Definition of Terms
This is the study of how people change physically, cognitively, socially and emotionally over the entire lifespan. Its major interest is on how and why the human organism grows and changes from its initial form in utero to an adult being. The term growth and development both refer to dynamic process. Often used interchangeably, these terms have different meanings. Growth and development are interdependent, interrelated processes. Growth generally takes place during the first 20 years of life; development continues after that.
- Is physical change and increase in size.
- It can be measured quantitatively.
- Indicators of growth include height, weight, bone size, and dentition.
- Growth rates vary during different stages of growth and development.
- The growth rate is rapid during the prenatal, neonatal, infancy and adolescent stages and slows during childhood.
- Physical growth is minimal during adulthood. Development:
- Is an increase in the complexity of function and skill progression.
- It is the capacity and skill of a person to adapt to the environment.
Development is the behavioural aspect of growth.
- Refers to qualitative changes
Development can be defined as changes in a person’s physical and neurological structures, behaviour, and trails that emerge in orderly ways and are reasonably consistent in their 1st 20 years of life, these changes usually result in new, improved ways of reacting – ie behaviour that is healthier, more organized, more complex, more stable more efficient eg from creeping to walking, running; babbling to talking; concrete to abstract thinking. The Goals of Developmental Psychology
Developmental psychology is mainly concerned with the description, explanation, prediction, and modification of age related behaviours during the full life span from conception to death. Some developmental psychologists emphasize specific ages (e. g. , infancy, adolescence, or old age) while others concentrate on specific areas (such as, personality or cognitive development). The primary task of developmental psychology is to describe accurately changes and discover their underlying causes. It attempts to explain changes in behaviour that are as result of maturation and experience.
The description of behaviour is important in order to be able to answer questions about why a human being behaves the way he/she does and to change undesirable behaviour.
- To understand the changes with increasing age that appear to be universal ( ie. occur to all children regardless of their culture or experiences).
- To explain individual differences in behaviour.
- To understand the influence of context or situation on behaviour.
- to understand ourselves and others in order to reduce the effects of the generation gap.
- To understand the change in the age distribution of the population.
Compare and account for the developed and 3rd world’s composition of the young and old people. 6. For practical reasons such as jobs, parenthood, changes / crises in life, in order to be equipped with coping strategies. 7. For maintaining balance in a rapidly changing world eg early maturation, more healthy children, ‘future shock’ that is personal disorganisation in meeting the premature arrival of the future eg – Hiv/Aids, retrenchment, divorce, unwanted pregnancies, increased mental health problems, death of a spouse when you are just married and still very young. Reasons why we should Study Developmental Psychology?
Developmental psychology is important to teachers because it will enable them to:
- Identify behaviour problems and to bring about desirable changes in the behaviour of children and the society as a whole.
- Know the potentialities of each pupil in the class so that they may exploit them to the maximum for the benefit of the individual and the society.
- Guide students and understand why they behave the way they do.
- Make provisions for the development of whatever capacity pupils have by providing the appropriate experiences.
- Judge the rate of growth and development for a given child and to work with that rate.
- Make use of each stage of development by providing teaching material, incentives, companions and opportunities for the expression of behaviour appropriate to each stage of development.
- Understand the psychological processes like maturation, motivation, socialization, learning.
- Find solutions to questions related to instruction, discipline, behaviour, emotional disorders, language acquisition, social development, moral development etc.
- Formulate realistic expectations for children, respond sensitively to actual behaviour, recognize unusual development and understand the child.
- Predict behaviour.
- Control or change behaviour. Know the conditions necessary for the normal growth and development of the child.
- Provide a conducive environment for normal development and learning.
Historical Perspectives of Developmental Psychology Views of child psychology, education and child rearing Society is paramount, only in the context of a successful group structure can the individual be best fulfilled. Children are the responsibility of adults who to the best of their ability and love, should guide them through their maturation to adult hood with the goal of producing productive, responsible citizens working for the good of society in general.
Children grow and mature to more healthy intellectual, emotional and social adult hood under structured guidance. Society needs structure for survival. The individual is responsible to and for the group. Emphasises the individual above the society. Proposes unstructured free schools allowing children to grow, learn, mature as they will; self – fulfilment, self-honesty, self-understanding are seen as more important than the needs of society in general. Complete freedom and lack of interference in childhood produces the free adult, the less structure in society, the better. The individual is responsible to and for himself.
Developmental psychology is a recent discipline. The scientific study of children started slightly over a century ago with the pioneering work of Charles Darwin who researched on infant’s early sensory and perceptual capacities and children’s emotions, Darwin (1972) demonstrated that scientists could study infants and children. Later on John Watson continued the formal analysis of children’s learning capacities. Other psychologists such as Freud, Piaget, and Erik Erikson whom we shall talk about later in this topic, contributed significantly to our understanding of children.
Corrupt parents should be prevented from corrupting children (from pain, fear, grief) Society is composed of ; * Philosopher kings – 5% * Soldiers – 25% * Workers – 70% The 5% should not be allowed to rule until 60years when their passions have cooled. The goal of education and childrearing was the production of adults with efficiencies and skills that enhanced the state. Children should be moulded, taught responsibility and values, their individual skills and differences shaped to the needs of the many – the state. Mild discipline is required. Equal opportunities to be given to all regardless of sex.
Separate children from parents to be reared by state. Each person’s place would be decided by objectively determined abilities. Importance of self-control. Aristotle(384-322 B. C) Progressive selection. Apprenticeship model – rudimentary tasks – more and more complex aspects of the role. Those who did not reveal talent/drive/interest were sent home and others took their place. Children be apprenticed to skilled adults as models for their learning – models who could show the correct, the easiest way to accomplish goals; the model would tie the present task of the child to his performance as an adult.
Development is a product of interaction Development is a process that results from an interaction of an organism with its environment.
The genetic constitution of an individual and the environmental forces interact to influence development. It is difficult to assess the relative contribution of each of the two. Development comes from maturation, learning and influences from the environment. Maturation pattern is genetically programmed e. g the Hopi children walk at the right time despite being tied/ swaddled throughout so that they don’t sit or crawl. The environment can aid or hinder this process. Development depends on maturation and learning. Maturation refers to the sequential characteristic of biological growth and development.
The biological changes occur in sequential order and give children new abilities. Changes in the brain and nervous system account largely for maturation. These changes in the brain and nervous system help children to improve in thinking (cognitive) and motor (physical) skills. Also, children must mature to a certain point before they can progress to new skills (Readiness). For example, a four-month-old cannot use language because the infant’s brain has not matured enough to allow the child to talk. By two years old, the brain has developed further and with help from others, the child will have the capacity to say and understand words.
Also, a child can’t write or draw until he has developed the motor control to hold a pencil or crayon. Maturational patterns are innate, that is, genetically programmed. The child’s environment and the learning that occurs as a result of the child’s experiences largely determine whether the child will reach optimal development. A stimulating environment and varied experiences allow a child to develop to his or her potential. (ii) Development Follows an Orderly Sequence There is a high degree of similarity in the order in which various aspects of development occurs in all individuals.
Various directional trends have been identified, namely: Cephalocaudal development – meaning that development begins from the head and proceeds down towards the feet (tail). For example, Children acquire control over their heads prior to acquiring control over their limbs or they can use their hands before they can walk. According to this principle, the child gains control of the head first, then the arms, and then the legs. Infants develop control of the head and face movements within the first two months after birth. In the next few months, they are able to lift themselves up by using their arms.
By 6 to 12 months of age, infants start to gain leg control and may be able to crawl, stand, or walk. Coordination of arms always precedes coordination of legs. Proximodistal development – Meaning that development starts from the central organs and proceeds outwards towards the outer or external organs. The child acquires control over muscles closer to the center of the body before acquiring control over those in the periphery. They can control their arms before their fingers. Development proceeds from the center of the body outward. This is the principle of proximodistal development that also describes the direction of development.
This means that the spinal cord develops before outer parts of the body. The child’s arms develop before the hands and the hands and feet develop before the fingers and toes. Finger and toe muscles (used in fine motor dexterity) are the last to develop in physical development. Locomotion develops in a sequence in all infants of different cultures. The sequence is, sitting, crawling, standing, and walking. The time the infant takes to pass these stages may vary but the sequence is the same. Development is an Individualized Process Different individuals develop differently.
Each person has his own rate of physical, mental, emotional, and social development. However, the pattern is the same. Individual differences are present – although individuals follow the same pattern, they do so in their own style – smoothly, or in spurts due to differences in heredity, endowment and environmental differences. Understanding this fact of individual differences in rates of development should cause us to be careful about using and relying on age and stage characteristics to describe or label children. There is a range of ages for any developmental task to take place. This dismisses the notion of the “average child”.
Some children will walk at ten months while others walk a few months older at eighteen months of age. Some children are more active while others are more passive. This does not mean that the passive child will be less intelligent as an adult. There is no validity to comparing one child’s progress with or against another child. Rates of development also are not uniform within an individual child. For example, a child’s intellectual development may progress faster than his emotional or social development. Development is Cumulative This means that each new change is a product of the previous change and the experience one has.
Changes do not emerge out of nothing. This implies that other parts of the organism must have matured first. For example, speech organs mature first before language can be learned. Development is Continuous Development is a continuous process that begins from the time of conception and continues until death. However the rate of development varies from age to age. For example, there is a spurt in growth during the onset of adolescence. Growth and development is a continuous process. As a child develops, he or she adds to the skills already acquired and the new skills become the basis for further achievement and mastery of skills.
Most children follow a similar pattern. Also, one stage of development lays the foundation for the next stage of development. For example, in motor development, there is a predictable sequence of development that occur before walking. The infant lifts and turns the head before he or she can turn over. Infants can move their limbs (arms and legs) before grasping an object. Mastery of climbing stairs involves increasing skills from holding on to walking alone. By the age of four, most children can walk up and down stairs with alternating feet.
As in maturation, in order for children to write or draw, they must have developed the manual (hand) control to hold a pencil and crayon. Development is Interrelated Different aspects of development are interrelated. For example, walking is related to muscle development. Learning to talk is related to the development of speech organs etc. Developmental characteristics are consistent, definite, sequential and predictable.
- Different areas develop at different rates eg the brain develops first and faster. Developmental correlations eg delay in walking results in lag in motor or cognitive development.
- Development Proceeds from the General to the Specific Development takes place using the principle of mass differentiation and integration. For example, the development of language begins with the birth cry, as a mass or general response of which differentiation starts and the child acquires vocabulary of many words and gradually the skill of communication develops.
- In emotion, there is a general excitement at first and later specific emotions develop. Movement of the whole body is followed by control and movement of specific parts of the body.
- tasting food initially by use f mouth, later we differentiate by sight.
crying with whole body, later upper part only and finally with eyes only. * Grasping with whole hand, then fingers only In motor development, the infant will be able to grasp an object with the whole hand before using only the thumb and forefinger. The infant’s first motor movements are very generalized, undirected, and reflexive, waving arms or kicking before being able to reach or creep toward an object. Growth occurs from large muscle movements to more refined (smaller) muscle movements. Development proceeds from the simple (concrete) to the more complex.
Children use their cognitive and language skills to reason and solve problems. For example, learning relationships between things (how things are similar), or classification, is an important ability in cognitive development. The cognitive process of learning how an apple and orange are alike begins with the most simplistic or concrete thought of describing the two. Seeing no relationship, a preschool child will describe the objects according to some property of the object, such as color. Such a response would be, “An apple is red (or green) and an orange is orange. The first level of thinking about how objects are alike is to give a description or functional relationship (both concrete thoughts) between the two objects. “An apple and orange are round” and “An apple and orange are alike because you eat them” are typical responses of three, four and five year olds. As children develop further in cognitive skills, they are able to understand a higher and more complex relationship between objects and things; that is, that an apple and orange exist in a class called fruit. The child cognitively is then capable of classification. (viii) Development Proceeds in Stages
The development of the individual occurs in different stages. Each stage has unique characteristics and certain behaviours and traits that stand out more conspicuously than others. The following are the criteria of stages accepted by most psychologists:
- Change from one stage to another involves change in the form, pattern and organization of an individual’s behaviour.
- Each successive stage involves a new and qualitatively different organization of responses or behaviour
- Stages in development appear in a sequence that is fixed and unvarying from individual to individual
- Stages involve progress toward increasing complexity.
Different theories take different positions on the themes of development and account for different aspects of children’s behaviour. By so doing, they complement each other rather than compete with each other. Learning Perspectives Behavioural Theories This approach is exemplified in the work of J. B. Watson, Ivan Pavlov, and B. F. Skinner who developed central ideas of learning, and applied these ideas to children’s development. Behaviourism holds that theories of behaviour should be based on observations of actual behaviour rather than on speculation about motives or other unobservable factors.
Behavioural theories view development as a continuous process and not a discontinuous or stage-like process. Learning shape development throughout childhood and across the entire life span. According to the behaviourists, children play a relatively passive role in their own development. Like computers, which can only do what programmers tell them to do, children do only what the environment directs that they do. In classical conditioning, Pavlov showed that a dog would learn to salivate at the sound of a bell if that sound were always associated with the presentation of food.
The dog typically salivated at the appearance of food; if the food was repeatedly paired with the sound of a bell, eventually the dog learned to salivate at the sound of the bell whether or not it was accompanied by the food. Watson used classical conditioning to explain many aspects of children’s behaviour, especially emotions such as fear. For example, he conditioned a young child to peer fury animals, by showing the baby who was easily frightened by noise, a white rat and simultaneously making a loud noise. In operant conditioning, Skinner focused on the consequences of a person’s behaviour.
According to this theory, behaviour is modified by the type of rewarding or punishing events that follow it. Positive reinforcement for a particular behavior will increase the likelihood of that behaviour recurring. Punishment will decrease the chances of a behaviour being repeated. This approach has shown how children’s behaviours develop and how we can change such behaviours. For example, children’s aggressive behaviour is often increased rather than decreased by the attention parents pay to such behaviour as hitting and teasing.
Cognitive Social Learning Theory According to this theory, children learn not only through classical and operant conditioning but also by observing and imitating others (Bandura, 1989). Bandura showed that if children were exposed to aggressive behaviour of another person, they were likely to imitate their behaviour. Children at play watched a model punch and kick a large inflated doll in unusual ways. Later when they were left alone with the doll and other toys, they imitated the unusual aggressive behaviour, copying exactly what they had seen.
Other children who did not watch the aggressive model did not display aggressive behaviour. Children who watch a great deal of television violence are more likely to develop aggressive attitudes and behaviours (Comstock, 1991, Huston & Wright, 1998). The role of cognitive factors in imitation is important because children do not imitate blindly, or automatically but rather select specific behaviours to imitate. Four sets of processes determine how effectively a child will learn by observing the behaviour of others as shown in the figure below.
These theories focus on the role of heredity in determining development and behaviour. For example, Lorenz’s study of imprinting (the tendency of goslings and chicks to follow the first moving object they see during the critical period) behaviour in ducks and geese. Ethnologists are biologically oriented scientists who study behaviour in natural situations. Bowlby adapted some of the concepts of ethnology (specifically of imprinting) to explain the development and importance of the attachment bond that forms between the mother and the infant. Cognitive Developmental Perspectives
These perspectives hold that psychological structures and processes within the child help to determine his or her development. Piagetian Theory According to Piaget, the child plays a significant role in his/her development. Children use their current knowledge of how the world works as a framework for the absorption or assimilation of new experiences. Children modify their existing knowledge by incorporating new information into its framework or mental structures. Through the process of accommodation, they modify these frameworks in response to the new input from their environment.
Children actively interpret and make sense of the information and events they encounter. They are not passive receivers of experience. They actively seek experience in order to build their cognitive worlds. The way the child organizes new information depends on his/her level of cognitive development. Piaget proposed that children go through several stages of cognitive development, each characterized by qualitatively different ways of thinking, organizing knowledge, and solving problems. This view sees development as discontinuous.
Young children are bound to sensory and motor information and are less flexible and less able to think symbolically and abstractly. At adolescence, they are able to think logically and to engage in deductive reasoning. Young children are also more egocentric, that is, they are more centered on their own perspectives than older children and less able to take the view points or understand the feelings and perspectives of others. We will revisit this Piaget’s theory when we discuss cognitive development of children. Vygotsky’s Sociocultural Theory This theory emphasizes the interaction between the active child and his/her social environment.
The child grows and changes as a function of his/her efforts and support, guidance and help from others who are more skilled. The child’s social and cultural worlds have an impact on his/her development. Development is a product of social interaction. It evolves as the child and his/her significant others such as parents, teachers and so on solve problems such as learning to count or to read. Children are assisted by others in their social environment to learn to function intellectually on their own as individuals. Children have innate abilities such as perceptual and memory skills.
Interactions with others mold these basic skills/abilities into more complex, higher-order cognitive functions. A good example of Vygotskian theory in action in the modern classroom is peer tutoring, in which an older child helps a younger pupil learn to read, write, add, subtract, and so on. Information Processing Approaches Focus on children’s representations of information and how they operate on information to achieve their goals in a particular situation. Children take in information like computers, process it and produce behaviour (action, insight, verbalization, or a memory that is stored for later use).
Children attend to information, change it into a mental or cognitive representation, stores it in memory, compares it to other memories, generates various responses, makes a decision about the most appropriate response, and finally, takes some specific action. Psychodynamic/Psychoanalytic Perspectives This approach proposes that dynamic forces within the individual determine motivation and behaviour. The psychodynamic theory has been influential in clinical or applied settings than in scientific research, and for this reason has been less incorporated into the study of child development than other theories.
According to Freud’s psychoanalytic theory of development, psychological change and growth are governed by unconscious drives and instincts. He stressed the role of drives such as sex, aggression and hunger in determining behaviour. For Freud, the developing personality consists of three interrelated parts: the Id, the Ego, and the Superego. The Id operates on the pleasure principle, which is oriented toward maximizing pleasure and satisfying needs immediately. It is the irrational part of personality. As the infant develops, the ego or the rational (controlling) part of personality enlarges.
The ego attempts to gratify needs through appropriate socially constructive behaviour. The superego which is the third component of personality emerges when the child internalizes (accepts and absorbs) parental or social morals, values, and roles and develops conscience, or the ability to apply moral values in judging his/her own acts. According to Sigmund Freud, development is a discontinuous process (i. e. a process marked by distinct stages of development). He proposed five discrete stages of development. In each of these stages, biological forces orchestrate the relations between the developing child and his/her world.
These stages are: i) Oral Stage(0 – 1 year) The infant is preoccupied with eating and taking things into the mouth. Freud assumed that the infant derives great enjoyment and satisfaction from oral behaviours. ii) Anal Stage(1 – 3 years) The child is forced to learn to postpone the pleasure of expelling feces, as his/her parent struggles with the task of toilet training. iii) Phallic Stage (3 – 6 years) Children’s sexual curiosity is aroused. They become aware of anatomical differences between sexes. They derive pleasure from genital stimulation.
Boys get attracted to their mothers (Oedipus complex). They feel jealous of their fathers and see them as rivals. They fear that their fathers will punish them by cutting off their genitals. The Oedipus complex is resolved when boys give up their sexual feeling for their mothers and identify with their fathers. Girls experience the Electra complex in which they get attracted to their fathers. They see their mothers as rivals and blame them for their lack of a penis. They focus their sexual feelings on their fathers, who possess the penis which Freud believed they wanted.
When they finally realized that they cannot possess their fathers as mates, girls transfer their feeling to other males (Hetherington & Parke, 1999). They relinquish their resentment of their mother and begin to identify with her. iv) The Latency Stage (6 – 12 years) Sexual drives are temporarily quiet during this period. Children avoid relationships with opposite gender peers and become intensely involved with peers of the same gender. This is a time when they concentrate on learning various social skills. The Genital Stage(12 year onwards)
During this stage, sexual desires re-emerge, but this time they are more appropriately directed toward opposite sex peers. The way in which children resolve the psychological conflict in each of these stages has a profound impact on their later adult personality. For example, infants who have unsatisfied needs for oral stimulation may be more likely to smoke as adults. Toddlers whose parents toilet train them extremely early and in a very rigid manner may later be obsessively concerned with neatness and cleanliness. This approach views infancy and childhood experiences as aving a formative impact on later development. According to psychoanalytic theory, this is what is referred to as fixation. Fixation is a state of arrested development whereby an individual becomes stuck in a particular psychological battle, repeating the conflict in symbolic ways. Erikson’s Theory Erikson, a follower of Freud, turned to a view that gave greater emphasis to the effects of the social environment on the individual’s development. Erikson’s psychosocial theory holds that development was discontinuous and proceeds through a series of stages. He proposed eight stages of development.
Erikson specified the personal and social tasks that the individual must accomplish as well as the risks the individual confronts if he/she fails at the task of a particular stage. i) Infancy (0 – 1 year) Task: To develop basic trust in oneself and others. Risk: Mistrust of others and lack of self-confidence. Basic trust is developed through the care provided by others. If the infant finds others not trustworthy, he/she may develop mistrust of both himself and the world. ii) Early Childhood (1 – 3 years) Task: To learn self-control and establish autonomy. Risk: Shame and doubt about one’s own capabilities.
The child learns self-control if he/she is allowed to do things for himself/herself. iii) Play Age (3 – 6 years) Task: To develop initiative in mastering the environment. Risk: Feelings of guilt over aggressiveness and daring. iv) School Age (6 – 12 years) Task: To develop industry. Risk: Feelings of inferiority over real or imagined failure to master tasks. v) Adolescence (12 – 20 years) Task: To achieve a sense of identity. Risk: Role confusion over who and what the individual wants to be. Focus is on the search for a stable definition of the self. vi) Young Adulthood (20 – 35 years)
Task: Is to achieve intimacy with others. Risk: Shaky identity may lead to avoidance of others and isolation. This is a time when the young person is expected to achieve a stable intimate sexual relationship with another person. vii) Adulthood(35 – 50 years) Task: To express oneself through generativity. According to Erikson, generativity is the challenge of learning how to reach out and become concerned with the well-being of future generations. Risk: Inability to create something such as children, ideas, or products may lead to stagnation. viii) Mature Age (Old Age – 50 years to death) Task: To achieve sense of integrity.
Risk: Doubts and unfulfilled desires may lead to despair. If past accomplishments and failures lead to doubt and regret, despair may be the result. Psychodynamic theories have contributed to child psychology through highlighting:
- The impact of early experiences on later behaviour.
- The role of the family on socialization, especially Erikson’s work.
- Impact of social interaction on children’s development.
- The concept of identity development during adolescence.
Dynamic Systems Theory
This approach views the developing individual as a member of a system or series of systems that are complex, self-stabilizing and self-reorganizing.
The continuing interactions among system members and among systems make development a highly dynamic enterprise in which relationships and processes are the primary focus. A system comprises of regular interacting or interdependent group of parts. Bronfenbrenner’s Ecological Theory This theory stresses the importance of understanding the relationship between the organism and various environmental systems such as the family, school, community and culture. Development involves the interplay between children and their changing relationships with these different ecological systems.
The Microsystem is the setting in which the child lives and interacts with the people and institutions closest to him/her. Over time, the relative importance of these different interactions may change. For example, the family may be most important in infancy, whereas peers and school may become important foci in middle childhood and adolescence. The Mesosystem comprises the interactions among the components of the microsystem. For example, parents interact with teachers and the school system, family friends, health care providers, religious institutions, etc.
The Exosystem is composed of settings that impinge on children’s development but with which the children have largely indirect control. For example, a parent’s work may affect the child’s life if it requires that he/she travels a great deal or suddenly go on shift work. It also includes mass media, neighbours, legal system, etc. The Macrosystem represents the ideological and institutional patterns of a particular culture or subculture. For example, children who grow up in Kenya experience a different social ideology than children who grow up in America.
Children who live in a city slum are exposed to a different set of values than children in an affluent suburb. The Chronosystem is the time based dimension that can alter the operations of the four systems, the micro-, meso-, exo-, and macrosystems which change over time. Over time, both the child and his/her environment undergo change, and change can originate from the individual (e. g. puberty, illness, accident) or in the external world (e. g. the birth of a sibling, entering school for the first time, divorce). Thus development involves the interaction of a changing child with a changing matrix of ecological systems.
Ethological Theory This theory takes a biological evolutionary approach to describing development. It holds that behaviour must be viewed and understood as occurring in a particular context and as having adaptive or survival value. For example, in understanding social interactions among monkeys, one must consider habitat; that is, the kind of vegetation that is available to a band of monkeys for food and protection as a powerful determinant of such things as social organization and social dominance. Similarly, in attempting to understand children’s behaviour, the nature of the setting (e. . classroom, playground) in which the behaviour takes place is critical. This hypothesis is supported by the finding that some behaviour are common to all children regardless of the culture into which they are born and in which they grow to maturity. For example, emotional expressions like those of joy, sadness, disgust, and anger are similar across a wide range of cultures, including those of Kenya, Brazil, China, and United States of America. Behaviours such as smiling and crying have a biological basis and play an important role in ensuring that caregivers meet children’s needs.
Crying serves to communicate to the parent the fact that a child is distressed or hungry. Thus, it has a survival value, because it ensures that parents give the infant the attention he/she needs for adequate development. Ethologists acknowledge the role of learning and input from the environment to development. Social behaviours seem to be regulated by gestures, postures, facial expressions, and other non-verbal cues. Gestures such as bowing, kneeling, or lying down have been found to be successful in stopping an aggressive attack among boys (Ginsburg, Pollman & Wauson, 1977).
Children, just like animals develop dominating/domineering behaviours in groups. Life Span Perspective This is an approach that sees development as a process that continues throughout the life cycle, from infancy through adulthood and old age. Erikson was one of the first to extend the notion of development to the years of maturity and aging. Life span theory views childhood as of equal importance with other stages but does not accord it special significance in the shaping or forming of later stages of development. The individual is open or susceptible to change at all points in development.
Change over time can be traced to three sets of causes: Normative events, or age graded experiences, for example, the beginning of walking, onset of menstruation in adolescent girls are biological or maturational. The timing of these and other similar events does vary among individuals, but there is an average or normative schedule for such biological events. Other normative events are programmed by society to follow schedules that most people adhere to. For example, children enter school at approximately the age of 6 years and begin college at about 17 or 18 years of age.
Non-normative events: these are the unexpected events that often push development in new directions. They are non-normative in that they neither happen to everyone in the normal course of development nor follow any preset schedule. They happen without warning or anticipation. For example, divorce, jobless, or change of residence are events that may have an impact on the child, but are not normal expected occurrences. Cohort effect: cohort is a term used to describe a group of children who were born in the same year or the same general period (e. g. 2000 – 2005).
Cohorts share the same historical experiences. Historical context is an important source of influence on the developing child, making development different for different cohorts.
Self Assessment and Revision Questions
- Identify three developmental theories and give their major assumptions.
- . Compare Freud’s and Erikson’s stages of human development
- Compare and contrast theories of human development.
- Explain the basic assumptions of various theories of human development.
- Explain how the behavioural theories account for the development of behaviour among children
What is the most important factor in determining how we develop as human beings from the time of conception until death? Is development determined by inherited or environmental factors? Which is more important in determining development – heredity or environment? Scientists have been debating this issue since the beginning of the study of developmental psychology. Scientists such as, John Locke, J. B. Watson and B. F. Skinner believed that there are no inborn predispositions to development.
Their research tried to prove that life experiences are the only factors responsible for shaping human development. Other scientists have argued to the contrary, saying that hereditary factors are the most crucial in influencing the course of development. Most contemporary developmental psychologists are in consensus that the two factors interact to determine development. The Mechanisms of Heredity Human life begins with the joining of the mother’s egg cell with the father’s sperm cell. These cells (gametes) carry the instructions or the blueprints that determine what characteristics an individual will inherit.
Genetics is the science that studies heredity. The basis of human life is the protein molecules whose function is determined by arrangement of the 20 or so amino acids of which they are composed. In turn, the arrangement of the amino acids is determined by a specific genetic code contained in a sequence of deoxyribonucleic acid (DNA) molecules located on rod-like structures called chromosomes. The Chromosome A chromosome is a microscopic rod-like structure in the nucleus of a cell that contains genes which are the carriers of heredity. There are two types of cells in our bodies; body and sex cells.
Body cells contain identical genetic information. Each of our body cells contains an identical component of 23 pairs of chromosomes (each of which contain an identical sequence of DNA). One member of each pair of chromosome is inherited from the mother and the other pair from the father. That is, we inherit 23 chromosomes from each parent. The division of body cells involves Mitosis – a processes that results in genetically identical pairs of cells. Unlike body cells, mature sex cells (sperm and ovum) each contain 23 chromosomes and not 23 pairs.
The gametes result from a special kind of cell division called meiosis, which results in daughter cells that have only half the number of the parent cell. Sex Chromosomes Out of the 23 chromosomes contained in each sperm and each ovum, one, termed the sex chromosome determines whether the offspring will be male or female. The other 22 are called autosomes (i. e. , the 22 paired non-sex chromosomes). The sex chromosomes are X and Y. Only the male can produce a Y chromosome, whereas both females and males can produce X chromosomes.
The presence of a Y chromosome in a fertilized egg determines that the offspring will be a male; two X chromosomes determine a female. Thus, the fertilized egg may contain XX or XY pair. The X chromosome that is contributed by the mother to her son is sometimes believed to be the carrier of sex-linked, predominantly male defects and illnesses such as colour blindness, heredity baldness, and haemophilia. Genes Genes are the carriers of heredity. Each of the 23 chromosomes is believed to contain between 40,000 and 100,000 genes. These genes either in pairs or complex combination of pairs, determine our inherited characteristics.
For example, there are pairs of genes that correspond to eye colour, baldness, hair characteristics and almost every other characteristic of the individual. In addition, combinations of genes appear to be related to personality characteristics such as intelligence, temperament, aggression etc. Traits that result from the combination of many genes are termed polygenic. Genes for eye color and other traits take on a variety of forms called alleles i. e. , the alternative states of genes (allelomorph). Allelomorph is a term used to refer to the various states in which genes carry different traits.
A person is homozygous for a trait if alleles in the inherited pair for a trait are identical. For example, the pair for eye color can be blue-blue. A person is heterozygous if two different alleles form the pair of genes for a trait. For example, the pair for eye color may be brown–blue. Dominant and Recessive Genes Certain members of genes may be dominant over their corresponding member. When a dominant gene is paired with a corresponding recessive (a gene whose characteristics are not manifested in an offspring) gene, the characteristic corresponding to the dominant gene will appear in the individual.
For example, in humans, the brown-eyed gene is dominant; (it will exert its effect regardless of whether the other member of the gene pair calls for brown or blue eyes) whereas the blue-eyed gene is recessive. Phenotype versus Genotype Phenotype is the characteristic we observe in a given individual. It is the manifested characteristics. Genotype refers to one’s genetic makeup or our inherited chromosomal make up. It consists of the 46 chromosomes out of which 23 are inherited from each parent. For example, if you have blue eyes, then your eyes are part of your phenotype.
At the same time, the genes that correspond to blue eyes define your genotype. Two people who have brown eyes may have different genotypes for eye color; one may be Brown-Brown; the other Brown-Blue. The phenotypes are the same, but the genotypes are different, the Blue-eyed gene is masked by its Brown counterpart. Genetic Defects In most cases, genetic disorders are linked with recessive rather than dominant genes. This is because any abnormality that is linked with a dominant gene will be manifested in all carriers and will have relatively ittle chance of being passed on to an offspring, and especially if it leads to an early death. Abnormalities linked to recessive genes will be manifested only when the carrier has inherited the related recessive genes. Many individuals may be carriers for a single recessive gene of abnormality without manifesting the abnormality. An example of a genetic disorder linked with a dominant gene is Huntington’ chorea – a fatal neurological disorder. It manifests itself at the age of 30 or 40, and therefore it is hard to detect and keeps on being transmitted.
Examples of various genetic defects are discussed below: Sickle-cell Anaemia, a genetic disorder linked with a recessive gene. Effects of the defective gene are clearly discernible (noticeable) in abnormally shaped red blood cells (sickle-shaped rather than circular) which multiply as a function of lack of oxygen. These cells tend to clot or clog together, carrying less oxygen, thereby increasing in number and reducing oxygen even further. Thus, the cells can’t carry enough oxygen to the body. Individuals who are homozygous for the gene frequently die in childhood or are severely ill throughout life.
Those who are heterozygous are ordinarily healthy except in conditions of low oxygen such as high altitude. Sickle-cell anaemia is common among blacks in central African coastal areas. Down’s Syndrome or Mongolism, a condition in which victims have low IQ (20- 60), broad noses, square shaped ears, protruding tongues, small squarish heads, defective hearts, eyes with oriental appearance hence the term Mongolism. About one out of every 600 children is born with this defect. This defect is caused by an extra chromosome (chromosome 21). The person will have three rather than a pair, hence the label, trisomy 21.
Most cases of Down’s syndrome are due to non chromosome disjunction (failure to separate) of the 21st chromosome pair during meiosis. A smaller number of cases are due to translocation of chromosome 21 material to another chromosome (i. e. , part of one pair breaks away). In this case, the number is normal but chromosomal damage is present. Turner’s syndrome is a defect that affects female children. One sex chromosome is missing. The individual has only one sex chromosome (0X). Victims have underdeveloped secondary sex characteristics, are short, sterile, and have webbed necks (having loose folds of skin).
Injection of female sex hormone, oestrogen may enhance the development of feminine characteristics. Klinefelter’s Syndrome, a defect that involves an extra X chromosome in male children (47, XXY). Victims may have both male and female secondary sexual characteristics. The male secondary sexual characteristics may be underdeveloped. They may have low IQ, are tall, thin, have long arms and legs, and may also be sterile. Injection of the male sex hormone, testosterone may enhance the development of masculine characteristics. Phenylketonuria (PKU), a disorder that is related to two recessive genes.
The disease is caused by a recessive allele that fails to produce an enzyme necessary to metabolize the protein phyenylaline. Failure to digest this protein results to accumulation of poison in the bloodstream causing brain damage. If it is not treated immediately after birth, PKU damages the nervous system and causes mental retardation and hyperactivity. The Super male or XYY Syndrome, the victim may be tall, have low IQ, and has a strong tendency towards aggression and violence. XYY syndrome is prevalent among criminals. However, not all criminals have this syndrome.
Tay sacs Disease is a genetic disorder linked to a recessive gene. Both parents must be carriers of the trait for the child to have it. The victim dies after a few years. The child may appear normal at birth, but fat begins to accumulate in the brain cells. This results to blindness, deafness, and mental retardation and finally death. It is a disorder in which the nervous system also degenerates. It is common in Eastern Europe and among Jews. Haemophilia is a blood disorder characterized by poor blood clotting ability. It is associated with an X-linked recessive gene. It is treated by transfusions of clotting factors.
New gene-spicing techniques make it possible to provide these factors without running the risk of blood-borne infections by donated blood products. Nature-Nurture Interactions Development is influenced by both heredity (nature) and environment (nurture). For a long time psychologists have debated on the relative contribution of nature and nurture in determining our development and behaviour. Is our development decided upon by heredity or by environment? At the moment of conception an incredible number of personal characteristics and growth patterns are determined. The heredity instructions are carried by the chromosomes and genes.
The individual inherits 23 chromosomes from each parent to make a pair of 23 (46 chromosomes in total). Each chromosome contains thousands and thousands of genes which determine our inherited traits. Heredity determines the sequence of growth, the timing of puberty, skin colour, hair colour, body size, vulnerability to some diseases (e. g. mental disorders, sickle-cell anaemia), body shape, height, intelligence, athletic potential, personality traits and other traits considerably. Both heredity and environment are important in determining development. The two are inseparable.
As one grows, there is a constant interaction between the forces of nature and nurture. Therefore, the total person is a product of hereditary and environmental factors. Heredity shapes development by providing a framework of personal potentials and limits that are altered by environmental factors such as nutrition, culture, disease, learning, parents, peers, home, school, etc. The influence of environment starts after conception and continues until death. Our heredity does not change. Heredity equips the person with innate capacities and the environment determines whether he/she will reach full potential or not.
Today psychologists agree that heredity and environment interact to determine development. From an educational and developmental point of view, the most important thing to learn is that many of our characteristics can be influenced by the environment. Although there is little we can do about heredity, much of the environment still remains under our control. Therefore, we should improve the environment for our children to attain their full inherited potential.
Self Assessment and Revision Questions
Differentiate between the following concepts:
- Dominant and recessive genes
- Genotype and phenotype
- Mitosis and meiosis
- Sex chromosomes and autosomes
- Briefly explain the process of genetic inheritance
- Explain the causes and symptoms of four genetic disorders
- How many chromosomes are contained in a normal human zygote?
- What do you call a trait that has been determined by more than two pairs of genes
Prenatal development marks the beginning of life and development. It is therefore a very crucial period of development which in many ways may determine future development as we are going to see. It is during this period when our inherited traits are determined.
During this period, prenatal environmental factors may exert permanent influence on development. Critical periods This is a stage in development, or a specific time when certain events are supposed to occur in normal maturations. If these events do not occur at these times, then maturation is permanently inhibited. It is a stage of limited duration during which a particular influence, from another area of the developing organism or from the environment, evokes a particular response e. g foetal heart taking over blood circulatory responsibilities, neonate’s lungs breathing air, stimulus from the C. N. S and hypothalamus for the onset of puberty, rubella in the first trimester is dangerous; language development occurs between two – six years; mothers love/ cuddling are essential to social, emotional, personality development in adult hood. Conception Conception occurs when a sperm cell unites with an egg cell (ovum). It is also termed as fertilization. The newly fertilized egg cell (zygote) contains the entire genetic endowment in the form of 23 pairs of chromosomes, 23 from the male and 23 from the female. As soon as the zygote is formed, a process of cell division known as mitosis begins.
This is the process through which the cells multiply. It takes about 3-4 days for zygote to reach the uterus after fertilization. Stages of Prenatal Development Pre-embryonic Period or Germinal Stage (0-3 weeks). It is also referred to as the period of the ovum. The period begins immediately after conception. Three days or so after fertilization, the zygote is implanted in the thickened uterine wall. This is aided by finger-like extensions (called villi) that develop as the cell division continues. By the end of two weeks the cells will have multiplied greatly in number and will have begun to differentiate themselves.
The embryonic disc differentiates itself into 3 germ layers called germinal layers (the origin of human tissue). These germinal layers are: a) Endoderm (inner layer) – later develops to form the glands, digestive system (epithelium) and the respiratory system. b) Mesoderm (middle layer) – later develops to form the skeleton, muscles, connective tissue (ligaments), circulatory system, excretory and reproduction systems. c) Ectoderm (outer layer) – later develops to form the nervous system, brain, sense organs, skin, hair and teeth. It is not known how these cells start to specialize.
The needs of the body probably determine what develops first. This is communicated chemically. Twins A twin is one of two offspring produced in the same pregnancy. Twins can either be identical (in scientific usage, “monozygotic”), meaning that they develop from one zygote that splits and forms two embryos, or fraternal (“dizygotic”) because they develop from two separate eggs that are fertilized by two separate sperm. Twins are estimated to be approximately 1. 9% of the world’s population, with monozygotic twins making up 0. 2% of the total – and 8% of all twins.
The twin birth rate in the United States is slightly above 32 twin live births per 1,000 live births, while the Yoruba have the highest rate of twinning in the world, at 45 twins per 1,000 live births, possibly because of high consumption of a specific type of yam containing a natural phytoestrogen which may stimulate the ovaries to release an egg from each side. Due to the limited size of the mother’s womb, multiple pregnancies are much less likely to carry to full term than single births, with twin pregnancies lasting only 37 weeks (3 weeks less than full term) on average.
Zygosity is the degree of identity in the genome of twins. There are five common variations of twinning. The three most common variations are all fraternal (dizygotic): Male–female twins are the most common result, 50 percent of fraternal twins and the most common grouping of twins. Female–female fraternal twins (sometimes called “sororal twins”) Male–male fraternal twins The other two variations are identical (monozygotic) twins: * Female–female identical twins Male–male identical twins (least common)
Among non-twin births, male singletons are slightly (about five percent) more common than female singletons. The rates for singletons vary slightly by country. For example, the sex ratio of birth in the US is 1. 05 males / female, while it is 1. 07 males / female in Italy. However, males are also more susceptible than females to death in utero, and since the death rate in utero is higher for twins, it leads to female twins being more common than male twins. Studies show that there is a genetic basis for fraternal twinning.
However, it is only their mother that has any effect on the chances of having fraternal twins; there is no known mechanism for a father to cause the release of more than one ovum. Dizygotic twinning ranges from six per thousand births in Japan (similar to the rate of monozygotic twins) to 14 and more per thousand in some African countries. Fraternal twins are also more common for older mothers, with twinning rates doubling in mothers over the age of 35. With the advent of technologies and techniques to assist women in getting pregnant, the rate of fraternals has increased markedly.
For example, in New York City’s Upper East Side there were 3,707 twin births in 1995; there were 4,153 in 2003; and there were 4,655 in 2004. Triplet births have also risen, from 60 in 1995 to 299 in 2004. In the uterus, a majority of identical twins (60–70%) share the same placenta but have separate amniotic sacs. In 18–30% of identical twins each foetus has a separate placenta and a separate amniotic sac. A small number (1–2%) of identical twins share the same placenta and amniotic sac. Fraternal twins each have their own placenta and own amniotic sac.
There are an estimated 11 million sets of identical twins and triplets in the world today. Mechanism Regarding spontaneous or natural monozygotic twinning, a recent theory posits that identical twins are formed after a blastocyst essentially collapses; splitting the progenitor cells (those that contain the body’s fundamental genetic material) in half, leaving the same genetic material divided in two on opposite sides of the embryo. Eventually, two separate foetuses develop. Spontaneous division of the zygote into two embryos is not considered to be a hereditary trait, but rather a spontaneous or random event.
Incidence Monozygotic twinning occurs in birthing at a rate of about three in every 1000 deliveries worldwide. The likelihood of a single fertilization resulting in identical twins is uniformly distributed in all populations around the world. This is in marked contrast to fraternal twinning, which ranges from about six per thousand births in Japan (almost similar to the rate of identical twins, which is around 4–5) to 15 and more per thousand in some parts of India and up to 24 in the US, which might mainly be due to IVF (in vitro fertilization).
The exact cause for the splitting of a zygote or embryo is unknown. In-vitro fertilization techniques are more likely to create twins. Only about three pairs of twins per 1,000 deliveries occur as a result of natural conception, while for IVF deliveries, there are nearly 21 pairs of twins for every 1,000. Genetic and epigenetic similarity Identical twins are genetically identical (unless there has been a mutation during development) and they are always the same sex.
On rare occasions, identical twins may express different phenotypes (normally due to an environmental factor or the deactivation of different X chromosomes in female identical twins), and in some extremely rare cases, due to aneuploidy, twins may express different sexual phenotypes, normally due to an XXY Klinefelter’s syndrome zygote splitting unevenly. Identical twins actually have only nearly identical DNA, and differing environmental influences throughout their lives affect which genes are switched on or off. This is called epigenetic modification.
A study of 80 pairs of human twins ranging in age from three to 74 showed that the youngest twins have relatively few epigenetic differences. The number of epigenetic differences between identical twins increases with age. Fifty-year-old twins had over three times the epigenetic difference of three-year-old twins. Twins who had spent their lives apart (such as those adopted by two different sets of parents at birth) had the greatest difference. However, certain characteristics become more alike as twins age, such as IQ and personality.
This phenomenon illustrates the influence of genetics in many aspects of human characteristics and behaviour. Phenotype similarity Contrary to common opinion, identical twins are not always of the same phenotypical sex. There have been described cases where monozygocity resulted in 46, XO (i. e. female with Turner syndrome) and 46, XY (i. e. male). This is thought to be due to unequal distribution of zygotic protoplasm. However, as a rule, traits and physical appearances of DZ twins are very similar.
Identical twins look alike, although they do not have the same fingerprints (which are environmental as well as genetic). As they mature, identical twins often become less alike because of lifestyle choices or external influences. The children of identical twins would test genetically as half-siblings rather than first cousins. Half-identical twins Half-identical or semi-identical twins (also referred to as “half twins”) are the result of a very rare form of twinning in which the twins inherit exactly the same genes from their mother but different genes from their father.
Although examples of half-identical twins have been found, the exact mechanism of their conception is not well-understood, but could theoretically occur in polar body twinning where sperm cells fertilize both the ovum and the second polar body. This situation is not the same as the common form of fraternal twinning, in which two genetically different ova are fertilized by two genetically different sperm. In this case, the ova are genetically identical. Degree of separation
Various types of chorionicity and amniosity (how the baby’s sac looks) in monozygotic (one egg/identical) twins as a result of when the fertilized egg divides The degree of separation of the twins in utero depends on if and when they split into two zygotes. Dizygotic twins were always two zygotes. Monozygotic twins split into two zygotes at some time very early in the pregnancy. The timing of this separation determines the chorionicity and amniocity (the number of sacs) of the pregnancy. Dichorionic twins either never divided (i. e. : were dizygotic) or they divided within the first 4 days. Monoamnionic twins divide after the first week.
In very rare cases, twins become conjoined twins. Furthermore, there can be various degrees of shared environment of twins in the womb, potentially leading to pregnancy complications. It is a common misconception that two placentas means twins are dizygotic (non-identical). But if monozygotic twins separate early enough, the arrangement of sacs and placentas in utero is indistinguishable from dizygotic twins
It is connected to the placenta by the umbilical cord which contains 3 blood vessels – a vein to carry nourishment and two arteries to remove waste products. This period is very vulnerable to teratogenic influences. Such influences may be due to chemical changes in the mother’s bloodstream caused by viruses or drugs and are likely to lead to abnormalities of development, affecting the particular organ during the process of its formation. During this period:
- The head and blood vessels begin to form in the third week
- The heart begins to beat in the 4th week and hence blood flows through the tiny veins and arteries.
The brain, kidney, liver and digestive tract develops. Sex differentiation For the development of a boy, both XY, that is, genetic programming and particular pattern of hormone action are required for normal gender development. Between 4-8 weeks after conception the male hormone testosterone is secreted by rudimentary testes in the embryo. If this hormone is not secreted, the embryo will develop as physical female even though genetically it is male. If this hormone accidentally secreted for an XX embryo, it will have both male and female characteristics.
The embryonic period is thus a very crucial period of development (a period during which the systems are very sensitive to teratogenic influences). A teratogen is an agent that may cause abnormality during prenatal development. Malformations of the heart, central nervous system and spinal cord are likely to occur between the 3rd and 5th week. Malformation of the eyes, ears, arms and legs are likely to occur between the 4th and 7th week and that of the teeth, palate between the 7th and 8th week. This is a very sensitive/critical period as any disease will cause an abortion or deformity. 0 – 50% of all conceptions are miscarried at this stage. The Period of the Foetus (9th – 40th weeks) This period is characterized by growth and development of the organs and systems established during the embryonic period. The foetus increases in size and organs become more mature. During the third month, the foetus develops eyelids and sex differentiation occurs (i. e. external genitals develop). During the fourth month, there is movement development, which includes sucking (foetus can for example suck the thumb), head turning and limb movements. The mother begins to feel movements.
During the 5th, 6th and 7th months the foetus continues to develop significantly. It can survive in the sixth or 7th month because the respiratory system is fully developed. During the 8th and 9th month, there is further development of body systems. At the end of the 9th month, the foetus is ready to be born. Clinically, these six months are called the second and third trimesters. The first three months of gestation represents the first trimester. Birth Approximately 280 days (40 weeks) after conception, the foetus is born. This represents 9 calendar months or 10 lunar months.
This is the gestation period counting from the last menstruation period. The true gestation period is approximately 12-14 days shorter – hence approximately 266 days because ovulation occurs from 12-14 days after menstruation. The average full term baby weighs 2. 5 – 4. 3 kilogrammes. Prematurity There is variability in gestation period and in the rate of prenatal development. Thus, children vary in the degree of maturity at birth. The mean length of the gestation period is 266 days. Nearly 5 to 10 percent of all life births occur prematurely. Prematurity can have some negative effect on the development of the child.
Very rarely children born before 26 weeks of age survive. Premature births can be caused by poor maternal health, malnutrition, maternal age, smoking, drugs etc. The premature baby will have low activity level, problems in respiration, and will not be able to regulate body temperature effectively. For this reason, premature babies are kept in incubators for some time. Prematurity may also cause neonatal death. The neonate may be very weak and prone to illness. The premature baby is likely to be retarded in physical, motor and mental development, suffer speech difficulties, and have poor visual acuity (sensitivity).
However, this will depend on the kind of care given to the baby immediately after birth. If adequate care is given through proper incubation whereby temperature, oxygen levels and diet are carefully monitored and the infant physically stimulated at frequent intervals these anomalies may be substantially reduced or eliminated. Children who have low birth weight (small-for-date) are also likely to have problems in later development. Birth Injury When the neonate is born after prolonged or obstructed labour, brain injury becomes a common complication.
Sometimes a fracture in the skull, intra-cranial haemorrhage and cerebral laceration (tearing) may result. In such a case, development becomes retarded in the first two years of life and perceptional and motor defects may occur. Intra-cranial injury may lead to convulsive disorders, cerebral palsy and mental retardation. Anoxia (interruption of oxygen supply in the brain) is also common and damaging. A total lack of oxygen to the brain will kill the brain cells in 18 seconds. Anoxia may be caused by prematurity or abnormality in circulation or compression of the umbilical cord.
Epilepsy is most common in breech birth because of damage to brain cells caused by anoxia. Brain injury may be caused by instruments (such as forceps) applied to the head of the foetus during birth. Less serious disorders caused by brain injury include loss in auditory acuity, slow breathing, less neonate activity following birth, hyperactivity, psychomotor problems, lower attention level etc. Detecting whether the Neonate is Normal In 1953 Virginia Apger devised a standard scoring system for detecting problems in the neonate. Apger score is taken one minute and again 5 minutes after birth.
Observation is made on the pulse, breathing, muscle tone, general reflex response, and colour of the skin (or the mucous membranes, palms, and soles for non-white babies). A perfect Apger score is 10 points, with a score of 7 or more considered normal. The scoring is done as follows: Problem012 ______ Pulse absentless than 100more than 1000 Breathingabsentslow/irregularregular Colourblue or palebody pink/extremities bluecompletely pink Muscle tonelimpflexion of extremesactive motion Reflex response no responsegrimacevigorous A score below 7 may be an indicator to a problem.
Prenatal Environment Influences Normal development of the foetus would presumably take place under ideal prenatal environmental conditions. These include:
- A well developed amniotic sac with a cushioning of amniotic fluid.
- A fully functional placenta and umbilical cord * An adequate supply of oxygen and nutrients
- Freedom from disease, organisms and toxic chemicals There are a variety of conditions that affect the normal development of the unborn baby.
Many children are born with birth defects. Only a small proportion of birth defects result from inherited factors (e. . , Down’s syndrome). Majority of birth defects are caused by environmental factors during the prenatal period, or during child birth. An agent that can cause a birth defect, or even kill a foetus is called teratogen (teras for monster in Latin) and the field of study that focuses on birth defects and developmental abnormalities is called teratology. Teratology helps us understand the process of normal development and to prevent defects where possible. Following is a discussion of some of the common teratogens and their effects on development. Maternal Nutrition
Food supply for the foetus comes from the mother’s blood stream through the placenta. Good diet determines the health of the mother and the child. Food shortage during prenatal development may lead to permanent mental retardation as well as growth. Expectant mothers should eat enough and well balanced food. Malnutrition is associated with still-birth, pre-maturity and low-birth-weight babies and postnatal problems such as deficits in height and weight, mental deficiency, vulnerability to disease and so on. Specifically, lack of:
- Protein may result to reduced number of brain cells, neural defects and premature birth. Iron result to anaemia (blood deficiency)
- Calcium results to poor born formation
Vitamins result to poor mental functioning and physical abnormalities. However, an overdose of vitamin D may cause mental retardation Drugs Drugs that may be safe for use by adults may not be safe for the developing organism that shares the same environment with the mother. Pregnant mothers should not take drugs unless their health is really threatened. If medicine has to be taken at all, it should be prescribed by an authorized physician, say, a gynaecologist, especially during the first three months of pregnancy.
The following are some of the drugs that are known to cause some problems: Insulin – when given in large doses and in the first 14 weeks of pregnancy it may lead to the death of the foetus or to malformations. Thalidomide – it was used as a tranquilizer and sedative to treat morning sickness in the 1960s in Europe. It was widely prescribed for pregnant women, mostly in Britain and Germany in 1959 and 1960 (Brodzinsky, Gormly & Ambron, 1979). Two years later as many as 10,000 deformed babies were born. The deformities were associated with the mother’s intake of thalidomide.
- The defects caused depended on the time when the drug was taken during pregnancy. Those who took the drug:
- between the 34th and 38th day, the babies had no ears
- between the 38th and 45th day, the babies had defects in intestines or gall bladder
- between the 42nd and 47th day, the babies had missing or deformed legs
- after the 50th day, the babies had no deformities
The severity of withdrawal depends on the mother’s addiction and size of dose and how soon before delivery she took the drug. Smoking by pregnant mothers of cigarettes whose main ingredients include nicotine, tar, and carbon dioxide may likely lead to premature babies and underweight babies. Heavy smoking may result to spontaneous abortions, still-births, congenital malformations and neonate pneumonia. Constriction of veins due to smoking reduces the amount of oxygen and nutrients supplied to the foetus and hence the low weight and possible foetal damage.
Note that smoking may lead to poor appetite causing poor feeding habits of the mother and hence foetal malnutrition and the side effects. Alcohol consumption is harmful to the unborn baby even when consumed in small quantities (Claren and Smith, 1978: Bar and Martin, 1983). Excessive alcohol intake can lead to children who suffer from foetal alcoholic syndrome (FAS) whose symptoms include small heads, thin long upper lip, widely spread eyes, low forehead, short nose, retarded physical growth, flat cheekbones, possible mental retardation, low birth weight, small size and neurological abnormalities.
Note that, alcohol decreases appetite, affecting feeding. Women may drink due to tensions and stress. Therefore, the effect may be indirect due to stress and poor feeding habits. Moderate drinking may cause spontaneous abortion. Alcohol may cause damage to the muscles of the foetus and constriction of the umbilical cord cutting off needed oxygen to the foetus (Altural, et al. , 1982) Chemicals may damage the genetic material itself causing mutation or interfere with development after conception.
Some dangerous chemicals include:
Mercury which is found in cosmetics, lightening creams and in industrial waste can lead to mental retardation and physical deformities. Its effect received worldwide attention following the birth of a large number of severely deformed and retarded children in Minimata Bay – Japan. These deformities were traced to the presence of high levels of mercury in the fish that inhabitants of this community consumed in great quantities. The mercury got to the fish through industrial waste. Lead which can be found in automobile exhaust fumes and industrial waste if ingested by the expectant mother may cause miscarriage, anaemia, haemorrhage in the mother, premature birth, low weight, brain damage, physical defects and mental retardation. In men, exposure to lead may cause chromosomal abnormality that may affect their fertility.
Fungicides or insecticides contain ingredients like hydrocarbons and dioxin which may lead to still birth, miscarriage, physical deformities etc. Hormones that are mainly taken by mothers as medication may cause malformation of the foetal sexual organs.
Hormones taken and also produced by the mother and foetus may alter the cause of sexual development. In extreme cases they may result into the development of a body type opposite to the baby’s genetic sex. For example, androgens may cause mascularnization of the female foetus. Hormonal therapy can be administered to the baby after birth to set things right depending on the severity of the condition. Sometimes a sex operation may be necessary. Diethylstilbestrol (DES) can cause uterine and vaginal abnormalities in female fetuses. It was prescribed to prevent miscarriage in the 1950s.
It can also cause (possible) carcinogenesis in male and female foetus and also infertility. Radiation can damage the genetic material leading to physical or mental retardation. It can cause hazardous effects on the zygote, embryo and foetus whose cells divide rapidly. Excessive radiation through x-ray (e. g. , X-ray treatment of cancer) or through radiation in the atmosphere have produced marked effects on development. Radiation can lead to malformed limbs, malformed eyes, heart defects, leukaemia (cancer of the blood), mental retardation and abortion. The effects of low levels of radiation are ot well documented. Diseases * Rubella (German measles) has been associated with blindness, mental retardation, deafness and heart malformation.
- Herpes may cause brain infection and death
- Syphilis has been linked to blindness, deafness or insanity later in life, (after birth the baby can be given drops of silver nitrate or penicillin to prevent the eyes from damage).
- Gonorrhoea can affect the heart, spinal cord and cause blindness etc.
- Diabetes can cause respiratory and circulatory problems.
- HIV/AIDS virus can be transmitted to the infant during pregnancy or through breast feeding.
It can cause facial deformities, growth failure and eventually death. Maternal Factors i) Age: First time mothers over 35 years of age and teenage mothers have a higher rate of miscarriage, premature birth, still-birth and birth defects than mothers in the prime bearing age (20 – 35). The young mothers may not have yet completed their own development and their reproductive systems may not be ready to function. The old mothers’ systems may have passed their most efficient functioning stage. In both cases, pregnancy puts extra strain on a body that is not able to bear it. Hormonal balance may also play a part.
Children with Down’s syndrome are usually born to mothers over 40 years and sometimes to very young mothers. Children with Down’s syndrome have eyelids that resemble those of people from Mongolia – hence they are called mongoloids. The problem occurs during meiosis when the 21st chromosome fails to separate properly, hence resulting to a total of 47, instead of 46 chromosomes. Victims have very low IQs (20-60), broad nose, and protruding tongue. They are also likely to suffer heart malformations and respiratory disorders. ii)Rhesus factor (RH) incompatibility Rhesus factor is a component of the blood.
Its presence makes a person’s blood Rh positive and its absence Rh negative. The two types are genetically inherited and are incompatible under certain circumstance. When an Rh negative woman marries a Rh positive man, the baby’s blood will be Rh positive, since the Rh positive is a dominant trait. The baby’s blood type in this case will be incompatible to that of the mother. The Rh foetus produces substances called antigens that can pass through the semi-permeable membrane of the placenta and enter the Rh negative mother’s bloodstream. If this happens the mother’s blood produces antibodies to resist the invasion of the antigens.
These antibodies pass through the placenta to the foetus, thereby attacking it and destroying its red blood cells – a condition known as erythroblastosis foetalis which gives rise to severe anaemia. The toxic substance produced by the mother give the skin a yellow colouring called jaundice. The affected child may be born prematurely or may be still-born or mentally retarded. The antibody build up does not happen quickly enough to affect a first child, only those born later are affected. Blood transfusion is sometimes done immediately after birth or during pregnancy to save the child.
To prevent the build up of antibodies, Rh immune globulin can be administered to the mother within 72 hours after the birth or miscarriage of each child. iii) Maternal Emotional State In pregnancy, mother’s anxiety and stress can be caused by a variety of factors such as: extended family demands, quarrels, poverty, infidelity, sickness, superstitions, worry about what kind of a child to be born, too many children, sickness etc. Excessive emotional stress of rage, fear, anxiety and anger can stimulate the nervous system of the mother to send chemicals to the bloodstream.
At the same time, the endocrine glands will secrete hormones that affect cell metabolism. Such chemicals and hormones may find their way to the foetal blood through the placenta. Severe and prolonged emotional stress in early pregnancy may result in physical abnormalities. Excessive stress in the 7th week of pregnancy when the loop of the mouth and the bones of the upper jaw are forming in the foetus may result to cleft-palate and cleft-lip. This means that the chemicals produced during the stressful state interfere with the proper development of the upper jaw bone and the palate formation.
Though not well established, stress may bring about undesirable behaviours in the newborn for example, excessive crying, irritability, difficulty in breathing, diarrhoea and vomiting. Note that, stress may affect the mother’s feeding habits causing her to under feed or feed poorly. Thus, the effects may be related to poor feeding indirectly or for others, they may be due to drugs taken to relax when stressed. Congenital Abnormalities in Babies A congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life (neonatal disease), regardless of causation.
Of these diseases, those characterized by structural deformities are termed “congenital anomalies”; that is a different concept which involves defects in or damage to a developing fetus. A congenital disorder may be the result of genetic abnormalities, the intrauterine (uterus) environment, errors of morphogenesis, infection, or a chromosomal abnormality. The outcome of the disorder will depend on complex interactions between the pre-natal deficit and the post-natal environment.
Animal studies indicate that the mother’s (and possibly the father’s) diet, vitamin intake, and glucose levels prior to ovulation and conception have long-term effects on fetal growth and adolescent and adult disease. Congenital disorders vary widely in causation and abnormalities. Any substance that causes birth defects is known as a teratogen. 1. Spina Bifida. In this condition, there is a raw swelling over a portion of the spine at birth. This results in paralysis of the legs (either partial or complete), inability to control bladder functioning and inability to feel anything below the spina bifida.
In some cases, there is a build up and retention of water in the brain, which is known as hydrocephalus. This swelling can be closed by an operation by specialists. 2. Umbilical hernias. In this condition, parts of the digestive system are lying outside the stomach cavity. This is because the area around the navel is not very strong. Normally, cases of umbilical hernias around the navel heal on their own; if they don’t, surgery is required. 3. Sickle cell disease. This is a hereditary condition that is most commonly found among people of West African or African Caribbean descent.
The haemoglobin in the red blood corpuscles disintegrates at a quicker rate than normal. Haemoglobin is important, as it carries oxygen to the different parts of the body. Reduction in haemoglobin causes anaemia and blocks blood vessels in the hands, legs and stomach. An attack can last for a few days and can be treated with painkillers. This is also known as Sickle Cell disease.
Cystic Fibrosis. This is another hereditary illness, in which the tissues in the body produce unusually thick mucus. The commonly affected organs are the lungs, the intestines and pancreas.
If the lungs are affected, the air ducts are blocked and hence, vulnerable to infection. Children with this condition have an inability to digest food completely and have bad smelling bowel movements and constipation. They are well below the normal weight for their age. This illness has no cure, but if detected in the initial stages, lung damage can be reduced. These children are susceptible to chest infections and have to be treated with antibiotics. Chest physiotherapy is required regularly to remove thick phlegm. 5. Coeliac disease. In this condition, the child’s intestine reacts strongly to gluten, a protein found in wheat.
These children have a severe case of diarrhoea, where the stools are fatty, pale and don’t flush away. The child does not put on weight as required. The illness can be detected by a blood test. After being detected, the child will have to completely give up gluten containing food. Once this is done, stools return to normal and the child will put on weight. 6. Clubfoot. In this condition, the foot curves inwards or outwards. All babies are checked for this at birth, more so, if they were born in the breech position, as it occurs more frequently with these babies.
Often, they can be manipulated into the proper position, with little or no treatment. Surgery may be required in severe cases. This condition is also known as Talipes. 7. Cleft palate. In this condition, the cleft lip and the cleft palate are fused, thus the baby cannot be breast-fed. Various support groups will help you deal with the situation and corrective plastic surgery is possible. 8. Congenital dislocation of the hip. All babies are screened for this condition at birth and when they are eight weeks old. If this condition goes undetected, walking can become a problem later in life.
If diagnosed with this problem, the baby will have to wear a special splint for some time. Most recover without having to be operated on, but some do need an operation. This condition is prevalent more among girls and breech babies. 9. Cerebral palsy. In this condition, the parts of the brain that control body movements are damaged. This can happen before birth, during birth, or in the first two years after birth. In some cases, damage may not be noticed at birth, but as the child grows, it becomes evident. It is difficult to pinpoint as to what causes this damage.
There are a few tests that can be conducted when the baby is eight weeks old to screen him for cerebral palsy.
Self Assessment and Revision Questions
- Briefly explain how heredity and environment influence development. What major developments occur during the period of the embryo?
- Explain how nutrition affects development during pregnancy and in the early years. Explain the nature-nurture controversy
- How does Rh incompatibility affect the development of the foetus?
- How does maternal age and emotional stress influence foetal development?
- Identify two chemicals and explain how they can affect development during the prenatal period.
In this topic we are going to discuss physical and motor development from infancy through old age. Infancy 0 – 2 Years Physical Development Physical development is one of the overt and most obvious indicator of development. It has an effect on other aspects of development such as social and motor development. Physical development is affected by diet, parental care, social economic status, disease etc. Physical development is very rapid within the first two years.
Boys are slightly taller and heavier than girls. Development of the Nervous System Growth of the nervous system is rapid during the first two years after which it slows down. During the first six months, neural activity is dominated by the lower areas of the brain – spinal cord, brain stem and mid-brain. By the end of the first year, the higher parts of brain, that is, cerebral cortex become more active. By the end of the second year, anatomical features of brain are established. However, different parts continue to develop specialized functions. For example, some parts develop to specialize in language, speech, handedness, memory etc.
By birth, the brain weighs about 25% of its adult weight. By two years it weighs about75% of its adult weight. Development of nervous system facilitates the control of motor functions and refinement in perceptual abilities. The head grows slowly and matures earlier than other parts of the body. Motor Development All normal babies are born with reflexes (involuntary physical motor responses to a given stimulus). The presence of motor reflexes indicates maturity and normal functioning of the brain and nervous system. They help the baby to adapt to the post uterine environment and some are essential for survival.
- The absence of motor reflexes at birth may imply brain damage, neural depression or abnormality. These reflexes include:
- Sucking reflex in which the new born sucks anything (e. g. , fingers, toes, blankets etc) that touches its lips. This reflex ensures survival.
- Rooting reflex – when one cheek is touched or stimulated, babies move their heads towards the stimulus and open their mouths. This reflex helps the baby in finding the nipple. If brushed by the breasts, it turns to suck.
- Babinski reflex – if the soles of infants are stimulated or stroked the infant will spread their toes and raise the large one. Grasping or palmar reflex – if something is placed in the infant’s palm, it will grasp it tightly and increase the strength of the grasp if the object is pulled away.
- Walking reflex – if the infant is held upright on a flat surface and is moved forward, it would appear to walk in a coordinated way.
- Swimming reflex – when infants are held horizontally on their stomachs or back, their arms and legs stretch out as though swimming.
Initially, motor movements are undifferentiated and involve large muscles of the arms, legs and torso (body trunk). This is referred to as gross motor development. Later, there is development of fine motor skills involving smaller muscles such as finger, arms and hand muscles etc. Motor skills generally develop following the proximodistal (near to far) and cephalocaudal (head to tail) principles. For example, the child acquires ability to hold the head, then refines the use of arms/hands and then gains control of legs and feet. Schedule (timetable) of more important landmarks and their median age of occurrence.
Cite this Growth and Development Processes
Growth and Development Processes. (2016, Sep 27). Retrieved from https://graduateway.com/growth-and-development-processes/