Developmental Psychology PDF - Hereditary Influences on Development

chromosomes to each of their children. The genes DEVELOPMENTAL on each chromosome also function as pairs, the two PSYCHOLOGY members of each gene pair be...

chromosomes to each of their children. The genes DEVELOPMENTAL on each chromosome also function as pairs, the two PSYCHOLOGY members of each gene pair being located at the same sites on their corresponding chromosomes. Genes are actually stretches of deoxyribonucleic acid (DNA), a complex, “double-helix” molecule that Hereditary Influences resembles a twisted ladder and provides the on Development chemical basis for development. A unique feature of DNA is that it can duplicate itself. The rungs of this The science of genetics is the study of ladderlike molecule split in the middle, opening somewhat like a zipper. Then each remaining half of heredity: the genetic transmission of the molecule guides the replication of its missing heritable characteristics from parents to parts. This special ability of DNA to replicate itself is offspring. what makes it possible for a one-celled zygote to develop into a marvelously complex human being. Genotype - the genetic endowment that an individual inherits. As the zygote moves through the fallopian tube toward its prenatal home in the uterus, it begins to Phenotype - the ways in which a person’s replicate itself through the process of mitosis. At genotype is expressed in observable or first, the zygote divides into 2 cells, but the 2 soon measurable characteristics. become 4, 4 become 8, 8 become 16, and so on. Just before each division, the cell duplicates its 46 To understand the workings of heredity, we must chromosomes, and these duplicate sets move in start at conception, the moment when an ovum opposite directions. The division of the cell then released by a woman’s ovary and on its way to the proceeds, resulting in two new cells, each of which uterus via the fallopian tube is fertilized by a man’s has the identical 23 pairs of chromosomes (46 in sperm. Once we establish what is inherited at all) and thus the same genetic material as the conception, we can examine the mechanisms by original cell. By the time a child is born, he or she which genes influence the characteristics we consists of billions of cells, created through mitosis, display. that make up muscles, bones, organs, and other bodily structures. Mitosis continues throughout life, generating new cells that enable growth and The Genetic Material replacing old ones that are damaged. With each The very first development that occurs after division, the chromosomes are duplicated, so that conception is protective: when a sperm cell every new cell contains an exact copy of the 46 penetrates the lining of the ovum, a biochemical chromosomes we inherited at conception. reaction repels other sperm, thus preventing them from repeating the fertilization process. Within a few hours, the sperm cell begins to disintegrate, The Germ (or Sex) Cells releasing its genetic material. The ovum also In addition to body cells, human beings have germ releases its genetic material, and a new cell nucleus cells that servone special hereditary function—to forms around the hereditary information provided by produce gametes (sperm in males and ova in the father’s sperm and the mother’s ovum. This new females). Male germ cells in the testes and female cell, called a zygote, is only 1/20th the size of the germ cells in the ovaries produce sperm and ova head of a pin. Yet this tiny cell contains the through a process called meiosis. The germ cell biochemical material for the zygote’s development first duplicates its 46 chromosomes. Then an event from a single cell into a complete human being. called crossing-over often takes place: adjacent What hereditary material is present in a human duplicated chromosomes cross and break at one or zygote? The new cell nucleus con more points along their length, exchanging tains 46 elongated, threadlike bodies called segments of genetic material. This transfer of genes chromosomes, each of which consists of during crossing-over creates new and unique thousands of chemical segments, or genes—the hereditary combinations. Next, pairs of duplicated basic units of heredity that work to build a single chromosomes (some of which have been altered by protein. Chromosomes come in matching pairs. crossing-over) segregate into two new cells, each of Each member of a pair corresponds to the other in which contains 46 chromosomes. Finally, the new size, shape, and the hereditary functions it serves. cells divide so that each of the resulting gametes One member of each chromosome pair comes from contains 23 single, or unpaired, chromosomes. At the mother’s ovum and the other from the father’s conception, then, a sperm with 23 chromosomes sperm cell. Thus, each parent contributes 23 unites with an ovum with 23 chromosomes, producing a zygote with a full set of 46 Independent assortment - the principle chromosomes. Brothers and sisters who have the that each pair of chromosomes same mother and father have inherited 23 chromosomes from each of their parents. Why is it, segregates independently of all other then, that offspring of the same parents sometimes chromosome pairs during meiosis. barely resemble each other? The reason is that Monozygotic (identical) twins - twins meiosis makes us genetically unique. who develop from a single zygote that later divides to form two genetically Conception - the moment of fertilization, identical individuals. when a sperm penetrates an ovum, Dizygotic (fraternal) twins - twins that forming a zygote. result when a mother releases two ova at Zygote - a single cell formed at roughly the same time and each is conception from the union of a sperm and fertilized by a different sperm, producing an ovum. two zygotes that are genetically different. Chromosome - a threadlike structure Autosomes - the 22 pairs of human made up of genes; in humans there are chromosomes that are identical in males 46 chromosomes in the nucleus of each and females. body cell. Chromosomes are coils of X chromosome - the longer of the two DNA that consist of smaller segments sex chromosomes; normal females have called genes, the functional units of two X chromosomes, whereas normal heredity. males have only one. Genes - hereditary blueprints for Y chromosome - the shorter of the two development that are transmitted sex chromosomes; normal males have unchanged from generation to generation. one Y chromosome, whereas females have none. Deoxyribonucleic acid (DNA) - long, double-stranded molecules that make up A useful analogy is to consider the DNA of an individual as a series of books in a library. Until chromosomes.The “stuff” of heredity is a those books are “read” by an enzyme called RNA chemical called deoxyribonucleic acid polymerase, and transcribed into a readable copy of (DNA). The double-helix structure of a messenger RNA (m-RNA), the knowledge DNA molecule resembles a long, spiraling contained within the books is not actualized. And ladder whose steps are made of pairs of what books will be pulled down from the shelf and read is in part determined by environmental factors chemical units called bases. that turn genes on and off at different points in Human genome - complete sequence of development. Every cell in the normal human body genes in the human body except the sex cells (sperm and ova) has 23 pairs Mitosis - the process in which a cell of chromosomes—46 in all. Through a type of cell division called meiosis, which the sex cells undergo duplicates its chromosomes and then when they are developing, each sex cell ends up divides into two genetically identical with only 23 chromosomes—one from each pair. daughter cells. When sperm and ovum fuse at conception, they Meiosis - the process by which a germ produce a zygote with 46 chromosomes, 23 from cell divides, producing gametes (sperm or the father and 23 from the mother. At conception, then, the single-celled zygote has all the biological ova) that each contain half of the parent information needed to guide its development into a cell’s original complement of unique individual. Through mitosis, a process by chromosomes; in humans, the products of which the non–sex cells divide in half over and over meiosis contain 23 chromosomes. again, the DNA replicates itself, so that each newly formed cell has the same DNA structure as all the Crossing-over - a process in which others. Each cell division creates a genetic genetic material is exchanged between duplicate of the original cell, with the same pairs of chromosomes during meiosis. hereditary information. Sometimes a mistake in copying is made, and a mutation may result. versions of the same gene. Every person receives Mutations are permanent alterations in genetic one maternal and one paternal allele for any given material. When development is normal, each cell trait. When both alleles are the same, the person is (except the sex cells) continues to have 46 homozygous for the characteristic; when they are chromosomes identical to those in the original different, the person is heterozygous. In dominant zygote. As the cells divide, they differentiate, inheritance, the dominant allele is always specializing in a variety of complex bodily functions expressed, or shows up as a trait in that person. that enable the child to grow and develop. The person will look the same whether or not he or she is heterozygous or homozygous because the Genes - Small segments of DNA located in recessive allele doesn’t show. For the trait to be definite positions on particular chromosomes; expressed in recessive inheritance, the person functional units of heredity. must have two recessive alleles, one from each parent. If a recessive trait is expressed, that person Human genome - Complete sequence of cannot have a dominant allele. Let’s take red hair genes in the human body. as an example. Because red hair is a recessive Mutations - Permanent alterations in genes or trait, you must receive two recessive copies (r) of chromosomes that may produce harmful the gene—one from each parent—in order to characteristics. express red hair. Having hair that is not red (R; Autosomes - In humans, the 22 pairs of brown in this example) is a dominant trait, so chromosomes not related to sexual you will have brown hair if you receive at least one expression. copy (R) from either parent (Rr or RR). If you Sex chromosomes - Pair of chromosomes receive one copy of the red hair allele (r) and one copy of an allele for brown hair (R), you are that determines sex: XX in the normal human heterozygous (Rr or rR); if you have two copies of female, XY in the normal human male. the allele for brown hair, you are homozygous dominant (RR). In both cases, you will have brown At the moment of conception, the 23 chromosomes hair. If you inherited one allele for red hair from from the sperm and the 23 from the ovum form 23 each parent, you are homozygous recessive for this pairs. Twenty-two pairs are autosomes, trait (rr) and will have red hair. Thus, the only chromosomes that are not related to sexual situation in which you would have red hair is if you expression. The twenty-third pair are sex received two recessive copies (r), one from each chromosomes—one from the father and one from parent. the mother—that ­govern the baby’s sex. Sex chromosomes are either X chromosomes or Y chromosomes. The sex chromosome of every ovum Dominant inheritance - Pattern of is an X chromosome, but the sperm may contain inheritance in which, when a child receives either an X or a Y chromosome. The Y different alleles, only the dominant one is chromosome contains the gene for maleness, expressed. called the SRY gene. When an ovum (X) is fertilized Recessive inheritance - Pattern of by an X-carrying sperm, the zygote formed is XX, a inheritance in which a child receives identical genetic female. When an ovum (X) is fertilized by a recessive alleles, resulting in expression of a Y-carrying sperm, the resulting zygote is XY, a nondominant trait. genetic male. Polygenic inheritance - the interaction of A hereditary basis for sex differences becomes several genes. For example, there is not an quite clear if we examine the chromosomes of “intelligence” gene that determines whether or normal men and women. These chromosomal not you are smart. Rather, a large number of portraits, or karyotypes, reveal that 22 of the 23 genes work in concert to determine your pairs of human chromosomes, called autosomes, intellectual potential. Like intelligence, most are similar in males and females. Sex is determined individual variations in complex behaviors or by the 23rd pair (called the sex chromosomes). In traits are governed by the additive influences males, the 23rd pair consists of one elongated body of many genes with small but identifiable known as an X chromosome and a short, stubby companion called a Y chromosome. In females, effects. In other words, they are polygenic. both these sex chromosomes are X chromosomes. Multifactorial transmission - illustrates the interaction of nature and nurture and how they Genes that can produce alternative expressions of affect outcomes. Combination of genetic and a characteristic (such as the presence or absence environmental factors to produce certain complex of dimples) are called alleles. Alleles are alternate traits. Imagine that Rio has inherited athletic talent and comes from a family of avid athletes. If his Simple dominant-recessive inheritance - a family nurtures his talent and he practices regularly, pattern of inheritance in which one allele he may become a skilled athlete. However, if he is dominates another not encouraged or not motivated to engage in so that only its phenotype is expressed. athletics, his genotype for athletic ability may not be Dominant allele - a relatively powerful gene expressed (or may be expressed to a lesser extent) in his phenotype. Some physical characteristics that is expressed phenotypically and masks (including height and weight) and most the effect of a less powerful gene. psychological characteristics (such as intelligence Recessive allele - a less powerful gene that is and musical ability) are products of multifactorial not expressed phenotypically when paired with transmission. Many disorders (such as a dominant allele. attention-deficit/hyperactivity disorder) arise when Homozygous - having inherited two alleles for an inherited predisposition (an abnormal variant of a an attribute that are identical in their effects. normal gene) interacts with an environmental factor, Heterozygous - having inherited two alleles either before or after birth. for an attribute that have different effects. Genes are turned off or on as they are needed by Carrier - a heterozygous individual who the developing body or when triggered by the displays no sign of a recessive allele in his or environment. This phenomenon is called her own phenotype but can pass this gene to epigenesis, or epigenetics. Far from being fixed offspring. once and for all, epigenetic activity is affected by a Codominance - condition in which two continual bidirectional interplay with nongenetic heterozygous but equally powerful alleles influences. Environmental factors, such as nutrition, produce a phenotype in which both genes are smoking, sleep habits, stress, and physical activity, fully and equally expressed. can cause epigenetic changes People whose genotype for an attribute consists of What Do Genes Do? two alleles of the same kind are said to be How do genes promote development? At the most homozygous for that attribute. Thus, an NN basic, biochemical level, they call for the production individual is homozygous for normal vision and will of amino acids, which form enzymes and other pass only genes for normal vision to his or her proteins that are necessary for the formation and children. An nn individual is homozygous for functioning of new cells. Genes, for example, nearsightedness (the only way one can actually be regulate the production of a pigment called melanin nearsighted is to inherit two of these recessive in the iris of the eye. People with brown eyes have alleles) and will pass nearsightedness genes to his genes that call for much of this pigment, whereas or her children. Finally, an Nn individual is said to be people with lighter (blue or green) eyes have genes heterozygous for this visual trait because he or she that call for less pigmentation. Genes also guide cell has inherited alternative forms of the allele. This differentiation, making some cells parts of the brain person will have normal vision, because the N allele and central nervous system, and others parts of the is dominant. And what kind of allele will the circulatory system, bones, skin, and so on. Some heterozygous person pass along to children? Either genes are responsible for regulating the pace and a normal-vision gene or a nearsightedness gene. timing of development. That is, specific genes are “turned on” or “turned off” by other regulatory genes Sickle-cell anemia - a genetic blood disease at different points in the life span. Environmental that causes red blood cells to assume an un factors clearly influence how genes function. usual sickle shape and to become inefficient at distributing oxygen. Some of the effects of the external environment are experienced by all humans, and some are Sex-linked characteristic - an attribute experienced by only some people. The former are determined by a recessive gene that appears called experience-expectant interactions, and the on the X chromosome; more likely to latter are called experience-dependent interactions. characterise males. In humans, the Y chromosome is smaller and carries far fewer Alleles - alternative forms of a gene that genes than the X chromosome. One outcome can appear at a particular site on a of this is that males receive only one copy chromosome. of any gene that happens to be carried on the sex chromosomes, whereas females receive two copies. So, if a woman has a “bad” copy and inappropriate emotionality. Estimates of of a particular gene, she has a backup heritability range from 60 to 80 percent. A wide copy. array of rare gene mutations, some of which However, if a male has a “bad” copy of a involve missing or duplicated segments of particular gene, that gene will be expressed. DNA, may increase susceptibility to Heterozygote females who carry one “bad” schizophrenia. However, monozygotic twins copy of a recessive gene and one “good” one are not always concordant for schizophrenia, are called carriers. If such a woman has perhaps due to epigenetic processes. children with an unaffected male (a man who Researchers also have looked at possible has a “good” copy of the gene), she has a 50 nongenetic influences, such as a series of percent chance of passing the disorder on to neurological insults in fetal life or exposure to any sons they might have. Sex-linked influenza or rubella. Infants born in urban recessive disorders are more common in areas or those whose mothers experienced males than in females. For example, red-green obstetric complications or who were poor or color blindness, hemophilia (a disorder in severely deprived as a result of war or famine which blood does not clot when it should) are at higher risk as are infants born during the winter months. Advanced paternal age is also Polygenic trait - a characteristic that is a risk factor for schizophrenia, and there are influenced indications that, at least for boys, having very by the action of many genes rather than a young fathers may put children at elevated risk single pair. as well. Human development - Scientific study of processes of change and stability throughout the human life span. Researchers consider Four Common Sex life-span development to be from “womb to Chromosome Abnormalities tomb,” comprising the entire human life span from conception to death. Heredity - Inborn traits or characteristics inherited from the biological parents. Environment - Totality of nonhereditary, or experiential, influences on development. Epigenetics: The interaction between genes and the environment can alter gene expression, affecting development. Nature vs. Nurture: Development is a result of the dynamic interplay between genetic predispositions and environmental influences. Individual Differences: Variations in development among individuals are often due to the unique combination of hereditary factors and environmental contexts. Congenital defect - a problem that is present (though not necessarily apparent) at birth; such defects may stem from genetic and prenatal influences or from complications of the birth process. Schizophrenia is a neurological disorder that affects about 1 percent of the U.S. popula tion each year. It is characterized by loss of contact with reality; hallucinations and delusions; loss of coherent, logical thought;  Germline gene therapy - a procedure, not yet Down syndrome - Chromosomal disorder perfected or approved for use with humans, characterized by moderate-to-severe mental in which harmful genes would be repaired or retardation and by such physical signs as a replaced with healthy ones, thereby downward sloping skin fold at the inner permanently correct ing a genetic defect. corners of the eyes. Also called trisomy-21. Phenylketonuria (PKU) - a genetic disease in which the child is unable to metabolize phenylalanine; if left untreated, it soon causes hyperactivity and mental retardation. Behavioral genetics - the scientific study of how genotype interacts with environment to determine behavioral attributes such as intelligence, personality, and mental health. Heritability - the amount of variability in a trait that is attributable to hereditary factors. Selective breeding experiment - a method of studying genetic influences by determining whether traits can be bred in animals through selective mating. Kinship the extent to which two individuals have genes in common. Genetic abnormalities may also result from Twin design - a study in which sets of twins mutations—changes in the chemical structure of that differ in zygosity (kinship) are compared to one or more genes that produce a new phenotype. determine the heritability of an attribute. Many mutations occur spontaneously and are Adoption design - study in which adoptees harmful or even fatal. Mutations can also be are compared with their biological relatives induced by environmental hazards such as toxic industrial waste, radiation, agricultural chemicals and their adoptive relatives to estimate the that enter the food supply, and possibly even some heritability of an attribute or attributes. of the additives and preservatives in processed Concordance rate - the percentage of cases foods. in which a particular attribute is present for one member of a twin pair if it is present for Genetic counseling - a service designed to the other. inform prospective parents about genetic Heritability coefficient - a numerical diseases and to help them determine the estimate, ranging from.00 to +1.00, of the likelihood that they would transmit such amount of variation in an attribute that is due disorders to their children. to hereditary factors. Amniocentesis - a method of extracting Nonshared environmental influence (NSE) - amniotic fluid from a pregnant woman so that an environmental influence that people living fetal body cells within the fluid can be tested together do not share that should make these for chromosomal abnormalities and other individuals different from one another. genetic defects. Shared environmental influence (SE) - an Chorionic villus sampling (CVS) - an environmental influence that people living alternative to amniocentesis in which fetal cells together share that should make these are extracted from the chorion for prenatal individuals similar to one another. tests. CVS can be performed earlier in Introversion/extroversion - the opposite pregnancy than is possible with poles of a personality dimension: introverts are amniocentesis. shy, anxious around others, and tend to Ultrasound - method of detecting gross physi withdraw from social situations; extroverts are cal abnormalities by scanning the womb with highly sociable and enjoy being with others. sound waves, thereby producing a visual Empathic concern - a measure of the extent outline of the fetus. to which an individual recognizes the needs of others individual genotype establishes a range of and is concerned about their welfare. possible responses to different kinds of life experiences: the so-called range Consider the evidence for schizophrenia—a of-reaction principle. In other words, serious mental illness, characterized by severe Gottesman claims that a genotype sets disturbances in logical thinking, emotional boundaries on the range of possible expression, and social behavior, which typically phenotypes that one might display in emerges in late adolescence or early adulthood. A response to different environments. An survey of several twin studies of schizophrenia important corollary is that because people suggests an average concordance rate of.48 for differ genetically, no two individuals should identical twins but only.17 for fraternal twins. In respond in precisely the same way to any addition, children who have a biological parent who particular environment. is schizophrenic are at an increased risk of Passive genotype/environment becoming schizophrenic themselves, even if they correlations - the notion that the are adopted by another family early in life. These rearing environments that biological are strong indications that schizophrenia is parents provide are influenced by the genetically influenced. parents’ own genes, and hence are - canalization to refer to cases where correlated with the child’s own genes limit or restrict development to genotype. a small number of outcomes. One example Evocative genotype/environment of a highly canalized human attribute is babbling in infancy. All infants, even deaf correlations assumes that a child’s ones, babble in pretty much the same way genetically influenced attributes over the first 8 to 10 months of life. The will affect the behavior of others environment has little if any effect on this toward him or her. For example, highly canalized attribute, which simply smiley, active unfolds according to a maturational babies receive more attention and program. Less canalized attributes such as positive social stimulation than moody intelligence, temperament, and personality and pas can be deflected away from their genetic sive ones pathways in any of several directions by a variety of life experiences. In the ancestral Active genotype/environment past, an inability to walk or talk would have correlations - the notion that our had profound adaptive consequences. A genotypes affect the types of human who could not do these things environments that we prefer and seek would have been unlikely to survive. out. Because they are so important, natural 1. People with different genotypes are selection has designed them to develop in likely to evoke different responses a predictable and reliable way within a from others and to select different variety of environments. They are too environmental niches for themselves. important to be left to chance. Thus, traits such as these tend to be highly canalized. 2. Yet the responses they evoke and With respect to motor development, typical the niches they select depend to no babies follow a predictable sequence: small extent on the particular crawling or scooting, walking, and then run individuals, settings, and ning, in that order, at certain approximate circumstances they encounter. ages. This sequence is said to be Although a child may be genetically canalized, in that children will follow this predisposed to be outgoing and same blueprint irrespective of many extroverted, for example, it would be variations in the environment. A similar difficult to act on this predisposition if process occurs for language. Despite differences in linguistic environments, she lived in the wilds of Alaska with a babies the world over reach language reclusive father. In fact, this youngster milestones at approximately the same time could well become rather shy and and in the same order. Cognition and reserved when raised in such an personality, however, are not highly asocial environment. canalized. They are more subject to In sum, genotypes and environments variations in experience. Instead, an interact to produce developmental  change and variations in and constraints and a person’s behavior. In developmental outcomes. True, genes societies in which nutrition has dramatically exert some influence on those improved, an entire generation has grown up aspects of the environment that we to tower over the generation before. are likely to experience. But the Canalization - Limitation on variance of particular environments available to us expression of certain inherited characteristics. limit the possible phenotypes that are Genotype-environment interaction - usually likely to emerge from a particular refers to the effects of similar environmental genotype. Perhaps Donald Hebb conditions on genetically different individuals, (1980) was not too far off when he and a discussion of these interactions is a way said that behavior is determined 100 to conceptualize and talk about the different percent by heredity and 100 percent ways nature and nurture interact. To take a by the environment, for it seems that familiar example, many children are exposed these two sets of influences are to pollen and dust, but those with a genetic complexly intertwined. predisposition are more likely to develop allergic reactions. Ethology - the study of the bioevolutionary Genotype-environment correlation - basis of behavior and development with a Tendency of certain genetic and environmental focus on survival of the individual. influences to reinforce each other; may be Natural selection - an evolutionary process, passive, reactive (evocative), or active. Also proposed by Charles Darwin, stating that called genotype-environment covariance. individuals with characteristics that promote - Passive correlations: Parents, who adaptation to the environment will survive, provide the genes that predispose a reproduce, and pass these adaptive child toward a trait, also tend to characteristics to offspring; those lacking these provide an environment that adaptive characteristics will eventually die out. encourages the development of that Sensitive period - the period of time that is trait. optimal for the development of particular - Reactive, or evocative, correlations: capacities, or behaviors, and in which the Children with differing genetic individual is particularly sensitive to makeups evoke different reactions environmental influences that would foster from others. For example, parents who these attributes. are not musically inclined may make a Modern evolutionary theory - the study of special effort to provide musical the bioevolutionary basis of behavior and experiences for a child who shows development with a focus on survival of interest and ability in music. This the genes. response, in turn, strengthens the Behavioral genetics - Quantitative study of child’s genetic inclination toward relative hereditary and environmental music. influences on behavior. - Active correlations: As children get Heritability - Statistical estimate of older and have more freedom to contribution of heredity to individual choose their own activities and differences in a specific trait within a given environments, they actively select or population. create experiences consistent with Concordant - Term describing tendency of their genetic tendencies. twins to share the same trait or disorder. - Reaction range refers to a range of potential Niche-picking - Tendency of a person, expressions of a hereditary trait. Body especially after early childhood, to seek out size, for example, depends largely on environments compatible with his or her biological processes, which are genetically genotype. regulated. Even so, a range of sizes is Nonshared environmental effects - The possible, depending on environmental unique environment in which each child grows opportunities up, consisting of distinctive influences or influences that affect one child differently than in height, weight, size of vocabulary, or another. frequency of communication. Obesity - Extreme overweight in relation to qualitative change age, sex, height, and body type as defined by Discontinuous changes in kind, having a body mass index at or above the 95th structure, or organization. percentile. nature/nurture issue Temperament - Characteristic disposition, or the debate among developmental theorists style of approaching and reacting to situations. about the relative importance of biological Gestation - Period of development between predispositions (nature) and environmental conception and birth. influences (nurture) as determinants of human Gestational age - Age of an unborn baby, development. usually dated from the first day of an expectant active/passive theme mother’s last menstrual cycle. a debate among developmental Cephalocaudal principle - The upper parts of theorists about whether children the body develop before the lower parts of the are active contributors to their trunk. own development or, rather, pas sive recipients of environmental influence. Theory and Research continuity/discontinuity issue a debate among theorists about theory whether developmental changes Coherent set of logically related con are quantitative and continuous, cepts that seeks to organize, explain, or qualitative and discontinuous and predict data. (stagelike). hypotheses Possible explanations for phenomena, used to predict the outcome of research Yes, typically a hypothesis comes before a theory in scientific investigation. A hypothesis is an initial idea or prediction that researchers propose based on observations or previous knowledge. Through testing and gathering evidence, hypotheses can be either supported or refuted. When a hypothesis is repeatedly supported by multiple studies and evidence, it may evolve into a theory—a well-established and broadly accepted explanation that ties together many observations and facts about a natural phenomenon. mechanistic model Model that views human development as a series of predictable responses to stimuli. psychoanalytic perspective organismic model View of human development as Model that views human development as shaped by unconscious forces that internally initiated by an active organism motivate human behavior. and as occurring in a sequence of quali psychosexual development In Freudian theory, an unvarying tatively different stages. sequence of stages of childhood quantitative change personality development in which Changes in number or amount, such as gratification shifts from the mouth to the anus and then to the genitals. Piaget’s term for incorporation of new psychosocial development information into an existing cognitive In Erikson’s eight-stage theory, the structure. socially and culturally influenced process accommodation of development of the ego, or self. Piaget’s term for changes in a cognitive structure to include new information. learning perspective equilibration View of human development that holds Piaget’s term for the tendency to seek that changes in behavior result from a stable balance among cognitive experience or from adaptation to the elements; achieved through a balance environment. between assimilation and behaviorism accommodation Learning theory that emphasizes the sociocultural theory predictable role of environment in Vygotsky’s theory of how contextual causing observable behavior. factors affect children’s development. classical conditioning zone of proximal development (ZPD) Learning based on associating a Vygotsky’s term for the difference stimulus that does not ordinarily elicit a between what a child can do alone response with another stimulus that and what the child can do with help. does elicit the response. scaffolding operant conditioning Temporary support to help a child Learning based on association of be master a task. havior with its consequences. information-processing approach reinforcement Approach to the study of cognitive The process by which a behavior is development by observing and analyzing strengthened, increasing the likelihood the mental processes involved in that the behavior will be repeated. perceiving and handling information. punishment contextual perspective The process by which a behavior is View of human development that sees weakened, decreasing the likelihood of the individual as inseparable from the repetition. social context. social learning theory bioecological theory Theory that behaviors are learned by Bronfenbrenner’s approach to under observing and imitating models. Also standing processes and contexts of called social cognitive theory. human development that identifies five reciprocal determinism levels of environmental influence. Bandura’s term for bidirectional forces evolutionary/sociobiological that affect development. perspective observational learning View of human development that Learning through watching the behavior focuses on evolutionary and biological of others. bases of behavior. self-efficacy ethology Sense of one’s capability to master Study of distinctive adaptive behaviors challenges and achieve goals. of species of animals that have evolved cognitive perspective to increase survival of the species. View that thought processes are central evolutionary psychology to development. Application of Darwinian principles of cognitive-stage theory natural selection and survival of the Piaget’s theory that children’s cognitive fittest to individual behavior. development advances in a series of Quantitative research deals with objectively four stages involving qualitatively measurable, distinct types of mental operations. numerical data that can answer questions organization Piaget’s term for the creation of such as “how much?” or “how many?” and that categories or systems of knowledge. is amenable to statistical analysis. schemes Quantitative research on human development Piaget’s term for organized patterns of is based on the scientific method, which thought and behavior used in particular situations. has traditionally characterized most scientific adaptation inquiry. Its usual steps are: Piaget’s term for adjustment to new 1. Identification of a problem to be studied, information about the environment, often on the basis of a theory or of achieved through processes of assimilation and accommodation. previous research; assimilation 2. Formulation of hypotheses to be tested by research; 3. Collection of data; 4. Statistical analysis of the data to determine whether they support the hypothesis; 5. Formation of tentative conclusions; and 6. Dissemination of findings so other observers can check, learn from, analyze, repeat, ethnographic study and build on the results. In-depth study of a culture, which uses scientific method a combination of methods including System of established principles and participant observation. processes of scientific inquiry, which participant observation includes identifying a problem to be Research method in which the observer studied, formulating a hypothesis to be lives with the people or participates in tested by research, collecting data, the activity being observed. analyzing the data, forming tentative correlational study conclusions, and disseminating findings. Research design intended to discover sample whether a statistical relationship be Group of participants chosen to repre tween variables exists. sent the entire population under study. experiment random selection Rigorously controlled, replicable proce Selection of a sample in such a way that dure in which the researcher manipu each person in a population has an lates variables to assess the eff ect of equal and independent chance of one on the other. being chosen. experimental group In an experiment, the group receiving the treatment under study. control group In an experiment, a group of people, similar to those in the experimental group, who do not receive the treat ment under study To ensure objectivity, some experiments, particularly in medical research, use double-blind proce dures, in which neither participants nor experimenters know who is receiving the treat ment and who is instead receiving an inert In naturalistic observation, researchers look placebo. at independent variable people in real-life settings. The researchers do In an experiment, the condition over which the experimenter has direct not try to alter behavior or the environ control. ment; they simply record what they see. In dependent variable laboratory observation, researchers observe In an experiment, the condition that may and record behavior in a controlled or may not change as a result of changes in the independent variable. environment, such as a laboratory. By operational definition observing all A definition stated solely in terms of the participants under the same conditions, operations used to measure a investigators can more clearly identify any dif phenomenon. ferences in behavior not attributable to the Cross-sectional study: A study designed to environment. assess age-related differences, in which cognitive neuroscience people of different ages are assessed on Study of links between neural pro cesses and cognitive abilities. one occasion. case study Longitudinal study: A study designed to Study of a single subject, such as an assess changes in the same group of individual or family. individuals over an extended period of time. This method tracks the development moving away, or other personal or behavior of the same participants at circumstances. multiple points in time. Sequential study: A study design that Ethics of Research combines cross-sectional and longitudinal techniques. In resolving ethical dilemmas, researchers microgenetic design should be guided by three principles. a research design in which par ticipants are studied intensively 1. Beneficence, which is the obligation over a short period of time as developmental changes occur; to maximize potential benefits to attempts to specify how or why participants those changes occur. and to minimize potential harm. For example, psychophysiological methods suppose you are a researcher studying the methods that measure the relationships between physi effect of failure on self-esteem. If you are ological processes and aspects going to deceive some of your participants by of children’s physical, cog telling them they failed on a laboratory task, nitive, social, or emotional what steps will you take to mitigate any poten behavior/development. tial harm you might cause them? clinical method a type of interview in which a par 2. Respect for participants’ autonomy ticipant’s response to each ques and protection of those who are tion (or problem) determines what unable to exercise their own the investigator will ask next. judgment. For example, if you ecological validity the state of affairs in which the are conducting research with toddlers, and a findings of one’s research are an 2-year-old refuses to participate, should you accurate representation of pro force the child to participate? What is the cesses that occur in the natural appropriate action in this case? environment. 3. Justice, which, in this case, is the cohort a group of people of the same age inclusion of diverse groups together who are exposed to similar cul with sensitivity to any special impact tural environments and historical the research may have on them. For events as they are growing up. example, it may be important cohort effect an age-related difference among that your study includes an appropriate and cohorts that is attributable to representative selection of diverse people. If cultural/historical differences in this is the case, have you developed culturally cohorts’ growing-up experiences appropriate materials and methods to use? rather than to true developmental change. Society for Research in Child Development (2007) - developed standards for age-appropriate treatment of children in research, covering such principles as avoidance of physical or psychological harm, obtaining the child’s assent as well as a parent’s or guardian’s informed consent, and responsibility to follow Attrition: The loss of participants during a up on any information that could jeopardize the child’s well-being. study, which can affect the validity and informed consent reliability of the results. This is a common the right of research participants issue in longitudinal studies, where to receive a simple explanation of all aspects of research that participants may drop out over time due to may affect their willingness to various reasons such as losing interest, participate. benefits-to-risks ratio a comparison of the possible layer of the blastocyst will become the benefits of a study for advanc ing knowledge and optimizing embryo, and the outer layer of cells will life conditions versus its costs to develop participants in terms of inconve into tissues that protect and nourish the nience and possible harm. confidentiality embryo. the right of participants to conceal ment of their identity with respect to the data that they provide. protection from harm Conception begins with ovulation, the right of research participants when an ovary releases an egg into the to be protected from physical or psychological harm. fallopian tube. During intercourse, sperm are deposited in the female reproductive tract and Prenatal development is often divided into travel through the cervix and uterus to the fallopian tube. Fertilization occurs when a three major phases. The first phase, sperm cell successfully penetrates and called the period of the zygote, lasts merges with the egg, creating a zygote. This from conception through implantation, zygote contains a complete set of 46 when chromosomes, 23 from the mother and 23 the developing zygote becomes firmly from the father. The zygote then begins a attached to the wall of the uterus. The pe series of cell divisions as it moves towards the riod of the zygote normally lasts about 10 uterus, a process called cleavage. By the time to 14 days (Leese, 1994). The second it reaches the uterus, the zygote has phase of prenatal development, the developed into a blastocyst, a structure period of the embryo, lasts from the consisting of an inner cell mass that will eventually form the embryo, and an outer layer beginning of that will form the placenta. The blastocyst the 3rd week through the end of the 8th. implants itself into the uterine lining, marking This is the time when virtually all the major the beginning of pregnancy. The cells of the organs are formed and the heart begins to embryo continue to divide and differentiate, beat (Corsini, 1994). The third phase, the developing into various tissues and organs, period of the fetus, lasts from the 9th while the placenta provides nourishment and week of pregnancy until the baby is born. oxygen to the growing embryo through the During mother's bloodstream. this phase, all the major organ systems begin to function, and the developing organism grows rapidly As the fertilized ovum, or zygote, moves down the fallopian tube toward the uterus, it divides by mitosis into two cells. These two cells and all the resulting cells continue to divide, forming a ball-like structure, or blastocyst, that will contain 60 to 80 cells After the blastocyst, a stage of early within development, moves towards the uterus 4 days of conception. Cell differentiation approximately 6 to 10 days post-conception, has already begun. The inner small protrusions resembling burrs appear on its outer surface. Upon reaching the uterine wall, these protrusions penetrate into it, accessing the mother's bloodstream. This process, known as implantation, is a critical milestone in pregnancy. During implantation, the blastocyst firmly attaches itself to the uterine wall, positioning and embedding within it. This entire choreographed process, known as the "window of implantation," typically spans about 48 hours, occurring 7 to 10 days following ovulation. Once implanted, the blastocyst resembles a small, transparent blister on the uterine wall. This entire process, including the formation of a watertight membrane called the amnion around the developing embryo, is usually completed within 10 to 14 days after ovulation. Development of Support Systems tures that protect and nourish the developing organism (Sadler, 1996). One membrane, the amnion, is a watertight sac that fills with fluid from the pregnant woman’s tissues. Once implanted, the blastocyst’s outer layer rapidly forms four major support strucThe purposes of this sac and its amniotic fluid are to cushion the developing organism against blows, regulate its temperature, Piagetian Approach and provide a weightless environment that Sensorimotor stage - during this stage (birth to balloon-shaped yolk sac approximately age 2), infants learn about that produces blood cells until the embryo themselves and their world through their is capable of producwill make it easier for developing sensory and motor activity, infants the embryo to move. Floating in this learn watery environment is a ing its own. This through senses and motor activity. yolk sac is attached to a third membrane, Circular reactions, in which an infant learns the chorion, which surrounds the amnion to reproduce events originally and eventually becomes the lining of the discovered by chance. Initially, an activity such placenta. A fourth membrane, the as sucking produces allantois, forms the embryo’s umbilical an enjoyable sensation that the baby wants to cord. repeat. The repetition again produces pleasure, which motivates the implantation the burrowing of the blastocyst into the baby to do it yet again lining of the uterus. amnion a watertight membrane that surrounds the 1. First substage (birth to about 1 developing embryo, serving to regulate its temperature month), neonates practice their and to cushion it against injuries. reflexes, engaging in a behavior even chorion a membrane that becomes attached to the uterine tissues to gather nourishment for the embryo. when its normal stimulus is not Placenta an organ, formed from the lining of the uterus present. For example, newborns suck and the chorion, that provides for respiration and reflexively when their lips are touched. nourishment of the unborn metabolic wastes. But they soon learn to find the nipple umbilical cord a soft tube containing blood vessels even when they are not touched, and that connects the embryo to the placenta. they suck at times when they are not  hungry. Infants thus modify and extend and actions in memory, largely through the scheme for sucking. symbols such as words, numbers, and mental 2. Second substage (about 1 to 4 pictures—frees toddlers from immediate months), babies learn to repeat experience. They can pretend, and their repre purposely a pleasant bodily sensation sentational ability affects the sophistication of first achieved by chance (say, sucking their pretending. They can think about actions their thumbs, as in Figure 1a). Also, before taking them. They no longer have to go they begin to turn toward sounds, through laborious trial and error to solve showing the ability to coordinate problems—they can try solutions in their mind different kinds of sensory information (vision and hearing). schemes Piaget’s term for organized patterns of 3. Third substage (about 4 to 8 thought and behavior used in particular months) coincides with a new interest situations. in manipulating objects and learning circular reactions about their properties. Babies Piaget’s term for processes by which an infant learns to reproduce desired intentionally repeat an action not occurrences originally discovered by merely for its own sake, as in the chance. second substage, but to get results representational ability beyond the infant’s own body. For Piaget’s term for capacity to store mental images or symbols of objects example, a baby this age might and events. repeatedly shake a rattle to hear the noise. 4. Fourth substage (about 8 to 12 months), they have learned to generalize from past experience to solve new problems. They modify and coordinate previous schemes, such as the schemes for crawling, pushing, and grabbing, to find one that works. This substage marks the development of complex, goal-directed behavior. 5. Fifth substage (about 12 to 18 months), babies begin to experiment with new behavior to see what will happen. They now engage in tertiary circular reactions, varying an action to get a similar result, rather than merely Piaget believed that children under 18 months repeating pleasing behavior they have could not engage in deferred imitation, accidentally discovered. For example, a more complex ability requiring long-term a toddler may squeeze a rubber duck memory. Deferred imitation is the reproduction that squeaked when stepped on, to of an observed behavior after the passage of see whether it will squeak again. For time. As the behavior is no longer happening, the first time, children show originality deferred imitation requires that a stored in problem solving. By trial and error, representation of the action be recalled. Piaget they try behaviors until they find the argued that young children could not engage best way to attain a goal. in deferred imitation because they lacked the 6. Sixth substage (about 18 months to ability to retain mental representations. 2 years) is a transition to the preoperational object permanence - the realization that stage of early childhood. Representational something continues to exist when out of sight. ability—the ability to mentally represent symbolic development - is the growth of objects pictorial competence, the ability to understand the nature of pictures dual representation - it is difficult for toddlers but could not use tactile (touch) information to to simultaneously mentally represent both the recognize a shape they had previously seen. actual However, they were able to use textured object and the symbolic nature of what it objects bidirectionally. In other words, if the stands for. In other words, they can either objects used as stimulus focus on the particular chair they are faced were either smooth or nubby, the infants could with (“This is a miniature chair”) or the symbol transfer vision to touch and touch to vision and what it represents (“Chairs are for sitting equally well in”), and so they may confuse the two Joint attention—which is of fundamental importance to social interaction, language Piagetian approach acquisition, and the understanding of others’ Approach to the study of cognitive intentions and mental states—develops development that describes qualitative stages in cognitive functioning. between 10 and 12 months, when babies information-processing approach follow an adults’ gaze by looking or pointing in Approach to the study of cognitive the same direction Young children who follow development that analyzes processes an adults’ gaze at 10 to 11 months have a involved in perceiving and handling information. larger vocabulary at 18 months, 2 years, and 2½ years than those who do not. Also, the use of pointing by children to capture the attention of adults around them has strong positive effects on children’s language comprehension and production Categorization - Adults can understand that plants and animals are both living things. Furthermore, they can understand that some animals are pets, that among those pets are cats and dogs, and that a chihuahua is a type of dog. These nested relationships are known as categories. Dividing the world into Habituation - a type of learning in which meaningful categories is vital to thinking repeated or continuous exposure to a about objects or concepts and their stimulus, relationships. It is the foundation of language, such as the shaft of light, reduces attention to reasoning, problem solving, and memory; that stimulus. In other words, familiarity without it, the world would seem chaotic and breeds loss of interest. meaningless. According to Piaget, the ability to group things into categories does not appear Dishabituation - Increase in responsiveness until around 18 months. after presentation of a new stimulus. Causality - the principle that one event Visual preference - the tendency to spend (squeezing) causes another (quacking). Piaget more time looking at one sight rather than believed that at about 4 to 6 months, as infants another. become able to grasp objects, they begin to Visual recognition memory - Ability to distinguish a recognize that they can act on their familiar visual stimulus from an unfamiliar one when environment. shown both at the same time. violation-of-expectations Cross-modal transfer - the ability to use Research method in which information gained from one sense to guide dishabituation to a stimulus that another—as when a person negotiates a dark conflicts with experience is taken as evidence that an infant recognizes the room by feeling for the location of familiar new stimulus as surprising. objects. Cross-modal transfer of some, but not all, modalities appears to be available almost Number - multiple programs of research from birth. For example, in one study, supported infants’ ability to discriminate newborns were able to visually recognize a between small sets of numbers. Theorists cylinder or a prism they had previously held argued that this data suggested babies have an innate rudimentary ability to add and display. it is not until about 18 months of subtract. age—the point at which they show other signs implicit memory Unconscious recall, generally of habits of symbolism such as inner and skills; sometimes called procedural experimentation—that they combine two memory. (or more) words explicit memory Intentional and conscious memory, to form simple sentences. generally of facts, names, and events. symbolic function working memory the ability to use symbols (such Short-term storage of information being as images and words) to represent actively processed. objects and experiences. A-not-B error representational insight the tendency of 8- to 12-month the knowledge that an entity can olds to search for a hidden object stand for (represent) something where they previously found other than itself. it even after they have seen it moved to a new location. A second major hallmark of the early Neo-nativism - the belief that infants are preoperational period is the blossoming of born with substantial innate pre knowledge about the physical world, tend (or symbolic) play. Toddlers often which requires less time and experience to pretend to be people they are not be (mommies, demonstrated than Piaget proposed. superheroes), and they may play these Research suggests that infants know roles with props such as a shoe box or a something about the permanency of stick objects very early on; such knowledge that symbolize other objects such as a does not have to be “constructed” as baby’s crib or a gun. Piaget proposed but is part of an infant’s genetic heritage. This does not mean that dual representation (dual encoding) there the ability to represent an object simultaneously as an object itself is no development or that no experience is and as a representation of some necessary for the mature expression of thing else. an ability, but rather that babies are animism attributing life and lifelike prepared by evolution to make sense of qualities to inanimate objects. certain egocentrism aspects of their physical world that are the tendency to view the world from one’s own perspective while universally experienced (such as the failing to recognize that others permanency of objects) may have different points of view. appearance/reality distinction the ability to keep the true proper The Preoperational Stage (2 ties or characteristics of an object to 7 Years) in mind despite the deceptive ap pearance the object has assumed; preoperational period notably lacking among young Piaget’s second stage of cognitive children during the preconceptual development, lasting from about period. age 2 to age 7, when children Conservation - they do not yet realize are thinking at a symbolic level but are not yet using cognitive that certain properties of objects (such as operations.Language is perhaps the most vol obvious form of symbolism that young ume, mass, or number) remain unchanged children when the objects’ appearances are altered in some superficial way decentration centric, and illogical than older in Piaget’s theory, the ability of concrete operational children to grade-school children. Yet, it is now consider multiple aspects of a equally clear that stimulus or situation; contrast (1) preschoolers are capable of reasoning with centration. reversibility logically about simple problems or the ability to reverse, or negate, concepts an action by mentally performing that are familiar to them and (2) a number the opposite action (negation). of factors other than lack of cognitive identity training—teaching children to operations may account for their poor recognize that the object or substance performances on Piaget’s cognitive tests. transformed in a conservation task is still the same object or substance, regardless of its new appearance. For example, a The Concrete-Operational child being trained to recognize identities Stage (7 to 11 Years) on a conservation-of-liquids task might be Concrete-operational period - children told, “It may look like less water when we rapidly acquire cognitive operations and pour it from a tall, thin glass into this apply these important new skills when shorter one, but it is the same water, and thinking about objects and events that there has to be the same amount to drink.” they have experienced. A cognitive theory of mind (TOM) a person’s concepts of mental operation is an internal mental activity that activity; used to refer to how chil enables dren conceptualize mental activity children to modify and reorganize their and how they attribute intention to and predict the behavior of images and symbols to reach a logical others conclusion. belief-desire reasoning the process whereby we explain and predict what people do based on what we understand their de sires and beliefs to be. false-belief task a type of task used in theory-of mind studies, in which the child must infer that another person does not possess knowledge that he or she possesses (that is, that the other person holds a belief that is false). Summing Up Taken together, the evidence we have Mental seriation—the ability to mentally reviewed suggests that preschool children arrange items along a are not nearly as illogical or egocentric as quantifiable dimension such as height or Piaget assumed. Today, many researchers weight. believe that Piaget underestimated the Transitivity - the ability to recognize relations among abilities of preschool children because If, for example, Juan is elements in a serial order. hisproblems were too complex to allow taller than Pedro, and Pedro is taller than them to demonstrate what they actually Sam, who is taller, Juan or Sam? knew. horizontal décalage Piaget’s term for a child’s uneven Clearly, Piaget was right in arguing that cognitive performance; an in preschool children are more intuitive, ego ability to solve certain problems even though one can solve similar problems requiring the same men tal operations. The Formal-Operational thought structures, he was testing. Recently this holistic-structures Stage assumption has been challenged by (11 to 12 Years and Beyond) research formal operations ers who question whether cognitive Piaget’s fourth and final stage of development is at all stagelike. From their cognitive development, from age 11 or 12 and beyond, when the perspective, a “stage” of cognitive individual begins to think more development implies that abrupt changes rationally and systematically in intellectual functioning occur as the about abstract concepts and hypothetical events. By child acquires several new competencies contrast, formal operations, over a relatively brief period. Yet we’ve first seen between the ages of 11 and 13 seen that cognitive growth doesn’t happen years of age, are mental actions that way. Major transitions in intellect performed on occur quite gradually, and there is often ideas and propositions. very little consistency in the child’s hypothetico-deductive reasoning in Piaget’s theory, a formal performance on tasks that presumably operational ability to think measure the abilities that define a given hypothetically. stage. For example, it may be years inductive reasoning the type of thinking that scientists before a 7-year-old who can seriate or display, where hypotheses are conserve number will be able to conserve generated and then systematically tested in experiments volume. Furthermore, it now appears that imaginary audience different concrete-operational and a result of adolescent egocentrism; formal-operational adolescents believe that everyone around them is as interested in problems are mastered in different orders their thoughts and behaviors as by different children, a finding that they are themselves. suggests that there is less consistency and Piaget Failed to Distinguish coherence to cognitive growth than Piaget Competence from Performance assumed We have commented repeatedly Does Piaget “Explain” Cognitive throughout this chapter that Piaget Development? underestimated Even those researchers who claim that the cognitive capabilities of infants, cognitive growth is stagelike are bothered toddlers, and preschool children. One by reason for Piaget’s account of how children move this consistent underestimation of from one stage of intellect to the next. children’s abilities is that Piaget was Piaget Devoted Too Little Attention to concerned Social and Cultural Influences with identifying the underlying Children live in varied social and cultural competencies, or cognitive structures, that contexts that affect the way their world is presumably structured. Although Piaget admitted that determined how children perform on cultural factors may influence the rate of various cognitive tasks. He tended to cognitive growth, developmentalists now assume know that culture influences how children that a child who failed in one of his think as well problems simply lacked the underlying concepts, or Cognitive Schemes and existing models of the world, the schemes they al Cognitive Processes ready possess. The young child who sees According to Piaget, cognition develops a horse through the refinement and transformation for the first time may try to assimilate it of mental structures, or schemes (Piaget into one & Inhelder, 1969). Schemes are of her existing schemes for four-legged unobservable animals mental systems that underlie intelligence. and thus may think of this creature as a A scheme is a pattern of thought or action “dog and is most simply viewed as some gie.” enduring knowledge base by which Accommodation, children inter the complement of assimilation, is the pret their world. Schemes, in effect, are process of modifying existing structures in representations of reality. Children know order to account for new experiences. So their the child who recognizes that a horse is world through their schemes. Schemes not a dog may invent a name for this new are the means by which children interpret creature or perhaps say, What dat?” and and adopt the label that her companions use. organize experience. In so doing, she has modified (accommodated) her scheme for Organization is the process by which four-legged animals to include a new children combine existing schemes into category of experience—horses. new and more complex intellectual schemes. For example, an infant who has “gazing,” “reaching,” and “grasping” reflexes soon organizes these initially unrelated schemes into a more complex structure—visually directed reaching—that enables him to reach out and discover the characteristics of Organization is the tendency to create many interesting objects in the categories, such as birds, by environment; an inborn tendency to combine observing the characteristics that individual and integrate available schemes members of a category, such into coherent systems or bodies of as sparrows and cardinals, have in common. knowledge. According to Piaget, people The goal of organization is to promote create increasingly complex cognitive adaptation, the process of adjusting to structures called schemes, ways of the demands of the environment. organizing information about the world. These According to Piaget, adaptation occurs schemes can be either through two motor or mental in nature. Take sucking, for complementary activities: assimilation and example. A newborn infant has a simple scheme for sucking but soon develops varied accommodation. schemes for how to suck at the breast, a Assimilation is the process by which bottle, or a thumb. The infant may have to children open their mouth wider or turn their head try to interpret new experiences in terms of to the side or suck with varying strength. their  Adaptation is Piaget’s term for how of development involved learning how to do so children handle new information in light of in socially acceptable ways. In addition, what they already know. Adaptation occurs Freud believed that early experiences shaped through two complementary processes: later functioning, and he drew attention to (1) assimilation, taking in new information childhood as an important precursor to adult and incorporating it into existing cognitive behavior. Freud also promoted the idea structures, and (2) accommodation, adjusting that there was a vast, hidden reserve to our one’s cognitive structures to fit the new psyche, and what we consciously know about information. and experience is only the small tip of the Equilibration—a constant striving for iceberg of who we are. a stable balance—motivates the shift between assimilation and accommodation. For Newborns are governed by the id, which example, Anaya knows what birds are and operates under the pleasure principle—the sees a drive to seek immediate satisfaction of their plane for the first time. She labels the plane a needs and desires. “bird” (assimilation). Over time Anaya The ego, which represents reason, develops starts to notice differences between planes gradually during the first year or so of life and and birds. For example, she might notice that operates under the reality principle. The although both planes and birds fly, birds have ego’s aim is to find realistic ways to gratify the feathers, while planes are made of some id that are acceptable to the superego, which thing hard and smooth, and that birds have develops at about age 5 or 6. eyes and planes do not. These observations The superego includes the conscience and bring about an uneasy motivational state incorporates socially approved “shoulds” and known as disequilibrium. Anaya is then moti “should nots” into the child’s value system. The vated to change her understanding to more superego is highly demanding; if its standards closely reflect her observations—perhaps by are not met, a child may feel guilty and learning the label for plane and realizing that anxious. The ego mediates between the planes and birds are not, after all, the same impulses of the id and the thing. In other words, accommodation has demands of the superego occurred, and Anaya is now at equilibrium. psychosexual development In Freudian theory, an unvarying sequence of stages of childhood personality development in which gratification shifts from the mouth to the anus and then to the genitals. At each stage, the behavior that is the chief source of gratification (or frustra tion) changes—from feeding to elimination and eventually to sexual activity. invariant developmental sequence Freud considered the first three stages to be a series of developments that occur in one particular order be crucial for personality development. cause each development in the According to Freud, if children receive too little sequence is a prerequisite for those appearing later. or too much gratification in any of these PSYCHOANALYTIC stages, they are at risk of fixation, an arrest in psychoanalytic perspective development that can show up in adult View of human development as personality. shaped by unconscious forces that motivate human behavior. castration anxiety in Freud’s theory, a young boy’s Freud proposed that fear that his father will castrate humans were born with a series of innate, him as punishment for his rival biologically based drives such as hunger, sex, rous conduct. and aggression. He thought people were motivated to satisfy their urges, and that much  - Babies whose needs are not met MORAL DEVELOPMENT AND during the oral stage, when feeding is PROSOCIAL BEHAVIOR the main source of pleasure, may grow up to become nail-biters or smokers. - A person who, as a toddler, had too-strict toilet training may be fixated at the anal stage, and be obsessively clean, rigidly tied to schedules and routines, or defiantly messy. - A key event in psychosexual development occurs i