consequences  Physical symptoms, loss in brain wieght, low myelination, learning problems  Growth, and weight problems  Growth, learning problems  Lack of Affection: o Affection & stimulation is necessary for healthy physical growth & vital as food. o Nonorganic failure to thrive; growth disorder resulting from lack of parental love (present at 18 months of age)  symptoms similar to marasmus; wasted body, withdrawn behavior pattern & irritation  non-biological cause  can be corrected if treated early Learning Capacities o Learning  Changes in behavior as a result of experience. o Infants; capable of two forms of learning; classical conditioning & operant conditioning. o They also learn through their natural preference for novel stimulaton. o Shortly after birth, babies learn by observation (imitation)  Classical Conditioning: o A neutral stimulus (NS) is paired with a stimulus that elicit a reflexive response. o Once the baby’s nervous system makes the connection between the two stimuli; the previously neutral stimulus elicits the reflexive response itself. o With CC, infants can anticipate what is about to happen next; as a result, the world becomes more predictable. o Young infants can be classically conditioned most easily when the assoc. btw. two stimuli has survival value (stimulus paired with feeding). Learning Capacities  Classical Conditioning: E.g.: During nursing, the mother often strokes her baby’s forehead. Soon, mother recognizes that every time she touched her baby’s head, the baby made sucking movements. 1. 2. 3. o Before learning; Unconditioned Stimulus (UCS) must consistently produce a reflexive, Unconditioned Response (UCR). (UCS- Milk; UCR- Sucking) During learning; a Neutral Stimulus (NS) that does not lead to the reflex presented just before or about the same time as UCS. (NS-mother’s stroking forehead + UCS- Milk). Learning occurs, when the NS by itself produces the similar reflexive response. Now the NS turns into Conditioned Stimulus (CS) and the response it elicits becomes Conditioned Response (CR). (CS-stroking forehead; CR-Sucking) Extinction; occurs if the CS is presented enough times without being paired with UCS; so CR will no longer occur. E.g.: When the mother repeatedly strokes the baby’s head without feeding her, the baby will stop sucking in response to stroking. Learning Capacities  Classical Conditioning: o Young infants can be classically conditioned most easly when the assoc. btw. two stimuli has survival value (stimulus paired with feeding). Learning Capacities  Operant Conditioning: o In CC, babies build expectations but the beh. does not influence whether stimulus will occur. o In OC; infants act on the environment; stimuli that follow their behavior change the probability that the behavior will occur again. o •Nature of the stimulus; change the prob. of the behavior. Reinforcer Punishment • Increases probability of behavior occurring again • presenting desirable stimulus (Pos.) • removing unpleasant stimulus (Neg.) Reduces probability of behavior occurring again  presenting unpleasant stimulus (Pos.)  removing desirable stimulus (Neg.) E.g.: Sweet liquid, reinforces the sucking response (Pos. Rein.) Sour tasting liquid punishes newborn’s sucking response (Pos. Pun.) o Operant conditioning also plays role in the formation of social relationships. E.g.: When the baby gazes into the adult’s eye & the adult smiles, the infant looks & smiles again. As the behavior of each partner reinforces the other, both continue their pleasurable interaction Learning Capacities  Habituation: o At birth, the human brain is set up to be attracted to novelty. o Infants tend to respond more strongly to a new element that entered their environment. o Habituation refers to a gradual reduction in the strenght of a response due to repetitive stimulation (Looking, staring, heart rate, respiration may all decline, indicating a loss of interest). o Researchers can evaluate infant’s memory & knowledge by studying habituation. o Recovery  After habituation, when a new stimulus enters the environment; the baby start to response at high levels again. This increase in responsiveness is called Recovery. E.g.: A baby first habituates to an image (photo of the baby); then recovers to a new image (a photo of a bald men). Memory, perception & cognition capabilities of the baby; the Learning Capacities  Habituation: o Habituation can be used for studying infants, newborns, preterms & even fetuses. o Recovery (novelty preference); measures the infant’s recent memory. o Familiarity preference; measures remote memory (memory for stimulus presented weeks/ months earlier) o As the age of the infant increases, she/he shift from a novelty preference to a familiarity preference.  Imitation: •• Learning Capacities Newborns have ability ability to to imitate. o Imitation  Copying the beh. of another person. o Newborn’s can imitate facial expressions, certain gestures, head movements. o DEBATE: Reflex or voluntary capacity? o Mirror neurons offer offer biological explanation. o Mirror neurons fire identically when a primate hears or sees an action and when it carries out that action on its own. o Mirror neurons are believed to to be the the basis basis of a variety of interrelated, complex social abilities & empathy & understanding others’ intentions. o NIRS/NIROT findings; functioning of mirror-neuron system as 6 months of age. o Same motor cortex cortex areas areas are activated in in 6-months olds & adults when they observed observed a model that could be imitated. o IMITATION  Babies learn about others’ thoughts and feelings, about themselves themselves (others are like me), and also caregivers take great pleasure in a baby who imitates their facial gestures and actions, which helps get the infant’s relationship with parents off to a good start . Motor Development: Sequence and Trends o Motor development has an impact on social relationships & cognitive capabilities. o Motor, cognitive & language comepetencies develop together and support each other. o Gross motor development  Control over actions that help infants get around the environment. •Crawling, standing, and walking o Fine motor development: Smaller movements. •reaching and grasping Sequence is fairly uniform, though individual rate of motor progress differs. o Motor skills are interrelated  Each is a product of earlier motor attainments and a contributor to new ones. o Motor Development: Sequence and Trends • Gross & Fine-Motor Development in the First Two Years Rolls from side to back o Grasps cube o Rolls from back to side o Sits alone o Crawls o Stands alone o Walks alone o Builds tower of two cubes o Walks up stairs with help o Jumps in place o - 2 months - 3 months - 4,5 months - 7 months - 7 months -11 months -11/12 months - 11/12 months - 16 months - 25 months Motor Development: Sequence and Trends  Motor Skills as Dynamic Systems: Dynamic Systems Theory of Motor Development  Mastery of motor skills involves acquiring increasingly complex systems of action. o When motor skills work as a system- seperate abilities blend together; each cooperating with others. o E.g.: Control of head & upper chest combine into  Sitting with support. o E.g.: Standing, stepping & upright postural control combine into  Walking. o o Each new skill is joint product of: • CNS development • The body’s movement capacity • The child’s goals in mind • Environmental supports for the skill The broader physical environment also profoundly influences motor skills (e.g., Infants with stairs at home learn to crawl up stairs at an earlier age and also more readily master a back-descent strategy Motor Development: Sequence and Trends  Motor Skills as Dynamic Systems: o In learning to walk, toddlers practice 6 or more hours a day! o As movements are repeated thousands of times, they promote new synaptic connections in the brain that govern motor patterns. o Dynamic systems theory shows us why motor development can not be genetically determined. o Because it is motivated by exploration & desire to master new tasks, heredity can map it out only at a general level. o Rather than being hardwired into the nervous system, behaviors are softly assembled, allowing for different paths to the same motor skills. o There are cultural variations in motor development (e.g., in Jamaica- walking is promoted by frequently bouncing babies on their feet- these babies walk earlier) o Regulary exposing infants to the tummy-lying position during waking hours prevents delays in rolling, sitting, and crawling. Motor Development: Sequence and Trends Fine Motor Development: Reaching and Grasping o Of the all motor skills, reaching plays the greatest role in infant cognitive development. o Reaching & grasping at first occurs as gross & diffuse activity & move toward the mastery of fine movements. o Newborns; engage in prereaching;  Poorly coordinated swipes & swings toward an object  Rarely contact with the object.  Prereaching drops out around 7 weeks o Around 3-4 months; reaching reappears & improves in accuracy; o Ulnar grasp  Clumsy motion; fingers close against the palm; but even 4month-olds adjust their grasp to the size and shape of an object o 4-5 months; infants can move objects from hand to hand. o At the end of 1st year  Pincer grasp  The use of thumb & index finger to manipulate objects. o Between 8 and 11 months, reaching and grasping are well-practiced, so attention is released from the motor skill to events that occur before and after attaining the object. o Finally, these increased capacities increases infants’ attention to the way an adult reaches for and plays with that same object. Fine Motor Development: Reaching and Grasping Perceptual Development  Hearing: o Between 4 and 7 months  infants display a sense of musical phrasing. o Around 6-7 months  Infants can distinguish musical tones on the basis of variations in rythmic patterns. o At the end of 1st year  Infants recognize the same melody when played in different keys. Speech perception; o Newborns can distinguish all sounds in human languages. o They prefer human speech over non-speech sounds & native tongue rather than a foreign language. o Around 5 months  They become sensitive to syllable stress patterns in their own language; they become increasingly responsive to nativelanguage. o 7-9 months  Recognize familiar words in speech & analyze speech stream. Perceptual Development  Vision: o Supported by rapid maturation of the eyes and visual centers in the brain. o Around 2 months  Can focus on objects. o Around 4 months  Color vision becomes adultlike. o By 6 months  Visual acuity reaches 20/80; tracking moving objects improves. o Depth Perception: o The ability to judge the distance of objects from one another and from ourselves. o Awarness of heights (Visual Cliff Studies; Gibson & Walk, 1960) 3–4 weeks; Sensitivity to Motion Cues (Babies blink eyes defensively when an object moves toward their face).  2–3 months; Sensitivity to Binocular Cues (Two eyes have slightly different views of the visual cues).  5–7 months; Sensitivity to Pictorial Depth Cues (Changes in the texture of objects, relative size, overlapping objects, shadows of the objects).  Perceptual Development  Vision: Visual Cliff studies; http://www.youtube.com/watch?v=DrzmvI6iMrE Perceptual Development  Vision: o Infants with more crawling experience (regardless of when they start to crawl) are more likely to cross the deep side of visual cliff. o From extensive everyday experience, babies figure out how to use depth cues to refrain from falling-down. o Loss of body control that leads to falling differs for each body position; so babies should learn this separately for each posture.  Study  9-month-olds who were experienced sitters but novice crawlers placed on the edge of a shallow drop-off.  While in familiar sitting position; they avoided leaning out to reach an attractive toy.  In the unfamiliar crawling position; they headed over the edge. o Familiarity of the position & experience make babies to become aware of the consequences of their movements. Perceptual Development  Vision: o Pattern Perception: Newborns prefer to look at patterned rather than plain stimuli. o As infants get older, they prefer more complex patterns. E.g., 3-week-olds look longest at black & white checkerboards with few large squares; whereas 8-14 weeks prefer those with many squares. o A general principle, called Contrast Sensitivity  Contrast refers to the difference in the amount of light between adjacent regions in a pattern. o 1 month  Poor contrast sensitivity; prefer single, large simple patterns with high contrast  Bec. of their poor vision, young babies can’t resolve small features in more complex patterns; so they prefer looking at large, bold checkerboard. o 2-3 months  Detection of fine-grained detail improves; infants become sensitive to more contrast.  Can detect detail in complex patterns  Scan internal features of patterns Perceptual Development  Vision: Perceptual Development  Vision: o Pattern Perception: Once perceptual acuity increases, infants integrate the parts of patterns into a unified whole. o 4 months  They can peceive subjective boundaries that are not really present. o At 12 months  Infants can detect familiar objects represented by incomplete drawings even when most of the drawing is missing. Perceptual Development  Vision: o Face Perception: After habituating to one member of each pair of faces below, 6-month-olds were shown the familiar & novel face side by side. o For both pairs, they recovered (looked longer) to novel face; indicating they discriminated both human and monkey faces equally well. Perceptual Development  Vision: o Face Perception: Newborns prefer to look at photos & simplified drawings with features arranged naturally (upright) rather than unnaturally (upside-down or sideway) Perceptual Development Face Perception: o Babies prefer faces with eyes open & with a direct gaze. o Babies tend to look longer at faces judged by adults as attractive (may be the origin of social bias favoring attractive people). o 2 months  Prefer complex facial pattern to other complex patterns.  Can distinguish strange from familiar faces.  Prefer mother’s face over stranger. o 3 months  Can detect the features of different faces.  Distinguish photographs of two strangers even when faces are moderately similar.  Prefer and more easily discriminate among female faces than among male faces.  3-to 6-month-olds  Can identify races  If they are mostly exposed to members of their own race, they prefer to look at the faces of them. o 5–12 months  Can perceive emotional expressions on faces.  They can discriminate positive emotions from negative emotions expressed by faces. Perceptual Development Intermodal Perception: o Intermodal stimulation  Simultaneous input from more than one modality, or sensory system. o In intermodal perception, we make sense of these running streams of light, sound, tactile, odor, and taste information, perceiving them as integrated wholes. o 3 to 4-month-olds  Can match faces with voices on the basis of lip-voice synchrony, emotional expression, and even age and gender of the speaker. Understanding Perceptual Development: o Gibsons’ Differentiation Theory  Infants actively search for invariant features of the environment –those that remain stable- in a constantly changing perceptual world. o Think of perceptual development as a built-in tendency to seek order and consistency – a capacity that becomes increasingly finetuned with age.