Freud’s developmental theory is closely tied to his drive theory, which is best described in his 1905 work, Three Essays on the Theory of Sexuality.¹ In these essays, Freud outlined his theory of childhood sexuality and portrayed child development as a process that unfolds across discreet, universal, stages. He posited that infants are born as polymorphously perverse, meaning that the child has the capacity to experience libidinal pleasure from various areas of the body. Freud’s stages of development were based on the area of the body (oral, anal, or phallic) that is the focus of the child’s libidinal drive during that phase (Table 5-1). According to Freud, healthy adult function requires successful resolution of the core tasks of each developmental stage. Failure to resolve the tasks of a particular stage leads to a specific pattern of neurosis in adult life.

Table 5-1 Corresponding Theoretical Stages of Development

Sigmund Freud: Psychosexual Phases	Erik Erickson: Psychosocial Stages	Jean Piaget: Stages of Cognitive Development
Oral (birth-18 mo)	Trust vs. Mistrust (birth-1 yr)	Sensorimotor (birth-2 yr)
Anal (18 mo-3 yr)	Autonomy vs. Shame and Doubt (1-3 yr)	Preoperational (2-7 yr)
Phallic (3-5 yr)	Initiative vs. Guilt (3-6 yr)	Preoperational (2-7 yr)
Latency (5-12 yr)	Industry vs. Inferiority (6-12 yr)	Concrete operations (7-12 yr)
Genital (12-18 yr)	Identity vs. Role Confusion (12-20 yr)	Formal operations (11 yr-adulthood)

The first stage of development in Freud’s scheme is the oral phase, which begins at birth and continues through approximately 12 to 18 months of age. During this period, the infant’s drives are focused on the mouth, primarily through the pleasurable sensations associated with feeding. During this phase, the infant is wholly dependent on the mother; the infant must learn to trust the mother to meet his or her basic needs. Successful resolution of the oral phase provides a basis for healthy relationships later in life and allows the individual to trust others without excessive dependency. According to Freudian theory, an infant who is orally deprived may become pessimistic, demanding, or overly dependent as an adult.

Around 18 months of age, the oral phase gives way to the anal phase. During this phase, the focus of the child’s libidinal energy shifts to his or her increasing control of bowel function through voluntary control of the anal sphincter. Failure to successfully negotiate the tasks of the anal phase can lead to the anal-retentive character type; affected individuals are overly meticulous, miserly, stubborn, and passive-aggressive, or the anal-expulsive character type, described as reckless and messy.

Around 3 years of age, the child enters into the phallic phase of development, during which the child becomes aware of the genitals and they become the child’s focus of pleasure.² The phallic phase, which was described more fully in Freud’s later work, has been subjected to greater controversy (and revision by psychoanalytic theorists) than the other phases. Freud believed that the penis was the focus of interest by children of both genders during this phase. Boys in the phallic phase demonstrate exhibitionism and masturbatory behavior, whereas girls at this phase recognize that they do not have a phallus and are subject to penis envy.

Late in the phallic phase, Freud believed that the child developed primarily unconscious feelings of love and desire for the parent of the opposite sex, with fantasies of having sole possession of this parent and aggressive fantasies toward the same-sex parent. These feelings are referred to as the Oedipal complex after the figure of Oedipus in Greek mythology, who unknowingly killed his father and married his mother. In boys, Freud posited that guilt about Oedipal fantasies gives rise to castration anxiety, which refers to the fear that the father will retaliate against the child’s hostile impulses by cutting off his penis. The Oedipal complex is resolved when the child manages these conflicting fears and desires through identification with the same-sex parent. As part of this process, the child may seek out same-sex peers. Successful negotiation of the Oedipal complex provides the foundation for secure sexual identity later in life.³

At the end of the phallic phase, around 5 to 6 years of age, Freud believed that the child’s libidinal drives entered a period of relative inactivity that continues until the onset of puberty. This period is referred to as latency. This period of calm between powerful drives allows the child to further develop a sense of mastery and ego-strength, while integrating the sex-role defined in the Oedipal period into this growing sense of self.¹

With the onset of puberty, around 11 to 13 years of age, the child enters the final developmental stage in Freud’s model, called the genital phase, which continues into young adulthood.³ During this phase, powerful libidinal drives resurface, causing a reemergence and reworking of the conflicts experienced in earlier phases. Through this process, the adolescent develops a coherent sense of identity and is able to separate from the parents.

Erik Erikson

Erik H. Erikson (1902-1994) modified the ideas of Freud and formulated his own psychoanalytic theory based on phases of development.⁴ Erikson came to the United States just before World War II; as the first child analyst in Boston. He studied children at play, as well as Harvard students, and he studied a Native American tribe in the American West. Like Freud, he presented his theory in stages; and like Freud, he believed that problems present in adults are largely the result of unresolved conflicts of childhood. However, Erikson’s stages emphasize not the person’s relationship to his or her own sexual urges and instinctual drives, but rather, the relationship between a person’s maturing ego and both the family and the larger social culture in which he or she lives.

Erikson proposed eight developmental stages that cover an individual’s entire life.⁴ Each stage is characterized by a particular challenge, or what he called a “psychosocial crisis.” The resolution of the particular crisis depends on the interaction between an individual’s characteristics and the surrounding environment. When the developmental task at each stage has been completed, the result is a specific ego quality that a person will carry throughout the other stages. (For example, when a baby has managed the initial stage of Trust vs. Mistrust, the resultant ego virtue is Hope.)

Erikson’s stages describe a vital conflict or tension in which the “negative” pole is necessary for growth. For example, in describing the initial stage of Trust vs. Mistrust, Erikson notes that babies interact with their caregivers, and what is important is that the baby comes to find predictability, consistency, and reliability in the caretaker’s actions. In turn, the baby will develop a sense of trust and dependability. However, this does not mean a baby should not experience mistrust; Erikson noted that the infant must experience distrust in order to learn trust discerningly.

It should be noted that Erikson did not believe that a person could be “stuck” at any one stage; in his theory, if we live long enough we must pass through all of the stages. The forces that push a person from stage to stage are biological maturation and social expectations. Erikson believed that success at earlier stages affected the chances of success at later ones. For example, the child who develops a firm sense of trust in his or her caretakers is able to leave them and to explore the environment, in contrast to the child who lacks trust and who is less able to develop a sense of autonomy. But, whatever the outcome of the previous stage, a person will be faced with the tasks of the subsequent stage.

Jean Piaget

Like Erikson, Jean Piaget (1896–1980) was another developmental stage theorist. Piaget was the major architect of cognitive theory, and his ideas provided a comprehensive framework for an understanding of cognitive development. Piaget first began to study how children think while he was working for a laboratory, designing intelligence testing for children. He became interested not in a child answering a question correctly, but rather, when the child’s answer was wrong, why it was wrong.⁵ He concluded that younger children think differently than do older children. Through clinical interviews with children, watching children’s spontaneous activity, and close observations of his own children, he developed a theory that described specific periods of cognitive development.

Piaget maintained that there are four major stages: the sensorimotor intelligence period, the preoperational thought period, the concrete operations period, and the formal operations period (see Table 5-1).⁶ Each period has specific features that enable a child to comprehend certain kinds of knowledge and understanding. Piaget believed that children pass through these stages at different rates, but maintained that they do so in sequence, and in the same order.

Characteristics of the sensorimotor intelligence period (from birth to about 2 years) are that an infant uses senses and motor skills to obtain information and an understanding about the world around him or her. There is no conceptual or reflective thought; an object is “known” in terms of what an infant can “do” to it. A significant cognitive milestone is achieved when the infant learns the concept of object permanence, that is, that an object still exists when is it not in the child’s visual field. By the end of this period a child is aware of self and other, and the child understands that they are but one object among many.

From ages 2 to 6 a child uses preoperational thought, where the child begins to develop symbolic thinking, including language. The use of symbols contributes to the growth of the child’s imagination. A child might use one object to represent another in play, such as a box becoming a racecar. Piaget also described this period as a time when preschoolers are characterized by egocentric thinking. Egocentrism means that the child sees the world from his or her own perspective and has difficulty seeing another person’s point of view. For a child of this age, everyone thinks and feels the same way the child does. The capacity to acknowledge another’s point of view develops gradually during the preschool years; while a 2-year-old will participate in parallel play with a peer, a 4-year-old will engage in cooperative play with another child. Toward the end of this period, a child will begin to understand and to coordinate several points of view.

Just as a child in this stage fails to consider more than one perspective in personal interactions, he or she is unable to consider more than one dimension. In his famous experiment, Piaget demonstrated that a child in a preoperational stage is unable to consider two perceptual dimensions (such as height and width). A child is shown two glasses (I and II), which are filled to the same height with water. The child agrees that the glasses have the same amount of liquid. Next, the child pours the liquid from glass I to another, shorter and wider glass (III) and is asked if the amount of liquid is still the same. The child in the preoperational stage will answer “No,” that there is more water in glass I because the water is at a higher level. By age 7, the child will understand that there is the same amount of liquid in each glass; this is termed conservation of liquids, and it is a concept children master when they are entering the next stage. Children also learn conservation of number, mass, and substance as they mature.

During middle childhood (ages 7 to 11), Piaget described a child’s cognitive style as concrete operational. The child is able to understand and to apply logic and can interpret experiences objectively, instead of intuitively. Children are able to coordinate several perspectives and are able to use concepts, such as conservation, classification (a bead can be both green and plastic, whereas a preoperational child would see the bead as either green or plastic), and seriation (blocks can be arranged in order of largest to smallest).

These “mental actions” enable children to think systematically and with logic; however, their use of logic is limited to mostly that which is tangible.⁶ The final stage of Piaget’s cognitive theory is formal operations, which occurs around age 11 and continues into adulthood. In this stage, the early adolescent and then the adult is able to consider hypothetical and abstract thought, can consider several possibilities or outcomes, and has the capacity to understand concepts as relative rather than absolute. In formal operations, a young adult is able to discern the underlying motivations or principles of something (such as an idea, a theory, or an action) and can apply them to novel situations.

Piaget conceptualized cognitive development as an active process by which children build cognitive structures based on their interactions with their environment. Similarly, he determined that moral development is a developmental process. Piaget described the earliest stages of moral reasoning as based on a strict adherence to rules, duties, and obedience to authority without questioning. Considered in parallel to his stages of cognitive development, the preoperational child sees rules as fixed and absolute, and punishment as automatic. For the child in concrete operations, rules are mutually accepted and fair, and are to be followed to the letter without further consideration; however, as the child moves from egocentrism to perspective-taking he or she begins to see that strict adherence to the rules can be problematic. With formal operations, a child gains the ability to act from a sense of reciprocity, and is able to coordinate his or her perspective with that of others, thus basing what is “right” on solutions that are considered most fair.

Lawrence Kohlberg

Lawrence Kohlberg (1927-1987) elaborated on Piaget’s work on moral reasoning and cognitive development, and identified a stage theory of moral thinking that is based on the idea that cognitive maturation affects reasoning about moral dilemmas. Kohlberg described six stages of moral reasoning, determined by a person’s thought process, rather than the moral conclusions the person reaches.⁷ He presented a person with a moral dilemma and studied the person’s response; the most famous dilemma involved Heinz, a poor man whose wife was dying of cancer. A pharmacist had the only cure, and the drug cost more money than Heinz would ever have.

Heinz went to everyone he knew to borrow the money, but he could only get together about half of what it cost. He told the druggist that his wife was dying and asked him to sell it cheaper or let him pay later. But the druggist said “No.” The husband got desperate and broke into the man’s store to steal the drug for his wife. Should the husband have done that? Why?⁷

How a person responds to such a dilemma places the person within three levels of moral reasoning: preconventional, conventional, and postconventional. A child’s answer would generally be at the first two levels, with a preschooler most likely at level I and an elementary school child at level II. Kohlberg stressed that moral development is dependent on a person’s thought and experience, which is closely related to the person’s cognitive maturation.

Kohlberg is not without his critics, who view his schema as Western, predominantly male, and hierarchical. For example, in many non-Western ethnic groups the good of the family or the well-being of the community takes moral precedence over all other considerations.⁸ Such groups would not score well at Kohlberg’s post-conventional level. Another critic, Carol Gilligan, sees Kohlberg’s stages as biased against women. She believed that Kohlberg did not take into account the gender differences of how men and woman make moral judgments, and as such, his conception of morality leaves out the female voice.⁹ She has viewed female morality as placing a higher value on interpersonal relationships, compassion, and caring for others than on rules and rights. However, despite important differences between how men and women might respond when presented with an ethical dilemma, research has shown that there is not a significant moral divide between the genders.¹⁰

Attachment Theory: John Bowlby and Mary Ainsworth

John Bowlby (1907-1990) was a British psychoanalyst who was interested in the role of early development in determining psychological function later in life. Bowlby particularly focused his attention on the study of attachment, which can be defined as the emotional bond between caregiver and infant. Bowlby’s theory was grounded in his clinical work with families disrupted by World War II and with delinquent children at London’s Child Guidance Clinic. Attachment theory also had its roots in evolutionary biology and studies of animal behavior, such as Harry Harlow’s studies of rhesus monkeys deprived of maternal contact after birth.

Bowlby argued that human infants are born with a powerful, evolutionarily derived drive to connect with the mother.¹¹ Infants exhibit attachment behaviors (such as smiling, sucking, and crying) that facilitate the child’s connection to the mother. The child is predisposed to psychopathology if there are difficulties in forming a secure attachment, for example, in a mother with severe mental illness, or there are disruptions in attachment (such as prolonged separation from the mother). Bowlby described three stages of behavior in children who are separated from their mother for an extended period of time.¹² First, the child will protest by calling or crying out. Then the child exhibits signs of despair, in which he or she appears to give up hope of the mother’s return. Finally, the child enters a state of detachment, appearing to have emotionally separated himself or herself from the mother and initially appearing indifferent to her if she returns.

Mary Ainsworth (1913–1999) studied under Bowlby and expanded on his theory of attachment. She developed a research protocol called the strange situation, in which an infant is left alone with a stranger in a room briefly vacated by the mother.¹³ By closely observing the infant’s behavior during both the separation and the reunion in this protocol, Ainsworth was able to further describe the nature of attachment in young children. Based on her observations, she categorized the attachment relationships in her subjects as secure or insecure. Insecure attachments were further divided into the categories of insecure-avoidant, insecure-resistant, and insecure-disorganized/disoriented. Trained raters can consistently and reliably classify an infant’s attachments into these categories based on specific, objective patterns of behavior. Ainsworth found that approximately 65% of infants in a middle-class sample had secure attachments by 24 months of age.

Research into early attachment and its role in future psychological function is ongoing, and attachment theory continues to have a major influence in the study of child development and psychopathology. It has also influenced how the legal system approaches children, for example, contributing to a shift toward the “best interests of the child” doctrine in determining custody decisions that began in the 1970s.

BRAIN DEVELOPMENT

Normal brain development is the result of a series of orderly events that occur both in utero and after birth. Recent research suggests that the brain continues to develop well into adulthood. In addition, neurodevelopment is affected by the interaction between gene expression and environmental events, which is to say that both nature and nurture play an important role.

The mature human brain is believed to have at least 100 billion cells. Neurons and glial cells derive from the neural plate, and during gestation new neurons are being generated at the rate of about 250,000 per minute.¹⁴ Once they are made, these cells migrate, differentiate, and then establish connections to other neurons. Brain development occurs in stages, and each stage is dependent on the stage that comes before. Any disruption in this process can result in abnormal development, which may or may not have clinical relevance. It is believed that disruptions that occur in the early stages of brain development are linked to more significant pathologyy and those that occur later are associated with less diffuse problems.¹⁵

By around day 20 of gestation, primitive cell layers have organized to form the neural plate, which is a thickened mass comprised primarily of ectoderm. Cells are induced to form neural ectoderm in a complicated series of interactions between them. The neural plate continues to thicken and fold, and by the end of week 3 the neural tube (the basis of the nervous system) has formed (Figure 5-1).¹⁶

Figure 5-1 The embryonic development of the nervous system. The nervous system develops out of the outer layer of embryonic cells, called ectoderm. During the third week of development, the ectoderm along the midline of the embryo’s dorsal surface thickens to form the neural plate (1A). The center of the neural plate indents to form the neural groove. Over the next week, the groove deepens as the neural folds along each side of the neural groove curl toward each other at the midline (1B). By the end of the third week of gestation, the two neural folds have joined together at the midline to form the neural tube, which is the basis of the entire nervous system (1C). Neural crest cells at the dorsum of the neural tube separate to form the basis of the peripheral nervous system.

The neuroepithelial cells that make up the neural tube are the precursors of all central nervous system (CNS) cells, including neurons and glial cells. As the embryo continues to develop, cells of the CNS differentiate, proliferate, and migrate. Differentiation is the process whereby a primitive cell gains specific biochemical and anatomical function. Proliferation is the rapid cellular division (mitosis) that occurs near the inner edge of the neural tube wall (ventricular zone) and is followed by migration of these cells to their “correct” location. As primitive neuroblasts move out toward the external border of the thickening neural tube, this “trip” becomes longer and more complicated. This migration results in six cellular layers of cerebral cortex, and each group of migrating cells must pass through the layers that formed previously (Figure 5-2). It is believed that alterations in this process can result in abnormal neurodevelopment, such as a finding at autopsy of abnormal cortical layering in the brains of some patients with schizophrenia.¹⁷

Figure 5-2 The process of neuronal migration during brain development. Neurons originate from the proliferation of primitive neuroblasts in the ventricular zone. They must then migrate outward toward the brain surface to their ultimate destination in the cortex. Glial cells are thought to assist in the migration process by providing longitudinal fibers to guide the migrating cell.

Once an immature neuron arrives at its final location, it extends a single axon and up to several dendrites to establish connections to other neurons. The synapse, or the end structure of a neuron, makes contact with the dendrites of neighboring neurons. Neuronal growth and proliferation is determined by signals (such as neurotransmitters and growth factors). During subsequent stages of fetal development these connections continue to proliferate, such that at birth, a person has almost all the neurons that individual will use in his or her lifetime.

Postnatal brain development is a period of both continued cellular growth and fine-tuning the established brain circuitry with processes of cellular regression (including apoptosis and pruning).¹⁵ While the human brain continues to grow and to mature into the mid-twenties, the brain at birth weighs approximately 10% of the newborn’s body weight, compared to the adult brain, which is about 2% of body weight. This growth is due to dendritic growth, myelination, and glial cell growth.

Apoptosis, or programmed cell death, is a normal process that improves neuronal efficiency and accuracy by eliminating cells that fail to function properly. This may include extinguishing temporary circuits that were necessary at earlier periods during development, but that are no longer required. This system of first overgrowth and later pruning helps to stabilize synaptic connections and also provides the brain with the opportunity to establish plasticity in response to the environment.

There are “critical periods” of development when the brain requires certain environmental input to develop normally. For example, at age 2 to 3 months there is prominent metabolic activity in the visual and parietal cortex, which corresponds with the development of an infant’s ability to integrate visual-spatial stimuli (such as the ability to follow an object with one’s eyes). If the baby’s visual cortex is not stimulated, this circuitry will not be well established. Synaptic growth continues rapidly during the first year of life, and is followed by pruning of unused connections (a process that ends sometime during puberty).

Myelination of neuronal axons begins at birth, and occurs first in the spinal cord and brainstem and then in the brain. The cerebral cortex is not fully myelinated until young adulthood. Myelin acts to insulate axons and facilitates more efficient information-processing; however, myelin inhibits plasticity because a myelinated axon is less able to change connections in response to a stimulus.

Newer imaging techniques have made it possible to continue to study patterns of brain development into young adulthood. In one longitudinal study of 145 children and adolescents, it was found that there is a second period of synaptogenesis (primarily in the frontal lobe) just before puberty that results in a thickening of gray matter followed by further pruning.¹⁸ Perhaps this is related to the development of executive-function skills noted during adolescence. In another study, researchers found that white matter growth begins at the front of the brain in early childhood and moves caudally, and subsides after puberty. Spurts of growth from ages 6 to 13 were seen in the temporal and parietal lobes and then dropped off sharply, which may correlate with the critical period for language development.¹⁹

Social and emotional experiences help contribute to normal brain development from a young age and continue through adulthood. Environmental input can shape neuronal connections that are responsible for processes (e.g., memory, emotion, and self-awareness).²⁰ The limbic system, hippocampus, and amygdala continue to develop during infancy, childhood, and adolescence. The final part of the brain to mature is the prefrontal cortex, and adulthood is marked by continued refinement of knowledge and learned abilities, as well as by executive function and by abstract thinking.

Infancy (Birth to 18 Months)

Winnicott famously remarked, “There is no such thing as a baby. There is only a mother and a baby.”²¹ In this statement, we are reminded that infants are wholly dependent on their caretakers in meeting their physical and psychological needs. At birth, the infant’s sensory systems are incompletely developed and the motor system is characterized by the dominance of primitive reflexes. Because the cerebellum is not fully formed until 1 year of age, and myelination of peripheral nerves is not complete until after 2 years of age, the newborn infant has little capacity for voluntary, purposeful movement. However, the infant is born with hard-wired mechanisms for survival that are focused on the interaction with the mother. For instance, newborns show a visual preference for faces and will turn preferentially toward familiar or female voices. The rooting reflex, in which the infant turns toward stimulation of the cheek or lips, the sucking reflex, and the coordination of sucking and swallowing allow most neonates to nurse successfully soon after birth. Though nearsighted, a focal length of 8 to 12 inches allows the neonate to gaze at the mother’s face while nursing. This shared gaze between infant and mother is one of the early steps in the process of attachment.

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