Test 3 Study Guide Chapter 7 Physical Development in Early Childhood McGraw s study of Johnny and Jimmy was an early demonstration of the interplay between nature and nurture Early childhood AKA the play or preschool years is from ages 2 5 Normative development the pattern of development that is typical or average Individual differences the variation among individuals on a characteristic as well as what is typical or normative Physical Growth and Development o The rapid growth that characterizes infancy slows in early childhood o A typical preschooler is leaner than his baby brother and his teenage sister o Patterns of Normative Growth The first scientific studies of physical growth were designed to establish norms standards of what is typical for different ages Cross sectional research design is often used Studies have been used to create growth curve tables of normative development based on heights and weights of children of different ages Growth curves suggest that physical development is slow and steady during early childhood On average children grow 2 5 inches and gain 6 pounds per year Boys are slightly heavier and taller than girls but sexes are similar in body proportion When provided with healthy growth conditions children from various parts of the world follow similar growth patterns Growth is episodic occurring in fits and starts Characterizes growth in height weight head circumference and other measures Body Mass Index BMI weight kg divided by height meters squared Helps judge whether a child s weight is appropriate for his height Average 50th percentile 85th 94th percentile overweight 95th obese 5th percentile or lower clinically underweight 80 of children are within normal range for BMI Heredity is important About 2 3 of statistical variations of height and weight can be attributed to genetic factors Changes in diet and physical health have resulted in increases in height and weight within families in the last 100 years in the US Europe and Asia o Individual Differences o Diet and Nutrition Two changes in eating patterns coincide in early childhood Children s appetites decrease Graduating from baby food to adult food Some preschoolers are picky eaters between 18 and 29 When parents insist that kids clean their plates kids don t learn how to listen to internal hunger cues Danger that children will learn to over eat Childhood obesity had reached epidemic levels estimated that around 9 million US children are obese and many more are at risk overweight Serious health problems like heart disease and diabetes are now being seen in young people The best way to combat obesity is to prevent weight gain Parents can lower the risk of overweight children by Providing children with a variety of healthy foods at meals and snack times but not pressuring them to eat Not using foods to bribe punish or entertain children Encouraging and joining in active play and limiting sedentary past times like watching TV Serving as good role models by practicing healthy eating habits and exercising themselves and planning active family times Brain Development o Brain matures both structurally and functionally during early childhood o Important aspect of brain development is establishing and fine tuning communication between the brain and nervous system and within the brain o REVIEW Brain is composed of billions of cells called neurons with specialized extensions Dendrites collect info and carry it to the body of the neuron Axons transmit info away from cell body Connected by a synapse Synapse enables information to pass from one neuron to the next Neurotransmitters released when electrical impulses hit the tip of an axon o Improvements in the Brain s Communication Network Key process in the brain is synaptogenesis the development of connections between neurons which occurs through the growth of axons and dendrites Peaks at about 1 year but continues into childhood and throughout life Synaptic pruning selective elimination of unused and unnecessary synapses Equally important part of brain development Begins in first years and continues into young adulthood Synaptic density reduced by about 40 by adulthood Selective elimination of some synapses while others are strengthened supports brain adaptations and plasticity by making the brain more efficient Myelination the process through which cell axons become sheathed in myelin a white fatty substance providing insulation and improving signal transmission Areas of brain involved with vision and movement are myelinate first Early childhood fibers connecting cerebellum to cerebral cortex grow and myelinate improving children s balance and control of body movements Myelination in areas that govern hand eye coordination also continues through early childhood Myelination of frontal lobes most plastic area of the brain continues into late adolescence and early adulthood o Mirror Neurons o Brain Anatomy Discovery made in Italy at University of Parma during a study of monkeys Mirror neurons fired both when the monkeys were performing an activity and when observing an activity being completed by someone else Other scientist have found evidence of similar activity in humans with actions and experiencing another person s feeling or emotions May help explain why children learn so much from watching others Changes in gray matter working tissue of the brain s cortex occur from early childhood into adulthood Overall size of the brain doesn t change very much in early childhood but the relative size of specific structures does change First areas to mature are those related to the most basic functions senses and movement Next parietal lobes spatial orientation and language Last prefrontal cortex reasoning and executive functioning Right hemisphere controls left side of body and vice versa due to lateralization the localization of a function to one of the hemispheres of the brain Left hemisphere time and sequences processes speech registers external stimuli o Especially active from 3 6 years Right hemisphere o Especially active from 3 11 years with a small spurt from 8 10 Example of lateralization handedness Corpus callosum large bundle of fibers connecting the two hemispheres of the brain Develops rapidly between 3 and 6 years Communication between 2 halves of the brain facilitates quicker and smoother action Frontal lobes area of the brain that develops most in early childhood sometimes called the executive of the brain responsible for planning and organizing new