Developmental Theory

HISTORICAL OVERVIEW
Maureen Kessenich
Frederick J. Morrison

COGNITIVE AND INFORMATION PROCESSING
Jeffrey Bisanz
Elaine Ho
Melissa Kachan
Carmen Rasmussen
Jody Sherman

EVOLUTIONARY APPROACH
David C. Geary

VYGOTSKIAN THEORY
M. Susan Burns
Elena Bodrova
Deborah J. Leong

HISTORICAL OVERVIEW

Developmental psychology attempts to understand the nature and sources of growth in children's cognitive, language, and social skills. Within that context, there are four central themes that are unique to a developmental perspective and that bear on issues in childhood education. The first is the role of nature versus nurture in shaping development. Specifically, developmentalists want to know the contribution of genetic or maturational influences on development as well as the role played by environmental experiences. One important educational issue related to this topic is the question of whether a child's en-trance age, or maturational level, is important for school success. For this and other important educational questions, nature and nurture interact in complex ways to shape a child's academic growth.

The second question focuses on whether children's growth proceeds in a continuous or more stage-like fashion. Stage theories, such as those proposed by Jean Piaget, Erik Erikson, and Sigmund Freud, contend that development progresses through maturationally determined stages. While this perspective underscores the contributions of both biology and the environment, a greater emphasis is placed on a maturationally predetermined progression through a fixed developmental sequence. Many researchers and theorists dispute such a rigid, step-like theory of development, emphasizing instead a more continuous, gradual process influenced equally by both brain maturation and environmental stimulation. Two important educational questions relevant to this issue are the extent to which children can be taught particular concepts or skills prior to entering a given developmental stage, and whether concepts learned in one domain are automatically transferred to other similar domains as a child reaches a new developmental stage.

A distinct but related theme centers on the existence of critical or sensitive periods in human development. A critical or sensitive period is defined as a time of growth during which an organism is maximally responsive to certain environmental or biological events. Critical periods emphasize the interaction of both nature and nurture, with environmental experiences (nurture) activating biologically programmed (nature) developmental changes, or, conversely, biologically determined changes enabling an organism to assimilate certain environmental experiences. In terms of language development, educators often wonder whether there is a critical or sensitive period during which children should learn a second language. While certain components of language, such as phonological processing, are believed to be constrained by sensitive periods in development, other elements of language, such as vocabulary, clearly evolve over the lifespan.

The final theme concerns the importance of early experience in shaping later growth and development. Developmental scientists such as Mary Ainsworth, Alan Sroufe, and Freud emphasize the significance of early attachment and emotional conflict in predicting later psychological adjustment. It is argued that early risk factors have a more permanent influence on the course of development than later experiences. Early negative circumstances such as family conflict and social disadvantage have been linked to later delinquent behavior and school failure. Nevertheless, many children display resilience in the face of such early adverse social and environmental conditions. Thus, it is the cumulative impact of both early and later experiences that determines a child's developmental outcome. Children's literacy development, for example, is a product of both early experiences, such as parent–child book reading, as well as later experiences, such as reading instruction in school.

Modern developmental theory centers on these four central issues. An in-depth examination of these topics within a historical context will provide a more comprehensive understanding of developmental theory and its relevance for educational policies and practices.

Nature Versus Nurture

Philosophers and psychologists have debated the relative roles of nature and nurture in human development for centuries. The seventeenth-century English philosopher John Locke described a young child's mind as a tabula rasa (blank slate) upon which the child's experiences are written. Jean-Jacques Rosseau, an eighteenth-century French philosopher, also argued that human development was primarily a function of experience. He believed in the existence of a natural, unspoiled state of humankind that is altered and corrupted by modern civilization. In contrast, nineteenth-century scientists such as Gregor Mendel, Charles Darwin, and Sir Francis Galton highlighted the importance of heredity in shaping development. While all of these scientists provided meaningful insights into the role of heredity and the environment, modern researchers have sought to further explore the dynamic interactions between nature and nurture that shape human development.

The twentieth century saw the evolution of various theories of development that differentially emphasized the role of biological versus environmental factors. These theories can be classified according to four major developmental frameworks: (1) environmental learning (empiricism), (2) biological maturation (nativism), (3) cultural context, and (4) constructivist.

The environmental-learning framework, best exemplified by the behaviorist theories of John B. Watson and B. F. Skinner, underscores the paramount importance of empirical learning in development. According to behaviorist theories, learning is characterized as the process by which an organism's behavior is shaped by experience. While environmental-learning theorists do not completely discount the role of innate factors, they argue that it is the external environment that has the greatest influence on development.

Biological-maturationist theories represent the opposing swing of the theoretical pendulum. This framework posits that biologically and genetically predetermined patterns of change have a greater impact on development than environmental influences. During the early twentieth century, theorists such as Freud and Arnold Gessell proposed that experiential influences were secondary to innate maturational mechanisms. This perspective regained popularity in the late twentieth and early twenty-first centuries as a result of major advances in genetic research, as well as the introduction of twin studies and behavioral genetics. Researchers such as Robert Plomin, Noam Chomsky, and Steven Pinker assert that human characteristics such as personality, intelligence, and language acquisition are, to a great extent, genetically grounded and maturationally controlled.

The cultural-context perspective of psychologists such as Lev Vygotsky and Barbara Rogoff contends that while both biological and experiential factors exert important influences on development, such factors are filtered through an individual's social and cultural context. Lev Vygotsky believed that the activities, symbols, and customs of particular social groups are formed by the collective social, cultural, and historical experiences of their ancestors. Through influences on social customs and practices, parenting, and the environment, culture shapes children's cognitive, language, and social development. For example, children's academic performance has been found to vary cross-culturally, as demonstrated by studies showing that Asian immigrant children outperform their white peers in the United States, as well as the black-white test score gap.

Finally, the constructivist, or interactionist, approach stresses the balanced interaction of nature and nurture in forming the foundation for developmental change. In such a framework, both genetics and environment play an important role, and it is the dynamic relations among such internal and external influences that ultimately shape development. Piaget's theory of cognitive development asserts that children construct their knowledge based on the combination of input received from both maturational and environmental sources. Theorists such as Richard Lerner, Gilbert Gottlieb, Esther Thelen, and Linda Smith have taken this conceptualization one step further with the introduction of dynamic systems theories, which emphasize that the source of developmental change is in the process of bidirectional interaction among complex environmental and biological systems.

Frederick Morrison and colleagues have explored one facet of the nature-nurture question relevant to education by examining the importance of entrance age, or maturation level, on school readiness and academic growth. They found that younger first graders benefited as much from instruction in reading and math as older first graders, and that the younger students made significantly more progress than older kindergarteners of essentially the same age. Thus, entrance age–or maturation level–is not an important indicator of learning or academic risk.

The dispute over the relative importance of nature and nurture in children's development has endured for several centuries, and will no doubt continue to divide theorists for a long time to come. Increasingly, however, developmental scientists are concluding that, for most human characteristics, nature and nurture are inextricably linked and interact in complex ways to shape human growth.

Stages in Development

According to Piaget's stage theory, children progress through a sequence of qualitative transformations, advancing from simple to more complex levels of thought. Piaget believed these transformations to be universal, innately programmed shifts in a child's perception and understanding of the world. He proposed four main stages of cognitive development: sensorimotor, preoperational, concrete operational, and formal operational.

The transition from preoperational to concrete operational thought, at about five to seven years of age, corresponds with entry into formal schooling. While children in the preoperational stage are able to internally represent reality through the use of symbols such as language and mental images, concrete-operational children move beyond this simple mental representation of objects and actions and are able to logically integrate, order, and transform these objects and actions. For instance, because preoperational children cannot integrate information about height and width simultaneously, they are unable to recognize that water poured from a short, wide container into a tall, narrow container represents the same volume of water. Yet once they reach the age of reason, their maturational level converges with their accumulated experiences to facilitate a qualitative shift toward concrete operational thinking.

In addition to Piaget's stage theory of cognitive development, several others have proposed stage theories of psychosexual/personality development (Freud), psychosocial/identity development (Erikson), moral reasoning (Lawrence Kohlberg), and social development (Theory of Mind). These theories claim that children proceed through universal, age-specific stages of growth. Yet not all psychologists agree with such a rigid, step-like representation of development. Recently, neo-Piagetian theorists such as Kurt Fischer, Robbie Case, Annette Karmiloff-Smith, and others have attempted to reconcile the variability and domain-specificity observed in children's cognitive growth with Piaget's static stage theory.

In general, the neo-Piagetian perspective expands upon Piagetian theory by asserting that, while some general constraints or core capacities are hard-wired at birth, learning and experience lead to variation and domain-specificity in the acquisition of knowledge and skills. Cross-cultural studies have shown that varying cultural experiences result in the acquisition of different, contextually relevant skills. For example, children from a Mexican village known for its pottery-making learn conservation of solids (e.g., the fact that a ball of clay has the same mass even when it is molded into a long, thin roll) before conservation of number, which is generally mastered first in formally schooled children. Thus, most neo-Piagetians believe that while learning is constrained by innate mechanisms or information processing capacities, it proceeds in an individualized, domain-specific manner.

The question of whether certain knowledge or skills can be acquired before a child has reached a specified stage of development has also been addressed by neo-Piagetians. Renee Baillargeon conducted experiments with young infants and found that they recognize properties of object permanence prior to reaching that designated Piagetian stage of development. In addition, researchers have demonstrated that children can be taught concrete-operational concepts even before they have formally reached that stage of cognitive understanding–though these children are unable to transfer such knowledge outside the context of the testing situation.

Other theorists construe development as a constructive web (Kurt Fischer) or as a series of overlapping waves (Robert Siegler), rather than a sequence of qualitatively distinct steps. They recognize that cognitive development is the result of gradually acquired skills and abilities that build upon each other. Siegler, in particular, emphasizes the overlapping use of progressively more advanced strategies in the acquisition of skills such as addition. He found that children learning addition use various strategies in "overlapping waves," such as finger counting, verbal counting in their head, the Min strategy (taking the larger of two numbers as a base and adding the smaller number to it) and, eventually, retrieval from memory. They gradually move from using easier, less efficient strategies to more difficult, but more efficient, strategies.

The neo-Piagetian view resembles the information-processing perspective in that both contend that cognitive development is limited by general constraints that are hard-wired at birth. Information-processing researchers such as Robert Kail, Wolfgang Schneider, and David Bjorklund argue that children's learning is restricted by the broad processing capacities of the brain, which improve with age. This perspective regards development as a more gradual, continuous process that evolves as children's processing speed or capacity for holding information increases. Thus, the step-like progression of development is rejected for a more linear representation.

Critical Periods

A critical, or sensitive period is defined as a period of time in development when a particular environmental experience or biological event has its greatest influence. Evidence demonstrates that some physiological and psychological processes are constrained by critical periods.

The existence of sensitive periods in children's psychological development has been noted in aspects of language acquisition. Children deprived of verbal stimulation during the first few years of life are severely impaired in their capacity to learn language and have great difficulty acquiring normal language later on. In addition, while young infants are able to distinguish among the variety of phonemes present in all human languages, after about six months of age the infant's knowledge becomes more focused, and they are only able to discriminate between the various phonemes in their own native language. Consequently, infants can learn any language that they are exposed to, yet it is more difficult for an older child or adult to completely master a non-native or secondary language.

Taken together, such information lends support to the argument that the first few years of life represent a sensitive period for certain aspects of language development. However, the fact that children continue to benefit from exposure to new vocabulary, semantics, and grammatical rules well into elementary school and beyond leads researchers to question whether all language learning is restricted by a sensitive period. During the first few years of life, children's brains grow and become more organized, specialized, and efficient. Yet brain growth and development does not end at three years of age, but rather continues throughout childhood, benefiting from the effects of schooling and other environmental stimulation. Thus, the question of when educators should teach children a second language depends on the components of language being considered (e.g., phonology, semantics, vocabulary, grammar) and the level of proficiency desired.

Another area of development believed to be constrained by a sensitive period is attachment. Psychologists such as John Bowlby, Ainsworth, Sroufe, Erikson, and Freud contend that children's early attachment to their primary caregiver (e.g., mother, father) during the first few years of life sets the foundation for their later socioemotional development. Research conducted by Harry Harlow on infant monkeys found that those deprived of maternal attachment prior to six months of age had a more difficult time recovering socially than those deprived of maternal contact after six months of age, thus lending support to the existence of a critical period for social development in monkeys. Yet many "natural experiments" looking at orphan children who have been deprived of adequate affection and sensitivity from a primary caregiver have found that, if removed from such a socioemotionally impoverished environment and placed in a loving adoptive home, most children are able to recover socially, emotionally, and cognitively. Thus, while early experiences can and do have an impact on later development, children often demonstrate resilience in response to adverse early experiences.

Early Experience

Early experience is the consummate critical period. During the broad social reform of the late 1800s, scientists in the newly evolving field of developmental psychology brought attention to the harmful effects of child industrial labor and validated the importance of a healthy and nurturing environment for promotion of normal development. Throughout the twentieth century, psychologists such as Bowlby, Freud, Erikson, and Sroufe have stressed the profound importance of early socioemotional experiences on later psychological outcomes. In addition, scientists and policymakers have recognized the importance of early intervention programs, such as Head Start, that seek to enrich the cognitive development of socially disadvantaged children. During the late twentieth and early twenty-first centuries, public interest and government policy has advocated even earlier interventions, focusing on zero to three as the most important age range on which to concentrate resources. Yet, as theorists such as John Bruer argue, the importance of the first three years of life has reached "mythical" proportions. According to Bruer, it is important to recognize the cumulative nature of development, emphasizing both early and later experiences in shaping children's growth.

Evidence from researchers such as Baillargeon and Susan Rose has demonstrated that cognitive skills begin to develop very early in life, and that these skills follow rather stable trajectories over time. Such findings suggest that children's developmental course begins to solidify before they enter formal schooling, and even before they utter their first words.

A problem of particular interest is the poor state of literacy in America, and the impact of early experiences on literacy development. The amount of cognitive enrichment, verbal stimulation, and book reading, for example, that children are exposed to at an early age is predictive of later literacy skills. Research conducted by Betty Hart and Todd Risley (1995) found a wide range of variability in young children's vocabulary skills as early as two years of age, and this variability was highly correlated with the number of words spoken by their parents. Socioeconomically disadvantaged toddlers were exposed to a substantially lower number of words per day as compared to toddlers from professional families. It is clear from such research that children's early experiences can lead to striking differences among children from enriching versus impoverished environments. Furthermore, studies have shown that the achievement gap between low- and high-performing children widens once children enter school.

With respect to socioemotional development, psychologists such as Freud, Sroufe, Bowlby, Erikson, and Mary Main have claimed that children's early attachment relationships with their primary caregivers lay the foundation for later social functioning. Researchers have found that securely attached children are more cooperative with their mothers, achieve higher cognitive and academic scores, are more curious, and maintain better relationships with teachers and peers, as compared to insecurely attached children. Taken together, such research affirms the impact of early attachment and socioemotional experiences on later psychosocial and cognitive development.

While early risk factors such as poor attachment and socioeconomic disadvantage can have long-term effects on children's cognitive, academic, social, and emotional development, children do demonstrate varying levels of vulnerability and resilience toward such early conditions. Differences in temperament and coping abilities, for example, can moderate the degree to which a child's early experiences forecast their later developmental outcomes. Furthermore, while there is ample evidence that early experiences have a substantial effect on later cognitive and social outcomes, the real question is whether early experiences are any more important than later experiences. Growing evidence suggests that it is the cumulative effects of both early and later experiences that define an individual's trajectories later in life.

In summary, developmental theory pursues four central themes: (1) the importance of nature versus nurture, (2) stages in development, (3) the existence of critical or sensitive periods, and (4) the impact of early experience. Significant progress has been made over the last thirty years on each of these topics, resulting in a more complex view of human psychological growth and the forces that shape it. With regard to educational practice, modern developmental theory stresses that rigid notions of genetic determinism, stages, critical periods, or the lasting impact of early experience are being replaced by more flexible views that emphasize the malleability of human nature and its potential for change.