1. Passed back test #3; discussed proper essay format.

2. Passed out objectives to studying next three chapters.

3. Physical development in early childhood

 I.     GROWTH

    A.       BODY GROWTH in early childhood: slower and more continuous (no more rapid growth spurts until puberty)

• On the average, 2 to 3 inches in height and about 5 pounds in weight are added each year.

• The child gradually becomes thinner, girls retain somewhat more body fat, whereas boys are slightly more muscular. Posture and balance improve, resulting in gains in motor coordination.

• Individual differences in body size are even more apparent during early childhood than in infancy and toddlerhood.  (To determine if a child’s atypical stature is a sign of a growth or health problem, consider child’s ethnic heritage.)

    B.   Skeletal Growth: bones lengthen, changing body's proportions to more adult-like.

• Between ages 2 and 6, child develops approximately 45 epiphyses, or growth centers in which cartilage hardens into bone.

• X-rays permit doctors to estimate children’s skeletal age.

• Longer skeletal frame allows chest and abdomen to better accommodate internal organs: 'pot-bellied' look of infancy lost, and posture improves as body weight is better balanced: body as a whole is less 'top-heavy'.

• By the end of the preschool years, children start to lose their primary teeth. (Childhood tooth decay remains high, especially among low-SES youngsters in the United States.)

     C.     Asynchronies in Physical Growth: different body systems have their own unique, carefully timed patterns of     
              maturation.

• The general growth curve is a curve that represents overall changes in body size—rapid growth during infancy, slower gains in early and middle childhood, and rapid growth once more during adolescence.

• The head/brain grows fastest of all body parts in early childhood, just as it had in infancy/toddlerhood.

• The lymph system (part of the immune system) develops very fast up through infancy and childhhod, providing child with protection against infectious disease.

• Reproductive systems change little during childhood and then develop rapidly in adolescence.

II.  BRAIN DEVELOPMENT

    A.     Synaptic Growth and Pruning:

• The young child has many more neurons than needed, with many more synaptic connections than needed as well. Unused ones are 'pruned' away and the unstimulated neurons die, making room for increased synaptic connections of frequently-used neurons.

• Brain metabolism reaches a peak around 4 years of age, as overproduced cortical regions have high energy needs.

• The overabundance of synaptic connections supports the plasticity of the young brain; as 'extra' neurons and synaptic connections are lost, brain becomes less plastic.

• As extra neurons and synapses are lost, energy consumption of most cortical regions declines to near-adult levels.

B.  Lateralization

• The two hemispheres of the cortex develop at different rates.

• The left hemisphere shows dramatic activity between 3 and 6 years and then levels off. This is the part of the brain most usually involved in language development.

• Activity in the right hemisphere increases slowly throughout early and middle childhood, showing a slight spurt between ages 8 and 10.

• Lateralization continues as the different hemispheres further 'specialize' in function.

C.     'Handedness'    

• Genetic theory proposes that most children inherit a gene that biases them for right-handedness and left-hemispheric localization of language, but the genetic right-hand bias theory acknowledges that experience can profoundly affect handedness. The way most fetuses lie in the uterus—turned toward the left—may promote greater postural control by the right side of the body. (Example: identical twins often opposite handed due to position in womb.) However, practice heavily affects hand preference.

• Hand preference  is evident in 10 percent of 1-year-olds. By age 5, 90 percent of children clearly prefer one hand over the other.

• The dominant cerebral hemisphere is the hemisphere responsible for skilled motor action. The left hemisphere is dominant in right-handed individuals, who make up the majority of the population.

• In left-handed individuals, motor and language skills are often shared between the hemispheres and they tend to be less strongly lateralized than those of right-handers. Many left-handers are ambidextrous.

• Left- and mixed-handed children are more likely than their right-handed agemates to develop outstanding verbal and mathematical talents.

  For more information on 'handedness', see The Biology of Handedness

D.   Other Advances in Brain Development

• The cerebellum is located at the rear and base of the brain and aids in balance and control of body movement. The  fibers linking the cerebellum to the cerebral cortex do not complete myelinization until about age 4.

• The reticular formation maintains alertness and consciousness; it myelinates throughout early childhood and continues growth into adolescence.

• The corpus callosum is the large bundle of fibers that connects the left and right hemispheres. Myelinization does not begin until the end of the first year of life, but is fairly advanced by age 4 to 5, and continues to enlarge throughout childhood and adolescence. The development of the corpus callosum is also affected by experience (Example: musicians who play instruments  which demand different kinds of motion and activity by each hand carefully coordinated to produce music have thicker, denser corpus callosum.)

III.   FACTORS AFFECTING GROWTH AND HEALTH

       A.     Heredity and Hormones

• Children’s physical size and rate of growth are related to their genetic inheritance.

• Growth is also a function of the endocrine glands. The pituitary gland is a gland located near the base of the brain that releases hormones affecting physical growth. Lack of these hormones results in dwarfism and an excess results in giantism.

•   a.    Growth hormone (GH) affects the development of almost all body tissues, except the central nervous system and the genitals. Short children with GH deficiency can be treated with injections of GH.                                             b.    Thyroid-stimulating hormone (TSH) stimulates the thyroid gland to release thyroxine, which is necessary for normal development of the nerve cells of the brain and body growth. Lack of thyroxine in infancy cacauses sever mental retardation.

• Deprivation dwarfism is a growth disorder observed between 2 and 15 years of age that is caused by emotional deprivation. The pituitary is influenced by the brain through the hypothalamus. Deprivation dwarfism is characterized by very short stature, weight that is usually appropriate for height, immature skeletal age, and decreased GH secretion.

• Preschoolers with very stressful home lives suffer more respiratory and intestinal illnesses, as well as unintentional injuries. 

     B. Sleep

•   Sleep contributes to body growth, since GH is released during sleeping hours. 

•    Total sleep needs decline in early childhood  from about 12-13 hours at ages 2 and 3, to 10-11 hours during 4 to 6 years of age. (Of course there are large individual differences in how much sleep each child needs.)

• Bedtime routines and rituals help ready a child for sleep.

• About 20 to 25 percent of preschoolers experience difficulty falling and staying asleep. Because of the development of fears at this age and the newly developing imagination, many children have difficulty going to sleep in a room by themselves, and almost all children begin to have a few nightmares between ages 3 to 6.  

• Persistent sleep problems may be a sign of illness.

• Family stress can also prompt childhood sleep disturbances.  

    C.  Nutrition 

•    Preschoolers’ appetites decrease because growth slows dramatically after toddlerhood

•   In addition, they often become picky eaters. This is adaptive as young children are still learning which items are safe to eat and which are not.

• Because caloric intake is reduced, preschoolers to be offered only highly nutritious foods; 'empty' calories and junk food easily take away what little appetite they have.

• The social environment and emotional climate at mealtimes have a powerful impact on children’s eating habits.  Because they are wary of new foods at this age, it is important to introduce them without pressure. Repeated exposure to a new food also increases children’s acceptance.

• Insufficient amounts of iron, calcium, vitamin C, and vitamin A are the most common diet deficiencies of the preschool years.

• By age 7, low SES children in the U.S. are about an inch shorter than their middleclass peers due to both inadequate nutrition and greater frequency of illness, as well as increased stress in the family environment.

   D.     Infectious Disease 

• In well-nourished children, ordinary childhood illnesses have no effect on physical  growth.  

• However, in developing nations, disease is a major cause of malnutrition, which, in turn affects physical growth. Most growth retardation and deaths due to diarrhea in developing countries can be prevented with oral rehydration therapy (ORT), in which sick children are given a glucose-salt- water solution that replaces lost body fluids.  

• Another problem of childhood is lack of immunization for preventable diseases. Overall,  24 percent of American preschoolers lack essential immunizations, a rate rises to 40 percent for poverty stricken children. In contrast, fewer than 10 percent of preschoolers lack immunizations in Denmark a~ Norway and less than 7 percent in Canada, the Netherlands, and Sweden. In 1994, all medically uninsured American children were guaranteed free immunization,  a program that has led to steady improvement in early childhood immunization rates. However, many people have misconceptions about vaccinations and do not ensure timely vaccinations for their young children.

• The frequency of childhood illnesses rises with child-care attendance. However, children who have been in childcare have less frequent illnesses when they enter school than their peers who had in-home child care.  

E.   Childhood Injuries Accidental injuries cause more deaths in early childhood than any other reason, yet many such accidents are preventable.

• Auto accidents, drownings, and burns are the most common injuries during early childhood. Motor vehicle collisions are the leading cause of death among children over 1 year of age.  

• Because of their higher activity level and greater willingness to take risks during play, boys are more likely to be injury victims than girls.  

• Temperament play a role; irritability, inattentiveness, and negative mood are associated with higher rates of  injury. 

• Poverty, low parental education, and more children in the home are also strongly associated with injury.  

• Among Western industrialized nations, the United States ranks among the highest in childhood injury mortality.  

• Childhood injuries can be reduced through legislation (such as seat belt laws), improvement of the safety of the physical environment (changes in design of playgrounds, for instance) and through public education about the dangers and risks to young children.

• Applied behavior analysis (modeling and reinforcement) can improve the safety habits of both children and adults.

• Attention must also be paid to family conditions that can prevent accidental childhood injury.

• Unfortunately, intentional injuries to young children are also a concern in the United States, and family conditions, ignorance and substance abuse all contribute to the incidence of  child abuse. 

IV.   MOTOR DEVELOPMENT

    A.   Gross Motor Development 

• As children’s bodies become more streamlined and loss top-heavy, their center of gravity shifts downward toward the trunk and, as a result, their balance improves. Once their arms are free from having to help with balance, they contribute differently to  gross motor activities. 

• By age 2, the preschooler’s gait becomes smooth and rhythmic, leading to running, jumping, hopping, galloping, and skipping.  Arms and torsos are freed to experiment with new skills—throwing and catching balls, steering tricycles, and swinging on horizontal bars and rings.

• By the end of the preschool years, all skills are performed with greater speed and endurance. At ages 2 and 3, catching and throwing are awkward and stiff. Gradually, children use their shoulders, torso, trunk, and legs to support throwing and catching; consequently, the ball travels faster and further.

.    B.  Fine Motor Development.  Coordination of the fine motor skills follows gross motor skill development. and is most evident in two areas: self-help and drawing and 'writing'.

• During early childhood, preschoolers get great satisfaction from managing their own bodies and gradually become self-sufficient at dressing and feeding. Shoe tying, mastered around age 6, requires a longer attention span, memory for an intricate series of hand movements, and the dexterity to perform them.  

•  Children in Western cultures usually begin to scribble with crayons or pencils, finger and brush paint, and play with clay during their second year. At first, action, rather than the making of 'art' itself, is the (sensorimotor) goal.  As the young child’s ability to mentally represent the world expands, marks on the page take on definite meaning. The progression from scribbling to making representational art seems to be universal: The scribbling becomes making shapes on paper, and then outlines that represent objects and boundaries. By age 3, scribbles start to become pictures; the circular or 'mandala' form appears and is then labeled 'sun' or 'flower' or, with the addition of stick 'arms' and 'legs', a 'person'. 

• Solutions to figure drawing vary somewhat from culture to culture,  but overall they follow the same sequence. The circle with stick appendages , the  'tadpole' people,  gradually take on the more realistic proportions of conventional figures, in which the body is differentiated from the arms and legs and other body features are added, by around age 6. However, drawings at this age still contain perceptual distortions, such as a missing third dimension. Greater realism occurs gradually.

• Children in cultures with little interest in art produce simpler forms, while children whose culture emphasizes art and realistic representation can become quite skilled by the early school years

• In literacy-rich environments where children are frequently exposed to written words, young children experiment with lines and shapes in an attempt to reproduce letters, and later on, words.

• Often the first word printed is the child’s name, reflecting the egocentric nature of children of this age.

• In addition to gains in fine motor control, advances in perception contribute to the ability to correctly form letters.  

     C.      Individual Differences in Motor Skills 

• Body build influences gross motor abilities. African-American children tend to have longer limbs, so they often have better leverage in running, throwing and jumping than do Caucasian children.

• Boys are slightly ahead of girls in skills that emphasize force and power. Girls have an edge in fine motor skills and in certain gross motor skills that require a combination of good balance and foot movement, such as hopping and skipping.  

• However, gender differences in physical skills are very small. Social pressure for boys to be active and physically skilled and for girls to play quietly at fine motor activities may exaggerate these small, genetically-based differences.  

      D.   Enhancing Early Childhood Motor Development 

• Except for throwing, there is no evidence that preschoolers exposed to formal lessons in physical skills are ahead in motor development.

• Preschools, child-care centers, and playgrounds need to accommodate a wide range of physical abilities by offering a variety of pieces of equipment that differ in size or that can be adjusted to fit the needs of individual children.  

• Criticism of a child’s motor performance, pushing specific motor skills, and promoting a competitive attitude may undermine young children’s motor progress. Children should be allowed to enjoy their physical activities for their own sake and they will improve skills and physical competence in normal play and activities.

V.                PERCEPTUAL DEVELOPMENT 

•  During early childhood, sensitivity to invariant features sharpens further, becoming more selective and efficient.  

• Differentiation theory helps to explain how preschoolers learn to discriminate different letters of the alphabet.  

• Research reveals that the ability to tune into mirror images, as well as to scan a printed line carefully from left to right, depends in part on experience with reading materials.  

• Becoming a skilled reader involves more than discriminating visual forms, but perceptual skills do seem to be essential, since children with advanced visual abilities tend to read at higher levels.