Lifespan Development Psychology Psyc 2100 Lecture Block 4: Physical Development in Infancy and Toddlerhood The 1st 3 years have the fastest growth of the whole lifetime, espec the 1st few months. Birthweight doubles by 5 months (7 ? to 15 lbs.) and triples by 1 year (22 lbs.). In year 2, the baby gains 5-6 lbs; in year 3, 4-5 lbs. Baby gains 10-12 inches in height during the 1st year, 5 ins during the 2nd year and 3-4 inches during the 3rd year. To account for longer limbs and more weight, motor movements have to be recalibrated. Teething starts around 3-4 months with the 1st tooth showing betw 5 and 9 months. At age 1 year, babies usually have 6-8 teeth, and 20 teeth by 2 ? years. The brain is undergoing phenomenal growth during the first 2 years. There are 2 patterns of growth worth mentioning the cephalocaudal and the proximodistal principles. The cephalocaudal principle states that growth happens from top to bottom. The head and brain are disproportionately large compared to the rest of the body, and babies become more skilled with their hands before becoming skilled with their legs. At birth, the head is ? of the length of the body and the brain weighs 14 ounces. By age 2, the head is 1/5 and the legs ? of the body�s length, and the brain weighs 70% of its adult weight. The proximodistal principle states that growth follows an inner to outer pattern with the head and trunk developing before the extremities, the upper leg and arm muscles developing before the feet and hands. A baby is more skilled at gross motor movements before he/she becomes skilled at fine motor movements. >>>>>>>>>>>>>>>> Brain growth needs to be understood at the cellular level and at the cerebral cortex level. Neurons are nerve cells, the basic building blocks of the nervous system. They are cells that specialize in communication via electrical and chemical forms. During prenatal development, the neural tube produces more neurons than the brain will ever need. Those neurons that are stimulated will form synapses or connective gaps that allow communication betw neurons without touching each other. Glial cells take up half the space in an adult brain. As an infant�s brain matures, glial cells multiply and coat neuronal axons with myelin, an insulating fatty sheath. Myelination allows for faster communication and smoother movements. Glia (derived from the Gk. word meaning �glue�) outnumber neurons by 10 to 1, but neurons are 10X as big. So neurons and glial cells take up about the same amount of brain space. Glial cells provide structure and hold neurons together. They remove wastes like dead neurons by engulfing and digesting them. They handle other metabolic and clean-up tasks. There are 100 billion neurons in the human brain-- enough that if you count 1 per second, it�d take 3000 years to finish counting. And any 1 of these neurons may have several thousand direct connections to other neurons in the nervous system. So we�re talking big time complexity. When you consider there are 100 billion neurons and 100 trillion synapses in one person�s brain, the possible configurations are almost limitless-- 1000 times more than the # of stars in our entire galaxy. Neurotransmitters are chemical messengers of the brain. These chemical messengers travel across the synapse or tiny gap between neurons until they reach special proteins or receptor sites in the membrane of the next neuron which are configured just for them (like a key searching for the correct lock). The cerebral cortex is the gray, convoluted, spongy matter that makes up the outer covering of the brain (cortex means �bark�). It is only about 3 ml thick (1/4 th of an inch), yet it contains no less than 70% of the neurons in the CNS. Looks like a giant, wrinkled walnut with lots of ridges and valleys called corticalization. This corticalization--these ridges and valleys-- compact more surface area into a smaller space. If you were to iron out or flatten the cerebral cortex, you would have a 3 ft by 3 ft. square area. In order for this much surface area to fit into the skull it is all scrunched up. The cerebral cortex is divided into 2 halves or hemispheres and these 2 hemispheres are joined or connected by a thick band of fibers, a C-shaped bundle of axons, called the corpus callosum. The cerebral cortex is what sets humans apart from the rest of the animal kingdom. The frontal lobes are one of 4 distinct cortical regions. These take the longest development time and are responsible for human thought and planning. >>>>>>>>>>>>> Specialization occurs in the cerebral hemispheres. The cerebral hemispheres appear symmetrical in shape, but they are NOT so in how they function. Among normal persons, the hemispheres differ in abilities or specialize. You�ve heard this referred to as right-brain/ left-brain. Sensory information is received by the hemisphere that is opposite the side of the body from which the information came. And this hemisphere only controls that opposite body side. Eyes are an exception as sensory info from both eyes is sent to both hemispheres. For instance, language is a specialty of the left hemisphere. About 95% of all adults use the left side of the brain for speaking, writing, and understanding language. (97% of rt-handers and 68% of left-handers). The left hemisphere is also the seat of positive emotions like joy. The left side generally is involved with analysis and breaking information into parts. It processes info sequentially, in order, 1 item after the next. There is growing concern among educators that since the traditional school approach favors left-hemisphere or verbal processing, this shortchanges students who favor, or prefer, right-brain processing. Effective teachers use methods that employ both verbal and spatial skills, and as many sense modalities as possible (hearing, seeing, touching, smelling, tasting). This maximizes the chances that every student will be taught at least occasionally in the mode he or she learns best. The right hemisphere responds to only the simplest language and numbers. It is better at perceptual skills such as recognizing patterns, faces, and melodies. It is better at detecting, expressing and regulating emotion. And it is better with spatial skills such as arranging blocks to match a pattern, putting a puzzle together, reading a map and drawing a picture. (Hellige,1990). Negative emotions like anger and fear are seated in the right hemisphere. Prosody (or the changes in intonation, rhythm and stress that add emotional meaning to words and speech), appears to be controlled by the right hemisphere. So we�re talking about tone of voice, body language,and non-verbal cues. The right side is generally involved in holistic or all at once processing, and simultaneous processing. It does well with synthesis or putting isolated elements together. Caution is to be taken not to assign sole credit to either hemisphere. Both are active at all times even though some tasks may make more use of 1 hemisphere or the other. Each hemisphere does what it does best and shares the information with the other side. They share the work. Both hemispheres are involved in all learning tasks, so it is an oversimplification to claim that someone is right-brained or left-brained. In fact, front to back functioning may be as important as right/left functioning. Just remember that the brain is very complex in structure as well as in function, and to reduce function as belonging to the specific and sole control of 1 hemisphere is a gross oversimplification. It is also wrong to assume that a certain brain area is responsible for a psychological process, like the frontal lobe is responsible for worrying and mood. This assumption would prompt frontal lobe removal or severing it from the rest of the brain, if the intensity of worrying or mood swings interfered with life. Tens of thousands of lobotomies were done for 40 years beginning in the 1940�s. But these operations did not just stop worrying. They destroyed the ability to plan, decide and understand reality. Victims, including 1 of the Kennedy girls, were worse off with the cure. One Flew Over the Cuckoo�s Nest is a movie depicting this. These surgeries are rarely done anymore. >>>>>>>>>>>>>>>> Sensitive periods in brain development-- Environment interacts with genetics in determining growth including brain growth. Children who have the benefit of good nutrition and medical care and sanitation gain in height and weight over children with similar DNA with deficient nutrition and sanitation with no access to immunizations and antibiotics. Children with access to appropriate materials to play with, caring people to interact with and daily routines develop more maximally. Peek-a-boo and bedtime stories promote development. All of this phenomenal growth is channeled or molded via experience. Neurons change in size and shape depending on the kind and amount of sensory stimulation the baby receives from the environment. In the event of trauma or injury, the developing brain has a greater chance of recovery if it is still young. Plasticity or abil to recover or to modify is greatest with young babies and children. It is like regrouping and reassigning duties and growing new synapses and pathways in response to some environmental demand. Plasticity allows infants exposed to extreme early deprivation to overcome some of the trauma�s ill effects. Case history of Dusty�Doctors were very skeptical that he would even live much less be the highly functioning college student, with good grades, plenty of friends, a job and bright future 21 years later. born 14 wks too soon at 26 weeks gestation, in Feb but due in June. grade 4 intraventricular hemorrhage, worst stroke you can have and live, massive brain damage, �vegetable� prognosis with CAT scan technology, so wrong. resultant hydrocephalus requiring a VP shunt bronchopulmonary displasia and hyaline membrane disease retrolental fibroplasia (extremely nearsighted but could�ve been blind) double exchange blood transfusions to combat high bilirubin mild CP with left arm that does not work, and a limp (but he still beats every kid in the neighborhood on video games using 1 hand while they use 2; every finger he has programmed to do something different.) detached retina 9 surgeries to date asthma outgrown The reason I am so familiar with this case, is that Dusty is our son. He is our 6th child and our first adopted child. The 1st time I ever laid eyes on him, he was this tee-tiny little human with tubes coming out in all directions. He had his little rear-end stuck straight up in the air and he appeared to be fighting to get out of that glass box incubator. The 2nd time I saw him, my husband was with me, and he picked him out of all those critically ill infants before anyone pointed to the right baby. After this, we were not allowed back to visit because Charity Hosp found out we were the prospective adoptive parents and did not want to be caught in the middle if things fell through. Dusty was not quite 5 pounds by the time he was released to us and he was almost 3 months old. A miracle survivor who is still beating the odds. He is now a college grad.>>>>>>>>>>>>>> To emphasize how great the influence of sensory experience is on growth and development, animal experiments were done on cats and kittens and rats. Kittens fitted with goggles which permitted them to see either all vertical lines or all horizontal lines, later were blinded to those lines that had been blocked during early development. If they had goggles which prevented the sight of horizontal lines, then later, when no longer wearing the goggles, the kittens would run right into horizontal boards without seeing or perceiving them. Adult cats fitted with the same type of goggles did not act the same way. Their cortical connections had already been forged and were still operational. The kittens were deprived of the stimulation neces to establish connections and their brains were permanently impaired or stunted. Kittens were blindfolded over 1 eye in another experiment. They were permanently blinded in that eye even after the blindfold was removed, because the necessary connections stemming from sensory experience were never made at the critical time in brain development that they needed to be made. Rats were exposed to normal lab environments, enriched, stimulating lab environments and dull, isolated lab environments. Those with enriched experiences had thicker cortexes, heavier brains, more synaptic connections and higher levels of messenger activities by neurotransmitters, than rats exposed to normal cages. Those with isolated, stagnant environments had thinner cortexes and fewer synaptic connections than the rats exposed to normal conditions. (Rosenweig, 1984) >>>>>>>>>>>>>>>>> Infant development--- Sleep�Babies by the age of 6 to 9 months are taking 2 naps a day for a total of 12 to 13 hours of sleep in a 24 hour period. It is about this time that the amount of melatonin, the drowsy brain hormone, becomes greater at night than in day. Night sleeping habits depend on culture. Japan values conformity to the group, and the US values indiv assertiveness. Japan--respect, agreeableness, emotional maturity, self-control, courtesy, dependency, tight family bonds, newborns viewed as needing to be made dependent and bound to the group as soon as possible (thus the necessity to have infants and young children sleep with their mothers), mothers never separate from young children and infants, 90% of the world sleeps with their babies. USA�independency, individuality, autonomy; infants are born dependent and need to be socialized to become independent (thus the necessity to train a baby to sleep alone; 60% of American babies sleep in separate rooms from parents by age of 3 months; 80% do by age 6 months). My words of wisdom for what they are worth�insist toddlers begin the night in their own beds. Once they awaken and seek you in the night, allow them to stay or comfort and then lead them back if you have the energy. On stormy nights, we could awaken to find 3 or 4 in bed with us by morning. Whatever was enough to awaken a child, was important enough for me to welcome him/her rather than to be angry. Nutrition�Babies need twice as many calories per pound as adults do to sustain their energy needs and rapid growth. 25% of ingested calories are devoted to growth needs. Breast milk is recommended for many reasons�more digestible, nutritious, easy, does not have to be warmed or refrigerated, gives immunity against certain infections, is less likely to produce allergic symptoms, is cheaper, etc. Mothers who are nursing must be very careful about what they ingest, like drugs or alcohol. For those who should not or cannot breastfeed, then do not fret or feel like you are letting your baby down. Certain illnesses including the AIDS virus, and active untreated tuberculosis can be transmitted thr breast milk. There are some mothers who have good intentions but for 1 reason or another are not successful in establishing an adequate milk supply. Please lose no sleep over this. Guilt has no place in the bonding that should be taking place betw mother and child, and betw father and child. >>>>>>>>>>>>>>>>>>> More important than the type of feeding is the manner in which the feeding is delivered. Feedings should be more than just the physical offering of nourishment; they should also offer emotional nourishment. Never place a baby down with a propped bottle. Instead feedings should be guaranteed opportunities for baby and caregiver to click, to bond. The parent can talk, sing or simply smile. Forget the dishes and the deadlines. The baby needs to associate warm fuzzy feelings of getting full with a loving parent. The baby needs to focus on the human face and intercept the parental cues of joy and pleasure and contentment. Babies whose mothers are severely depressed are short-changed. They experience the negative emotions of the mother rather than the positive ones. In response, the babies actually show more activ in the right frontal lobe (known to be associated with negative emotions of fear, anger and depression) and less activ in the left frontal lobe (known to be associated with positive emotions of cheerfulness and joy). Dawson et al, 1997. A baby should never be placed in the crib with a bottle. He/she should be held until the bottle is finished. Not only does this require that the parent and baby have necessary bonding time together, but also it prevents the bacteria in milk from multiplying in numbers enough to make the baby sick, and it prevents the tooth decay that results from continual exposure to milk. When choosing a daycare, be particular about how feedings are administered to your baby. For 6 months, according to the American Academy of Pediatrics, all a baby needs is breast milk or iron enriched formula. They do not need water or juice or solid foods. At the age of 1 year, babies can drink homogenized whole milk. They need the calories and fat found in whole milk and should not be given skim milk. It is a good idea to dilute juices with water so that children by the age of 2 to 3 years, drink no more than 4-8 ounces of pure juice a day. Solid vegetables and fruits should be introduced one at a time after age 6 months, so that any allergic reactions can be noticed. For ravenous babies who do not appear satisfied for long with a full breast or bottle feeding, rice cereal may be introduced before 6 months of age, after clearing it with the baby�s pediatrician. >>>>>>>>>>>>>>>>>>>> Proper nutrition with sufficient protein is imperative for physical and emotional growth and for learning. Learning is a relatively permanent change in an organism�s disposition to behave as a result of experience; the nurture side of the nature/nurture interaction. relatively permanent: excludes temporary changes in behavior due to maturation, fatigue, or illness. disposition to behave: includes learning that exists but which may not be exhibited. Learning cannot be measured directly, only indirectly through behavior observation. Learning has survival function. It�s primary function is to develop behaviors that are adaptive to an ever-changing environment. Learning involves changes in neurons and the strengthening of their synapses, the locations of which depend on what is being learned. >>>>>>>>>>>>>>>>> Babies are born able to learn from experience using their senses. Their learning is limited or constrained by maturation meaning certain biological capacities (neurological, motor or sensory) have to be in place before certain learning can occur. In other words, a baby cannot learn to walk until the muscles and nerves which operate the muscles are developed or mature enough. A baby cannot talk until certain neurological, sensory and motor abilities have kicked in. Babies are capable of learning through their natural preferences for novelty and by watching others. They are capable of learning via classical conditioning and operant conditioning. But the simplest form of learning is habituation and babies do this well. Researchers rely on habituation to study infant behavior and memory. Habituation is boredom or stopping to respond reflexively to repetitive stimuli. This can be measured by watching for a decrease in looking, heart rate and breathing rate. A new stimulus will cause the habituation to end and recovery to take place with increase in looking, heart rate and breathing rate. Newborns are programmed to be drawn towards novelty. As infants age a bit, they replace the attraction of novelty with the attraction of familiarity.>>>>>>>>>>>>>>>> Classical conditioning involves the pairing of an US with a neutral stimulus to produce a response. The response can be a physiological response like salivation or muscle tension, or it can be an emotional response like fear, anger or joy. There are 4 main components of classical cond�US, CS, UR, CR. US is an uncond (unlearned) stimulus that automatically produces an emotional or physiological response. Example�meat powder, camera flash. CS is a cond (learned) stimulus that used to be a neutral stimulus until associated or paired with an US. A CS evokes the physiological or emotional response after learning. Example�bell, tuning fork, footsteps, camera, sound of can opener. UR is an uncond (unlearned) response which occurs naturally. Example�salivation, blinking. CR is a conditional (learned) response to a previously neutral stimulus. Example�salivation, blinking. The UR and CR are the same response but are triggered by different stimuli. Generally the UR is the most intense response. Most of human emotions are produced by stimuli that have acquired significance thr clas cond. Hearing your favorite song may stir romantic memories. Smelling certain fragrances may elicit feelings of warmth or hate. The words �school� or �homework� may trigger a wave of dread or fear to a child who is struggling. Getting nailed at a red light may make you anxious or afraid at every red light for weeks. In the beginning, all of these examples necessitated a paired association of a CS with an US to evoke an UR which became a CR after learning or conditioning. Babies can be classically conditioned. Even 2 hour old infants can be taught to turn their heads and suck when their foreheads are stroked, by stroking their foreheads at the same time they are fed. A classical experiment published in 1920 by Watson & Rayner, showed that fear can be conditioned in an 11 month old baby. This type of experiment would never be allowed past the ethics boards today. Little Albert loved furry animals including white furry rats, but during the lab experiment, Watson introduced a frightening loud noise, every time the baby reached for a furry white rat. This caused the baby to cry, and after repeated pairings with the rat and the noise, Little Albert cried whenever he saw the rat even with no noise. And the fear generalized so that the baby also feared furry white objects like rabbits and dogs and Santa Claus beards. >>>>>>>>>>>>>>>>> In addition to classical conditioning, infants can learn via operant conditioning. Operant cond is learning in which voluntary behav is strengthened or weakened by consequences. Conseq�events that follow behav like praise and reward or punishment. [[Antecedents�events that precede behav like cues and prompts can also strengthen or weaken voluntary behavior. Antecedents are supported by cognitivists not behaviorists.]] Operant cond is the way we learn new behaviors like smiling, not simply pair or associate existing involuntary behaviors like blinking. It is responsible for almost every learned skill or ability we have acquired since our births. 2 day old babies have been operantly conditioned by rewarding them with music when sucking increases. 2-6 month old babies can repeat an action days or weeks later if the new situation is very similar to the original situation, meaning the same activity (kicking to make a mobile move). The amount of time that memory lasts for an operantly conditioned action, increases with age. A 2 mon old may remember for 2 days; a 6 mon old may remember for 2 weeks; an 18 mon old may remember for 13 weeks. >>>>>>>>>>>>>>>>>>> Motor Development 2 of the most accomplished motor feats in the 1st year are the pincer grip using thumb and forefinger instead of the whole hand, and walking upright on 2 legs. Some of the motor milestones that occur along the way are� Controlled eye movements begin to develop right away, enabling an infant to learn, and they continue until age 7 years. They allow babies to follow people with their eyes and to keep looking at things despite their own head and body movements. Babies cannot follow rapid side-to-side or up-and-down motions before the ages of 2 to 4 months. Rolling over--- from front to back comes first and then back to front, with practice taking place betw 3 and 5 months. The cerebellum is maturing enough for baby to try and roll over. The cerebellum coordinates motor control. Babies can turn over accidentally even before 3 months, so should never be left alone on an elevated surface. Grasping movements develop from whole-hand grasping, like gripping a rattle, at 3 to 4 months of age to thumb-forefinger grasping of small things, like a cheerio, by age 1 year. Before 6 months of age a baby has trouble voluntarily letting go of things. Have you ever seen a baby with a popsicle or ice cream? He/she will be crying because the cold is hurting, but be incapable of ending the hurt by releasing the freezing item. Reaching movements begin at about 15 weeks of age. Infants will reach using visual guidance but will also reach in the dark for something glowing or something making noise even if they cannot see their hands. Their reaching becomes more refined not automatically but thr effort, practice and opportunity. The reaching movement becomes integrated using eye/hand coordination and leaning. 8 month-old babies simultaneously reach and lean for objects beyond arm�s length. This movement is integrated. All of it is done at once. Babies do not reach first, fail to grab the item of interest, and then decide to try leaning forward. >>>>>>>>>>>>>>>>> Sitting---By about 7 months, babies can sit alone but take a couple more months to get to sitting without help. Prior to walking there are a variety of movements that babies may choose to use to get from point A to point B, from here to there. They may pull themselves along on their tummies using their arms and elbows. They may push themselves forward using their legs and knees. They may scoot across the floor on their behinds, using legs and arms. Crawling on all fours without the tummy on the floor does not occur in all babies. Pull to stand---Regardless of which mode of transportation that a baby uses to get around, by the time he/she is a year old, he/she is able to pull to standing and step from side to side holding onto furniture. Walkers and exersaucers and doorway bouncers are a NO-NO for more than 20 minutes daily. They are implicated in adversely affecting spine development. With siblings who are more active, walkers and exersaucers may be a temporary protection for the younger babies. Guard against using them excessively---a large playpen for floor play may be better�but not foolproof---older babies can still throw toys on top of baby or climb in too. Walking---The first steps taken without holding onto anything usually occur around the 1st birthday. Full-fledged walking is variable. Babies can begin way before their 1st birthday or closer to 1 and a 1/2 years old. Walking depends on nature mostly. It depends on the maturation of muscles and the nerves that operate them. Walking is also influenced by nurture or practice and experience. Babies with eager beaver parents who practice walking constantly holding the child out to 1 and then to the other, may walk sooner, but not appreciably sooner. An important piece of information here is that later intelligence is not related to the age at which a baby begins walking. Early walkers are not necessarily smarter than later ones; later ones are not necessarily less intelligent. In addition, babies who skip crawling and go right into walking are not any less intelligent than those who crawl 1st. Spatial coding---By 21 months, due to increased right hemispheric development of the cortex, children are skillful with spatial coding or the ability to use environmental cues to get their bearings. They are more able to find their way even if blindfolded and turned around like you do to children for Pin the Tail on the Donkey (Newcombe, Nora). >>>>>>>>>>>>>>>>> Sensation�raw material; incoming flow of information. Perception�finished product; brain organization of incoming information into meaningful patterns. Perception organizes sensations or incoming info by answering 3 basic questions� --How far away is the object? depth --Where is it going? motion --What is it? size and shape constancy >>>>>>>>>>>>>>>>> Depth perception answers �How far away is the object?� Depth perception is the abil to percive the distance of an object and the 3-dimensional characteristics of objects. Depth perception uses monocular and binocular cues. Monocular cues are depth cues that can be processed by either eye alone. By the age of 5 months, infants begin to acquire monocular cues. linear perspective�(5 to 7 months) parallel lines seem to meet in the distance. The closer the lines, the farther the distance (ie�railroad tracks, treeline on the highway). interposition (overlap)�(5 to 7 months) when 1 object partially blocks the view of another object, the blocked object is perceived as farther away. [[motion parallax--closer objects whiz by when you�re in motion (car, train) and distant things like the skyline go slowly. ]] Binocular cues are depth cues that require information from both eyes working together. Babies begin to acquire binocular cues by age 3 months. convergence�(1 thr 5 months) the more the eyes converge or rotate inward to focus on nearer objects, then the greater the strength of the muscle signals and the greater the strain. retinal disparity�(3 thr 5 months) eyes are set a couple of inches apart. The image on the retina is different for each eye. The greater the difference in the 2 images, the closer the object is. The more identical the 2 images, the farther away the object is. ie�Center a finger in front of your face and close 1 eye and then the other. Now focus on an object far off and close 1 eye and then the other. See the difference? With both eyes open, the 2 images fuse into