Review the theories of language development and the emphasis these place on innate ability and environmental influences upon language development. Then discuss how this may relate to children learning dual languages.
During the first 2 years, body size increases dramaticallyâ€”faster than at any other time after birth. Rather than steady gains, infants and toddlers grow in little spurts. Body fat is laid down quickly in the first 9 months, whereas muscle development is slow and gradual. As with all aspects of development, children vary in body size and muscleâ€“fat makeup. The best way to estimate a childâ€™s physical maturity is by using skeletal age. Two growth patternsâ€”cephalocaudal and proximodistal trendsâ€”describe changes in the childâ€™s body proportions.
At birth, the brain is nearer than any other physical structure to its adult size, and it continues to develop at an astounding pace throughout infancy and toddlerhood. Neurons, or nerve cells, that store and transmit information, develop and form an elaborate communication system in the brain. As neurons form connections, stimulation becomes necessary for their survival. The cerebral cortex is the largest, most complex brain structureâ€”accounting for 85 percent of the brainâ€™s weight, containing the greatest number of neurons and synapses, and responsible for the unique intelligence of our species. At birth, the two hemispheres of the cerebral cortex have already begun to specialize, a process called lateralization. However, the brain is more plastic during the first few years than it will ever be again. Animal research and natural experiments with children who were victims of deprived early environments provide evidence for sensitive periods in brain development. Appropriate stimulation is key to promoting experience-expectant brain growthâ€”the young brainâ€™s rapidly developing organization, which depends on ordinary experiences. Experience-dependent brain growth, in contrast, occurs throughout our lives as a result of specific learning experiences. Rapid brain growth means that the organization of sleep and wakefulness changes substantially between birth and 2 years, but the social environment also plays a role.
Physical growth, like other aspects of development, results from the continuous and complex interplay between genetic and environmental factors. Heredity, nutrition, and emotional well-being all affect early physical growth. Dietary diseases caused by malnutrition affect many children in developing countries. If allowed to continue, body growth and brain development can be permanently stunted. Breastfeeding provides many benefits to infants, especially for those in the developing world where safe, nutritious alternatives are not widely available. Breastfeeding also helps protect against later obesity. Babies who do not receive affection and stimulation may suffer from nonorganic failure to thrive, which has symptoms resembling those of malnutrition but has no physical cause.
Babies come into the world with built-in learning capacities that permit them to profit from experience immediately. Classical and operant conditioning, habituation and recovery, and imitation are all important mechanisms through which infants learn about their physical and social worlds.
Like physical development, motor development follows the cephalocaudal and proximodistal trends. Babiesâ€™ motor achievements have a powerful effect on their social relationships. According to the dynamic systems theory of motor development, each new motor skill is a joint product of central nervous system development, movement capacities of the body, the childâ€™s goals, and environmental supports for the skill. Cultural differences in infant-rearing practices affect the timing of motor development.
Perception changes remarkably over the first year of life. Hearing and vision undergo major advances during the first 2 years as infants organize stimuli into complex patterns, improve their perception of depth and objects, and combine information across sensory modalities. From extensive everyday experience, babies gradually figure out how to use depth cues to detect the danger of falling. According to Eleanor and James Gibsonâ€™s differentiation theory, perceptual development is a matter of detecting invariant features in a constantly changing perceptual world.
According to Piaget, by acting directly on the environment, children move through four stages of cognitive development in which psychological structures, or schemes, achieve a better fit with external reality. The first stage, called the sensorimotor stage, spans the first two years of life and is divided into six substages. In this stage, infants make strides in intentional behavior and understanding of object permanence until, by the end of the second year, they become capable of mental representation, as seen in their sudden solutions to sensorimotor problems, mastery of object permanence, deferred imitation, and make-believe play. Recent research suggests that some infants display certain understandings earlier than Piaget believed, raising questions about the accuracy of his account of sensorimotor development.
Information-processing theorists, using computer-like flowcharts to describe the human cognitive system, focus on many aspects of thinking, from attention, memory, and categorization skills to complex problem solving. With age, infants attend to more aspects of the environment and take information in more rapidly. In the second year, as children become increasingly capable of intentional behavior, attention to novelty declines and sustained attention improves. As infants get older, they remember experiences longer and group stimuli into increasingly complex categories. Also, categorization shifts from a perceptual to conceptual basis. Information processing has contributed greatly to our view of young babies as sophisticated cognitive beings. However, its greatest drawback stems from its central strengthâ€”by analyzing cognition into its components, information processing has had difficulty putting them back together into a broad, comprehensive theory.
Vygotsky believed that complex mental activities have their origins in social interaction. Through joint activities with more mature members of their society, children come to master activities and think in ways that have meaning in their culture.
Infant intelligence tests primarily measure perceptual and motor responses and predict later intelligence poorly. Speed of habituation and recovery to visual stimuli, basic information-processing measures, are better predictors of future performance. Home and child-care environments, as well as early intervention for at-risk infants and toddlers, exert powerful influences on mental development.
As perception and cognition improve during infancy, they pave the way for an extraordinary human achievement: language. The behaviorist perspective regards language development as entirely due to environmental influences, whereas nativism assumes that children are prewired with an innate language acquisition device to master the intricate rules of their language. The interactionist perspective maintains that language development results from interactions between inner capacities and environmental influences.
Babies begin cooing around 2 months, followed by babbling, which gradually reflects the sound and intonation patterns of the childâ€™s language community. First words appear around 12 months, and two-word utterances between 18 and 24 months. However, substantial individual differences exist in the rate and style of early language progress. As toddlers learn words, they may apply them too narrowly (underextension) or too broadly (overextension), in part because their language comprehension develops ahead of their ability to produce language. Adults in many cultures speak to young children using child-directed speech, a simplified form of language that is well-suited to their learning needs. Deaf parents use a similar style of communication when signing to their deaf babies. Conversational give-and-take between adults and toddlers is one of the best predictors of early language development and academic success during the school years.
Although Freudâ€™s psychoanalytic theory is no longer in the mainstream of human development research, his emphasis on the importance of the parentâ€“child relationship was accepted and elaborated on by other theorists, notably Erik Erikson. Erikson believed that the psychological conflict of the first year of life is basic trust versus mistrust, and that a healthy outcome depends on the quality of the parentâ€“child relationship. During toddlerhood, the conflict of autonomy versus shame and doubt is resolved favorably when parents provide appropriate guidance and reasonable choices. If children emerge from the first few years without sufficient trust and autonomy, the seeds are sown for adjustment problems.
All humans and other primates experience basic emotionsâ€”happiness, interest, surprise, fear, anger, sadness, and disgustâ€”that have an evolutionary history of promoting survival. Emotions play powerful roles in organizing social relationships, exploration of the environment, and discovery of the self. Cognitive and motor development, caregiverâ€“infant communication, and cultural factors all affect the development and expression of emotions.
Infantsâ€™ emotional expressions are closely tied to their ability to interpret the emotional cues of others. As toddlers become aware of the self as a separate, unique individual, self-conscious emotionsâ€”guilt, shame, embarrassment, envy, and prideâ€”appear. Toddlers also begin to use emotional self-regulation strategies to manage their emotions. Rapid development of the cerebral cortex, sensitive caregiving, and growth in representation and language contribute to the development of effortful control, which is necessary for self-regulation.
Infants vary widely in temperament, including both reactivity (quickness and intensity of emotional arousal, attention, and motor activity) and self-regulation (strategies for modifying reactivity). Research findings have inspired a growing body of research on temperament, examining its stability, biological roots, and interaction with child-rearing experiences. The goodness-of-fit model explains how temperament and environment can together produce favorable outcomes when child-rearing practices match each childâ€™s temperament while encouraging more adaptive functioning.
Attachment refers to the strong affectionate tie we have with special people in our lives that leads us to feel pleasure when we interact with them and to be comforted by their nearness in times of stress. By the second half of the first year, infants have become attached to familiar people who have responded to their needs. Today, the ethological theory of attachment, which recognizes the infantâ€™s emotional tie to the caregiver as an evolved response that promotes survival, is the most widely accepted view. By the end of the second year, children develop an enduring affectionate tie to the caregiver that serves as an internal working model, a guide for future close relationships. Attachment security is influenced by opportunity for attachment, quality of caregiving, infant characteristics, and family circumstances. Babies form attachments to a variety of familiar people in addition to mothersâ€”fathers, siblings, grandparents, and professional caregivers. Mounting evidence indicates that continuity of caregiving is the crucial factor that determines whether attachment security in early life is linked to later development. Children can recover from an insecure attachment history if caregiving improves.
During the first two years, knowledge of the self as a separate, permanent identity emerges, beginning with self-recognitionâ€”identification of the self as a physically unique being. Self-awareness is associated with the beginnings of empathyâ€”the ability to feel with another person. Self-awareness also contributes to effortful controlâ€”the extent to which children can inhibit impulses, manage negative emotion, and behave in socially acceptable ways. Self-control allows toddlers to become compliant and acquire the ability to delay gratification.