Developmental Psychology: Prenatal to Adolescence

Heidi Keller. The International Handbook of Psychology. Editor: Kurt Pawlik & Mark R Rosenzweig. Sage Publications. 2000.

Conceptions of Development

Development constitutes the essence of human life. Folk conceptions and philosophical treatises over the centuries as well as the scientific study of development during the last decades have largely focused on child development, although Charlotte Bühler during the 1920s/1930s in Vienna already represented the view that development comprises the whole life span.

The scientific interest in children and childhood was on the one hand linked to the influence of education in developmental sciences at the turn of the nineteenth century (as an example, the journal Pedagogical Seminary was founded in 1891). On the other hand, childhood was perceived as a state of immaturity which promised to shed light on the origins of psychological processes. Wilhelm Wundt in Leipzig promoted this expectation as well as Karl Bühler in Vienna.

The interest in child psychology found its first expressions in extensive descriptive data collections based on diaries that psychologists, such as the couples Scupin and Stern published about their own children. Controlled observation, mainly administered during longitudinal assessments (the same individuals are observed on several occasions over time), has remained the favorite methodological tool of developmental psychology, despite a short period of experimental child psychology during the 1950s and 1960s. And even the scientific value of diaries has been rediscovered recently. Thus, the scientific study of child development qualifies as expression of the Zeitgeist emphasizing specific topics and tools.

The expertise of psychologists from different cultures has nourished a growing awareness about the cultural conceptions of the child as being part of an indigenous view of human psychology (cf. Doi, 1978; Enriquez, 1993; Nsamenang, 1992; Sinha, 1996). The cultural accounts of developmental processes form a special challenge to developmental theories, since the definition of the life span differs across cultures, thus questioning a consensual understanding of development from birth to death. Mainly rooted in religion, circular views incorporating ancestral states are contrasted with Western linear thinking (Erny, 1968). In Western Cameroon, the prenatal period until the naming ceremony about 7 days after birth when the umbilical cord falls off, forms one developmental stage in which the child is considered as not yet being human, since it still belongs to the spirits; also in Hindu or Buddhist views, life does not end with death, not only due to spiritual continuation, but also due to reincarnation. The different patterning of the life course in different cultures, therefore, underscores the fact that there is not one normative developmental pathway with possible deviations but different, however equally appropriate and adaptive, developmental trajectories.

A Brief Glance at the History of Developmental Theories

Theories of human development and particularly child development, as documented in the psychological literature, mainly refer to Euro-American tableaus of describing, explaining, and predicting planful changes during ontogenesis. Textbook chapters on the history of developmental psychology often refer to the individual achievements of forefathers like G. Stanley Hall (1844-1924), James Mark Baldwin (1861-1934), William Stern (1871-1938), or Arnold Gesell (1880-1961), to name just a few. It is interesting that women, often teaming with their husbands like Clara Stern and Charlotte Bühler, remain largely unnoticed when historical milestones are celebrated.

The main concern of the early develop-mentalists remains today the most compelling question of developmental psychology: the interplay between biology and culture. This discussion is rooted in the dichotomous view on development as expressed in the tabula rasa metaphor on the one hand, that had been developed by English empiricist philosophers such as John Locke attributing development completely to the effect of sensory input, and on the other hand in the nativist view, based on René Descartes’ or Wilhelm Leibnitz’ philosophical accounts stating that specific ideas are inborn and Jean Jacques Rousseau’ treatise on natural growth and maturation.

Hall introduced, among other ideas, the extension of Haeckel’ recapitulation theory beyond embryonic development with the claim that onto-genetic development from birth to adolescence recapitulates the phylogenetic development of the species. As early as 1895, James Mark Baldwin promoted the modern view that the developmental question is not about whether nature or nurture shape ontogenesis, but how they interact. With his segmentation of the life course into phases and stages and the formulation of the principles of assimilation and accommodation, he was most influential in the theorizing of Jean Piaget. William Stern conceptualized the interplay between heredity and environment along the principles of convergence. Individual dispositions converge with environmental factors. According to Stern, the milieu can only exert effects if there are dispositions that are receptive to the particular effects (Stern, 1923), a thought that was later reformulated by Norbert Bischof (1996) as ‘inborn environment.’ Arnold Gesell was especially concerned with growth which he also conceived of as the result of the interplay between inheritance and environment, with a special emphasis on continuity (‘continuous self-conditioning’ Gesell, 1928, p. 57). Beyond his theoretical contributions, special merits are certainly due to his methodological approach of developing observational tools and techniques. Mainly interested in physical maturation, he documented a wealth of careful observations in a special observation room and introduced the frame-by-frame analysis of filmed material, his ‘cinemanalysis.’ Even today observation studios in psychological laboratories all over the world are called ‘Gesell domes.’

The giants in developmental theorizing introducing modern times are without any doubt Jean Piaget (1896-1980) and Lev Semenovich Vygotsky (1896-1934) whose influences are still present, Piaget’ mainly in the cognitive developmental domain and Vygotsky’ mainly with respect to cultural psychology. Piaget is predominantly associated with his invariant sequence of ontogenetic stages of cognitive development (sensorimotor stage, 0-24 months; preoperational stage, 2-4 years; concrete operations, 7-12 years; stage of formal operations, 12-16 years) and the mechanisms constituting developmental progress: assimilation as the adaptation of the environment to the mental concepts of the infant/child and accommodation as the adaptation of the child’ mental concepts to the environment, both aiming at equilibrium. But he himself was rather interested in formulating a theory of genetic epistemology. Thousands of empirical studies have been inspired by his theoretical accounts since the 1960s. Evidence about infants’ early capabilities and competencies, domain-specific learning mechanisms (versus general-purpose models) as well as the cultural shaping of cognitive mechanisms challenge his conceptions. Nevertheless his tremendous oeuvre will remain an especially valuable contribution to developmental theorizing also for the future. Vygotsky whose life span covered only 38 years, introduced a different Zeitgeist when he founded his theoretical approach on Marxist ideology. According to him, the child constructs the mind through social experiences. Especially his conception of the ‘zone of proximal development’ (the distance between the actual and the potential level of development which can be reached with the help of expert partners) has stimulated developmental research tremendously. He formulated, partly together with Aleksander Romanovich Luria, the history of human development as moving to successive transitional points where development becomes directed into new channels by achieving new levels of functioning. In particular the cultural psychology school relies much on Vygotsky’ formulations with a present new shift of attention after the recent political changes in Eastern European societies.

This treatment of theoretical viewpoints is cursory and selective, highlighting significant contributions for the understanding of the main conceptual issues relating to children’ development. For further conceptions of development, especially relating to a life span view, the reader is referred to the introductory section of Chapter 15.

Evolutionary Psychology: A Modern View about Development

The prevalent eclectic theoretical orientations that form the background of contemporary empirical research to a large extent combine fragments from different origins with respect to different developmental domains. We promote the theoretical approach of evolutionary or Darwinian psychology in this chapter, representing a biologically based, however explicitly contextually-culturally shaped account of human behavior and development. The evolutionary perspective has the capacity to analyze developmental processes from an encompassing, yet detailed theoretical framework, even with the claim for a unitary theory. Yet, the reception of evolutionary theorizing has not been unequivocally positive. On the contrary, it seems to challenge metaperspectives on the human nature, thus provoking skeptical and even hostile reactions. Nevertheless, its acceptance is increasing, especially due to its capacity to provide answers for the central developmental concerns:

  • The interplay between culture and biology,
  • The question of continuity and plasticity, and
  • The sequence of developmental tasks.

Evolutionary theorizing starts on the assumption that humans as well as other species aim at replicating their genes. The life history represents a holistic strategy for the optimal achievement of this ultimate goal. Although the individual acts as a ‘carrier of genes’ (Hamilton, 1964), social behavior and psychological functioning have evolved as important tools which enable the individual to pursue these ‘interests,’ implicitly as well as explicitly, effectively. Psychological development is contingent upon environmental conditions, defining adaptation as a context dependent specialization. In order to be able to react flexibly to environmental demands, individuals are considered to be equipped with open genetic programs (Mayr, 1974; for gene—environment interaction see Chapter 15), mainly consisting of devices for the easy learning of specific environmental information at particular times during ontogeny. This view supports the evidence of critical periods in a non-deterministic way. Central tendencies canalize the content and timing of learning. The human capacity for lifelong learning, often named plasticity, thus does not imply randomness or infinite possibilities as sometimes claimed by lifespan psychologists.

In evolutionary terms individual life histories can be described as—mostly implicit and non-conscious—trade-offs between different components of fitness,1 mainly survival and growth (requiring somatic effort) and reproduction (requiring reproductive effort), consisting of mating effort and parental investment. Accordingly, the duration of phases or stages during the life cycle differs with different contexts. This framework therefore allows to capture cross-cultural differences in the patterning of life cycles in terms of contextual adaptations as well as interindividual differences. It is assumed that culture, and hence also norms and value systems, evolved during phylogeny in order to facilitate the functioning of social groups which had to increase the number of members beyond genetic relatives for better exploitation of resources and more effective defense against predators. Also cultural patterns, thus, are considered as following the reproductive logic of fitness optimizing. This argument does not claim, however, that every single behavior or any cultural achievement has an adaptational function.

Evolutionary developmentalists have proposed socialization models which identify developmental trajectories contingent upon the childhood context. The availability and abundance of resources is associated with a special way of caring for the offspring (parenting effort) which then leads to particular qualities of the infant—parent relationship which have somatic consequences in terms of timing of puberty. Reproductive styles can consequently be more quantitatively oriented (low resources, low parental investment, insecure child—parent attachment, early onset of puberty, early age at first childbirth, many offspring, close spacing of children, low parental investment towards own offspring), or more qualitatively oriented (abundant resources, high parental investment, secure infant—parent attachment, later onset of puberty, later age at first childbirth, fewer offspring, high parental investment in one’ own offspring), thus supporting intergenerational continuity.

Since individuals have to solve their developmental tasks by partitioning the different fitness components across the life span, life trajectories are supposed to form coherent responses to environmental demands, thus expressing structural continuity. Evolutionary thinking can be viewed as extending the classical culture and personality school, especially the approach by Beatrice and John Whiting. These scholars assigned a crucial role to the context or ecology for shaping the economy and social structure of a society which then influences child-rearing practices and childhood experiences. These form a special blueprint for later personality development.

During the 1950s, the Whitings set up a comparative research design in six different cultural contexts (Orchard Town in New England, Juxtlahuaca in Mexico, Tarong in the Philippines, Taira in Japan, Khalapur in India, and Nyansongo in Kenya), that was aimed at demonstrating empirically this interplay of ecology, culture, and psychology. This study program will be taken into consideration at different places in the course of this chapter.

Evolutionary theorizing is different from psychological developmental theories in several important ways. Adult functioning is not conceived of as the developmental goal, but the whole life span, especially the pattern of developmental phases is an evolutionary end product. Predictions from evolutionary theorizing are not restricted to specific developmental domains, but cover the whole array of psychological functioning and allow one to address interindividual, differential and cross-cultural differentiation at the same time. Evolutionary assumptions can be tested also in modern industrialized societies, although even some evolutionary theorists (cf. Tooby & Cosmides, 1992) express their concerns about the applicability to modern men. Finally, evolutionary assumptions allow one to test prospectively proximate functioning, thus being open for support as well as rejection of specific hypotheses. In any case, evolutionary theorizing adds a new dimension to the understanding of development by asking: Why and how could this behavior and development possibly contribute to the fitness of this particular person?

Beginnings

The Prenatal Period

Although the beginning of life is functionally defined when the mother’ and father’ germ cells join, the understanding of the onset of life is nevertheless largely culturally determined. As we have already argued, the cultural view might postpone the beginning of (social) life even after actual birth. In Western societies on the other hand, there has been a heated discussion about the prenatal actual beginning of life before birth in the context of abortion laws. From a biological perspective, any human being begins life as a zygote with a diameter of 0.14 mm and with a weight of a fifteen-millionth of a gram. Remarkable quantitative and qualitative changes occur during the 9 months of pregnancy, preparing the fetus for extra-uterine life. Pregnancy can be divided into three different periods. The germinal periodcovers the time from conception to implantation about 8-10 days later. The embryonic period lasts for about 6 weeks from the attachment of the blastocyst to the uterus until the end of the eighth week when the major organs are shaped. At the end of this period, the organism begins to react to direct stimulation that the mother will not notice until the end of the fourth month due to the tinyness of the embryo. The developmental sequence of the embryo is followed by the cephalocaudal (from head to feet) and the proximodistal pattern (from the inner part to the periphery). The fetal period covers the time from 9 weeks after conception until birth. The fetal period prepares the organism for extra-uterine life in terms of recept-ability of stimulation and refining patterns of motor activity, although the newborn is extremely altricial, that is, physiologically premature caused by the limitation of the birth canal with respect to brain size. The fetal period is characterized by a high level of motor activity occurring spontaneously as well as in response to stimulation. At about 17 weeks, the activity rate declines due to brain development which allows for more inhibitory control, resuming by the end of the sixth month. Fetal activity seems to be crucial for normal limb development. During the last 4-5 months of pregnancy, infants respond with heart rate changes to light penetrating the mother’ womb and to sounds. And it seems to be evident that they recognize after birth what they have been exposed to regularly during the last two or three months of pregnancy. Experiments with mothers reading text passages regularly several times a day for 3 months or playing the same music again and again have supported the assumption of fetal learning. The uterine environment and, thus, the mother’ physiology and psychology affect the fetus in various ways by chemical messages through the wall of her abdomen, the placenta, and the umbilical cord. Physical cues are transmitted by the mother’ activity rate and patterns of movement.

Supportive as well as detrimental influences can be specified. Supportive factors which facilitate the transition to parenthood are constituted by a good health condition and an acceptant and relaxed psychology of the expectant mother. In particular paternal and family support reduce maternal stress and increase the readiness for allocating investment to the expected child. On the other hand, father’ absence has detrimental effects on infant and child mortality as demonstrated by the South American Ache people (Hill & Hurtado, 1991).

The regular experience of a substantial degree of the stress secretions adrenaline and cortisone has sizable effects on the fetus’ motor activity in terms of irritability and hyperactivity with an increasing probability for miscarriage or premature delivery and developmental disturbances after birth, such as disorders of eating, sleeping, and elimination. In large parts of the world, extreme malnutrition is the major threat of maternal and infants’ lives. Several studies have demonstrated that in times of famine spontaneous abortions, stillbirths, and death at birth increase remarkably. Also less serious conditions like malnourishment, usually associated with low economic security and unstable living arrangements, have consequences with respect to birth defects, premature birth, or small-for-date babies. On the other hand, intervention programs have demonstrated that with food supplement in impoverished areas, health status conditions and also intellectual development can be substantially improved. Since measles immunization reaches about 80% of the Western as well as the non-Western world, this disease has more or less disappeared as a major teratogenetic factor. However, a new threat for children’ lives has appeared since the 1980s with the AIDS virus. Although more than 6,000 pregnancies in the USA are affected by AIDS, it is a much bigger problem in some African or Asian societies. About 50% of the babies of HIV positive mothers become affected by the virus passing through the placental barrier or by exposure to mother’ blood during delivery. The problems increase further when the mothers, or, in two-parent families, even both parents die early, leaving their children orphaned. The Zambian government runs programs addressing especially the situation of these children.

Drugs such as medication, coffee, alcohol, nicotine, cocaine, and heroine are again more Western-biased dangers to children’ and of course mothers’ health. Smoking is one of the few known factors associated (though not causally linked) to the Sudden Infant Death Syndrome (SIDS)—the unexpected death of otherwise healthy babies, especially during the first 6 months of life. Serious alcohol consumption during pregnancy is significantly associated with the fetal alcohol syndrome (FAS), including an abnormal small head with an underdeveloped brain, eye abnormalities, congenital heart disease, and facial malformations. Mental retardation can occur even if the full FAS is not seen.

Generally the teratogenic effects are most disastrous if damage occurs during the first weeks of pregnancy. If individual organs have already developed, their susceptibility to detrimental effects is highest during their initial growth period. The effects are interindividually variable. Not all infants exposed to a specific substance at a specific time develop the same consequences. General genetic, health, and contextual factors of mothers and babies individualize the effects.

Birth and the Newborns’ Condition

The fact of birth is a memorable event with special rites and ceremonies all over the world. In industrialized cultures, hospital birth is the rule with medical technology determining the experiences to a large extent. Delivery is often a painful experience so that many modern mothers decide to take anesthetics, especially peridural anesthesia which affect ‘only’ the lower part of the body. In cases where labor is difficult and especially painful or the baby is not in the headfirst position, the baby is delivered by Cesarean section. During the last decades, the practice of Cesarean section has come under serious criticism, since it obviously increased disproportionally in frequency in some hospitals on Fridays. On the other hand, medical intervention saves the lives of thousands of infants and mothers.

At the beginning of the normal birth process, infants produce adrenaline which facilitates the absorption of the liquid from the lungs and, thus, breathing and increases the blood flow. The pressure through the birth canal provides the infant with tactile and vestibular experiences which are supposed to influence the regulation of behavioral states like sleep, wakefulness, or fussiness. Any medication affects the attentional system of the infant and thereby bonding and attachment processes. During the process of delivery, infants may experience oxygen deficits which can be very harmful for brain development. The American anesthesiologist Virginia Apgar developed in 1953 a quick screening technique of the neurological condition of the infant which continues to be used worldwide. The Apgar Test consists of a rating (0, 1, 2) of five vital signals (heart rate, respiratory effort, muscle tone, reflex responsivity, and color). The test is administered 1, 5, and 10 minutes after birth. The optimal score is 10. A score of 4 or below necessitates immediate medical intervention.

Studies conducted in the 1970s documented that early relationship formation, especially on the part of the mother (bonding), might be facilitated by extended contact between mother and newborn. Although these results could not be replicated satisfactorily, they had beneficial societal consequences in changing the usual hospital routines. Rooming-in (the infant stays in the mother’ room for the day or even over night) was introduced and appreciated especially by first-time mothers. Also fathers’ attendance at delivery was supported. The presence of fathers, however, is not popular or even taboo in many non-Western cultures where the delivering woman is surrounded by other women of her kin or village supporting and guiding her. There are also cultures where the expectant mother gives birth without the assistance of anybody else. An expectant Eipo mother in Papua New Guinea who feels that she is close to delivery separates from her community. She gives birth in a kneeling position which is popular across different cultures and evaluated by gynecologists as the physiologically most appropriate way to deliver. She might even decide about the life of the newborn during the first minutes, since resources for subsistence in the small valleys are restricted.

One of the major risks which threatens a more or less normal pregnancy concerns preterm birth at a gestational age (from conception to birth) less than 37 weeks and low birth weight less than 2,500 grams, possibly based on fetal growth retardation. Ten percent of all births in the USA are preterm with the special risks of immature lungs, digestive and immune systems. Besides teratogenic factors, especially living in poverty contexts and reproductive patterns associated with these risk factors, like very young age at first birth, poor health of the mother, and close spacing of children, define the reality of large, mainly rural populations of non-Western societies. In India, the prevalence of low birth weight babies according to the above definition ranged between 26-57% in urban slums and 35-41% in rural communities, according to national statistics of 1987-1988 compiled by UNICEF. A 1993-1994 survey of the Deepak Charitable Trust in a rural area of the state of Gujarat reports 38% of low birth weight babies.

Low birth weight increases the risk of neurological deficiencies, impairment of growth potential and decrease in intellectual capacities. Prematurity can be compensated during the course of the following development, especially when the family context is affluent and supportive.

The Equipment of the Newborn

The normal full-term baby enters the world well prepared for the first developmental tasks to master. Crucial for survival and development is a special caregiving environment. Therefore infants ought to be able to attract and maintain the attention of their caregivers. The special combination of facial features like a large head in relation to the body, a round face, relatively large eyes, and a prominent forehead constitute the ‘Kindchenschema’ (babyness) that Konrad Lorenz (1969) had identified to attract attention and elicit caregiving responses also in other species than humans. Commercial industry is taking advantage of this stimulus pattern in distinct ways and also comic heroes are designed accordingly. However, not all infants are equally attractive and also human parents make a difference. Mothers of less attractive newborn girls were more attuned to other people than mothers of attractive girls (Langlois, Ritter, Casey, & Sawin, 1995). This differential treatment albeit often denied from a moral perspective, is in line with evolutionary considerations about preferred allocation of investment to the offspring who promises greatest reproductive value. Attractiveness, especially in terms of body and facial symmetry, constitutes certainly a powerful evolutionary tool. Interestingly one of the aims of Indian baby massage is to enhance symmetry. Also the sad, but still numerous cases of neglect, abuse, and infanticide mainly follow an implicit evolutionary logic: they are more frequent in step-families (which include about 80-90% of step-fathers), in low economic circumstances, young parents (mothers less than 20 years) and directed more to disabled or malformed infants during the first six months of their lives (Daly & Wilson, 1988).

The resemblance that a baby has with the mother and especially the father is a further significant denominator of the newborn. Due to paternal insecurity, mothers of newborns like to assure the resemblance of the baby with the paternal line in order to secure the future paternal investment. Resemblance checks decrease with increasing age of the baby. Also the sex of the baby and the ordinal position are biological marker variables with a tremendous impact on developmental trajectories.

Any normal full-term infant is equipped with a set of functioning senses and the capacity and motivation to attend to the environment and to learn. Research activities since the 1950s have accumulated convincing evidence about infants’ preparedness for active participation in development and have terminated a view of infancy as being the era of the ‘buzzing blooming confusion’ that William James had assumed, or as being the reflex creature without cortex that William Stern had in mind. The slogan of the ‘competent infant’ appeared, who can see and hear at birth and before, who is receptive to touch, responds to movement, can differentiate between different tastes and smells, and has functioning thermoreceptors. The pieces of information from different sensory systems can be interrelated. Newborns usually try to locate a noise with orienting movements of the eyes and the head. Newborns are able to direct their attention selectively to environmental cues, especially movement, contour, and contrast. They prefer novel, but not too discrepant information over familiar, and complex, but not too complex information over simple. With their short memory span of about 1 second, they detect contingencies between external events as well as person-based contingencies. They develop expectations about the occurrence of events. Another special capacity of newborns consists in the ability to segment spoken language into linguistic units (phonemes); the ability to process any spoken language becomes restricted to the mother tongue after a few weeks. Nevertheless, other research has shown that children can acquire a second language with native facility if they start the second language by age 7. Recent research has furthermore indicated that newborns have a rudimentary knowledge of biological and physical concepts.

Newborns’ Behavioral States

Newborns’ behavior is patterned into psycho-physiological states. Extensive long-term observations of newborns by ethologically oriented scholars like Peter Wolff in the 1960s have painted a differentiated picture of different levels of arousal and activity associated with distinct modes of brain activity. Newborn babies all over the world spend most of their time, about 16 from 24 hours, asleep, yet in two different sleeping states. Quiet sleep is characterized by low muscle tone and motor activity and regular breathing. REM sleep is characterized by Rapid Eye Movements with a higher muscle tone and more motor activity, like startles, facial grimaces, and irregular breathing. New-borns begin their sleep cycle with REM sleep, lasting for about 20 minutes, then to fall into quiet sleep for about the same time span. After two to three months, this pattern reverses in industrial countries, indicating a major shift to diurnal regulation and, thus, adult sleeping patterns. Babies in other parts of the world, however, continue to wake up several times during the night and nurse. This is related to sleeping arrangements which follow different cultural scripts. Infants in the Western world are trained very early to sleep alone in their own cot or bed and even room, thus expressing an early emphasis on the development of independence. Members of cultures with permanent contact between infant and caregiver stressing relatedness more than independence, favor co-sleeping arrangements. As John Whiting reviewed in the 1960s, mothers slept with their infants in 2/3 of the societies that he had assessed. But also the co-sleeping practices can vary tremendously. In urban slum areas in India, the whole family sleeps on the floor in the only room of the house. If there is a bed available, the father will sleep on it, possibly also his brother, if he lives with the family. In West Cameroonian Nso farmers, the mother sleeps in her bed, the children behind her, the youngest one closest to her. The mother faces the door in order to protect her children from bad spirits which might wish to harm the baby or take it back. The father sleeps alone in his own house or room.

Also waking time is differentiated into two states according to arousal and activity level. Alert inactivity is a state of concentrated attentiveness to the environment with only low motor activity. Babies in the state of alert inactivity are most interested in social interactions. Active wakefulness describes increased motor activity which might lead to irritability and distraction. Two transitory states between waking and sleeping can be observed. One can be described as drowsiness with low motor activity and eyes glazed; the other can be categorized as fussiness with high motor irritability, often leading to crying. It is interesting that in the Western literature crying is described as a behavioral state. This is due to the extended duration of crying in Western babies as compared with infants who are carried a good portion of the day. !Kung San babies have the same crying frequencies as American babies, similar cry curves over the day with an evening peak and a similar cry curve over the first months with a peak at about 2 months of age. However, their cry durations are significantly shorter than that of American babies.

There are tremendous interindividual differences within all of these areas. Infants differ with respect to their activity levels, having different needs concerning the amount of sleep which often diverge from their parents’ needs and expectations, they differ in their amounts of crying, their attention spans vary, the learning rates are different, the transitions between the states are more or less smooth. These inter-individual differences are mainly captured by two integrative concepts in the literature: temperament and emotional regulation.

The Study of Temperament and Emotional Regulation

The vast interest in the study of temperament in infants and small children that arouse, astonishingly without any reference to the older European temperament research in personality, can be traced back mainly to the New York longitudinal study conducted by Alexander Thomas and Stella Chess in the late 1950s. With questionnaire data that the two pediatricians collected from parents of a broad socioeconomic and ethnic variety, they tried to identify the stylistic components of behavior, with respect to nine behavioral traits which were then combined into three types:

  • Easy babies who made up about 40% of the sample with regular rhythms, neutral to positive mood, and adaptable to new situations;
  • Difficult babies who were mainly irregular in their rhythms and had difficulties to adapt to new situations with a negative mood made up 20%;
  • Slow to warm-up babies covering another 15% of the sample needed more time to adapt to new situations than easy babies with a tendency to withdraw, but in a mild style with neutral mood.

The field expanded with different scholars defining a wide variety of temperamental dimensions, like sociability, emotionality, reactivity, self-regulation. These temperament researchers basically assume that temperamental differences are correlated with physiological parameters and that temperament is genetically based and stable from the beginning. Twin studies comparing monozygotic twins sharing 100% of alleles with dizygotic twins or siblings (sharing 50% of alleles), have been conducted in order to estimate similarities and differences in behavior with respect to the genetic influence. A second method assesses the correlation between genetically related and adopted siblings with respect to the exhibition of particular behaviors. Empirical evidence clearly demonstrates that genetic influence cannot be demonstrated shortly after birth. This might possibly be due to the birth experience or the strong effect of biorhythms on the behavior. From 4 months on, temperamental differences seem to be stable and from 6 months on, the genetic influence on temperamental dimensions is relatively visible (40-60%). However, similar estimations are reported also for intelligence and other personality traits like aggressiveness, implying that temperament is not more genetically based than other personality traits. Thus, the question remains open what differentiates temperament from inter-individual differences in behavior in general or personality in particular.

Shared environmental influences like the impact of parental education or socioeconomic circumstances do not influence temperamental traits. Non-shared environmental influences like pre- and perinatal conditions, differential parental treatment associated with sex or sibling position on the other hand, exert substantial influences on temperamental traits, also validating again evolutionary assumptions about the effects of differential parental investment. There are interesting ethnic differences: cross-cultural researchers have reported differences in activity level between Caucasian and non-Caucasian babies; Chinese-American and Mayan babies seem to be more placid and less active as compared with Euro-American babies. Patricia Greenfield and Carla Childs (1991) have integrated slow movement patterns of Zinancantec Indian babies which might be genetically rooted into a cultural contextual perspective when they report that slow movements are cultural highly valued in this community and shape the developmental context from intrauterine experiences until mate preferences.

Recently—maybe due to the conceptual and methodological problems associated with the study of temperament—emotional reactivity and regulation is regarded as a specific area of research. Based on discrete emotion theory, it is assumed that infants are equipped with basic emotions at birth, like joy, fear, anger, disgust, and distress. These emotions communicate the mood and viability of the infant and regulate approach and avoidance behaviors towards familiar and unfamiliar persons and objects. In particular the dynamic aspects of emotion, like arous-ability and intensity are related to the physiological underpinnings. Also vagal tone and the release of cortisol have been associated with the internal regulation of novelty and stress. There is, however, no one-to-one equivalence of physiological and behavioral manifestations of emotions, thus stressing the view that emotional experience is regulated in different functional systems. This differentiation allows the baby to learn the expression of emotions according to cultural scripts as well as the possibly adaptive strategy of deception concerning emotions in specific social contexts.

Relationship Formation as the First Integrative Developmental Task

The Cultural Formation of a Primary Social Matrix

Psychological development synthesizes a biologically based, yet culturally shaped conception of the self. Crucial for this integrative achievement is the acquisition of a social identity, based on social relationships. Accordingly, the development of primary relationships, the construction of a social matrix, is an early universal developmental task across cultures. However, the social contexts and the cultural scripts differ.

The seminal contributions of John Bowlby and Mary Ainsworth since the late 1960s have alerted researchers to the importance of developing attachment towards the primary caregivers, especially the mother, as a phylogenetically evolved behavioral system. The formation of a specific attachment quality at the end of the first year is assumed to be based on preceding interactional experiences, mainly maternal sensitivity as the prompt, consistent, and adequate response to infants’ cues, especially distress, and organizes the consequent social and cognitive behavioral development. Three attachment qualities were identified in Mary Ainsworth’ original Baltimore sample of 105 children: secure attachment (B-attachment) comprises about 70% of the sample and is mainly defined as proximity seeking after distress; insecure avoidant attachment (A-attachment) with 20% of the sample consists mainly in contact avoiding after distress; insecure ambivalent attachment (C-attachment) with 10% of the sample consists of proximity seeking as well as avoiding behaviors after distress. A fourth type was later added by Mary Main as a disorganized (D) pattern of attachment consisting mainly of unpredictable and inappropriate, but intensive behaviors like stereotypical movements or freezing of movements. The attachment quality is supposed to be translated during the next two years into an internal working model which comprises representations of the self, the caregiving persons and the relationships. Mary Ainsworth developed a laboratory assessment procedure, the Strange Situation Test, in order to assess the quality of attachment. During a field study in Ganda, she had observed that Ganda babies became distressed and upset when their mothers left the room in the family’ home. Since American East-Coast babies were not especially irritated when their mothers left the room, she set up a standard procedure of separations, stranger contact, and reunion episodes in a laboratory in order to increase the stress on the baby so that the attachment system becomes activated. The procedure itself, which had been originally invented as a cultural adaptation, i.e. increasing stress in US-American babies, soon became a standardized tool, also used for cross-cultural comparisons, thus ignoring the idea that attachment as well as its expression might vary across cultures.

Cross-cultural studies of infants’ social experiences as well as microanalytical observations of early interactional exchanges allow one to describe the early interactional patterns more precisely than the rating-based evaluations of attachment researchers. Humans display a universal repertoire of infant-oriented behavior supporting and maintaining preverbal dialogues. They create the frame for eye contact with continuous looking, they imitate smiles and vocalizations and they talk to infants with a special language register—baby talk or motherese—which has been observed in very different languages like Mandarin Chinese or German, consisting of a high pitch, simple structure, and prosodic contours. During the first weeks of infants’ lives, these behavioral competencies are practiced until they culminate around the third month of life with extended periods of mutual eye contact framing an intensive interactional exchange of mimical and vocal/verbal behaviors. During this time, interindividual differences also become most pronounced. After the three months’ period infants’ interest in eye contact declines, although parents continue monitoring their infants’ view until the end of the first year. Interindividual differences in infants’ amount of eye contact, especially during the three months focal time period, and the developmental course over the first year have been demonstrated to be dependent upon mainly two characteristics of caregivers’ behavior which seem to be independent of each other: contingency and warmth. Contingency represents the promptness of the parental response towards the infant’ interactional signals. A substantial amount of parental reactions occurs within a second, thus, stressing the intuitive nature of parenting. This time window is within infants’ memory capacity and allows the perception of causality with a sense of self as a causal agent as a consequence. Warmth conveys positive emotionality and attunement to the baby and is mainly embedded in emotional sharing and close bodily proximity. Parental warmth lays ground for the acquisition of conceptions of belongingness and interrelatedness (Keller, Lohaus, Völker, Cappenberg, & Chasiotis, 1999). The differential patterns of interactional exchange around the third month of life allows the assessment of interactional quality much earlier than attachment theory has proposed with the end of the first year.

The interactional patterns that have been described so far are mainly based in facial exchange and characteristic for Western-biased care arrangements. There are, however, other parental care systems prevalent during the early months that can be identified across different cultures which are equally part of the phylo-genetic inheritance. The first and most basic parenting system is constituted by primary care. Although being part of any caregiving surrounding, it might constitute the sole system of parenting, especially in poverty contexts where infant mortality is high and therefore individual bonds of the mother to her children are usually not very intensive. Leigh Minturn and William Lambert have described a pattern of nursing in response to crying as the only maternal attention towards infants in the context of the Six Culture Study initiated by Beatrice and John Whiting for Indian Rajput villagers. Marten de Vries, having observed Masai babies, makes the interesting statement that infants that were fussy and of difficult temperament could more easily survive a year of extreme famine than infants that had been classified as of easy temperament. The fussier babies could alert their mothers’ attention more than the easier babies and received more nursing.

A second parenting system which affords a higher parental investment consists of the body contact system (‘back and hip cultures’ according to John Whiting who sees their prevalence in the warm regions of the world). Body contact implies close proximity and thus warmth as a major socialization medium. Continuous infant carrying is reported from many different parts of the world, such as Africa, Papua New Guinea, Indonesia, South America, with foraging people or wandering pastoral groups demonstrating the highest amounts of infant carrying. Parenting effort in terms of the body contact system allows the mother to care for her baby and continue at the same time with her subsistence activities and daily chores. Child care becomes a co-occurring activity with the child never being alone, but at the same time never being the center of attention.

The third system of parenting is constituted by body stimulation as an exclusive dyadic activity. Body stimulation provides the infants with extensive motor experiences which foster the early development of a body self. This parenting system can be identified, for example, in African societies where babies are held and rocked in an upright position. The Indian custom of baby massage constitutes another example of body stimulation.

The fourth caregiving system consists of face-to-face interactions which are prevalent in the Western industrialized world and in the middle and upper middle classes of non-Western societies. The display of face-to-face interaction, including verbal/vocal exchange, as a socialization context is obviously related to the caregiver’ experience of formal schooling (Greenfield & Cocking, 1994), especially language-based social interactions and instructions. Caregiving contexts with extended face-to-face exchange usually do not have extended body contact contexts. US-American babies are carried only half as often as Gusii babies. In fact, carrying and body contact mainly constitute reactions towards distress in Western contexts. Face-to-face exchange requires an exclusive focus of attention from the caregiver towards the infant and therefore represents a costly investment strategy.

The most prominent mode of caregiving all over the world, however, consists of varying composites of these different systems which accentuate different caregiving behaviors differently and, thus, provide infants with diverging experiences in the process of developing a sense of self (Keller, in press).

Although the mother is the primary caretaker in virtually all cultures, there are nevertheless substantial differences with respect to the definition of family and accordingly the composition of the social environment for the infant. In the Western world, the mother spends more than 90% of the waking time with the infant and is usually the only one to address all the infant’ needs. In an extended or joint household as in Africa or India, mothers usually attend to distress, whereas social play and physical exercises might be mainly performed by grandmothers or siblings forming multiple caretaking arrangements. Child care can also be understood as the obligation of a whole village when family literally means the place where the fire burns, as in rural parts of the Ivory Coast. In particular the role of fathers has received a lot of attention in the 1970s and 1980s in the literature. Although the factual involvement with infants might be usually small, covering not much more than presence during about an hour of infants’ waking time in Western studies, with a few known exceptions of high paternal involvement like the Aka Pygmies in Central Africa, the indirect effects of father’ presence and support are significant as the detrimental effects of father’ absence, especially for small children, e.g. in the South American Ache, have revealed. The early relational experiences form the starting points for different developmental trajectories or pathways across the lifespan.

By about 3 months of age, infants have achieved a neurological and behavioral organization that enables them to venture for new developmental tasks. Robert Emde and colleagues have labeled this developmental transition as the first bio-behavioral shift. In fact, in very different cultures a developmental transition is celebrated during this age span. In India, rituals are performed that expose the infant to the sun. In Cameroonian Fulani pastorals, infants are introduced into the social community. Western infants are expected to sleep through the night. To what extent infants from different cultures undergo the same maturational and neurological processes at this time is an open question. The acquisition of the diurnal rhythm in Western babies seems not to be a maturational achievement in the first place, but the result of applying implicit or explicit developmental and educational theories of parents (cultural scripts). We have already reported that sleep—wake states develop differently in different cultural contexts. Similarly the motor precocity of African babies might result from prior experiences with the body stimulation system, when Kipsigis babies from rural Kenya are taught to walk from the eighth week on (Bril, 1989). At the other extreme, South American Ache children start walking at 23 months on average. It can be assumed that the differential nature of the early experiences has consequences for the consequent patterns of development. There is, however, not much empirical evidence from longitudinal studies in non-Western cultures. In the following section, we will therefore concentrate on developmental consequences related primarily to face-to-face contexts.

Developmental Consequences of Early Relationship Formation

Attachment theory presented one of the first prospective approaches for developmental predictions on the assumption that the quality of attachment organizes future developmental outcomes. Securely attached children have been demonstrated to be socially more competent in interactions with their peers in preschool classes, develop more reciprocal and mutually rewarding friendships, perform better on cognitive tasks, and show less developmental problems in the following years. Also interaction researchers could document that the mode and quality of interactional patterns at about three months of age have co-occurring as well as consequent developmental consequences. The infant’ amount and quality of eye contact as well as maternal interactional contingency can be related to the amount of infant crying at the same developmental time span. Consequences in different developmental domains have been identified during the following years in terms of later relationship quality, quality of exploration during the preschool years, timing of language acquisition, and development of disorders and problems during the preschool years. Interaction diagnostics and therapy programs have resulted from those studies. These developmental pathways are part of evolutionary socialization models when reproductive styles are related to early childhood experiences which seem to be especially mediated by the acquisition of early relational concepts.

Thus the quality of the early interactional experiences may have psychological, social, and somatic consequences. Not only shaping the structure of behavioral development, but also timing of the acquisition of developmental milestones seem to be influenced in a non-random way. The early onset of psychological achievements such as object permanence, exploration, and language, is supported by a secure early relationship quality that allows the child to direct its available energy actively to its own developmental progress. The early onset of somatic markers such as puberty, on the other hand, seems to be related to insecure and unstable patterns of early relationship formation.

The Competent Child: Toddlers and Preschoolers

Cultural Conceptions of Competence and Learning

In many different cultures, a next developmental transition is assumed at the age of about 2 years. US-American parents regard ‘the terrible twos’ as a new challenge for family development. On the South Pacific Island of Fiji, children at about 2 years gain Vakayalo, meaning that they are now responsible for their actions because they are able to tell right from wrong. Also Hudson Bay children have gained iluma or reason at 2 years (cf. Cole & Cole, 1996). Weaning at about 2 years initiates a new developmental stage in the Northwest Cameroonian Nso children who start to organize games with their peers to rehearse social roles like Awowonie. This mother and father game comprises household chores as well as selling, singing and dancing, funeral ceremonies, child rearing, and hunting.

Besides the struggle for independence, especially in Western societies, the emerging mental capabilities and competencies and the accompanying social responsibilities form this developmental transition. However, cultures differ with respect to their definition of competence and the modes to acquire it. Cross-cultural studies asking whether the Piagetian stages of intelligence development are universal, have identified a different conception of competence comprising social cooperation, duty and responsibility, respect and harmony in many agrarian African and Asian societies as an alternative to the Western ideal of analytical reasoning.

The differential evaluation of components constituting competence seems to be dependent on the affordances of the eco-cultural context. Based on a study comprising 21 samples from different cultures, John Berry (1976) demonstrated that there is a relationship between ecological conditions and the cognitive style of field dependence/independence. Foraging people were more independent in their perception when perceiving more details within a comprehensive visual field. This capacity allows good spatial orientation. Agrarian people for whom this ability is not crucial for survival, on the other hand, scored lower in those tasks.

The preferred and culturally esteemed modes of learning also differ across cultures. The development of Western analytical intelligence is based on formal instruction and schooling. Cultural tools like reading, writing, and calculating are acquired, independent of the daily life context. Children are expected to be curious and to ask questions in order to acquire knowledge which forms their individual action potential. Cultures stressing social competence as part of intelligence rely on observational learning within the daily life context for which the child is responsible when deciding when and how long to observe and practice. The child is rather an apprentice in this participatory learning environment where asking questions often seems to be inappropriate. The acquired competence contributes to the ‘shared knowledge’ of the family or primary social group. The context dependency of learning has also been documented for Brazilian street children who can calculate their trading transactions very effectively without showing any transfer to school math.

Emerging Mental Capabilities

The achievement of toddlerhood and the preschool years with the most significant developmental consequences consists in the dawning of representational thinking. The concrete and solid world of the infant becomes complemented by and transformed into a mental world that allows insightful and rational actions. Three cognitive milestones open this new territory: emerging language starting at about one year; the understanding of the concept of time at about 2½ years; and finally the developing theory of mind at about 3½ to 4 years (cf. Bischof-Köhler, 1998). These achievements allow the child to integrate the early conception of the self as being composed from self-recognition, agency, relatedness, and body awareness in different degrees with expectations about social relationships such as empathy and reciprocity. This integration results in the establishment of a system of norms and values.

A long and interesting debate is documented in the behavioral sciences as to whether these capacities are uniquely human or whether they also characterize the behavior of other species, especially nonhuman primates. Wolfgang Köhler (1921) was the first to document that chimpanzees do not only follow trial and error during problem solving, but come to ‘insightful’ solutions by mental probing when they visually scan the problem situation (how to reach a banana) to come up spontaneously with a correct solution after a short while (to use boxes as platforms). However, Birch (1945) experimentally documented with six chimpanzees, aged 4-5 years, that the ‘insight’ was largely dependent on prior experiences. Nevertheless, today there seems to be no doubt that at least rudimentary forms of cognitive representations and language are existent in nonhuman primates. Chimpanzees can produce utterances and learn a symbol language (Premack & Premack, 1983). They can interpret relational functions (like ‘smaller than’), they can learn to perform simple mathematical calculations and follow verbal instructions (cf. Dunbar, 1996). The vocal production of different primate societies have been identified as communicative in nature. They inform each other about approaching individuals and their social ranks (Cheney & Seyfarth, 1994). Also simple forms of anticipation have been observed when chimpanzees collect stones before they set out for an area where nuts are growing which they crack (Boesch & Boesch, 1990). They can recognize themselves in a mirror and have a rudimentary focus of social cognition when they demonstrate that they understand the intention of others. Again Wolfgang Köhler had observed that the chimpanzee Sultan demonstrated to a younger female how to reach a banana after having observed that she did not understand what Köhler wanted her to learn. With the understanding of the intentions and desires of others, deception and cheating co-evolved. Volker Sommer reports many examples of ‘tactical deception’ among primates in his book ‘Lob der Lüge’ (praise the lie) (1992).

However, nonhuman primates do not produce language spontaneously. Neither do they have the strong desire to learn the names of things or to name objects. Also language trained chimpanzees do not display a distinct motivation to teach language to their offspring and they do not keep the stones with which they crack the nuts for the next occasion.

Representational Development

Humans have developed new dimensions to the prerequisites by the flexible use of capacities and the extension of mental action beyond the actual situation. Only humans organize their past experiences and their future plans on an ongoing time axis. They can think about own and others’ mental states and manipulate these mentally. Most important, however, seems to be the uniquely human desire to accumulate knowledge. Humans are curious, they prefer novelty over familiarity, they explore their surroundings, and they ask questions. Daniel Berlyne (1960) even proposed to conceive of epistemic curiosity as an independent motive. Although childhood is especially characterized as an exploratory stage, curiosity and the motive to become knowledgeable and understanding remain lifelong motors of human development.

Language Development

Two hypotheses have been developed for explaining and locating the occurrence of language during human history. The dominant view relates the emergence of language to the developing tool use about 50,000 years ago. The production and the use of tools are regarded as being linked to verbal instructions. Robin Dunbar (1996), however, argues that language developed as long as about 500,000 years ago, mainly to stabilize larger social groups (‘acoustical grooming’). The social character of early language acquisition seems to support this theoretical account.

Human infants are equipped with the cognitive and sensory capacities to learn language from birth on. They prefer human language over other sounds and decode meaningful language units (phonemes) from the verbal input. They are motivated to produce sounds which are culturally unspecific, until about the 9th month and start afterwards with cultural ‘jargoning’ (Cole & Cole, 1996). Language acquisition is embedded in the early social exchange with the primary caregivers. Despite the universal occurrence of characteristics of infant-directed speech (motherese, baby talk) with high frequency, high pitch, pronounced contours, simple structure, and many repetitions, early language acquisition also follows distinct cultural scripts. Caregivers express cultural norms and values and, thus, the cultural communication code with the early language input. Senegalese Wolof mothers address more statements and questions to their infants than French mothers who modulate and adapt their utterances more to the babies’ signals (Rabain-Jamain & Sabeau-Jouannet, 1997). Although language development starts at birth, the occurrence of the first (proto-)words, mainly ‘mom’ or ‘dad,’ around the 10th to the 14th months demarcates a developmental milestone.

Language development proceeds then as a continuous process with three different knowledge systems interacting: prosodic competence is based on the recognition and production of rhythmical language units; linguistic competence allows development of meaning of words and phrases; and pragmatic competence directs the adequate communicative usage of phrases in different contexts (cf. Grimm & Wilde, 1998).

Children in most diverse cultural contexts obviously go through a one-word stage which is usually followed by a brief two-word period. By about 18 months, infants have acquired the 50-words limit from which they expand their vocabulary with an enormous developmental speed. By 16 years, about 60,000 words constitute adult language. The 50-words threshold demarcates the qualitative reorganization of the early lexicon. Children have acquired the abstract cognition that things have names. They are now ready to form immediately an idea about the meaning of an unknown word in an otherwise familiar and structured context (‘fast mapping’). Newly acquired words may be over-generalized when the children address all adult males as ‘dad’ or name all animals as dogs. On the other hand, they overdiscriminate word meanings when they restrict a word to a specific specimen, like duck only for plastic ducks, not for real animals (cf. Grimm & Wilde, 1998). The reorganization of language development following the 50-word register includes grammar learning, a decrease in the production of nouns and an increase in verbs and adverbs, most pronounced between 27 and 31 months. Syntax becomes now important as a bootstrapper, especially for abstract meanings. This developmental stage also covers phrase building which further allows decoding the meaning of non-obvious and non-concrete words.

About 13 to 20% of US-American and German children are ‘late talkers,’ since they have not yet acquired 50 words by the age of 2 years. Half of these late talkers have caught up with normal language performance by the age of 3 to 4 years. However, 6 to 10% of these populations have developed pathology which also extends to cognitive and socio-emotional development.

Language development obviously is not based on the genetically fixed Language Acquisition Device (LAD) that Noam Chomsky had proposed in 1975. Besides, language development can only partly be explained by reward and imitation. Language acquisition depends largely on the participation of children in social interactions with experienced tutors. Michael Tomasello and his colleagues (1993) demonstrated that children learned the meaning of words when objects were named which were part of children’ ongoing activities and when mothers named words which were part of children’ activities. This intuitive didactic (cf. also ‘zone of proximal development’) is a component of the parenting repertoire and is displayed by parents from different cultures across developmental domains, from Western style language acquisition to learning to run errands in Nigerian Yoruba toddlers. Although some cultural accounts on parameters of early language input exist, not much is known about language acquisition processes from non-Western cultures, including the fact that many non-Western children are raised in more than one mother tongue (Mohanty & Pradesh, 1993).

The Theory of Mind

The notion of a theory of mind was introduced by David Premack and G. Woodruff with their programmatic article ‘Does the chimpanzee have a theory of mind?’ (1978) and describes the capacity to think about own and other mental states in terms of desires and beliefs. It is assumed that basic conceptions of domains like physics, biology, and psychology are inborn and organized parallel to scientific theories. The slogan of the child as an intuitive scientist allows one to describe cognitive development as restructuring different domains according to the respective level of knowledge. The cognitive world of the child is understood as complex, but unitary. This view contradicts Piaget’ view which described children’ difficulty to reason about other peoples’ mental states with egocen-trism as an immature stage of development.

Researchers differ in their opinions about the exact onset of a theory of mind. ‘Boosters’ (cf. Chandler, Fritz, & Hala, 1989) acknowledge social referencing (refer visually to the mother in ambiguous situations) as early as the first year as an index of a theory of mind which is followed by symbol play during the second year and the recognition of others’ mental states and emotions in three-year-olds. ‘Scoffers’ restrict the theory of mind to the competence to recognize false beliefs. In particular the following experimental situation to assess false beliefs by Heinz Wimmer and Josef Perner (1983) has received tremendous attention.

In a doll play situation, the doll ‘Maxi’ puts candies into one drawer and then leaves the room. The candies are then relocated by the adult experimenter into a different drawer. Maxi returns and the participating child is asked where Maxi will look for the sweets.

Most three-year-old children answer that Maxi will look into the drawer where the candies actually are, without acknowledging that Maxi has no information about the relocation. Only 3½-to 4-year-old children can recognize the false belief. There is scarce evidence from other cultural backgrounds about the timing of the development of reasoning about other peoples’ thinking. Jeremy Avis and Paye Harris (1991) presented a similar hiding story to Baka children from Southeast Cameroon. These children too could give the right answers somewhere between 3 and 5 years.

Only at that age do children understand the relationship between accessibility of information, the resulting knowledge and possibility of actions in others and themselves. As a consequence, children apply the view about right and wrong opinions for themselves as well as for others. At the same age, children begin to disentangle causality and intentionality. Until then, they attribute an intention to any event, even in the inanimate world. This new achievement opens the door for deceiving others intentionally, which occurs first at about 4½ years. They are now able to describe the perspective of another person correctly, start referential communication, such as referring to the informational level of another person and start to differentiate appearance from reality. John Flavell and colleagues have demonstrated this differentiation with examples like a sponge that appeared to be a rock and a stone that appeared to be an egg. Chinese, Japanese, British, and US-American three-year-olds were likely to answer incorrectly, four-year-olds seemed to be in a transition state and five-year-olds finally seemed to be able to differentiate fact from fancy consistently. Older siblings seem to accelerate the development of a theory of mind, thus underlining the impact of non-parental socialization influences.

Social Cognition

The main social cognitive progress that toddlers achieve is the development of empathy. Empathy describes the sharing and understanding of the emotional state or intention of another person as distinct from oneself. Thus empathy is different from emotion contagion which might already occur in infants when they start crying upon hearing other babies cry. Doris Bischof-Köhler (1989) has studied empathy with the following quasi-experimental design. Children from 15 to 24 months played with an adult playmate in a laboratory room. Suddenly a teddy bear lost its arm or a spoon broke. The adult displayed open distress. The children reacted with four different patterns of behavior. The ‘empathic helper’ understood the situation, tried to help and to console the playmate. ‘Helpless-confused’ children felt obviously uncomfortable, sometimes seemingly concerned, but without knowing what to do. ‘Emotionally infected’ children started crying themselves, because they obviously could not attribute the distress to the adult, but rather felt it themselves. ‘Unconcerned children’ finally continued playing without paying attention to what had happened to their playmate. It is interesting that the achievement of empathy was directly related to the ability to recognize oneself in a mirror. The classical procedure to assess mirror recognition consists in confronting the infant who has been marked with something unusual in the face, like a red nose or a black dot on the cheek with the mirror image. All self-directed behaviors, including self-naming, are interpreted as indicating self recognition. All children classified as ‘empathic’ had recognized themselves in the mirror. The ‘confused’ and the ‘emotionally infected’ children were obviously in a transition state of self recognition with avoiding the mirror image; the ‘concerned’ children finally did not recognize themselves in the mirror. Having developed the representation of a distinct image of the self allows also the distinct perception of the emotional reality of another person. Based on maturational mechanisms, empathy can only occur during the second year of life, whereas mirror recognition might occur several months earlier. Later stages of empathy development during early childhood (∼ 3-6 years) are related to language and symbol use. Empathy can then be expressed in more subtle ways even for people who are not present. Between 6 and 9 years finally, children start to understand the reality of other persons beyond the actual situation with acknowledging the effects of illness or poverty, thus beginning to become aware of societal concerns.

The development of empathy can be regarded as an important precursor for the prosocial motive of sympathy which enables the child to help and support others; however, also other factors like mood and perceived competence modulate the actual behavior in a concrete situation. Prosocial behaviors, like sharing, helping, and cooperating with others, are part of the evolutionary heritage. Due to evolutionary theorizing, altruism first developed in the context of kin selection, since supporting genetic relatives seemed to improve the own inclusive fitness (nepotistic altruism). However, with the necessity of enlarging the size of social groups for better resource acquisition and protection against predators, reciprocal altruism developed, since it became beneficial to help others, if returns could be expected. The representation of time even enabled our ancestors to postpone the expected returns into the future. The expectations of reciprocity become a major link between individuals and foster group cohesion. A balanced reciprocity account of giving and taking seems to be part of social relationships in most diverse cultural environments, even in ritualized ways like the Potlatch of native North American Indians or the Kula that Bronislaw Malinowski so vividly described in the ‘Argonauts of the Western Pacific’ (1979).

Doris Bischof-Köhler points to negative social consequences which also become accessible with the development of empathy, like envy, gloating, ill will, and aggression. Some authors also understand guilt as a consequence of em-pathic identification in terms of feeling responsible for the other’ situation. These tendencies are also rooted in humans’ evolutionary heritage.

The Development of Gender Identity

After having established a basic sense of self, children are ready for the next developmental task, i.e. to acquire their gender identity at about 2 years. Gender identity denotes the self-representation of the sex or gender, whereas the gender role is assigned to the social display of the identity. One of the earliest theoretical proposals for the explanation of the developmental processes of gender identity is rooted in Sigmund Freud’ stage model of development. Starting from the assumption that all biological drives have the goal of survival and procreation of the species, the fundamental sex drive (libido) is conceived of as the motor of development. Sexual gratification proceeds during development through stages that denote the parts of the body that satisfy the drive. The first stage is the oral stage, where the mouth is the primary source of pleasure. In the second year of life the anal stage focuses on sphincter control. During the fourth year, the phallic stage, the genitals become the center of pleasure seeking. During this stage, the developmental pathways of boys and girls begin to diverge. Boys develop sexual feelings for their mothers and often express the wish to marry her. Girls mainly experience penis envy. Between 6 and 7 years, the turmoil calms down in a latency stage which lasts until puberty. During the latency stage, the sexual desires are suppressed, instead adult skills and values are acquired. During puberty, sexuality reappears in the genital phase and is now directed towards mating partners.

Especially for boys, identification with the father is achieved by solving the conflicts related to the Oedipus complex (the analogous Electra complex for female development is not similarly elaborated). Feelings of anxiety and guilt as directed at the father while desiring the mother, are transformed into identification with the father, at the same time laying the foundation for moral development (the super ego).

Freud was attacked from many different perspectives for his speculative theorizing. Although his stage model may need reformulation, he should nevertheless receive credit as one of the few early scholars who claimed that childhood development is central for adult personality formation.

Social learning theorists have proposed that observation and imitation are the roots of development in general and sex role adoption in particular, thus excluding the emotional character of Freudian identification. Observation and imitation are complemented by parental reward and prohibition/punishment strategies that are especially salient for sex-typical activities (like rough and tumble play).

During recent decades, by far the most attention has been given to the cognitive approach proposed by Lawrence Kohlberg (1966) which is based on Jean Piaget’ cognitive developmental theory. According to this view, the child constructs the gender concept actively like any other cognitive schema. Identity formation is pursued through several consecutive stages. Children start by becoming aware of categorical differences between the sexes. Mostly based on parameters of outer appearance, like body shape or hair style, they are able by 2 to 3 years of age to differentiate men from women. This view is in line with evolutionary theorizing which postulates epigenetic rules that facilitate the acquisition of gender-related information early in life (cf. Daly & Wilson, 1988). The next stage consists in recognizing similarities with the one or other sex. At about 3 years, children are able to label themselves as boys or girls and have thus acquired the basic or core gender identity. The next stage concerns gender stability when children begin to understand that sex roles do not change over time, which is followed by gender constancy, the independence of the gender schema of situation or context. Even wearing a dress, a boy remains a boy. Gender schema theorists have modified the original Kohlbergian approach with supplementary assumptions, that children’ gender schema knowledge nourishes the interest in gender-linked activities and behavior.

With the establishment of the core gender identity (stage 1), children’ preferences in fact become biased against sex. Boys do not want to play with girls and do girlish things and vice versa. The gender topic controls children’ activities to a large extent and they develop marked preferences for their own sex.

The Emergence of Moral Standards

Children are now ready to become aware of the evaluation of behavior, of what is considered to be good or bad, right or wrong in their family. The earliest awareness of moral standards are children’ assessments of the evaluative response of their caregivers. This view implies that in the beginning moral standards are imposed from outside, especially from the experience with powerful others, ascribing cultural standards a prominent place for defining the content of moral obligations. Jean Piaget proposed to conceive of this ‘morality of constraints’ as heter-onomous morality. He told children pairs of stories in which a child causes a mishap—in one case pursuing a selfish interest and in the other case an effort to be helpful. He then asked the children evaluative questions about the stories. Until middle childhood, children’ evaluations are guided by the amount of the mishap without taking the intention into consideration. With increasing interactions with peer groups, the heteronomous standards are replaced by autonomous morality which is based on an understanding of norms and rules as arbitrary agreements. Through the process of internalization, the external knowledge becomes part of the inner psychological functioning and part of the conception of the self. Based on the achievements of the theory of mind, an inner voice observes and guides the evaluation of self and others. This inner voice constitutes the conscience and acts as the keeper of moral standards. Shame and guilt are moral emotions that develop during the second until the sixth year (Erikson, 1976). The internal standards are visible in behavior which becomes regulated through self control. Related to self control is the ability for compliance with caregivers’ demands. The ability to inhibit immediate impulses is based on the newly acquired capacity of time representation, allowing to plan ahead.

The developmental status of the child that is about to enter middle childhood reflects the emotional experiences as well as the cognitive achievements in his or her behavioral organization that are expected from the cultural scripts constituting the symbolic environment in which their developmental pathways are embedded.

Childhood: Social Priming and Cognitive Apprenticeship

Childhood demarcates the developmental period that begins around the 6th year of age and lasts until the beginning of puberty. Although the worlds of childhood differ remarkably across cultures, the beginning forms again a pancultural transition. In Germany, mandatory school attendance starts at 6 years of age. The Ifaluk of Micronesia believe that 6-year-old children begin to perform valued adult behaviors, like the ability to work, to adhere to social norms and demonstrate compassion for others (Lutz, 1987). The Ngoni of Malawi associate the loss of milk teeth around 6 years of age with more independence and responsibilities (Read, 1968). At about 6 years, Kenyan Kipsigis children are considered as mature enough to perform small purchases (Harkness & Super, 1983). The Cameroonian Nso children start understanding why the social norms are supposed to be the way they are, why there are taboos, and why they should be respected. They run errands, and tether goats and chickens.

This transition marks maturational, social, and cognitive changes which extend the children’ range of action to the larger cultural context by the assignment of responsibilities.

Cultural Conceptions of Childhood

The enormous differences of childhood in different cultures were summarized by Urie Bronfen-brenner (1977) as the two worlds of childhood when he described the lives of US-American and those of former Soviet Union children. His report clearly demonstrated that different political ideologies have a tremendous impact on socialization contexts and activities that are adhered to children within these contexts. Cross-cultural evidence, however in line with sociobiological thinking, indicates that the differing worlds of childhood (as well as adulthood) are mainly shaped by the availability of economic resources and the respective level of industrialization.

The Western child extends his home range and starts exploring the physical surroundings on its own or with friends and peers. In particular the detailed description of Roger Barker and Herbert Wright (1951) of ‘One Boy’ Day’ in ‘Midwest,’ USA, has evidenced that adults’ supervision over children’ time has tremendously decreased. The streets and empty urban lots became the attractive places to be, especially for boys. Martha Muchow has reported similar observations from pre-war Hamburg in Germany where a distant department store became a favorite location with boys, who were more adventurous and enterprising than girls. Except for exploration and play, children’ days are largely structured by school attendance and extra-curricular classes like sports, ballet, and drama. In contrast to their agrarian, foraging, or pastoral non-Western counterparts, Western children’ activities are either part of their education or recreation. Although many parents promote group activities, so that their youngsters rehearse social behavior, the socialization goals are focused on individual performance and achievement.

Enlarging the ecology with peers is also part of the Nso farmers’ childhood socialization in West Africa. Peers learn from each other, playing adult roles in coffee plantations, uninhabited houses, or corners of the central compound. Each child brings his or her own basket with food which they eat together at midday. Out of their own curiosity, they leave the compound searching for firewood, hunting rabbits, fetching water, harvesting bush nuts. Also sex-segregated activities are common when boys play and form ‘secret societies’ to which girls do not have access. Sibling care is part of the daily program of children at that age with girls being more involved than boys.

The West African pastoral Fulani child’ activities during this age span also mainly consist of informal learning from the activities of others and from stories. These children gradually start running minor errands and become primed into the significance of cattle in the society. Especially boys might be given the task of keeping the calves from straying into huts or eating grain. Cattle education preoccupies boys’ time at this period as they learn the types of grass which most appeal to the cattle and general dietary needs of herds. Girls start accompanying their mothers to sell butter, milk, or cosmetics fabricated from leaves and bark of trees. They learn to prepare the special Fulani shelter and other household utensils. On attaining 7 or 8 years of age, the male child is initiated by circumcision, and he immediately abandons the feminine world.

Still another world of childhood is characterized by children’ participation in the labor force, outside the social protection of the family or the village. Especially children from urban slums have to contribute to the family income, mostly by trading on their own in the streets of the big cities. There is, however, also a substantial number of children living in the streets and supporting themselves. In 1985 UNICEF estimated that there were 100 million street children in the world. Most of them continue to maintain contact with their families. Violence against children living in streets is a major threat in many parts of the world.

Reorganization of Mental Skills

Starting at about 5 years, changes in brain structure and function have important consequences for mental development. The change in the electroencephalogram (EEG) is especially dramatic. Until about 5 years, awake children display more theta activity, which is characteristic of adult sleep, than alpha waves, which characterize adult attentional processes. After a phase of equal amounts of theta and alpha activity between 5 and 7 years, alpha activity becomes predominant, thus establishing the adult pattern. Myelinization, the process in which neurons become covered with the fat substance myelin, increases and allows higher speed of transmission of nerve impulses, the numbers of synapses (connections between neurons) increases and the EEG activity becomes more synchronized. At about 8 years, these activities reach a plateau and remain stable thereafter. These maturational changes allow children more complex functioning of their mental activities. The formation of explicit action plans, the emerging self-reflection, the extension of the memory span accompany these maturational changes which, however, cannot be causally linked (Case, 1992). Jean Piaget (1983) directed special attention to concrete operations as the emerging new form of thought. These mental actions or operations allow to combine, separate, and transform information following logical laws, however still restricted to concreteness in terms of tangible objects or thoughts about objects. According to his general cognitive developmental theory, Piaget assumed that concrete operations transform all psychological domains. He assumed that general principles are acquired, like conservation and reversibility. Conservation denotes that a property (like sex and gender) or a substance (like amount of liquid) remain the same, although appearance or shape might vary. Reversibility or negation describe the understanding of the possibility or impossibility of reversing states and actions. Piaget proposed specific and most creative experimental procedures for assessing diverse mental capabilities.

The most popular conservation task starts with the presentation of two identical glasses filled with the same amounts of liquid. The experimenter asks the child whether the amounts are the same in the two glasses. If the child agrees, the experimenter pours the content of one glass into a smaller and thinner glass and asks the child whether the higher rise of liquid in the new glass still represents the same amount of liquid or more or less. Children about 3 to 4 years old insist that there is more liquid, since they can only focus on a single dimension or attribute. Only around age 8, can children consider the height and circumference of the glasses and make correct judgments.

Piaget’ conclusions are nevertheless challenged by discoveries like the domain and context specificity of cognitive functioning as well as the procedural character of mental activity. Cross-cultural studies have shown that the performance of cognitive capacities mainly relies on the familiarity of problem and material.

The Social World of Childhood

The most dramatic change in the lifestyle in middle childhood is the significant increase in time that children spend with peers as compared with their parents. Nevertheless the peer group is differently defined in different cultures. In the Western world, the peer group is composed of self-selected age mates who share interests and attitudes. However, accessibility like the neighborhood or parental selection of contexts like school classes, holiday preferences, friends’ network and the like, play a major role. In the Arabian world, the peer group is constituted mainly by family members, the most intimate one being constituted of siblings, followed by cousins and finally neighbors as a more distant peer group.

Yet siblings play a special role in children’ development not only in traditional societies. Being raised with siblings creates a distinct socialization climate, especially with respect to the ordinal position or birth rank that a child inherits. Frank Sulloway (1997) recently documented with a wealth of biographical information that the ordinal position within a family may constitute rather predictable developmental challenges in terms of becoming more conservative or more creative, as one example. Psychological interest in sibling research became especially evident in studies which tried to assess the developmental transition from a one-child family to two-children families with the necessity to reorganize the family system. For the parents this transition constitutes the second major task of family development after the transition to parenthood with the first child. There is evidence that the second child experiences less unshared attention from the parents, especially the mother,’ since the added demands on the mother’ attention reduce her interaction time. It can further be assumed that especially inexperienced Western mothers have developed more trust and security in their competence of child care, so that their interactional style becomes less anxious and tense and thus more emotionally warm. But siblings also influence each other directly as studies, especially of cognitive development, have demonstrated. Children with siblings seem to be advanced with respect to social perspective-taking skills as compared with single children, and younger siblings appreciate the advice provided by their older siblings when they consult more with their sibling than with a friend in mastering tasks.

But relationships between siblings can be conflictual and stressful at the same time. With the parental investment theory, John Trivers proposed a sociobiological account of differences in parents’ allocation of investment in boys and girls depending on the available resources. Parents should tend to invest more in their girls in poor contexts, since their reproductive success is less variable than that of boys who in turn should be ‘preferred’ under affluent circumstances. There are historical as well as contemporary data confirming this view. On the other hand, the preference for sons over daughters, e.g. in India, extends also to poverty contexts. More research is needed, especially tackling the interaction between sex and birth position, to better understand these processes.

The peer group is often contrasted with family constituting ‘external influences’ on children’ development. These comparisons, however, seemingly compare apples with pears. Children do not become friendly or hostile because their peers are friendly or hostile. As we have argued earlier, there is developmental continuity translating early interactional experiences into a working model of the self which facilitates the acquisition of specific personality traits in interaction with genetic predispositions. The first follow-up studies of attachment research in the 1970s documented that securely attached children have smooth and rewarding relationships with their peers. On the psychological basis laid by the early relationship formation, social roles within the peer groups are negotiated, social ranks are established, and the experience of reward and frustration shapes the continuous process of personality development. Thus, the subtle and organizational influence of early family environment and the following socialization contexts need longitudinal research where previous and concurrent influences can be compared; self reports (questionnaires) administered during children’ middle childhood obviously cannot capture the developmental dynamics adequately.

Numerous studies have investigated children’ play groups and analyzed their interactional format as well as the group structure and its dynamics. The ways in which children are helpful and constructive to each other, observe rules, cheat each other, behave aggressively, are insecure, plus their physical attractiveness, make children popular, neglected or rejected. Children who are rejected often differ from popular children in many respects. Except for attractiveness, they may have difficulties in assessing social situations correctly and accordingly behave inadequately. Assessment difficulties may be related to distraction or distortion of the perception due to difficult family backgrounds. Children from poor families may be insecure; battered children or those from neglectful and abusing families may want to hide their problems. Children from immigrant families are often confronted with value systems at school and in peer groups that are different from those promoted at home, which may result in conflict in all contexts.

Piaget (1932/1965) concluded from his observations and interviews that boys and girls play different games and play the same games differently. Although his view has found support as well as contradiction, there is nevertheless a clear sex segregation to be stated during this developmental period. Children engage primarily in same-sex groups and may even avoid the other sex. Boys’ activities seem to be more competitive, aggressive, stressing physical strength, whereas girls are more interested in domestic activities and relationships. Girls congregate mostly in pairs or three friends, whereas boys gather in larger groups with less intimate personal relationships. Similarity seems to be the basis for friendships. The sex differentiation of behavioral development prepares children for different sex roles. Competition and cooperation form the two dominating and discriminating value systems. Although cultural and societal values, especially in the industrialized societies, may change, children’ behavioral preferences during middle childhood obviously do not alter dramatically.

Moral Reasoning and Moral Behavior

Moral judgments are reflected in meaning structures that undergo qualitative changes during development. Based on Piaget’ conceptions of developmental progress from heteronomous to autonomous orientations, Lawrence Kohlberg proposed a widely accepted modified stage theory (see Kohlberg, 1966, 1976). He conducted a 30-year longitudinal study with 72 male participants who were 10 to 16 years when first assessed. The main modifications based on six assessments consisted in the definition of six stages which form three levels: the preconventional level comprises stage 1, heteronomous morality, and stage 2, instrumental morality. Heteronomous morality is governed by avoidance of punishment from an egocentric point of view without recognizing the interests of others. Instrumental morality implies that rules are followed only if there is a personal and immediate interest. The conventional level (level II) comprises stage 3, good-child morality, and stage 4, law-and-order morality. The good-child morality which first appears at about 10 to 11 years of age, integrates social relations as a necessary part of the moral perspective. Children no longer depend on external qualifications for their judgments of right or wrong, but take reciprocal relations, shared feelings, and agreements into consideration. Stage 4 (law-and-order morality) concerns the institutionalization of social relationships. The group takes priority over the individual.

The post-conventional level (level III) comprises stage 5, social-contract reasoning, and stage 6, universal ethical principles. Social-contract reasoning expresses an obligation to the law, focusing again more on an individual, but socially responsible level. Universal ethical principles finally do not represent an empirical stage, but a deontological position. Later authors, including Elliot Turiel and colleagues, have argued that the types of rules described for the stages, especially personal concerns, conventions, and morality, do not represent an onto-genetic line of development, but are already differentiated early during development, yet have developmental contents. Personal concerns are defined as rule systems, created by the individual. Conventions concern the social expectations of a group that are consensually followed by the individuals. Moral rules finally concern social regulations that are rooted in encompassing principles of justice and welfare.

There is an extensive and ongoing debate about the universality or relativity of moral standards. Kohlberg’ theory has undergone extensive cross-cultural testing. Lutz Eckensberger and Roderick Zimba conclude that, from a comprehensive review of cross-cultural data, stages 2 to 4 seem to exist transculturally, but that also cultural specifications are apparent. A variety of perspectives on morality has been offered across cultures, like the Indian moral of duty, the Confucian principle of giri-vinjo (obligation), or the Javanese principles of hormab, respect for older people, and rukunas, describing harmony in social relations. These conceptions might be related to Carol Gilligan’ conception of morality of care and responsibility that she contrasted as female morality with Kohlberg’ male view. However, many questions concerning indigenous conceptions of morality remain open.

There is another open question concerning the relationship of children’ reasoning about moral issues and their concrete actions. Research clearly indicates that there is no one-to-one concordance between the level of moral reasoning and the respective actions. Sociobiology explains this discrepancy on the assumption that people in the first place pursue their own interests, that is, genetic interests. Regulating ideas are nevertheless important, since cooperation generally promises also better individual success (‘the true egoist cooperates’).

The Changing Sense of Self

With the shift in social behavior and cognition, the sense of self also alters remarkably, and children are capable of reporting about themselves, their feelings and attitudes. The significant dimensions that reorganize the internal representation of the self concern physical appearance, social comparisons with peers, activities that are mastered, and psychological characteristics. Children, but also adults with different cultural backgrounds, differ with respect to the way they describe themselves. Individuals from Western cultures describe themselves in terms of their psychological attributes, stressing especially their uniqueness and their activities, whereas members of traditional cultures describe themselves predominantly in terms of their social relationships, like being a daughter, a friend.

At about 6 years of age, children discover that internal experiences and outer appearance might diverge; at about 8 years psychological differentiation becomes complemented with the discovery that one individual person can have different, even contradictory feelings or intentions.

At around the same time, the appreciation of others concerning one’ own person becomes vital for the evaluation and estimation of the self. Thus, self-esteem which was intricately intertwined with the perceptual sense of self finds expression in the reflexive self that is now emerging.

Adolescence: Family Foundation or Educational Moratorium

Adolescence as the transformation phase between childhood and adulthood is not only shaped by cultural influences, but constitutes itself a culture-specific phenomenon. In traditional societies, children have now acquired the behavior, the skills, and the knowledge to participate in adult life, found a family, and contribute to the families’ subsistence. There is a continuous transition from childhood to adulthood (cf. Saraswathi, 1999). In Western societies as well as middle and upper classes of traditional societies, adolescence represents a culturally defined educational moratorium, disrupting the continuity between childhood and adulthood. In most cultures, transitional rituals are celebrated (‘rites de passage’), introducing the new social status. The cultural diversity of adolescence phases was first documented by Margaret Mead in 1928 (Mead, 1928/1961), an achievement that certainly is not negated by the criticism concerning her methods of data collection.

Puberty and Maturational Changes

Puberty is the main somatic marker of adolescence. The development of the reproductive system with its endocrinological changes, but also the changes in body shape and growth mark distinct developmental changes. Puberty in males is initiated by interaction among the hypothalamus, the pituitary gland, and the testes, finally discharging gonadotropins into the blood. These hormones stimulate the testes to produce testosterone which initiates changes in the body development. The most visible male somatic markers are the growth spurt and the spermarche. The growth spurt refers to a sudden increase in height where boys might acquire about 22 cm in a relatively short period of time. The testes begin to produce sperm cells which are released spontaneously for the first time, usually during sleep. The first ejaculations occur as nocturnal emissions (wet dream). Boys develop muscles and strength.

Puberty in females is also related to the interaction of hypothalamic activity with the pituitary glands releasing gonadotropic hormones which stimulate the ovaries to produce estrogen and progesterone triggering the physical development necessary for reproduction. Menarche is the visible somatic marker of puberty in girls. Girls also have a growth spurt, however less pronounced than boys. Girls develop breasts and their hips acquire their specific shape due to fat deposit. Evolutionary theorists argue that the hip—waist ratio is a universal descriptor of attractiveness, independent of stature.

There are vast interindividual differences in the timing of puberty. The average age at which puberty begins in today’ industrialized societies is between 12 and 13 years for girls and 13 to 14 years for boys. The onset of puberty has become markedly earlier over recent decades, mainly related to better nutritional provision. However, the historical changes are not as marked for boys as they are for girls. Data from poverty contexts indicate that menarche is reached on the average at 15 to 17 or even 18 years. Interindividual variability associated with early and late maturation has been related to social development, personality formation, and development of deviant behavior. The results are contradictory: some studies indicate that early-maturing boys are psychologically and socially more mature, other studies portray early-maturing boys as more anxious, less exploratory, and less curious than late-maturing boys. The latter view is also supported by data indicating that early-maturing boys are more likely to smoke, use drugs, drink alcohol, and may even get into conflict with the law. The picture for early-maturing girls even seems to be more negative. They have problems with their stature, being taller and heavier than late-maturing girls and, maybe even more important, than boys. They seem to be less emotionally stable and self-controlled and seem to be at risk for drug and alcohol abuse or deviant behavior, such as shoplifting and running away.

Sociobiology offers an interesting perspective on early and late maturation when addressing not only the consequences, but also highlighting the precursors. As we have outlined earlier, evolutionary models describe developmental pathways from early social and economic childhood experiences, mediated by quality of attachment and emotional balance to the onset of puberty. Among others, studies from New Zealand, the United States, and Germany indicate that, especially for girls, the early childhood context—particularly divorce of the parents, all the more if this occurred during the first five years of the child’ life—accelerates onset of puberty.

Changing Social Relationships

The peer groups of middle childhood acquire a new quality during adolescence. Especially in Western industrialized societies, cliques with about six youngsters who are in regular touch with each other, constitute the primary peer group. Crowds, as a larger collection of people forming ‘reputation-based collectives,’ define a looser social organization. Nevertheless, crowds set standards and define trends and prestige, so the crowd puts pressure on peers to conform. Peer pressure is especially influential during the early years of adolescence.

Adolescents in traditional societies have attained adult status. The male Nso adolescents from Cameroon are now admitted to the manly activities of the community and the secret societies which women do not have access to. Nso girls, as many other adolescent girls in traditional societies, marry and start having children.

Parent—Child Relationship

Adolescence has been characterized, especially in European philosophy and poetry, as a period of increased instability, turmoil, with inevitable emotional conflict with parents. In Western societies, adolescence is a developmental time span where children develop distance from their parents and parental attempts to control the children contradict the liberation tendencies of children, who rather seek advice and guidance from their peers. The visibility of specific youth cultures which openly express divergence from the prevailing adult values often masks the fact that most youth continue to have warm and friendly relationships with their parents. As empirical studies have revealed, adolescents and their parents are generally in agreement on important issues like religion, family planning, and moral issues. Contradictions often refer to more marginal areas like hairstyle, mode of dressing, and time for coming home at night. In the public discussion of developmental influences, peer influence is often overestimated. However, finding the own way is largely dependent on the cultural scripts for individuation. Conforming to parental and family values, respecting the assigned role, and behaving accordingly are no matters of negotiation in many traditional societies. ‘Mammy woteri’ and ‘Baa woteri’ are Nso Cameroonian adolescent girls and boys who are at the end of the apprenticeship stage, and can do almost everything that the mother does (household chores, child care), and all that is considered as the duty of the father in a household—disciplining the young ones, clearing the farms, and tapping palm wine. Generally the family’ role remains important, also during this life stage and across cultures.

Cognitive Development

Adolescent thinking mirrors the transition to adult cognitive functioning. Piaget labeled his last stage of intelligence development as formal operational thinking. It mainly differs from concrete operations by the ongoing mental capability to consider all aspects of a problem or a situation at the same time.

Formal operational thinking allows one to develop hypotheses about possible outcomes of problems or situations and evaluate them comparatively. With this new achievement, thinking about thinking becomes possible and complex metacognitive systems of reasoning are developed. Related to this ability is second-order thinking, which allows one to follow different lines of thinking with their respective logical implications at the same time. Domain-specific increase of knowledge can be regarded as a second motor of changes in reasoning and thinking. Information-processing theories explain the flexible and integrative thinking of adolescents as a result of using more efficient strategies of information management.

The universality of formal operational thinking has been addressed as controversially as the other stages of intelligence development. On the one hand, it is argued that formal operations are necessary in order to meet the demands of adult roles and the responsibilities of adult life in any culture. However, even in middle class US-American samples, only 30-40% solve the problems proposed by Jean Piaget and Bärbel Inhelder as characterizing formal operational thinking. This specific problem solving capacity can be improved by instruction and tutoring. The interindividual differences in achieving and mastering this mode of thinking clearly perpetuate into adulthood. Sex differences, with males outperforming females in the Piagetian task, revealed the importance of the context for activating specific modes of thinking. Obviously, more boys will be interested in science contexts which mainly constitute the experimental tasks. As well as the importance of the context expressing differential interests, different strategies and modes of thinking may also exist and vary according to sex. Mathematicians have identified two successful strategies to solve mathematical tasks, with boys preferring a more analytic procedural/functional problem solving style and girls a more holistic intuitive, predicative, but equally successful strategy. The evidence that training and tutoring increase the ability for formal operational thinking includes the cross-cultural variability for attendance of formal schooling. However, Piaget himself acknowledged that difficult contextual conditions and a different exposure to training might enhance or delay the attainment of developmental stages. The analysis of these different contextual demands challenges cultural psychologists to identify and analyze indigenous ways of thought development.

Acquiring a Metaperspective on the Self

In the psychological literature, adolescence is often considered as the time span where identity formation sets the major developmental task. In particular the conception of Erik Erikson (1968) accentuated adolescence as the time to resolve the developmental crisis on the basis of the results of earlier developmental tasks. Successful graduation would be the favorite developmental goal, but impairment of the life cycle might also result. The basic developmental challenges of the preceding life stages consisted in establishing trust and autonomy, taking initiative and developing industry. These characteristics have to be synthesized together with the physical changes, cognitive skills, social experiences, and expectations for the future into one’ adult sense of self. These views on the self can differ with respect to successful integration, as James Marcia (1980) concluded from interviews with male college students. He developed four identity patterns which can be described as ‘identity diffusion’ (the adolescent tried out several identities without finding his/her own way; the prevalence of identity diffusion decreases from the pre-highschool years to the college upper class years); ‘identity achievement’ (the adolescent has made choices concerning self-evaluation, social commitments, and occupational goals and has set up plans for the future; this pattern increases over time); ‘foreclosure’ (describing committed adolescents, but without having gone through any form of identity crisis; being relatively stable with about 35% over the age-groups studied), and ‘moratorium’ (describing an identity pattern of adolescents who experience an identity crisis and take their time out in order to develop their own perspective; this pattern also remains relatively stable over the age groups, covering about 12-28%).

Generally, the different cultural socialization scripts and practices find their expression in different conceptions of the selves that can be described as independent or individualistic and interdependent or collectivistic. Hazel Markus and Shinobu Kitayama (1998) described the independent construal of the self as expressing the notion of a distinct and separate person with an emphasis on unique personal attributes organized as distinctive wholes, abstracted from social responsibilities and duties. This actional self conception is conceived of as independent, assertive, competitive, self-assured, self-sufficient, and direct. The interdependent construal of the self describes the person as fundamentally connected with other human beings, who subordinates individual interests to the collectivity by being attentive, respectful, dependent, emphatic, self-controlled, dutiful, self-sacrificing, conforming, and cooperative. These different culturally defined identity conceptions are acquired during developmental pathways which can be described as continuous processes of synthesizing social-izatory experiences beginning at birth or even earlier with means of constructing and co-constructing one’ own reality.