1.1 Concepts of growth, development and maturation

Human development refers to the biological and psychological development of the human being throughout the lifespan. It consists of the development from infancy, childhood, and adolescence to adulthood. The scientific study of psychological human development is sometimes known as Developmental psychology.

Human development is a lifelong process of physical, behavioral, cognitive, and emotional growth and change. These two terms, growth and development are used interchangeably. Both relate to the measurement of changes occurred in an individual after conception in the womb of the mother. However, in the strict sense of terminology, these two terms have different meanings:

Growth: can be defined as an increase in size, length, height and weight or changes in quantitative aspect of an organism/individual.

Hurlock has defined Growth as “change in size, in proportion, disappearance of old features and acquisition of new ones”.

Development: is a series of orderly progress towards maturity. It implies overall qualitative changes resulting in the improved functioning of an individual.

According to Crow and Crow (1965) development is concerned with growth as well as those changes in behavior which results from environmental situation.”

Growth refers to physiological changes.	Development refers to overall changes in the individual. It involves changes in an orderly and coherent type towards the goal of maturity.
Growth is one of the parts of developmental process.	Development is a wider term and growth is one of its parts.
Changes take place in particular aspect of the body and behavior.	Changes in the organism as a whole.
Growth stops once maturity is attained.	Development is a continue process: from womb to tomb.
Changes may be measured. As in case of height or weight.	Can’t be always measured.
Changes in the quantitative respect is termed as growth.	Development changes in the quality along with quantitative aspect.
Growth occurs due to the multiplication of cells.	Development occurs due to both maturation and interaction with the environment.
Not affected by leaning	Learning and experience effects development
May or may not bring development. A child may grow in terms of height and weight but this growth may not bring any functional improvement/development.	Development is also possible without growth.

Maturation:

Maturation is the process of learning to cope and react in an emotionally appropriate way. It does not necessarily happen along with aging or physical growth, but is a part of growth and development. A situation a person must deal with at a young age prepares them for the next and so on into adulthood. Maturation does not stop when physical growth ends - it continues through adulthood. An adult who loses a parent, for instance, learns to cope with a new emotional situation that will affect the way he or she deals with situations that follow.

According to Garry and Kingsley “Maturation is the process whereby behavior is modified as a result of growth and development of physical structures.”

Types of Maturation

Physical Maturation

As the name suggests it indicates the physical development and growth that we go through as we get older. A child goes through some very distinct physical maturity as they progress through all their development stages. For example, in the early stages of development, a child depends on reflexes majorly. Then as they age, they develop their motor skills and coordination. They also grow taller and add more weight as they develop. Their body goes through hormonal changes as they leave adolescence and enter early adulthood.

Cognitive Maturation

This refers to the cognitive development of children from birth to adulthood. It refers to how babies think, learn, interact with their environment, etc. Some important aspect of cognitive development is the processing of information, language development, reasoning skills, development of intellects and memory.

This process of cognitive development begins right at infancy. An infant uses their sensory organs to explore their surroundings. By three months infants can actually distinguish faces and sounds. And as they go through adolescence and their teenage year, the cognitive development continues. Each stage is earmarked with certain benchmarks that the teachers can focus on to chart the child’s cognitive maturity.

Principles of Development

From the scientific knowledge gathered through observation of children, some principles have emerged. These principles enable the parents and the teachers to understand how children develop. What is expected of them? How to guide them and provide proper environment for their optimum development?  It seems that the process of development is operated by some general principles. These rules or principles may be named as the principles of development. Some of these principles are briefly explained below:

1. Principle of Continuity:  Development is a process which begins from the moment of conception in the womb of the mother and goes on continuing till the time of death.   It is a never ending process. The changes however small and gradual continue to take place in all dimensions of one’s personality throughout one’s life.

2. Principle of Individual differences:  Every organism is a distinct creation in itself. Therefore, the development which undergoes in terms of the rate and outcome in various dimensions is quite unique and specific. For example, all children will first sit up, crawl and stand before they walk. But individual children will vary in regard to timing or age at which they can perform these activities.

3. Principle of lack of uniformity in the developmental rate:  Though development is a continuous process it does not exhibit steadiness and uniformity in terms of the rate of development in various dimensions of personality or in the developmental periods and stages of life.   Instead of steadiness, development usually takes place in fits and starts showing almost no change at one time and a sudden spurt at another. For example, shooting up in height and sudden change in social interest, intellectual curiosity and emotional make-up.

4. Principle of uniformity of pattern: Although there seems to be a clear lack of uniformity and distinct individual differences with regard to the process and outcome of the various stages of development, yet it follows a definite pattern in one or the other dimension which is uniform and universal with respect to individuals of a species. For instance, the development of language follows a somewhat definite sequence quite common to all human beings.

5. Principle of proceeding from general to specific:  While developing in relation to any aspect of personality, the child first picks up or exhibits general responses and learns to show specific and goal-directed responses afterwards. For example, a baby starts by waving his arms in general random movement and afterwards these general motor responses are converted into specific responses like grasping or reaching out. Similarly when a new born baby cries, his whole body is involved in doing so but as he develops, it is limited to the vocal cords, facial expression and eyes etc. In development of language, a baby calls all men daddy and all women mummy but as he grows and develops, he begins to use these names only for his own father and mother.

6. Principle of integration:   By observing the principle of proceeding from general to specific or from the whole to the parts, it does not mean that only the specific responses are aimed for the ultimate consequences of one’s development. Rather, it is a sort of integration that is ultimately desired. It is the integration of the whole and its parts as well as the specific and general responses that enables a child to develop satisfactorily in relation to various aspects or dimensions of his personality.

7. Principle of interrelation: The various aspects of one’s growth and development are interrelated.  What is achieved or not achieved in one or the other dimension in the course of the gradual and continuous process of development surely affects the development in other dimensions.  All healthy body tends to develop a healthy mind and an emotionally stable and socially conscious personality.  On the other hand, inadequate physical or mental development may results in a socially or emotionally maladjusted personality. That is why all efforts in education are always directed towards achieving harmonious growth and development in all aspects of one’s personality.

8. Principle of interaction: The process of development involves active interaction between the forces within the individual and the forces belonging to the individual. What is inherited by the organism at the time of conception is first influenced by the stimulations received in the womb of the mother and after birth, by the forces of physical and socio-psychological environment for its development. Therefore, at any stage of growth and development, the individual’s behaviour or personality make-up is nothing but the end-product of the constant interaction between his heredity endowment and environmental set-up.

9. Principle of interaction of maturation and learning: Development occurs as a result of both maturation and learning. Maturation refers to changes in an organism due to unfolding and ripening of abilities, characteristics, traits and potentialities present at birth. Learning denotes changes the changes in behaviour due to training and experience.

10. Principle of predictability: Development is predictable, which means that, to a great extent, we can forecast the general nature and behaviour of a child in one or more aspects or dimensions at any particular stage of its growth and development. Not only such prediction is possible along general lines but it is also possible to predict the range within which the future development of an individual child is going to fall. For example, with the knowledge of the development of the bones of a child it is possible to predict his adult structure and size.

11. Principle of cephalocaudal and proximodistal tendencies: Cephalocaudal and proximodistal tendencies are found to be followed in maintaining the orderly sequence and direction of developments.

According to cephalocaudal tendency, development proceeds in the direction of the longitudinal axis, ie. head to foot. For example, before it becomes able to stand, the child first gains control over his head and arms and then on his legs.  In terms of proximodistal tendency, development proceeds from the near to the distant and the parts of the body near the centre develops before the extremities. For example, in the beginning the child is seen to exercise control over the large fundamental muscles of the arm and the hand and only afterwards the smaller muscles of the fingers.

12. Principle of spiral versus linear advancement.  The path followed in development by the child is not straight and linear and development at any stage never takes place with a constant or steady pace.  At a particular stage of his development, after the child had developed to a certain level, there is likely to be a period of rest for consolidation of the developmental progress achieved till then. In advancing further, development turns back and then moves forward again in a spiral pattern.

1.2 Growth curve and stages of human development from infancy to childhood

Overview of postnatal growth: Scammon’s curves 

The curves of systematic growth reported by Scammon about 60 years ago. Upon analysis of the size of various parts and organs of the body, Scammon proposed that the growth of different tissues and systems could be summarized in four patterns (or curves) of growth.  

1. General Curve 

The general, or body, curve describes the growth of the body as a whole and of most of its parts – the growth pattern of stature, weight and most external dimensions of the body.

It is also characteristic of the growth pattern of most systems of the body, including muscle mass, the skeleton, (with the exception of certain parts of the skull and face), the respiratory system, the heart and blood vessels, the digestive system, and the urinary portion of the uro-genital system.

The growth pattern is S - shaped (sigmoid) and has four phases: rapid growth in infancy and early childhood, steady but rather constant growth during middle childhood, rapid growth during the adolescence spurt, and slow increase and eventual cessation of growth after adolescence. 

2. Neural Curve

The neural curve characterizes the growth of the brain, nervous system, and associated structures, such as the eyes, upper face, and parts of the skull. These tissues experience rapid growth early in postnatal life, so that about 95% of the total increment in size of the central nervous system between birth and 20 years is already attained by about 7 years of age. Neural tissues shows steady gain after 7 years of age, with a slight growth spurt during adolescence.  

3. Genital Curve 

The genital curve characterizes the growth pattern of the primary and secondary sex characteristics. The former include the ovaries, fallopian tubes, uterus and vagina in females, and the testes, seminal vesicles, prostate and penis in males. Secondary sex characteristics include breast development in females, pubic and axillary hair in both sexes, and facial hair and growth of the larynx in males. Larynx growth is related to voice changes that occur during male adolescence. Genital tissues show slight growth in infancy, followed by a latent period during most of childhood. Genital tissues then experience extremely rapid growth and maturation during the adolescent spurt. 

4. Lymphoid Curve 

The lymphoid curve describes the growth of the lymph glands, thymus gland, tonsils, appendix and lymphoid patches of tissue in the intestine. These tissues are involved, in general with the child’s developing immunological capacities, including resistance to infectious diseases.

Lymphatic tissues show rapid growth during infancy and childhood, reaching a maximum at about 11 to 13 years of age. At these ages, children have, on a relative basis, about twice as much lymphoid tissue as they have as adults. The decline of the lymphoid curve during the second decade of life is related to the involution (shrinking) of the thymus and tonsils at this time. 

Scammon’s curves thus indicate the differential nature of postnatal growth. Growth occurs in different areas and tissues of the body at different times and at different rates. Although somewhat simplified and diagrammatic, the curves give a sense of order to the structural and functional changes that occur with growth and maturation. Nevertheless, there are several exceptions to the four curves. The craniofacial skeleton is one such exception. The upper part of the face, the orbits of the eyes, and the cranial vault follow the neural curve and complete a good portion of their growth by about 7 years of age. The lower face, including the jaw, follows the general curve. Thus the upper part of the face has a different growth pattern than the lower part.

Stages of human development from infancy to adulthood

Even though development is a continuous process, some theorists believe that various stages can be identified for the sake of locating major shifts and determining the developmental tasks. This helps in monitoring the pace of developmental changes. It must be pointed out that there is no sharp dividing line between them. Each stage has certain characteristic features and prepares the ground for the next stage. Some theorists have suggested stages in specific areas of development. For instance Piaget who identified stages of cognitive development and Freud who suggested stages of psycho-sexual development. These theories are explained in other lessons.

1. Infancy

Infancy comprises the first year of life. This is a period of rapid growth in most bodily systems and dimensions and rapid development of the neuromuscular system.  

After birth, the growth is oriented towards functional state of life. Growth is mainly by addition of more cells or increase in the protoplasm. It can be said that anabolic processes exceed catabolic processes and there is increase in size, shape and weight. This characterizes the infant stage.  

Immediately after birth the rate of growth increases. In case weight the peak velocity is reached at two months after birth. The cells become larger in size. The cervical and lumber curvatures of the spinal column appear as the baby begins to straighten the head and tries to sit up and to stand. During infancy growth is very rapid. More than 50 percent of birth length and 200 percent of birth weight take place during the first year of life.

2. Childhood 

Childhood ordinarily spans from the end of infancy (the first birthday) to the start of adolescence. The infant attains childhood before reaching adolescence. It is often divided into early childhood and middle childhood.

· The early childhood (2-6 years):  is the period of eruption of milk teeth. Motor skills are refined, language develops, ties are formed with peers, and the child learns through play.

· The middle childhood (7 to 11 years) is the period of eruption of permanent teeth, though not all erupt. These are the school years when the child acquires literacy skills, thought processes are refined, friendships emerge and self-concept is formed.

3. Adolescence 

Adolescence (11-20 years): This period is marked by puberty which signals the onset of rapid physical and hormonal changes, emergence of abstract thinking, sexual maturity, stronger peer ties, sense of self and autonomy from parental control. During this period there is a marked acceleration of growth which is known as adolescence growth spurt. The adolescence spurt is a constant phenomenon and occurs in all children, though it varies in intensity and duration from one child to another. In boys it takes place, on the average from age 12 to 15. In girls the spurt begins about two years earlier than in boys. Differentiation in primary and secondary sexual characteristics marks the adolescence period. There are changes in the reproductive organs, in body size and shape, in the relative proportions of muscle, fat and bone and in a variety of physiological functions.

4. Adulthood

This period starts from 20 years to till death. Generally this period is divided in three sub categories. These are as follow.

· Early adulthood (20-40 years): This is the stage of life when the youngster leaves home for the sake of education, or to find a career, and to form intimate relationships leading to marriage and having children.

· Middle adulthood (40-60 years): At this stage the person is at the peak of his/ her career. There is a need to help children begin independent lives, and to look after own parents who are aging.

· Late adulthood (60 years till death): This period is marked by retirement from work, decrease in stamina and physical health, bonding with grand-children, and dealing with impending old age and death of self and spouse.

FACTORS AFFECTING HUMAN DEVELOPMENT

All children also do not have same type of intelligence. Some have more musical talents, others have more intrapersonal intelligence, others also have more linguistic abilities etc. So, children differ from each other because several factors influence on their development. Some of the important factors have been enumerated below:

1. Hereditary Factors:- Heredity exerts an influence on human development. The child carries genetic endowments from his/her parents. It is genetically transmitted characteristics from one generation to the next. The physical characteristics like height, weight, eye color etc. and psychological characteristics such as intelligence, personality, creativity and so on are innately determined and hereditary. The genetic code provides the base on which brain and body grow and manifest in observable appearance and behavior.

2. Environmental Factors:- Another important factor of human development is the environment where an individual lives. The child lives and grows in his environment. Environment consists of a wide range of stimuli and it provides the necessary input and experiential base for development of the child. Enrichment or impoverishment of the environment would produce differences in his abilities. For example, a child may have inherited music talent from his parents through transmission of genes, but he may not excel in music field if he does not get the proper environment and support to develop his innate ability.

3. Home Environment:- Home environment exerts tremendous influence on child‟s understanding of the external world. It builds self-concept and prepares him to face the external world. The child begins to acquire knowledge through interaction with parents and other family members. During his early years of development, the behaviours of the child are modulated by the home environment. The environment of the family can be supportive or stressful for the child. If it is supportive, warm and harmonious environment, the child develops normally. In unsupportive and stressful home environment, broken families or uncaring parents in the family, children may develop as maladjusted persons.

4. Cultural Factors:- Culture refers to a system of beliefs, attitudes and values that are transmitted from one generation to the next. It is a product of past human behavior and is also a shaper of future aspirations. The development of the child is influenced by family as well as by the society. The child learns the habits, beliefs, attitude, skills and standards of judgment through the socialization processes. The socialization processes of the child take place according to the culture, customs and traditions of the society. For example, greeting someone is a familiar experience but behavioral experiences are different in different cultures. In Indian culture, people greet others by saying namaskar, folding hands or lying down near the feet but in Western culture, people greet by handshake or kissing or saying hello etc.

5. Socioeconomic Status (SES):- Socioeconomic Status plays a pivotal role in human development. The index of socioeconomic status is determined by parental education, occupation and income. The children of low socioeconomic status may develop as mal-nourished, suffer from lack of knowledge in many aspects and their normal development may get hampered. The parenting in high socioeconomic status families would be different from low socio-economic status families. Children of the high socioeconomic groups of the society get better social opportunities, are nurtured with better nutrition, good medical treatment and are exposed to more intellectual stimulation than low socioeconomic group.

6. Education and Training:- Each child is equipped with certain abilities which need to be nurtured through proper education and training. Therefore, the first and foremost step is to identify and recognize the ability of the child and the next step is to provide adequate opportunities to develop the same. If proper identification of the ability is not possible and adequate facilities are not available to the child, then his innate ability may not be developed. Thus, adequate education and training have influence on human development.

1.3 Domains of development (Physical, Cognitive, Socio-emotional, moral and language).

1. Physical development

It is important to know how children develop physically because physical development influences children’s behaviour directly by determining what they can do and indirectly their attitudes towards self and others. Physical development involves changes in body size and body proportions which is measured in terms of height and weight.  The physical development involves growth of bones, fat muscle, teeth, puberty changes of primary and secondary characteristics and neurological development.

2. Cognitive development

Cognition refers to the mental activities involved in acquisition, processing, organization, storage and use of information. These activities include perceiving, imagining, reasoning and judging. A single and global measure of an individual’s general level of cognitive development is called intelligence.  The neuron patterns in the brain are the determining factors of intellectual development.  Mental growth is the process of organization of behaviour patterning which brings the individual to a stage of psychological maturity.

The observational studies on children’s intellectual development by Jean Piaget, (1896-1980) a Swiss psychologist, is considered as an important landmark in this area.  Piaget’s theory covers the entire range of ages from infancy through adolescence. 

3. Socio-emotional development

Social and Emotional refers to your child's ability to make and maintain relationships.

Every child is born with potentialities for both pleasant and unpleasant emotions. Even infants have the ability to respond emotionally. The first sign of emotional behaviour in the new born infant's  'general excitement' due to intense stimulation. However, the emotional status of the infant in the next few months is not very clear-cut and appears to be diffused. With age, emotional responses become less diffused and random. For example, at first, the child expresses displeasure by screaming/crying but later his reactions include resisting, throwing objects, stiffening of the body etc. As the child becomes older linguistic responses increase and child's motor responses decrease especially in fear and anger.

Social development refers to development of the ability to behave in accordance with social expectations, which involve social perception, thinking and reasoning about people, one self and social relationship. These are called "Social Cognition'. The process of learning the standards of behaviors, roles and values in a given culture is called 'Socialization'. Socialization is largely determined by child's cognitive development as well as social stimulation available to the child.

4. Moral development

The independence that comes with adolescence requires independent thinking as well as the development of morality — standards of behavior that are generally agreed on within a culture to be right or proper. Just as Piaget believed that children’s cognitive development follows specific patterns, Lawrence Kohlberg (1984) argued that children learn their moral values through active thinking and reasoning, and that moral development follows a series of stages.

It involves an individual’s growing ability to distinguish right from wrong and to act in accordance with those distinctions.

5. Language development

Language involves receptive and expressive forms when receptive language ability is limited expressive language development is affected. Speech is only one form of expressive language. It is the most useful and most widely used form in expressing our thoughts and feelings.  If speech is to be an useful form of communication, the speaker must use words used by others. 

1.4 Main characteristics and features of development across stages (Prenatal development, Infancy, Childhood, Adolescence, Adulthood)

Prenatal development

1. The ovum

Conception occurs when an egg from the mother is fertilized by a sperm from the father. In humans, the conception process begins with ovulation, when an ovum, or egg (the largest cell in the human body), which has been stored in one of the mother’s two ovaries, matures and is released into the fallopian tube. Ovulation occurs about halfway through the woman‘s menstrual cycle and is aided by the release of a complex combination of hormones. In addition to helping the egg mature, the hormones also cause the lining of the uterus to grow thicker and more suitable for implantation of a fertilized egg.

2. The Zygote

Within several hours, half of the 23 chromosomes from the egg and half of the 23 chromosomes from the sperm fuse together, creating a zygote—a fertilized ovum. The zygote continues to travel down the fallopian tube to the uterus. Although the uterus is only about 4 inches away in the woman‘s body, this is nevertheless a substantial journey for a microscopic organism, and fewer than half of zygotes survive beyond this earliest stage of life. If the zygote is still viable when it completes the journey, it will attach itself to the wall of the uterus, but if it is not, it will be flushed out in the woman‘s menstrual flow. During this time, the cells in the zygote continue to divide: The original two cells become four, those four become eight, and so on, until there are thousands (and eventually trillions) of cells. Soon the cells begin to differentiate, each taking on a separate function. The earliest differentiation is between the cells on the inside of the zygote, which will begin to form the developing human being, and the cells on the outside, which will form the protective environment that will provide support for the new life throughout the pregnancy.

3. The Embryo

Once the zygote attaches to the wall of the uterus, it is known as the embryo. During the embryonic phase, which will last for the next 6 weeks, the major internal and external organs are formed, each beginning at the microscopic level, with only a few cells. The changes in the embryo‘s appearance will continue rapidly from this point until birth. While the inner layer of embryonic cells is busy forming the embryo itself, the outer layer is forming the surrounding protective environment that will help the embryo survive the pregnancy. This environment consists of three major structures: The amniotic sac is the fluid-filled reservoir in which the embryo (soon to be known as a fetus) will live until birth, and which acts as both a cushion against outside pressure and as a temperature regulator. Theplacenta is an organ that allows the exchange of nutrients between the embryo and the mother, while at the same time filtering out harmful material. The filtering occurs through a thin membrane that separates the mother‘s blood from the blood of the fetus, allowing them to share only the material that is able to pass through the filter. Finally, the umbilical cord links the embryo directly to the placenta and transfers all material to the fetus. Thus the placenta and the umbilical cord protect the fetus from many foreign agents in the mother‘s system that might otherwise pose a threat.

4. The Fetus

Beginning in the 9th week after conception, the embryo becomes a fetus. The defining characteristic of the fetal stage is growth. All the major aspects of the growing organism have been formed in the embryonic phase, and now the fetus has approximately six months to go from weighing less than an ounce to weighing an average of 6 to 8 pounds. That‘s quite a growth spurt.

The fetus begins to take on many of the characteristics of a human being, including moving (by the 3rd month the fetus is able to curl and open its fingers, form fists, and wiggle its toes), sleeping, as well as early forms of swallowing and breathing. The fetus begins to develop its senses, becoming able to distinguish tastes and respond to sounds. Research has found that the fetus even develops some initial preferences. A newborn prefers the mother‘s voice to that of a stranger, the languages heard in the womb over other languages (DeCasper & Fifer, 1980; Moon,

Infancy and Toddlerhood Stage

Developmental psychologists used the term infancy to denote the period of development that generally is from birth to two years of age. The word infant means “without language”. Infancy includes development in the areas of cognition, perception, motor activity, emotion, sociability and language. In the beginning of infancy period infants can recognise human faces and after that they can differentiate between known and unknown faces and react differently. Development on different areas take place through infancy to toddlerhood, i.e, the first three years of life.

1. Physical development:

It refers to the changes in the body. This development is rapid during infancy. Infants increase their body weight almost triple and increase in height by about one-third during the first year alone. Not only body size and weight of the infant increase but also brain size expands rapidly during the first 18 months and brain weight of the infant reaching more than half of the adult brain due to rapid growth of dendrites and axons within the brain and glia cells. Physical development also includes development in vision, hearing, perceptual development etc. Infants motor development takes place in a sequential order and this type of development proceeds from head towards the limbs. Infant first controls his head and trunk, then lift his chest, sit upright, crawling, creeping, stand with help, stand along with holding some objects, walking and so on. This development occurs due to improvement of skills and control of other body parts like legs, arms, etc. Gradually children develop their eye, head and hand coordination and are able to pick up things.

Piaget noted that the sensory motor stage of cognitive development occurs during infancy. During infancy period there are development in vision, control of muscles and nervous system, start to eat and sleep on regular intervals, sit on their own and to hold objects themselves.

2. Social and Emotional Development:

Infants at about two months old demonstrate social smiling in response to human faces. When they are four months old, they show laughter and express anger, sadness and surprise by six months. By 8 or 10 months, they actively seek information about other people‟s feelings. They learn to respond when somebody calls them by their names at about age six to twelve months. They also have face to face contact. They are afraid of when their parents or care-taker leaves them. They start expressing anger if their needs are not met. Thus, social and emotional development starts during the period of infancy to toddlerhood itself Children start expressing their feelings of trust, fear, confidence, love, etc. They express affection as a form of emotion to others as a part of social emotional development.. If a child is neglected during this period, it affects his social emotional development negatively. During this period as children are attached with their care givers, parents and other siblings, etc., so children develop separation anxiety if they are separated from them. This appears at the age of nine months.

3. Cognitive Development

Infants express their intellect by making various sounds like gurgling, cooing, etc. They observe their own hands and feet. They gradually learn the relationship between their actions and the external world. They can manipulate various objects to produce effects. Infants seem to acquire knowledge about the world only through motor activities and sensory impressions. They try to focus their eyes on various objects and people, put everything in their mouth. Children develop ability to form mental representation during infancy. Around the end of the 9th month infants demonstrate object permanence. By babyhood stage they learn to make sounds like mama, papa, they try to copy various activities as others do. By 12 months of age many children are able to say some words which can be understood by others. During infancy children start developing language ability, learn through their sense organs and explore the world in their own ways. In this period children are dependent on others where as in toddlerhood stage, creativity and socialisation begins. In infancy period emotions are of simple type but in toddlerhood emotions are of varying types and growth is faster than other periods of life.

Childhood stage

This stage includes two sub-stages: one is early childhood and another is late childhood. This period covers the period between the age of 3 to 11 years. Sometimes the girls at 13 years and boys at 14 years of age are considered as adolescents and till then the child is considered being in the childhood stage. During this period significant physical and psychological changes take place. But compared to infancy, growth rate is slow but stable during the childhood. In this stage, children gain 2 to 3 inches in height and 5 to 6 pounds in weight every year. They learn to walk, run, jump and play. They can gain knowledge to distinguish between what is good and what is bad. Their physical capacities increased independently, they perform tasks and meet adult expectations in several ways.

1. Physical Development:

Early childhood stage covers the age range from 3 to 6 years. Children begin to develop athletic appearance and they lose their babyish roundness. As abdominal muscles develop, the trunk, arms and legs grow longer. Their brain and head grow rapidly than any other parts of the body. The late childhood period extends from 6 to 11 years. This period is known as pre-adolescence. The different parts of the body become stronger during this period. Children learn to use their body parts appropriately with speed and for proper behaviours. During late childhood period some of the habits like table manners interactions with others, eating appropriately, etc. may also be modified wherever needed. In this period importance is given to physical strength of children. If a particular child is not growing physically at per with other children of his age, the child may be emotionally and socially depressed.

2. Psycho-Social Development:

In early childhood stage children can say full sentences, express their feelings and emotions and communicate their needs and feelings and emotions and communicate their needs and feelings with others. During early childhood children have better control of their physical movement and can have better coordination of their body parts. They also learn how to cooperate with other children and conflict resolution when they are about the age of five or six years they are independent in various ways. There are three important socio-emotional developments, such as; development of self, gender roles and moral development, take place during childhood period. Through the process of identification the child comes to know who he is and differentiates from who he wants to be. The child is aware of this process through his observation and imitation of parents and significant others. The child‟s personality is laid down by this identification. The child learns the socially appropriate behaviours by observing and participating in the social events. When the children are about the age of 5 to 6 years they can understand that they belong to a particular gender and also learn to behave gender roles.

3. Cognitive Development:

The childhood period is important for cognitive development of children. Children are curious to know the answers of questions like, “why”, “Where” and “How” for everything that happens. Cognitive abilities include memory, reasoning, perception, problem solving and thinking abilities which continue to emerge throughout childhood. Jean Piaget worked on childhood cognitive development. He concluded that children are not less intelligent than adults but they simply think differently. Piaget explained that human beings acquire knowledge through interaction with the environment in which he lives in, Piaget named early child hood (2 to 7 years) as the preoperational stage of cognitive development which there is a great expansion in the use of symbolic thought, or representational ability. But they are not able to use logic. In this stage children do not need to be in sensory motor contact with an object, person or event in order to think about it. They are aware that superficial alternations do not change the nature of things and also understand the cause-effect relationship. They develop the ability to classify objects, people and events. Children can count and deal with quantities. They become more able to imagine how others might feel and aware of mental activity and the functioning of the mind.

Adolescence stage

The term adolescence is derived from the Latin word adolescere, which means to sprout into maturity. It is the intermediate period between childhood and adulthood. This period is otherwise called as the age of teenagers. It includes three sub periods, such as: early adolescence (12 yrs -14 yrs), middle adolescence (14 yrs -17 yrs) and late adolescence (17 yrs -19 yrs). Adolescence is the developmental transition between childhood and adulthood entailing major physical, cognitive and psychological changes. During this period physical changes that occur are universal, but social and psychological changes largely depend on the cultural contexts. As this is the transitional phase of life adolescents rebel against their parents and society most often. Therefore, this period is labelled as storm and stress period.

1. Physical Development

Sexuality and identity formation are two major challenges of the period of adolescence. During this period the most rapid physical growth occurs. There are changes in the growth rate, sexual characteristics, and behaviour. Adolescent boys and girls develop in their height, weight, strength and development of bones, muscles, etc. Puberty and sexual maturity for both boys and girls marks the beginning of the adolescent period. Growth spurts and development of secondary sex characteristics signal about the onset of adolescence. Menstruration is the first sign of puberty for girl whereas appearance of few whiskers is the sign of puberty for boys. The approximate age for sexual maturation is 12.5 years for boys and 10.5 years for girls. Puberty begins in response to changes in the hormonal system. Sex hormones like testosterone in males and estrogen in females are secreted from the sex glands. The secretion of sex hormones help in pubertal development and also closely associated with emotions. During this period emotion like aggression is found in boys and depression is marked in girls. They try to imitate their idols. Girls are conscious about their shapes and do what their friends do while boys try to go for body building.

2. Psycho-Social Development

During this period the physical changes in adolescents bring about a wide variety of psychological changes. Adolescents become innovative and take interest in learning various skills with great interest. They feel that no one understands them, and they often consider themselves to be „superman‟. Their sense of uniqueness is expressed in the form of personal fable around them away from the world of reality. They are argumentative and they have a tendency to find fault with the authority figures. They do not able to differentiate between ideal and real. Adolescents are very self-conscious and it is expressed in the concept of imagery audiences. These imaginary audiences criticise, encourage and motivate an adolescent. Peer group influence is very important during adolescence. They want to do what their friends are doing, Adolescents abuse alcohol and drugs under peer pressure. Developmental psychologists viewed that adolescence as a period of risk, turmoil, uncertainty and conflict, if proper care is not taken during this period children became antisocial, abusive or depressed.

3. Cognitive Development

During adolescence not only there are changes in body structures occur but also they think differently from younger children. Jean Piaget opined that adolescents enter the highest level of cognitive development, i.e. formal operational stage of cognitive development. During this period adolescents thoughts change from concrete objects to abstract events. They can think flexibly enough about the world. They accumulate knowledge through interaction and apply the learned concepts to new tasks. Teenagers develop their reasoning skills and engage in hypothetical deductive reasoning. As adolescents develop their logical thinking, they are becoming aggressive and argumentative. They are able to understand abstract concepts such as congruence and mass and they think in terms of theoretical concepts. They are conscious about others opinion regarding them and curious enough to know about spirituality, traditions and beliefs. Thus, during adolescence people deal with problems on an abstract level, to form hypothesis and to reason from proposition that are contrary to fact.

Adulthood Stage

An adult is someone who is responsible, mature, self-supporting and well integrated into society. Also people do not develop these attributes and characteristics at the same time and with same skills. This adult stage has three sub-stages of development. First stage is early adulthood, second stage is middle adulthood, and third stage is late adulthood.

In early childhood period adults are at the peak of physical health, strength and energy. At this period of life adults take many important decisions of life like choice of career, type of friends, residence, etc. independently and accept responsibility and consequences for their own decisions. Every adult tries for recognition, job security and to excel in his job.

Middle adulthood period is explained in terms of a gradual decline in one‟s physical abilities, physical health, stamina etc, but the decline is gradual in nature. Both men and women feel tired easily. In this period people experience stress due to the double responsibility of caring for the aged parents and the growing children.

The term “late adulthood” is roughly equivalent to old age. This is the final stage of physical change.

1. Physical Development

Physical growth and development is at its maximum during this period. Physical strength usually is more than previous years due to mature physical structures. strength, speed, coordination and endurance for activity is greatest during this period. A number of sensory and neural functions are optimal levels during this period. Full brain weight and mature brain wave patterns are observed at this stage of development. Changing life style pattern has an impact on growth and development.

2. Psycho-Social Development

During early years of adulthood, people face the problem of choosing, preparing for and entering into careers brings a lot of social changes in the adult. They have cordial relationships with their siblings. They spend very few times with friends because their energies are consumed for family and work. Middle adulthood people have children of adolescent age. It is very difficult to handle their problems. Conflicts occur between parents and children regarding „giving‟ and „getting‟ independence. Parents have to help their children in their search for identity. Middle aged adult also have important responsibilities towards their parents. In this period they also try to b satisfied at work place. People are worried about their jobs and pay packages because they have to meet the daily needs of themselves and of the family.

3. Cognitive Development

Intellectual ability and cognitive skills are high in early adulthood. Middle adulthood people can not learn new skills. Recent research suggests that intellectual development continues into late adulthood. Intellectual development continued and that are influenced by the accumulation of the experiences of life, i.e. verbal skills, social knowledge and moral judgements. During this period people show changes in logic and morality. It is observed that creativity peaks in the early adulthood but forms of creativity that require experience, revision and interpretation either remain unchanged or increase in middle age. People utilise their cognitive skilss and creativity particularly at the work place in order to get recognition. Studies revealed that intelligence declines with age, but there is no certainty that intelligence and age are related with each other.

1.5 Debates in Human Development: Nature vs Nurture, universalism vs. contextualism

NATURE VS. NURTURE

The nature versus nurture debate is one of the oldest philosophical issues within psychology.

• Nature refers to all of the genes and hereditary factors that influence who we are—from our physical appearance to our personality characteristics.
• Nurture refers to all the environmental variables that impact who we are, including our early childhood experiences, how we were raised, our social relationships, and our surrounding culture.

The nature-nurture debate is concerned with the relative contribution that both influences make to human behavior.

It has long been known that certain physical characteristics are biologically determined by genetic inheritance.  Color of eyes, straight or curly hair, pigmentation of the skin and certain diseases (such as Huntingdon’s chorea) are all a function of the genes we inherit.  Other physical characteristics, if not determined, appear to be at least strongly influenced by the genetic make-up of our biological parents.

Height, weight, hair loss (in men), life expectancy and vulnerability to specific illnesses (e.g. breast cancer in women) are positively correlated between genetically related individuals.  These facts have led many to speculate as to whether psychological characteristics such as behavioral tendencies, personality attributes and mental abilities are also “wired in” before we are even born.

Those who adopt an extreme hereditary position are known as nativists.  Their basic assumption is that the characteristics of the human species as a whole are a product of evolution and that individual differences are due to each person’s unique genetic code. In general, the earlier a particular ability appears, the more likely it is to be under the influence of genetic factors.

Characteristics and differences that are not observable at birth, but which emerge later in life, are regarded as the product of maturation. That is to say we all have an inner “biological clock” which switches on (or off) types of behavior in a pre programmed way.

The classic example of the way this affects our physical development are the bodily changes that occur in early adolescence at puberty.  However nativists also argue that maturation governs the emergence of attachment in infancy, language acquisition and even cognitive development as a whole.

At the other end of the spectrum are the environmentalists – also known as empiricists.  Their basic assumption is that at birth the human mind is a tabula rasa (a blank slate) and that this is gradually “filled” as a result of experience (e.g. behaviorism).

From this point of view psychological characteristics and behavioral differences that emerge through infancy and childhood are the result of learning.  It is how you are brought up (nurture) that governs the psychologically significant aspects of child development and the concept of maturation applies only to the biological. 

For example, when an infant forms an attachment it is responding to the love and attention it has received, language comes from imitating the speech of others and cognitive development depends on the degree of stimulation in the environment and, more broadly, on the civilization within which the child is reared.

Examples of an extreme nature positions in psychology include Bowlby's (1969) theory of attachment, which views the bond between mother and child as being an innate process that ensures survival. Likewise, Chomsky (1965) proposed language is gained through the use of an innate language acquisition device. Another example of nature is Freud's theory of aggression as being an innate drive (called thanatos).

In contrast Bandura's (1977) social learning theory states that aggression is a learnt from the environment through observation and imitation. This is seen in his famous Bobo doll experiment (Bandura, 1961). Also, Skinner (1957) believed that language is learnt from other people via behavior shaping techniques.

Others examples are:

Intelligence

When someone achieves greatness thanks to an innovation or other breakthrough, it is usually agreed that the individual has a high level of intelligence. Often, when exploring the background of the individual, the influences of nature versus nurture are questioned. 

· Nature - Those who would argue that nature is largely to thank for the individual’s ability to achieve greatness might point to his or her parents and use their level of intelligence as a reason for why he or she is so successful. Perhaps the child developed early skills quickly and this would be used to show that the child was clearly, “born smart.”

· Nurture - Those who would argue that a child's intelligence was affected by nurture would look at the child's educational background as well as how his or her parents raised her. These individuals would state that the intelligence level which permitted the child to be so successful, is largely the result of the child's upbringing and the school system.

Personality

The development of personality traits is often part of the nature versus nurture debate. People want to know how children develop their personalities. 

· Influence of the parents - Often it is easy to see similarities between a child’s personality and one or both of her parents’ personalities. In this situation, it would seem that the child's personality has developed largely from the influence of the parents. 

· Effects of nature - In some situations, children develop personalities, or tendencies toward certain behaviors, such as shyness or aggression, that can’t seem to be explained because neither parent demonstrates the same trait. In this situation, it can be argued that nature is at play in the development of the child's personality. 

Homosexuality

The debate about homosexuality and whether the genesis of which is the result of nature or nurture has spanned throughout history, but has taken on even greater importance in more recent years as the rights of these individuals are being hotly debated throughout the world. 

· Effects of environment - Some individuals believe that homosexuality is a choice. Others believe that it is the result of something having negatively affected an individual, such as sexual assault, causing the individual to become homosexual. These debates focus on the influence of nurture and the individuals feel that environmental factors are the cause of one’s homosexuality. 

· Biological factor - Other individuals believe that homosexuality is a biological factor, no more a choice than eye color or foot size. These individuals are debating from the perspective of nature being responsible for the development of the individual. 

These examples show several ways that the nature vs. nurture debate plays out in real life. 

It is widely accepted now that heredity and the environment do not act independently. Both nature and nurture are essential for any behaviour, and it cannot be said that a particular behaviour is genetic and another is environmental. It is impossible to separate the two influences as well as illogical as nature and nurture do not operate in a separate way but interact in a complex manner.

UNIVERSALISM VS. CONTEXTUALISM

Universalism implies that it is possible to apply generalized norms, values, or concepts to all people and cultures, regardless of the contexts in which they are located. These norms may include a focus on human needs, rights, or biological and psychological processes and are based on the perspective that all people are essentially equivalent. As an example, the United Nations’ Universal Declaration of Human Rights asserts various rights to all people – e.g., to marry, own property, and access equal protection under the law – regardless of culture or nationality.

The concept of universalism is prevalent across the social, political, and physical sciences. In the field of psychology, universalism conventionally refers to the idea that the range of human experience – from basic needs and psychological processes to core values – is intrinsic and therefore similar across humans and cultures. 

Developmental contextualism is a perspective that views human development as inextricably and reciprocally linked to the multiple contexts of individuals’ lives (Lerner 1991, 1995). While the perspective is applicable to human development across the life span, the focus of this essay is on its relevance for understanding and facilitating positive adolescent development. Essentially, developmental contextualism implies that adolescent development cannot be examined independent of the people and places that comprise an adolescent’s life space (i.e., contexts). Key contexts for adolescents include family, peers, school, and community (Hill 1983). Moreover, there is a reciprocal relationship between adolescents and these contexts such that not only do contexts and the individuals comprising them influence adolescents, but adolescents also shape the contexts (Lerner 1991, 1995). 

Contextualism, a world view or paradigm which suggests the role of social, cultural, and historical change in individual development, became the focus of increasing interest throughout the 1970s. Nevertheless, despite the suggestion that contextualism offered a new philosophical position from which to derive concepts and theories of development, criticism occurred because it was believed that the dispersive nature of contextualism obviated the formulation of a useful definition of development. We review the characteristics of the contextual paradigm and argue for a principled integration (as opposed to an eclectic one) between selected features of contextualism and of organicism. The former approach offers a dispersive view of the nature of variables involved in development and the latter provides an integrative one. We attempt to forge a probabilistic epigenetic, or developmental-contextual, paradigm for the study of human development, one which relies on the concept of integrative levels and which conceives of the causal variables of development as interacting in a temporally probabilistic manner.