What are developmental stages?

Physical and Psychological Factors

The development of the human being from infant to child to adolescent to adult is a story of increasing physical, cognitive, social, and emotional adequacy in coping with environmental demands. Major observers of human development have added a key corollary concerning the nature and pace of this development: It occurs in stages.

Development in stages implies several features about the process. The first implication is that developmental changes are not simply quantitative but also qualitative, changes not only in degree but also in kind. With advancement to another stage, perceptions, thoughts, motives, and social interactions are fundamentally altered. A second implication is that development is uneven in its pace—sometimes flowing and sometimes ebbing, sometimes fast and sometimes slow and steady in apparent equilibrium. A third implication is that the order of the stages is invariant: one always moves from lower to higher stages. No individual skips stages; each subsequent stage is a necessary antecedent to the more mature or advanced stages to come. The invariant sequence is preordained by the biological maturation of neurological systems and by the necessary requirements of human societies.

Descriptions of development in terms of stages are found in the writings of many psychologists, especially cognitive psychologists, who are interested in age-related changes in thinking styles, and psychoanalytic psychologists, influenced by Sigmund Freud, who concern themselves with changes in the growing child’s emotional involvements. The most significant, influential, and comprehensive of stage descriptions of development are those of two seminal scientists, Jean Piaget
(1896–1980) and Erik Erikson
(1902–94).

Piaget, a cognitive developmental
psychologist, outlined a series of shifts in children’s cognition, their ways of thinking about and interpreting the world. They include the sensorimotor stage in infancy, the preoperational stage beginning in toddlerhood, the intuitive preoperational substage of the preschool child, the concrete operations stage of the school-age child, and the formal operations stage beginning in adolescence.

Erikson, who updated psychoanalytic theory, outlined a series of age-related shifts in motives and ways of relating to others, each one related to a psychosocial
crisis. These psychosocial stages include an infancy stage of trust versus mistrust, a toddlerhood stage of autonomy versus shame and doubt, a preschool childhood stage of initiative versus guilt, a school-age stage of competence versus inferiority, and an adolescent stage of identity versus role diffusion.

The approaches of Piaget and Erikson originated independently, each emphasizing different aspects of development. The stages that they describe, however, should be viewed as complementary. Since the social changes result in large part from shifts in the child’s thinking, the psychosocial stages of Erikson closely parallel the cognitive stages outlined by Piaget.

In infancy, a period lasting from birth to about eighteen months, sensorimotor cognitive development is initiated by rapid brain development. During the first six months of life, the nerve cells in the forebrain that control coordinated movements, refined sensory discriminations, speech, and intellect increase greatly in number and size and develop a rich network of connections. This neural growth makes possible dramatic progress in the child’s ability to discriminate relevant objects and to coordinate precise movements of arms, legs, and fingers in relating to these objects. The infant who was capable of only a few reflexes at birth by six months can grasp a dangling object. The infant who was born with very poor visual acuity by six months can recognize detailed patterns in toys and faces. The infant shows recognition and knowledge of an object by relating to it repeatedly with the same pattern of movements. During the first few months of life, the infant has very limited ability to recall objects when they
are not directly seen or heard and, in fact, will fail to look for a toy when it is not in view. Sensorimotor integrations, therefore, form the infant’s principal method of representing reality. Only gradually does attention span increase and does the infant acquire the capacity to think about missing objects. The capacity to keep out-of-sight objects in mind, the gradual appreciation of object permanence, is a key achievement of the sensorimotor stage.

The corresponding psychosocial stage of infancy is built around the establishment of trust, some sort of sustaining faith in the stability of the world and the security of human relationships. Crucial to the establishing of this trust is the stability of the infant’s relationship with a primary caregiver, most commonly a mother. Babies begin to pay special attention to the caregiver on a schedule determined by their cognitive development. The primary caregiving adult is among the first significant objects identified by the infant. Indeed, it appears that infants are wired to be especially responsive to a human caregiver. Infants of only two or three months of age find the human face the most interesting object and will focus on faces and facelike designs in preference to almost any other stimulus object. By the age of six months, infants clearly recognize the caregiver as special but for some time cannot appreciate that the caregiver continues to exist during absences. Thus, conspicuous anxiety sometimes occurs when the caregiver leaves.

It is little wonder that an infant perceives the caregiver as special. The human caregiver is wonderfully reinforcing to the infant. Relief from all kinds of pain, smiling responses to infantile smiles, vocal responses to infant babbling, soft and warm cuddling contact, and games all offer to the infant what is most craved. By six to nine months of age, the baby seems dependent on the caregiver for a basic feeling of security. Until the age of two or three, most infants seem more secure when their mother or primary caregiver is physically present. The relationship between the quality and warmth of infant-mother interactions and the infant’s feelings of security has been supported by voluminous research on mother-infant attachment.

By about age two, neural and physical developments make possible the advance to more adaptive styles of cognitive interpretations. Piaget characterized the cognitive stage of toddlerhood as preoperational. Brain centers important for language and movement continue to develop rapidly. Now the child can deal cognitively with reality in a new way, by representing out-of-sight and distant objects and events by words, images, and symbols. The child can also imitate the actions of people not present. Thinking during this stage remains limited. The child cannot yet hold several thoughts simultaneously in mind and manipulate them—that is, perform mental operations. This stage is, therefore, “preoperational.”

Erikson described the psychosocial crisis of toddlerhood as autonomy versus shame and doubt. This crisis results in part from the child’s cognitive growth. The preoperational child has acquired an increasing ability to appreciate the temporary nature of a caregiver’s absence and to move about independently. The toddler can now assert autonomy and often does so emphatically. Resistance to parental demands is possible, and the toddler seems to delight in such resistance. “No” becomes a favorite word. Since this period corresponds to the time when children are toilet trained, parent-child tugs-of-war often involve issues of bowel control and cleanliness. The beginning of shame, the humiliation that comes from overextending freedom foolishly and making mistakes, begins to serve as a self-imposed check on this autonomy.

Piaget characterized the thinking of three-, four-, and five-year-olds as “intuitive.” This thinking is still preoperational. Children can represent to themselves all sorts of objects but cannot keep these objects in the focus of attention long enough to classify them or consider how these objects could be regrouped or transformed. If six tin soldiers are stretched into three groups of two, the preschool child assumes that there are now more than before. Thinking is egocentric because children lack the ability to put themselves in the perspective of others while keeping their own perspective. Yet preschool children make all sorts of intuitive attempts to fit remembered events and scenes into underlying plots or themes. Fanciful attempts to understand events often result in misconstruing the nature of things. Children at this stage are easily misled by appearances. A man in a tiger suit could become a tiger; a boy who wears a dress could become a girl and grow up to be a mother. Appearance becomes reality.

Erikson characterized the corresponding psychosocial stage of the preschool child as involving the crisis of initiative versus guilt. The child’s new initiative is expressed in playful exploration of fanciful possibilities. Children can pretend and transform themselves in play as never before and never again. From dramatic play, the child’s conceptions of the many possibilities of the world of bigger people are enacted. The earlier psychoanalyst, Freud, focused particularly on how children experience their first sexual urges at this time of life and sometimes weave into their ruminations fantastic themes of possession of the opposite-sex parent and jealous triumph over the same-sex parent. To Erikson, such themes are merely examples of the many playful fantasies essential to later, more realistic involvements.

Piaget characterized the cognitive stage of the school-age child as the concrete operations stage. The child is capable of mental operations. The school-age child can focus on several incidents, objects, or events simultaneously. Now it is obvious that six tin soldiers sorted into three pairs of two could easily be transformed back into a single group of six. Regardless of grouping, the total quantity is the same. The formerly egocentric child becomes cognitively capable of empathetic role taking, of assuming the perspective of another person while keeping the perspective of the self in mind. In making ethical choices, the child can now appreciate the impact of alternative possibilities on particular people in particular situations. The harshness of absolute dictates is softened by empathetic understanding of others.

Erikson characterized the psychosocial crisis of the school-age child as one of competence versus inferiority. Now is the time for children to acquire the many verbal, computational, and social skills that are required for adequate adulthood. Learning experiences are structured and planned, and performances are evaluated. Newly empathetic children are only too aware of how their skill levels are perceived by others. Adequacy is being assessed. The schoolchild must not only be good but also be good at something.

The cognitive stage of the adolescent was described by Piaget as formal operational. The dramatic physical changes that signal sexual maturity are accompanied by less obvious neural changes, especially a fine tuning of the frontal lobes of the brain, the brain’s organizing, sequencing, executive center. Cognitively, the adolescent becomes capable of dealing with formal operations. Unlike concrete operations, which can be visualized, formal operations include abstract possibilities that are purely hypothetical, abstract strategies useful in ordering a sequence of investigations, and “as if” or “let us suppose” propositions.

Erikson’s corresponding psychosocial crisis of adolescence was that of identity versus role diffusion. The many physical and mental changes and the impending necessity of finding occupational, social, marital, religious, and political roles in the adult world impel a concern with the question, “Who am I?” To interact as an adult, one must know what one likes and loathes, what one values and despises, and what one can do well, poorly, and not at all. Most adolescents succeed in finding themselves—some by adopting the identity of family and parents, some after a soul-searching struggle.

Disorders and Effects

Stage theories define success as advancement through the series of stages to maturity. Psychosocially, each successful advance yields a virtue that makes life endurable: hope, will, purpose, competence, and finally fidelity to one’s own true self. As a final reward for normal developmental success, one can enjoy the benefits of adulthood: intimacy, or the sharing of one’s identity with another, and generativity, or the contribution of one’s own gifts to the benefit of the next generation and to the collective progress of humankind. Cognitively, maturity means the capacity for formal operational thought. Hypothetical thinking of this type is basic to most fields of higher learning, to the sciences, to philosophy, and even to the comprehension of such abstract moral principles as justice.

Advancement to each subsequent stage of cognitive development is dependent on both neurological maturation and a culture that presents appropriate problems. Adults who fail to attain concrete operational thought are considered intellectually disabled. A failure in neurological maturation is a frequent cause. Failures to attain formal operational thought, on the other hand, are not unusual among normal adults. Cultural experience must nourish advancement to formal operational thinking within a domain of inquiry by the provision of moderately novel and challenging but not overwhelming tasks. When people are not confronted with such complex problems within some domain, then abstract, formal operational thought fails to occur. Abstract ethical reasoning is a case in point. Cross-cultural studies suggest that concepts of justice that involve the application of abstract rules are rare in cultures where people seldom confront questions of ethical complexity.

Psychosocial pathology is evidenced by development arrested in one of the immature stages of psychosocial development. It results from a social environment that fails to foster growth or exaggerates the particular apprehensions that are most acute in one of the developmental stages.

The development of trust in infancy requires a loving, available, and sensitive caretaker. If the infant’s caretaker is unavailable, missing, neglectful, or abusive, the pathology of mistrust develops. The world is perceived as unstable. Close personal relationships are viewed as unreliable, fickle, and possibly malicious. Later, closeness in relationships may be rejected. Confident exploration of the possibilities of life may never be attempted.

Similarly, the apprehensions of each subsequent psychosocial stage can be exaggerated to the point of pathology. The toddler, shamed out of troublesome expressions of autonomy, may compensate for doubts with the rigidly excessive controls of the compulsive lifestyle. The preschool child can become so overwhelmed with guilt over playful fantasies, particularly sexual and aggressively tinged fantasies, that adult possibilities become severely restricted. The school-age child can become so wounded by humiliations in a harshly competitive school environment that the child becomes beaten down into enduring feelings of inferiority. An adolescent may so fear the risks of exploring the possibilities of life that future adulthood becomes a shallow diffusion of roles, a yielding to social pressures and whims unguided by any knowledge of who one really is.

The successful confrontation of the tasks of adulthood—finding a partner to share intimacy and caring for the next generation—are most easily attainable for adults who have overcome each of these earlier developmental hurdles.

Perspective and Prospects

Stage theories of development are found as early as 1900 in the work of American psychologist James Mark Baldwin and in Freud’s psychoanalysis. Baldwin, much influenced by Charles Darwin’s theory of evolution by natural selection, hypothesized that the infant emerges from a sensorimotor stage of infancy to a symbolic mode of thinking, an advancement yielding enormous evolutionary advantages. Freud, the Viennese psychoanalyst, based his conception of emotional development on what he called psychosexual stages. Progression occurs from an oral period of infancy, when sensory pleasure is concentrated on the mouth region, to an anal stage of toddlerhood, when anal pleasures and the control of such pleasures become of concern. When sexual pleasure shifts to the genital region in the three-year-old, the love of the opposite-sex parent becomes sexually tinged, and the child becomes jealous of the same-sex parent. Working through these so-called Oedipal fantasies was, to Freud, crucial to the formation of personality.

Neither Baldwin nor Freud and his followers were the sort of rigorous scientists most respected by scientific psychology in the mid-twentieth century. Far more influential in American psychology between 1920 to about 1960 were behavioral conceptions of the developmental process as steady, incremental growth. To behaviorists such as B. F. Skinner, becoming an adult was conceived as a process of continuously being reinforced for learning progressively more adequate responses.

The stage approaches of Piaget and Erikson were introduced to most American psychologists in 1950, the year that both Piaget’s Psychology of Intelligence and Erikson’s Childhood and Society were published in English. Piaget’s description of cognitive stages was much more complete than Baldwin’s earlier account and was much better supported by clever behavioral observations. Erikson’s thesis of psychosocial stages incorporated most of Freud’s observations about stages. Erikson treated the social environmental pressures intrinsic to each stage as events of primary importance and shifts in the locus of bodily pleasures as secondary.

By the 1970s, Piaget’s and Erikson’s accounts of stages were awarded an important place in most developmental texts. This influence occurred for several reasons. First, researchable hypotheses were derived, and most of this research was supportive. Cross-cultural comparisons suggested that these stages could be found in a similar sequence in differing cultures. Second, the theses of Piaget and Erikson were mutually supportive. The stage-related cognitive changes, in fact, would seem to explain the corresponding psychosocial concerns. Finally, these approaches generated productive spinoffs in related theory and research. In 1969, basing his work on the cognitive changes outlined by Piaget, Lawrence Kohlberg elaborated a stage sequence of progressively more adequate methods of moral reasoning. In 1978, basing her work on Erikson’s hypotheses about trust, Mary Ainsworth began a productive research program on the antecedents and consequents of stable and unstable mother-infant attachment styles.

The most recent challenges to cognitive and psychosocial stage theory arise from the alternative perspectives of biopsychology and information-processing theory. Some psychologists argue that biologically rooted temperament, rather than the social environment, affects both styles of attachment and identity formation. Not only do babies respond to caregivers, but caregivers respond to babies as well. A baby who begins with a shy, passive temperament may be more susceptible to an avoidant attachment style and more likely to elicit detached, unresponsive caregiver behavior. Temperament, it is maintained, is more important than psychosocial environment.

Information processing theorists have challenged the discontinuity implied by stage concepts. They suggest that the appearance of global transformations in the structure of thought may be an illusion. Development is a continuous growth of efficiency in processing and problem solving. The growing child combines an expanding number of ideas, increases the level and speed of processing by increments, and learns more effective problem-solving strategies. To select particular points in this continuous development and call them “stages,” they argue, is purely arbitrary.

The final research to settle the question of the ultimate nature of stages has not been performed. A psychosocial stage theorist can acknowledge the role of temperament but still maintain that loving, trust-creating environments are also significant in encouraging the child to apply temperamental potential in positive social directions rather than in angry antagonism or frightened withdrawal. At the very least, Piagetian and Eriksonian stage concepts have the practical usefulness of highlighting significant developmental events and interpersonal reactions to these events. The warmth of caregivers for infants, the later tolerance of children’s struggles to become themselves, and environments that present challenging problems appropriate to the child’s developmental level are vital to emotional and intellectual growth.

For some purposes, it may be instructive to break the achievement of cognitive and emotional growth into increments that can be seen as if under a microscope. For other purposes, it is instructive to go up for an aerial view to gain perspective on the nature and direction of such achievements. The aerial view is the contribution of stage theories of development.

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