In Freudian psychology, psychosexual development is a central element of the psychoanalytic sexual drive theory, that human beings, from birth, possess an instinctual libido that develops in five stages. Each stage – the oral, the anal, the phallic, the latent, the genital – is characterized by the erogenous zone, the source of the libidinal drive. Sigmund Freud proposed that if the child experienced sexual frustration in relation to any psychosexual developmental stage, he or she would experience anxiety that would persist into adulthood as a neurosis, a functional mental disorder. Sigmund Freud observed that during the predictable stages of early childhood development, the child's behavior is oriented towards certain parts of his or her body, e.g. the mouth during breast-feeding, the anus during toilet-training. He argued that adult neurosis is rooted in childhood sexuality, suggested that neurotic adult behaviors are manifestations of childhood sexual fantasy and desire; that is because human beings are born "polymorphous perverse", infants can derive sexual pleasure from any part of their bodies, that socialization directs the instinctual libidinal drives into adult heterosexuality.
Given the predictable timeline of childhood behavior, he proposed "libido development" as a model of normal childhood sexual development, wherein the child progresses through five psychosexual stages – the oral. Sexual infantilism: in pursuing and satisfying his or her libido, the child might experience failure and thus might associate anxiety with the given erogenous zone. To avoid anxiety, the child becomes fixated, preoccupied with the psychologic themes related to the erogenous zone in question, which persist into adulthood, underlie the personality and psychopathology of the man or woman, as neurosis, personality disorders, et cetera; the first stage of psychosexual development is the oral stage, spanning from birth until the age of one year, wherein the infant's mouth is the focus of libidinal gratification derived from the pleasure of feeding at the mother's breast, from the oral exploration of his or her environment, i.e. the tendency to place objects in the mouth. The id dominates, because neither the ego nor the super ego is yet developed, since the infant has no personality, every action is based upon the pleasure principle.
Nonetheless, the infantile ego is forming during the oral stage. Weaning is the key experience in the infant's oral stage of psychosexual development, his or her first feeling of loss consequent to losing the physical intimacy of feeding at mother's breast. Yet, weaning increases the infant's self-awareness that he or she does not control the environment, thus learns of delayed gratification, which leads to the formation of the capacities for independence and trust. Yet, thwarting of the oral-stage — too much or too little gratification of desire — might lead to an oral-stage fixation, characterised by passivity, immaturity, unrealistic optimism, manifested in a manipulative personality consequent to ego malformation. In the case of too much gratification, the child does not learn that he or she does not control the environment, that gratification is not always immediate, thereby forming an immature personality. In the case of too little gratification, the infant might become passive upon learning that gratification is not forthcoming, despite having produced the gratifying behavior.
The second stage of psychosexual development is the anal stage, spanning from the age of eighteen months to three years, wherein the infant's erogenous zone changes from the mouth to the anus, while the ego formation continues. Toilet training is the child's key anal-stage experience, occurring at about the age of two years, results in conflict between the id and the ego in eliminating bodily wastes, handling related activities; the style of parenting influences the resolution of the id–ego conflict, which can be either gradual and psychologically uneventful, or which can be sudden and psychologically traumatic. The ideal resolution of the id–ego conflict is in the child's adjusting to moderate parental demands that teach the value and importance of physical cleanliness and environmental order, thus producing a self-controlled adult. Yet, if the parents make immoderate demands of the child, by over-emphasizing toilet training, it might lead to the development of a compulsive personality, a person too concerned with neatness and order.
If the child obeys the id, the parents yield, he or she might develop a self-indulgent personality characterized by personal slovenliness and environmental disorder. If the parents respond to that, the child must comply, but might develop a weak sense of self, because it was the parents' will, not the child's ego, which controlled the toilet training; the third stage of psychosexual development is the phallic stage, spanning the ages of three to six years, wherein the
Prenatal and perinatal psychology
Prenatal psychology can be seen as a part of developmental psychology, although it was developed in the heterogenous field of psychoanalysis. Its scope is the description and explanation of experience and behaviour of the individual before birth and postnatal consequences as well. In so far as the actual birth process is involved. Pre- and perinatal aspects are discussed together. Prenatal and perinatal psychology explores the psychological and psychophysiological effects and implications of the earliest experiences of the individual, before birth, as well as during and after childbirth. Although there are various perspectives on the topic, a common thread is the importance of prenatal and perinatal experiences in the shaping the future psychological development. There is a debate among scientists regarding the extent to which newborn infants are capable of forming memories, the effects of any such memories on their personality, the possibility of recovering them from an unconscious mind, which itself is the subject of argument in the field.
A widespread assumption concerning the prenatal phase was that the fetus is completely shielded from outside stimuli. Thus and consciousness would develop after birth. Meanwhile, there is a great number of scientific studies which show that behaviour and learning is developed before birth; this holds for subhuman species, as for rat fetuses acoustic conditioning can be demonstrated. The physiological development while the prenatal phase – that of the brain – is of particular importance for any prenatal psychology. In the first eight weeks after insemination the developing child is called embryo. After the inner organs have developed it is called fetus; the basis of perception and behaviour is the brain. While in gestation, a giant neuronal net is developing, delivering the condition for any mental process. About half of the developing neurons become destroyed again while the development of the brain because of the "programmed cell death“. At birth the infantile brain contains 100 billion neurons – as many as in the brain of an adult.
At birth, every cortical neuron is connected with about 2500 neurons. Synapses develop, are destroyed, over the whole life span, - a process called neuroplasticity. In the 1930s the physiologist Davenport Hooker examined reflexes or reactions of aborted fetuses extrauterine. Nowadays, the motor skills of embryo and fetus can be examined with ultrasound techniques quite easily. From the eighth week on the embryo moves the rump, shortly after that his extremities. With the means of sonography one could demonstrate that these were not simple reflexes, but endogenously provoked movements. According to Alessandra Piontelli the fetus shows all patterns of movement, which can be found in the newborn. Breath movements can be seen from the 19th week on, with the fetus taking amniotic fluid into his lungs. Eye movements are shown to exist from the 18th week on, from the 23rd week on there are rapid-eye-movements; these are connected with dreaming. Fetuses drink amniotic urinate into it; the sense modalities of the fetus develop prenatally and are functioning well at birth.
The examination of such abilities is connected with experimental examination of behaviour, provoked by stimuli. Such studies exist since about a century. Ray examined vibro-acoustic conditioning of human fetuses. According to Hepper it rested uncertain. Hepper claims to have repeat such conditioning experiments with the earliest vibro-acoustic conditioning in the 32nd week of gestation. Prenatal learning is examined by using the habituation paradigm; the fetus gets exposed to a stimulus, f. i. an acoustic one. Afterwards the experimenter watches the extinction of the reaction while repeating the same stimulus again and again; this procedure becomes completed by the use of a new stimulus and the recording of the according reaction. When the new stimulus is identified by the fetus as different from the old one, it releases a new pattern of reaction, f. i. accelerated frequency of the heart. If this does not happen, the new stimulus cannot be distinguished from the old focal stimulus. In 1991 a study demonstrated the acoustic habituation by recording the heart frequency of foetuses in the 29th week of gestation.
Such studies can be used for examining memory. Fetuses older than 34. Weeks of gestation can reproduce learned content over a period of 4 weeks; the earliest vibro-acoustic conditioning is successful at 22-week-old fetuses. Maybe habituation to taste is possible earlier; such habituation was demonstrated in fetal rats. Babies remember musical patterns they once heard in the womb, as W. Ernest Freud – a grandson of Sigmund Freud – could demonstrate; the empirical proof used the registration of motorical activity. The development of speech is based on prenatal learning, as the well known study of DeCasper and Fifer from 1980 seems to demonstrate; this study used operant conditioning as a paradigm. Several empirical studies demonstrated. Most psychoanalytical theories assume that the development of objects, the self and consciousness begins after birth; some psychoanalysts explicitly write, that pre- and perinatal aspects are responsible for certain symptom formations, among them Otto Rank, Nandor Fodor, Francis J. Mott, Donald Winnicott, Gustav Hans Graber und Ludwig Janus.
They think. The fetus has
An embryo is an early stage of development of a multicellular diploid eukaryotic organism. In general, in organisms that reproduce sexually, an embryo develops from a zygote, the single cell resulting from the fertilization of the female egg cell by the male sperm cell; the zygote possesses half the DNA from each of its two parents. In plants and some protists, the zygote will begin to divide by mitosis to produce a multicellular organism; the result of this process is an embryo. In human pregnancy, a developing fetus is considered as an embryo until the ninth week, fertilization age, or eleventh-week gestational age. After this time the embryo is referred to as a fetus. First attested in English in the mid-14c; the word embryon itself from Greek ἔμβρυον, lit. "young one", the neuter of ἔμβρυος, lit. "growing in", from ἐν, "in" and βρύω, "swell, be full". In animals, the development of the zygote into an embryo proceeds through specific recognizable stages of blastula and organogenesis; the blastula stage features a fluid-filled cavity, the blastocoel, surrounded by a sphere or sheet of cells called blastomeres.
In a placental mammal, an ovum is fertilized in a fallopian tube through which it travels into the uterus. An embryo is called a fetus at a more advanced stage of development and up until hatching. In humans, this is from the eleventh week of gestation. However, animals which develop in eggs outside the mother's body, are referred to as embryos throughout development. During gastrulation the cells of the blastula undergo coordinated processes of cell division, and/or migration to form two or three tissue layers. In triploblastic organisms, the three germ layers are called endoderm and mesoderm; the position and arrangement of the germ layers are species-specific, depending on the type of embryo produced. In vertebrates, a special population of embryonic cells called the neural crest has been proposed as a "fourth germ layer", is thought to have been an important novelty in the evolution of head structures. During organogenesis and cellular interactions between germ layers, combined with the cells' developmental potential, or competence to respond, prompt the further differentiation of organ-specific cell types.
For example, in neurogenesis, a subpopulation of ectoderm cells is set aside to become the brain, spinal cord, peripheral nerves. Modern developmental biology is extensively probing the molecular basis for every type of organogenesis, including angiogenesis, myogenesis and many others. In botany, a seed plant embryo is part of a seed, consisting of precursor tissues for the leaves and root, as well as one or more cotyledons. Once the embryo begins to germinate—grow out from the seed—it is called a seedling. Bryophytes and ferns produce an embryo, but do not produce seeds. In these plants, the embryo begins its existence attached to the inside of the archegonium on a parental gametophyte from which the egg cell was generated; the inner wall of the archegonium lies in close contact with the "foot" of the developing embryo. The structure and development of the rest of the embryo varies by group of plants; as the embryo has expanded beyond the enclosing archegonium, it is no longer termed an embryo.
Embryos are used in various fields of research and in techniques of assisted reproductive technology. An egg may be fertilized in vitro and the resulting embryo may be frozen for use; the potential of embryonic stem cell research, reproductive cloning, germline engineering are being explored. Prenatal diagnosis or preimplantation diagnosis enables testing embryos for conditions. Cryoconservation of animal genetic resources is a practice in which animal germplasms, such as embryos are collected and stored at low temperatures with the intent of conserving the genetic material; the embryos of Arabidopsis thaliana have been used as a model to understand gene activation and organogenesis of seed plants. In regards to research using human embryos, the ethics and legalities of this application continue to be debated. Researchers from MERLN Institute and the Hubrecht Institute in the Netherlands managed to grow samples of synthetic rodent embryos, combining certain types of stem cells; this method will help scientists to more study the first moments of the process of the birth of a new life, which, in turn, can lead to the emergence of new effective methods to combat infertility and other genetic diseases.
Fossilized animal embryos are known from the Precambrian, are found in great numbers during the Cambrian period. Fossilized dinosaur embryos have been discovered; some embryos do not survive to the next stage of development. When this happens it is called spontaneous abortion or miscarriage. There are many reasons; the most common natural cause of miscarriage is chromosomal abnormality in animals or genetic load in plants. In species which produce multiple embryos at the same time, miscarriage or abortion of some embryos can provide the remaining embryos with a greater share of maternal resources; this can disturb the pregnancy, causing harm to the second embryo. Genetic strains which miscarry their embryos are the source of commercial seedl
Human embryonic development
Human embryonic development, or human embryogenesis, refers to the development and formation of the human embryo. It is characterised by the process of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, the development of the human body entails growth from a one-celled zygote to an adult human being. Fertilisation occurs when the sperm cell enters and fuses with an egg cell; the genetic material of the sperm and egg combine to form a single cell called a zygote and the germinal stage of development commences. Embryonic development in the human, covers the first eight weeks of development. Human embryology is the study of this development during the first eight weeks after fertilisation; the normal period of gestation is 38 weeks. The germinal stage refers to the time from fertilization through the development of the early embryo until implantation is completed in the uterus; the germinal stage takes around 10 days. During this stage, the zygote begins in a process called cleavage.
A blastocyst is formed and implanted in the uterus. Embryogenesis continues with the next stage of gastrulation, when the three germ layers of the embryo form in a process called histogenesis, the processes of neurulation and organogenesis follow. In comparison to the embryo, the fetus has more recognizable external features and a more complete set of developing organs; the entire process of embryogenesis involves coordinated spatial and temporal changes in gene expression, cell growth and cellular differentiation. A nearly identical process occurs in other species among chordates. Fertilization takes place when the spermatozoon has entered the ovum and the two sets of genetic material carried by the gametes fuse together, resulting in the zygote; this takes place in the ampulla of one of the fallopian tubes. The zygote contains the combined genetic material carried by both the male and female gametes which consists of the 23 chromosomes from the nucleus of the ovum and the 23 chromosomes from the nucleus of the sperm.
The 46 chromosomes undergo changes prior to the mitotic division which leads to the formation of the embryo having two cells. Successful fertilization is enabled by three processes, which act as controls to ensure species-specificity; the first is that of chemotaxis. Secondly there is an adhesive compatibility between the egg. With the sperm adhered to the ovum, the third process of acrosomal reaction takes place; the entry of the sperm causes calcium to be released. A parallel reaction takes place in the ovum called the zona reaction; this sees the release of cortical granules that release enzymes which digest sperm receptor proteins, thus preventing polyspermy. The granules fuse with the plasma membrane and modify the zona pellucida in such a way as to prevent further sperm entry; the beginning of the cleavage process is marked when the zygote divides through mitosis into two cells. This mitosis continues and the first two cells divide into four cells into eight cells and so on; each division takes from 12 to 24 hours.
The zygote is large compared to any other cell and undergoes cleavage without any overall increase in size. This means that with each successive subdivision, the ratio of nuclear to cytoplasmic material increases; the dividing cells, called blastomeres, are undifferentiated and aggregated into a sphere enclosed within the membrane of glycoproteins of the ovum. When eight blastomeres have formed they begin to develop gap junctions, enabling them to develop in an integrated way and co-ordinate their response to physiological signals and environmental cues; when the cells number around sixteen the solid sphere of cells within the zona pellucida is referred to as a morula At this stage the cells start to bind together in a process called compaction, cleavage continues as cellular differentiation. Cleavage itself is the first stage in the process of forming the blastocyst. Cells differentiate into an outer layer of an inner cell mass. With further compaction the individual outer blastomeres, the trophoblasts, become indistinguishable.
They are still enclosed within the zona pellucida. This compaction serves to make the structure watertight, containing the fluid that the cells will secrete; the inner mass of cells differentiate to polarise at one end. They form gap junctions, which facilitate cellular communication; this polarisation leaves a cavity, the blastocoel, creating a structure, now termed the blastocyst. The trophoblasts secrete fluid into the blastocoel; the resulting increase in size of the blastocyst causes it to hatch through the zona pellucida, which disintegrates. The inner cell mass will give rise to the pre-embryo, the amnion, yolk sac and allantois, while the fetal part of the placenta will form from the outer trophoblast layer; the embryo plus its membranes is called the conceptus, by this stage the conceptus has reached the uterus. The zona pellucida disappears and the now exposed cells of the trophoblast allow the blastocyst to attach itself to the endometrium, where it will implant; the formation of the hypoblast and epiblast, which ar
Biologically, an adult is a human or other organism that has reached sexual maturity. In human context, the term adult additionally has meanings associated with social and legal concepts. In contrast to a "minor", a legal adult is a person who has attained the age of majority and is therefore regarded as independent, self-sufficient, responsible; the typical age of attaining legal adulthood is 18, although definition may vary by legal rights and country. Human adulthood encompasses psychological adult development. Definitions of adulthood are inconsistent and contradictory. Conversely, one may be an adult but possess none of the maturity and responsibility that may define an adult character. In different cultures there are events that relate passing from being a child to becoming an adult or coming of age; this encompasses the passing a series of tests to demonstrate that a person is prepared for adulthood, or reaching a specified age, sometimes in conjunction with demonstrating preparation. Most modern societies determine legal adulthood based on reaching a specified age without requiring a demonstration of physical maturity or preparation for adulthood.
And cross-culturally, adulthood has been determined by the start of puberty. In the past, a person moved from the status of child directly to the status of adult with this shift being marked by some type of coming-of-age test or ceremony. After the social construct of adolescence was created, adulthood split into two forms: biological adulthood and social adulthood. Thus, there are now two primary forms of adults: social adults. Depending on the context, adult can indicate either definition. Although few or no established dictionaries provide a definition for the two word term biological adult, the first definition of adult in multiple dictionaries includes "the stage of the life cycle of an animal after reproductive capacity has been attained". Thus, the base definition of the word adult is the period beginning at physical sexual maturity, which occurs sometime after the onset of puberty. Although this is the primary definition of the base word "adult", the term is frequently used to refer to social adults.
The two-word term biological adult stresses or clarifies that the original definition, based on physical maturity, is being used. The time of puberty varies, but begins around 10 or 11 years old. Girls begin the process of puberty at age 10 or 11, boys at age 11 or 12. Girls complete puberty by 15–17, boys by age 16 or 17. Nutrition and environment usually play a part in the onset of puberty. Adulthood means that one has reached the age of majority – when parents lose parenting rights and responsibilities regarding the person concerned. Depending on one's jurisdiction, the age of majority may or may not be set independently of and should not be confused with the minimum ages applicable to other activities, such as engaging in a contract, voting, having a job, serving in the military, buying/possessing firearms, traveling abroad, involvement with alcoholic beverages, sexual activity, being a model or actor in pornography, running for President, etc. Admission of a young person to a place may be restricted because of danger for that person, concern that the place may lead the person to immoral behavior or because of the risk that the young person causes damage.
One can distinguish the legality of acts of a young person, or of enabling a young person to carry out that act, by selling, renting out, permitting entrance, allowing participation, etc. There may be distinction between commercially and enabling. Sometimes there is the requirement of supervision by a legal guardian, or just by an adult. Sometimes there is no requirement, but rather a recommendation. Using the example of pornography, one can distinguish between: being allowed inside an adult establishment being allowed to purchase pornography being allowed to possess pornography another person being allowed to sell, rent out, or show the young person pornography, see disseminating pornography to a minor being a pornographic actor: rules for the young person, for other people, regarding production, etc. With regard to films with violence, etc.: another person being allowed to sell, rent out, or show the young person a film. Niger, Democratic Republic of Congo and Cameroon define adulthood at age 15, but marriage of girls at an earlier age is common.
In most of the world, including most of the United States and China, the legal adult age is 18 for most purposes, with some notable exceptions: British Columbia, New Brunswick and Labrador, Northwest Territories, Nova Scotia, Yukon Territory in Canada. In contrast to biological perspectives of aging and adulthood, social scientists conc
Developmental psychology is the scientific study of how and why human beings change over the course of their life. Concerned with infants and children, the field has expanded to include adolescence, adult development and the entire lifespan. Developmental psychologists aim to explain how thinking and behaviors change throughout life; this field examines change across three major dimensions: physical development, cognitive development, socioemotional development. Within these three dimensions are a broad range of topics including motor skills, executive functions, moral understanding, language acquisition, social change, emotional development, self-concept, identity formation. Developmental psychology examines the influences of nature and nurture on the process of human development, processes of change in context and across time. Many researchers are interested in the interactions among personal characteristics, the individual's behavior, environmental factors, including the social context and the built environment.
Ongoing debates include biological essentialism vs. neuroplasticity and stages of development vs. dynamic systems of development. Developmental psychology involves a range of fields, such as educational psychology, child psychopathology, forensic developmental psychology, child development, cognitive psychology, ecological psychology, cultural psychology. Influential developmental psychologists from the 20th century include Urie Bronfenbrenner, Erik Erikson, Sigmund Freud, Jean Piaget, Barbara Rogoff, Esther Thelen, Lev Vygotsky. John B. Watson and Jean-Jacques Rousseau are cited as providing the foundations for modern developmental psychology. In the mid-18th century Jean Jacques Rousseau described three stages of development: infants and adolescence in Emile: Or, On Education. Rousseau's ideas were taken up by educators at the time, it focuses on how and why certain modifications throughout an individual’s life-cycle and human growth change over time. There are many theorists. For example, Erik Erikson developed a model of eight stages of psychological development.
He believed that humans developed in stages throughout their lifetimes and this would affect their behaviors In the late 19th century, psychologists familiar with the evolutionary theory of Darwin began seeking an evolutionary description of psychological development. James Mark Baldwin who wrote essays on topics that included Imitation: A Chapter in the Natural History of Consciousness and Mental Development in the Child and the Race: Methods and Processes. James Mark Baldwin was involved in the theory of developmental psychology. Sigmund Freud, whose concepts were developmental affected public perceptions. Sigmund Freud believed that we all had a conscious and unconscious level. In the conscious, we are aware of our mental process; the preconscious involves information that, though not in our thoughts, can be brought into consciousness. Lastly, the unconscious includes mental processes, he believed there is tension between the conscious and unconscious because the conscious tries to hold back what the unconscious tries to express.
To explain this he developed three personality structures: the id, superego. The id, the most primitive of the three, functions according to the pleasure principle: seek pleasure and avoid pain; the superego plays the moralizing role. Based on this, he proposed five universal stages of development, that each is characterized by the erogenous zone, the source of the child's psychosexual energy; the first is the oral stage. During the oral stage, "the libido is centered in a baby's mouth." The baby is able to suck. The second is the anal stage, from one to three years of age. During the anal stage, the child defecates from the anus and is fascinated with their defecation; the third is the phallic stage. During the phallic stage, the child is aware of their sexual organs; the fourth is the latency stage. During the latency stage, the child's sexual interests are repressed. Stage five is the genital stage. During the genital stage, puberty starts happening. Jean Piaget, a Swiss theorist, posited that children learn by constructing knowledge through hands-on experience.
He suggested that the adult's role in helping the child learn was to provide appropriate materials that the child can interact with and use to construct. He used Socratic questioning to get children to reflect on what they were doing, he tried to get them to see contradictions in their explanations. Piaget believed that intellectual development takes place through a series of stages, which he described in his theory on cognitive development; each stage consists of steps. He believed that these stages are not separate from one another, but rather that each stage builds on the previous one in a continuous learning process, he proposed four stages: sensorimotor, pre-operational, concrete operational, formal operational. Though he did not believe these stages occurred at any given age, many studies have determined when these co