• Finnish: varhaiskypsä
• German: frühreif

• Finnish: pikkuvanha, edistynyt, etevä
• German: frühreif

See also

• prodigy

Child development refers to the biological and psychological changes that occur in human beings between birth and the end of adolescence, as the individual progresses from dependency to increasing autonomy. Because these developmental changes may be strongly influenced by genetic factors and events during prenatal life, genetics and prenatal development are usually included as part of the study of child development. Related terms include "developmental psychology", referring to development throughout the lifespan and "pediatrics", the branch of medicine relating to the care of children. Developmental change may occur as a result of genetically-controlled processes known as maturation, or as a result of environmental factors and learning, but most commonly involves an interaction between the two.

Age-related development terms are: newborn (ages 0–1 month); infant (ages 1 month – 1 year); toddler (ages 1–3 years); preschooler (ages 4–6 years); school-aged child (ages 6–11 years); adolescent (ages 11–18). However, organizations like Zero to Three and the World Association for Infant Mental Health use the term infant as a broad category, including children from birth to age 3, a logical decision considering that the Latin derivation of the word infant refers to those who have no speech, and speech is generally well-established by 3 years. The optimal development of children is considered vital to society and so it is important to understand the social, cognitive, emotional, and educational development of children. Increased research and interest in this field has resulted in new theories and strategies, with specific regard to practice that promotes development within the school system. In addition there are also some theories that seek to describe a sequence of states that comprise child development.

Developmental milestones

Milestones are changes in specific physical and mental abilities (such as walking and understanding language) that mark the end of one developmental period and the beginning of another. For stage theories, milestones indicate a stage transition. Studies of the accomplishment of many developmental tasks have established typical chronological ages associated with developmental milestones. However, there is considerable variation in the achievement of milestones, even between children with developmental trajectories within the normal range. Some milestones are more variable than others; for example, receptive speech indicators do not show much variation among children with normal hearing, but expressive speech milestones can be quite variable.

A common concern in child development is developmental delay involving a delay in an age-specific ability for important developmental milestones. Prevention of and early intervention in developmental delay are significant topics in the study of child development. Developmental delays should be diagnosed by comparison with characteristic variability of a milestone, not with respect to average age at achievement. An example of a milestone would be eye-hand coordination, which includes a child's increasing ability to manipulate objects in a coordinated manner. Increased knowledge of age-specific milestones allows parents and others to keep track of appropriate development.

Continuity and discontinuity in development

Although the identification of developmental milestones is of interest to researchers and to children's caregivers, many aspects of developmental change are continuous and do not display noticeable milestones of change. Continuous developmental changes, like growth in stature, involve fairly gradual and predictable progress toward adult characteristics. When developmental change is discontinuous, however, researchers may identify not only milestones of development, but related age periods often called stages. A stage is a period of time, often associated with a known chronological age range, during which a behavior or physical characteristic is qualitatively different from what it is at other ages. When an age period is referred to as a stage, the term implies not only this qualitative difference, but also a predictable sequence of developmental events, such that each stage is both preceded and followed by specific other periods associated with characteristic behavioral or physical qualities.

Stages of development may overlap or be associated with specific other aspects of development, such as speech or movement. Even within a particular developmental area, transition into a stage may not mean that the previous stage is completely finished. For example, in Erikson's discussion of stages of personality, this theorist suggests that a lifetime is spent in reworking issues that were originally characteristic of a childhood stage . Similarly, the theorist of cognitive development, Piaget, described situations in which children could solve one type of problem using mature thinking skills, but could not accomplish this for less familiar problems, a phenomenon he called horizontal decalage.

Mechanisms of development

Although developmental change runs parallel with chronological age, age itself cannot cause development. The basic mechanisms or causes of developmental change are genetic factors and environmental factors. Genetic factors are responsible for cellular changes like overall growth, changes in proportion of body and brain parts, and the maturation of aspects of function such as vision and dietary needs. Because genes can be "turned off" and "turned on", the individual's initial genotype may change in function over time, giving rise to further developmental change. Environmental factors affecting development may include both diet and disease exposure, as well as social, emotional, and cognitive experiences. However, examination of environmental factors also shows that young human beings can survive within a fairly broad range of environmental experiences. Plasticity may involve guidance by endogenous factors like hormones as well as by exogenous factors like infection.

One kind of environmental guidance of development has been described as experience-dependent plasticity, in which behavior is altered as a result of learning from the environment. Plasticity of this type can occur throughout the lifespan and may involve many kinds of behavior, including some emotional reactions. A second type of plasticity, experience-expectant plasticity, involves the strong effect of specific experiences during limited sensitive periods of development. For example, the coordinated use of the two eyes, and the experience of a single three-dimensional image rather than the two-dimensional images created by light in each eye, depend on experiences with vision during the second half of the first year of life. Experience-expectant plasticity works to fine-tune aspects of development that cannot proceed to optimum outcomes as a result of genetic factors working alone.

In addition to the existence of plasticity in some aspects of development, genetic-environmental correlations may function in several ways to determine the mature characteristics of the individual. Genetic-environmental correlations are circumstances in which genetic factors make certain experiences more likely to occur. For example, in passive genetic-environmental correlation, a child is likely to experience a particular environment because his or her parents' genetic make-up makes them likely to choose or create such an environment. in evocative genetic-environmental correlation, the child's genetically-caused characteristics cause other people to respond in certain ways, providing a different environment than might occur for a genetically-different child; for instance, a child with Down syndrome may be treated more protectively and less challengingly than a non-Down child. Finally, an active genetic-environmental correlation is one in which the child chooses experiences that in turn have their effect; for instance, a muscular, active child may choose after-school sports experiences that create increased athletic skills, but perhaps preclude music lessons. In all of these cases, it becomes difficult to know whether child characteristics were shaped by genetic factors, by experiences, or by a combination of the two

Research issues and methods

Establishing a useful database of information about child development requires systematic inquiry about developmental events. Different aspects of development involve different patterns and causes of change, so there is no simple way to summarize child development. Nevertheless, the answering of certain questions about each topic can yield comparable information about various aspects of developmental change. The following questions were suggested for this purpose by Waters and his colleagues . 1) What develops? What relevant aspects of the individual change over a period of time? 2) What are the rate and speed of development? 3) What are the mechanisms of development - what aspects of experience and heredity cause developmental change? 4) Are there normal individual differences in the relevant developmental changes? 5) Are there population differences in this aspect of development (for example, differences in the development of boys and of girls)?

Empirical research that attempts to answer these questions may follow a number of patterns. Initially, observational research in naturalistic conditions may be needed to develop a narrative describing and defining an aspect of developmental change, such as changes in reflex reactions in the first year. This type of work may be followed by correlational studies, collecting information about chronological age and some type of development such as vocabulary growth; correlational statistics can be used to state the connection between the two. Comparative studies examining the extent and course of development over time are the basic method for studying developmental change. Such studies examine the characteristics of children at different ages. These methods may involve longitudinal studies, in which a group of children are re-examined on a number of occasions as they get older,or cross-sectional studies, in which groups of children of different ages are tested once and compared with each other, or there may be combinations of these approaches. Some child development studies examine the effects of experience or heredity by comparing characteristics of different groups of children in a necessarily non-randomized design. Other studies can use randomized designs to compare outcomes for groups of children who receive different interventions or educational treatments.

Speed and pattern of development

The speed of physical growth is rapid in the months after birth, then slows, so birth weight is doubled in the first four months, tripled by age 12 months, but not quadrupled until 24 months.Growth then proceeds at a slow rate until shortly before puberty (between about 9 and 15 years of age), when a period of rapid growth occurs. Growth is not uniform in rate and timing across all body parts. At birth, head size is already relatively near to that of an adult, but the lower parts of the body are much smaller than adult size. In the course of development, then, the head grows relatively little, and torso and limbs undergo a great deal of growth.

Speed and pattern of development

Receptive language, the understanding of others' speech, appears to have a gradual course of development beginning at about 6 months.. However, expressive language, the production of words,moves rapidly after its beginning at about a year of age, with a "vocabulary explosion" of rapid word acquisition occurring in the middle of the second year. Grammatical rules and word combinations appear at about age two. Mastery of vocabulary and grammar continue gradually through the preschool and school years. Adolescents still have smaller vocabularies than adults and experience more difficulty with constructions like the passive voice.

Babies from one month old can produce "ooh" sounds which appear to grow out of pleasurable interactions with caregivers in a mutual "dialogue". According to Stern, this process is communication of affect between adult and infant in a mutual, rhythmic interaction. The attunement and "gaze-coupling" in which infant and adult take different roles is thought to anticipate the give-and-take of later dialogue.

From about 6 to 9 months babies produce more vowels, some consonants and "echolalia", or the frequent repetition of sounds like "dadadada" which appear to have some phonetic characteristics of later speech. It is thought that a crucial part of the development of speech is the time carers spend "guessing" what their infants are trying to communicate thus integrating the child into their social world. The attribution of intentionality to the infant's utterances has been called "shared memory" and forms a complex series of actions, intentions and actions in response in an improvised way. First words have the function of naming or labelling but also condense meaning as in "milk" meaning "I want milk". Vocabulary typically grows from about 20 words at 18 months to around 200 words at 21 months. From around 18 months the child starts to combine words into two word sentences. Typically the adult expands it to clarify meaning. By 24-27 months the child is producing three or four word sentences using a logical, if not strictly correct, syntax. The theory is that children apply a basic set of rules such as adding 's' for plurals or inventing simpler words out of words too complicated to repeat like "choskit" for chocolate biscuit. Following this there is a rapid appearance of grammatical rules and ordering of sentences. There is often an interest in rhyme, and imaginative play frequently includes conversations.

By three years the child is beginning to use complex sentences, including relative clauses, although still perfecting various linguistic systems. By five years of age the child's use of language is very similar to that of an adult. The ability to engage in extended discourse emerges over time from regular conversation with adults and peers. For this the child needs to learn to combine his perspective with that of others and with outside events and learn to use linguistic indicators to show he is doing this. They also learn to adjust their language depending on to whom they are speaking. Typically by the age of about 9 a child can recount other narratives in addition to their own experiences, from the perspectives of the author, the characters in the story and their own views.

Mechanisms of language development

Although the role of adult discourse is important in facilitating the child's learning, there is considerable disagreement amongst theorists about the extent to which children's early meanings and expressive words arises directly from adult input as opposed to intrinsic factors relating to the child's cognitive functions. Findings about the initial mapping of new words, the ability to decontextualise words and refine meaning are diverse. Another is the multi-route model in which it is argued that context-bound words and referential words follow different routes; the first being mapped onto event representations and the latter onto mental representations. In this model, although parental input has a critical role,children rely on cognitive processing to establish subsequent use of words. However, naturalistic research on language development has indicated that preschoolers' vocabularies are strongly associated with the number of words addressed to them by adults.

There is as yet no single accepted theory of language acquisition. Current explanations vary in emphasis from learning theory, with its emphasis on reinforcement and imitation, (Skinner), to biological, nativist theories, with innate underlying mechanisms, (Chomsky and Pinker), to a more interactive approach within a social context, (Piaget and Tomasello). There is some support for this from the development of sign language amongst deaf children thrown together at a young age in special schools in Nicaragua who spontaneously developed a pidgin which was then developed into a creole by a younger generation of children coming into the schools, (ISN).. However, the universal presence of the physical environment and very often a social environment, and the contingent relations that each effects on the development of an individual's language behavior, must be accounted for by any and all language development theories (Moerk 1986, 1989,1996).

Individual differences

Slow Expressive Language Development (SELD) a delay in the use of words coupled with normal understanding, is characteristic of a small proportion of children who later display normal language use. Dyslexia is a significant topic in child development as it affects approximately 5% of the population (in the western world). Essentially it is a disorder whereby children fail to attain the language skills of reading, writing and spelling commensurate with their intellectual abilities. Dyslexic children show a range of differences in their language development, from subtle speech impairments to mispronunciations to word-finding difficulties. The most common phonological difficulties are limitations of verbal short-term memory and phonological awareness. Such children often have difficulties with long-term verbal learning such as months of the year, learning tables, left and right or a foreign language. From the late 1980s the phonological deficit hypothesis has become the dominant explanation. The difficulties in early articulation, basic phonological skills and acquiring basic building blocks means that dyslexics have to invest too many resources in just coping with the basics rather than acquiring new information or skills. Early identification enables children to receive help before they fail. Third is the phallic stage which lasts for about three years and it is during this stage that the oedipal conflict arises wherein a boys desires for his mother are in conflict with his fear of castration by the rival father. Freud argued that children pass through a stage in which they fixate on the mother as a sexual object (known as the Oedipus Complex) but that the child eventually overcomes and represses this desire because of its taboo nature. Freud's attempts to formulate a comparable process for girls fixating on fathers, the lesser known Electra complex, was less successful. The fourth stage is the repressive or dormant latency stage of psychosexual development. This is followed by a genital stage during which the properly developing human should mature from pleasure seeking infant into the sexually mature, genital stage of psychosexual development. In Freuds theory, each stage contains conflict which requires resolution to enable the child to develop.

Erik Erikson

Erikson, a follower of Freud's, synthesized both Freud's and his own theories to create what is known as the "psychosocial" stages of human development, which span from birth to death, and focuses on "tasks" at each stage that must be accomplished to successfully navigate life's challenges. An example of this might be when a parent "helps" an infant clap or roll his hands to the Pat-a-Cake rhyme, until he can clap and roll his hands himself.

Vygotsky (1978) was strongly focused on the role of culture in determining the child's pattern of development. He argued that "Every function in the child's cultural development appears twice: first, on the social level, and later, on the individual level; first, between people (interpsychological) and then inside the child (intrapsychological). This applies equally to voluntary attention, to logical memory, and to the formation of concepts. All the higher functions originate as actual relationships between individuals." He wrote extensively on child development and conducted research (see Little Albert experiment). Watson was instrumental in the modification of William James’ stream of consciousness approach to construct a stream of behavior theory. Watson also helped bring a natural science perspective to child psychology by introducing objective research methods based on observable and measurable behavior. Following Watson’s lead, B.F. Skinner further extended this model to cover operant conditioning and verbal behavior. In doing this, Skinner's radical behaviorism focused the science on private events such as thinking and feeling and how behavior is shaped by the effects it comes into contact with in the environment.. Skinner labeled such effects "operants" because this type of behavior "operates" on the environment; hence, an operant is a relation between behavior and the effect, rewarding or punishing, it comes into contact with.

In the 1960s, while at the University of Kansas in the home economics/family life department,Sidney Bijou and Donald Baer began to apply behavior analytic principles to child development in an area referred to as "Behavioral Development" or "Behavior Analysis of Child Development". Skinner’s behavioral approach and Kantor’s interbehavioral approach was adopted in Bijou and Baer’s model. Bijou and Baer created a three-stage model of development (e.g., basic, foundational, and societal). In behavior analysis, the stages are neither essential nor explanatory. They posit that these stages are socially determined, although behavior analysts tend to focus much more on change points or cusps rather than stages. While not all cusps result in a stage change, all stage changes do involve cusps. In the behavioral model, development is represented as behavior change and is dependent on a combination of factors including the level/kind of stimulation, behavioral function, and the learning/genetic history of the organism. This model is closer to Skinner’s model than Watson's in that it rejects the idea of a purely passive organism. Behavior analysis in child development is between mechanistic and contextual, pragmatic approaches.

From its inception, the behavioral model has been focused on prediction and control of the developmental process. The model was greatly enhanced by basic research on the matching law of choice behavior developed by Richard J. Herrnstein, especially in the study of reinforcement in the natural environment as related to antisocial behavior. As the behavioral model has become increasingly more complex and focused on metatheory, it has become concerned with how behavior is selected over time and forms into stable patterns of responding. A detailed history of this model was written by Pelaez. In 1995, Henry D. Schlinger, Jr. provided the first behavior analytic text since Bijou and Baer comprehensively showing how behavior analysis-a natural science approach to human behavior-can be used to understand existing research in child development.

Dynamic systems theory

The use of dynamic systems theory as a framework for the consideration of development began in the early 1990s and has continued into the present century. Dynamic systems theory stresses nonlinear connections (e.g., between earlier and later social assertiveness)and the capacity of a system to reorganize as a phase shift that is stage-like in nature. Another useful concept for developmentalists is the attractor state, a condition (such as teething or stranger anxiety) that helps to determine apparently unrelated behaviors as well as related ones. Dynamic systems theory has been applied extensively to the study of motor development; the theory also has strong associations with some of Bowlby's views about attachment systems. Dynamic systems theory also relates to the concept of the transactional process, a mutually interactive process in which children and parents simultaneously influence each other, producing developmental change in both over time.

See also

• Child psychology
• Child prodigy
• Evolving capacities
• Critical period
• Early childhood education
• Sensitive Periods
• Attachment in children

• Pedagogy
• Play (activity)
• Professional practice of behavior analysis
• Child life specialist
• Applied Behavior Analysis
• Feral child

References

Moerk, E.(1996). Input and learning processes in first language acquisition. Advances in Child Development and Behavior, 26, 181-229. Moerk, E.L. (1986). Environmental factors in early language acquisition. In G. J. Whitehurst (Ed.), Annals of child development (Vol. 3). Greenwich, CT:JAI press. Moerk, E.L.(1989). The LAD was a lady and the tasks were ill defined. Developmental Review, 9, 21-57.

Further reading

• Infants, Children, and Adolescents by Laura E. Berk.
• Theories of Childhood: an Introduction to Dewey, Montessori, Erikson, Piaget & Vygotsky by Carol Garhart Mooney.

External links

• Child Development and Developmental Delay
• High Quality Infant Growth, Developement and Care Online Guide
• Child and Family WebGuide: typical development
• Behavioral Development Bulletin for more information on Behavior Analysis and ChildDevelopment

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