Major Characteristics of Development

Infancy

Physical – Physical development obviously starts long before the common “infantile” stage that we all think of today. Brain development begins in the weeks following conception. A noticeable brain is apparent after only three to four weeks, when the neural plate folds up to form the neural tube. The bottom of the tube becomes the spinal cord. “Lumps” then emerge at the top of the tube and form the forebrain, midbrain, and hindbrain. The so-called primitive or lower portions of the brain develop earliest, and regulate such biological functions as digestion, respiration, and elimination; they also control sleep-wake states and permit simple motor reactions. All of the above traits of the brain are what makes life possible. By three months after conception, the midbrain and hindbrain are well on their way to being developed, but the forebrain still has a long way to go. Gradually these two hemispheres become larger and more convoluted, making for a characteristically human brain. Many processes are involved in early brain development, but I won’t go into much detail as they are not true parts of infancy physical development.

These processes include 1proliferation of brain cells, where neurons are produced at a staggering rate during the prenatal period, 2migration, when neurons migrate from their place of origin to places where they will become part of specialized functioning units, and finally 3organization, which is a complex process involving differentiation of neurons, synapse formation, and competition among and pruning of neurons. The brain weighs about 25% of its adult total at birth, and by age 2, it reaches 75%. Lateralization is one important feature of brain organization, which causes the two hemispheres of the cerebral cortex to become asymmetrical.

Aside from brain development, other tremendous amounts of growth and development occur during the first two years of infancy. Reflexes are one of the newborn’s greatest strengths. Two types of reflexes include survival reflexes and primitive reflexes. Survival reflexes all have a clear adaptive value, where primitive reflexes are not clearly useful to the infant, though have been proven to be extremely useful in diagnosing infants’ neurological problems. Primitive reflexes typically disappear during the early months of infancy. Infants are able to establish organized and individualized patterns of daily activity.

In the first few months of life, infants grow rapidly, gaining nearly an ounce of weight a day and an inch in length each month. By age 2, they have already attained about half of their eventual adult height and weigh 27 to 30 pounds. They may grow a couple of centimeters one day and then not grow at all for a few weeks. In the end, 90-95% of the infants’ days are growth free, and yet their occasional bursts of physical growth add up to a substantial increase in size and weight. Bones and muscles also develop quickly during infancy. The two month year old is only able to lift his/her head up when lying on their stomach, while by 12 months of age, can walk well alone, and drink from a cup. This is an example how just how fast and critical physical development is throughout infancy.

Cognitive – Piaget’s first of four cognitive stages of development is the sensorimotor stage, which claims that infants deal with the world directly through their perceptions/senses and their actions/motor abilities. At this point, they are unable to use any sort of symbols, such as gestures or representative images, to help them mentally devise solutions to problems. Infants learn a great deal about the world and acquire tools for solving problems directly through their sensory and motor experiences.

Psychosocial – Erikson’s first conflict, trust versus mistrust. This is Erikson’s proposal that revolves around whether or not an infant becomes able to rely on other people to be responsive to his or her needs. To develop this trust, infants have to have reliable guardians, to feed them when hungry, clean them when dirty, and give them a sense of mutual love and trust. If these needs are not fit, the infant will develop an untrusting relationship with any future friends, including his/her parents.

I would consider a toddler between an infant and a child, but more towards the infant, so I will put Erikson’s stage of autonomy versus shame and doubt in this stage. Autonomy versus shame and doubt is Erikson’s second stage, where toddlers have to learn how to trust themselves enough to assert their wills. Young ones at this age are determined to do things alone, without others help as a means to demonstrate their independence and control over their parents. This is about the time when toddlers usually learn and use the word “no” and “me” quite often to proclaim that they have wills of their own. If in this stage, parents punish or humiliate them for their accidents (toileting or spilling a drink), they may end up doubting their competence or even believing that they are fundamentally bad people.

Childhood

Physical – Development of the body and motor behavior during childhood is much slower than it was during infancy, however it is much steadier. From age 2 until puberty, children gain about 2-3 inches in height and 5 to 6 pounds in weight each year. Children master the ability to move capably in a changing environment. By age 3, they can walk or run in a straight line, though they cannot easily stop or turn while running. Children’s motor skills are very responsive to practice, as their arm movements can improve from 25-30%, compared to the 10% shown by adults who practice. From age 3 to 5, eye-hand coordination and control of the small muscles are improving rapidly. By 8 or 9, they can use household tools such as screwdrivers and have become skilled performers at games that require eye-hand coordination. Handwriting quality and speed also improve steadily from age 6-15. Reaction times also increase greatly throughout childhood.

Cognitive – The child’s cognitive development is based on Piaget’s preoperational stage, which is when children (ages 2-7) acclaim the capacity for symbolic thought but are not yet capable of logical problem solving. Children at about four or five years old can use words as symbols to talk about a problem and can mentally imagine doing something before actually doing it. However, at this stage, children continue to lack the tools of logical thought, and must rely on their perceptions, which causes them to be easily fooled by appearances. Some common mistakes of preoperational children include: thinking that large objects will sink in water, even when they are light, such as a Styrofoam block. Another classification of this stage is the egocentric thinking that causes children to have difficulty adopting perspectives other than their own, which may cause them to cling to incorrect ideas simply because they want them to be true. Once past this stage, children (ages 7-11) advance to the concrete operations stage and are more logical thinkers. Trial-and-error is used as an approach to problem solving, and problems that involve thinking about the “real” world of concrete objects are performed well. Children here can mentally categorize or add and subtract objects. They can also draw sound and general conclusions based on their observations, yet continue to have difficulty dealing with abstract and hypothetical problems.

Psychosocial – By the time the child reaches about four or five years old, they enter into Erikson’s third conflict (assuming they’ve achieved a sense of autonomy) known as initiative versus guilt. In this stage, children develop a sense of purpose by devising bold plans but must also learn not to step on other people in the process. New motor skills are acquired, and plans are devised to build a virtual fantasy land of their own (during play), while pride in accomplishing their own achievements is important. Erikson believed that a sense of initiative paves the way for success in elementary school, when children face his fourth conflict of industry versus inferiority. During this conflict stage, children must gain a sense of industry by mastering the important cognitive and social skills such as reading, writing, cooperative teamwork etc, which are necessary to win the approval of both adults and their peers.

Adolescence

Physical – Dramatic physical changes take place during adolescents. The growth spurt is one major part of development. Like infants, adolescents may grow in spurts rather than continuously. Muscles also develop rapidly, and total body weight increases in both girls and boy, though distributed differently. Sexual maturation is a defining part of the adolescent period. The adrenal glands increase production of a adrenal androgens as early as 6 to 8, which contributes in small part to characteristics such as pubic and underarm hair. The more obvious signs of sexual maturity emerge with increased production of gonadal hormones (produced in either the ovaries or testes). For girls, the most dramatic event in sexual maturation is menarche, which is the first menstruation period, normally occurring between age 11 and 15.

For the average boy, sexual maturation begins at about age 11 with an initial enlargement of the testes and scrotum. Pubic hair appears soon thereafter, and about six months later, the penis grows rapidly at about the same time that the growth spurt begins. The marker of sexual maturation in boys is semenarche, or a boy’s first ejaculation, usually during the sleep, called a “wet dream”. Somewhat later, boys begin to sprout facial hair, first at the corner of the upper lip and finally on the chin and jaw line. As the voice lowers, many boys have the embarrassing experience of hearing their voices “crack” up and down uncontrollably and at different times while talking. Most boys will not see the signs of any chest hair until their late teens or early twenties. As the adolescent years progress, the physical performance of boys continues to improve, whereas that of girls often levels off or even declines.

Cognitive – Adolescents (ages 11-12) enter the cognitive stage known as formal operations, and are able to think more abstractly and hypothetically than school-age children. They can define “justice” abstractly, in terms of fairness, rather than concretely, in terms of cop = good and robber = bad. They now have the ability to formulate hypotheses or predictions in their heads, plan in advance how to systematically test their ideas experimentally, and imagine the consequences of their tests.

Psychosocial – According to Erikson, adolescence is a time of “identity crisis”, or a critical period in the life long process of forming one’s identity, a conflictual stage which he labeled identity versus role confusion. During this stage, adolescents try to define themselves in terms of career, religion, and sexual identity. They try to figure out where they are heading in life, and how they fit into society. Often times adolescents in this stage change their minds and experiment with new looks, majors, and new experiences.

Adulthood

Physical – Only minor changes occur in physical appearance in the 20’s and 30’s, but many people do notice signs that they are aging as they reach their 40’s. At this point, skin becomes wrinkled, dry and loose. Hair thins and often turns gray from loss of pigment producing cells, and to most people’s dismay, they put on extra weight throughout much of adulthood as their metabolism declines. Some people find these changes difficult to accept. After the initial weight gain during the 40’s, people typically begin to lose weight starting at about age 60. This loss of weight in old age is usually coupled with a loss of muscle over the entire span of adulthood. Also as age increases, so does level of activity. Aging is also associated with decreased bone density, reduced muscle mass and joint changes, which can all lead to shortened stature, stooped posture, fractures, and pain. Extreme bone loss in later life can result from osteoporosis, which involves pain and can actually result in death if one falls and fractures a hip. As joints age during old age, the cushioning between bones wears out, and the joints become stiffer, which may cause pain from arthritis or joint inflammation.

Aging also involves a gradual decline in the efficiency of most bodily systems from the 20’s on, believe it or not. A decline in the reserve capacity is another fact of physical aging. By the age of 65, it is not likely that you will not have something wrong with your body. Hormone levels fluctuate on a somewhat day-to-day basis in men, and men with high levels of testosterone tend to be more sexually active and aggressive than other men. On the contrary, hormone levels in women shift drastically each month as they progress through their menstrual cycles. These changes may lead to symptoms known today as PMS. The ending of a woman’s menstrual periods occurs in midlife, and is known as menopause. This usually occurs at age 51, after which, levels of estrogen and other female hormones decline, so that the woman who has been though menopause has a hormone mix that is less feminine and more masculine. After menopause, a woman is no longer ovulating or menstruating, and therefore is no longer capable of conceiving a child. A similar event that occurs in men at this stage, is described in the as the concept of “climacteric”, which refers to the loss of reproductive capacity in either sex in later life. Among 50-70 year old men, half complain of erectile dysfunction.

Another key and inevitable part of the aging process is the slowing down of the central nervous system, and other sensory systems. This may cause people to walk more slowly, take longer to react to stop lights, or cause a lack of balance. One key to the prevention of this is to try to remain active, and use old skills as often as possible. Overall, the poor functioning in old age may represent any combination of the effects of aging, disease, disuse, and abuse. In the end however, the sad truth is that, death is always the case.

Cognitive – Through early adulthood, basic principles of the formal operations stage are further expanded, giving people a thoroughly systematic method of solving problems, and allowing them to think logically about the implications of purely hypothetical ideas.

Psychosocial – The stage which most greatly defined the difference between Erikson’s and Freud’s views. Erikson labeled three stages during adulthood. The first conflict, intimacy versus isolation, occurred during early adulthood, where the young adult who has not resolved the issue of identity versus role confusion may be threatened by the idea of entering a committed, long-term relationship and being “tied down”, or possibly over dependent on a partner as a source of identity. Upon crossing this dilemma, comes the middle age conflict/issue of generativity versus stagnation. Adults here struggle to gain a sense that they have produced something meaningful through their work or volunteer activities. If everything goes as planned, they will have a genuine concern about the welfare of future generations, instead of being “in a rut” absorbed with their own problems. The final conflict in Erikson’s psychosocial developmental process is integrity versus despair. Here, older adults try to find a sense of meaning in their lives that will help them face the inevitability of death. If successful, they are able to look back over their lives and say there is little or nothing they would change if they had the chance to do it all over. If not successful, they may dwell on past failures and paths not taken, all making the preparation for death worse.