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Chapter Two: Theories of Development What Theories Do Developmental theory—systematic statement of principles and generalizations that provides a coherent framework for studying development What Theories Do, cont. Theories form basis for hypotheses that can be tested by research studies formulating right question is more difficult that finding right answers generate discoveries offer insight and guidance by providing coherent view What Theories Do, cont. Different Types grand theories—comprehensive, traditional theories minitheories—theories that focus on specific area of development originated in psychology originated more in sociology through study of social groups and family structures emergent theories—new, comprehensive groupings of minitheories multidisciplinary approach includes historic events and genetic discoveries Grand Theories Grand Theories—powerful framework for interpreting and understanding change and development that applies to all individuals in all contexts, across all contents Psychoanalytic Theory Psychoanalytic theory interprets human development in terms of motives and drives Freud’s Ideas Sigmund Freud Three stages of development in first six years oral, anal, phallic in early childhood, latency and then adolescence, genital each stage includes potential conflicts how a person experiences and resolves conflicts determines personality and patterns of behavior Erikson’s Ideas Erik Erikson, a follower of Freud, proposed 8 developmental stages, each characterized by a developmental crisis trust vs. mistrust autonomy vs. shame initiative vs. guilt industry vs. inferiority identity vs. role diffusion intimacy vs. isolation generativity vs. stagnation integrity vs. despair Behaviorism Behaviorism is built on laws of behavior and processes by which behavior is learned focus: ways we learn specific behaviors that can be described, analyzed, and predicted with scientific accuracy Laws of Behavior Conditioning—any process in which behavior is learned Classical conditioning—Ivan Pavlov process by which a neutral stimulus become associated with a meaningful stimulus stimulus and response (respondent conditioning) Operant conditioning—B. F. Skinner process by which a response is gradually learned via reinforcement or punishment also called instrumental conditioning Social Learning Extension of learning theory that includes modeling which involves people observing behavior and patterning their own after it Modeling process in which people observe, then copy behavior Alfred Bandura—most likely to occur if model is admired or observer is inexperienced self-efficacy motivates people to change themselves and their contexts Cognitive Theory Focuses on the structure and development of thought processes, which shape perceptions, attitudes, and actions. Jean Piaget’s 4 Stages sensorimotor pre-operational concrete operational formal operational Cognitive Theory, cont. Cognitive equilibrium—state of mental balance Cognitive adaptation—assimilation, accommodation of ideas Emergent Theories Emergent theories arise from several accumulated minitheories and may be the new systematic and comprehensive theories of the future Sociocultural Theory Seeks to explain growth of individual knowledge, development, and competencies in terms of guidance, support, and structure supplied by the society human development is the result of dynamic interaction of the developing persons and their surrounding culture Guided Participation Guided participation—tutor engages learner in joint activities, providing instruction and direct involvement in learning Apprenticeship in thinking—mentor provides instruction and support needed by novice The Zone of Proximal Development Zone of proximal development—range of skills learner can perform with assistance but not independently learner is drawn into learning by teacher Cultural variations: Basic principles are universal, but skills, challenges, and opportunities vary from culture to culture, depending on the values and structures of the culture’s society Epigenetic Theory Emphasizes the interaction between genes and the environment—the newest developmental theory stresses that we have powerful instincts and abilities that arise from our biological heritage. Timing and pace of certain developmental changes are genetically guided performism—everything is set in advance by genes and then is gradually manifested in the course of maturation With, On, and Around the Genes Genetic refers to the entire genome that makes up the particular genes that cause each person to be unique each human has a genetic foundation that is unique epigenetic theory acknowledges the powerful instincts and abilities that arise from our biological heritage With, On, and Around the Genes, cont. Epi = with, around, before, after, on, or near = surrounding factors epigenetic—surrounding factors that affect expression of genetic instructions some surrounding factors may be stress factors; others may be facilitating factors Genetic-environmental Interactions genes never function alone Genetic Adaptation Adaptation of the Genes selective adaptation means that genes for the traits that are most useful will become more frequent, thus making survival of species more likely What Theories Can Contribute Psychoanalytic theory has made us aware of importance of early childhood experiences Behaviorism has shown effect of immediate environment on learning Cognitive theory helps us understand how intellectual process and thinking affect actions What Theories Can Contribute, cont. Sociocultural theory has reminded us that development is embedded in a rich and multifaceted context Epigenetic theory emphasizes interactions between inherited forces and immediate contexts Other Theories Brief Solution Focused Narrative Art Play PsychoDrama Object-Relations Jungian Transactional Analysis 12 - step Social Learning Biblio-therapy What Theories Can Contribute, cont. Eclectic perspective approach taken by most developmentalists in which they apply aspects of each of the various theories rather than staying with just one “Integrated” is better Eclectic verses Integrated Eclectic picks from multiple sources without common thread: Integration Integration picks from theories with purpose and with commonality Level of Concepts Technique Template Theory The Nature-Nurture Controversy Is it heredity or environment that shapes us? How much is a result of any given characteristics, behavior or pattern of development is a result of genes and how much is a result of experiences Policy and practice: nature/nurture theories are implicit in many public policies Theoretical Perspectives on Hyperactivity and Homosexuality AD/HD and homosexuality—How and to what extent are nature and nurture involved in each case? Evidence from AD/HD research that it can come from either Theoretical Perspectives on Hyperactivity and Homosexuality, cont. Earlier assumptions about homosexuality: more nurture than nature. As hypotheses tested, nurture was revealed as less crucial sexual orientation may be a matter of nature sexual expression may be a matter of cultural attitude (nurture) but not sexual orientation evidence supporting nature as main factor (e.g., affect of genetic linkage, prenatal hormones) Theoretical Perspectives on Hyperactivity and Homosexuality, cont. Ideology often adds to complexity and polarization of opinions on many subjects when nature and nurture are considered Important to separate assumptions from facts done via research and testing of hypotheses Chapter Three: Heredity and Environment The Genetic Code Development that is dynamic, ongoing, interactional, and unique; just four chemicals are the basic building blocks of the genetic code What Genes Are Genes are made up of DNA—the complex protein code of genetic information DNA directs the form and function of each body cell as it develops What Genes Are, cont. Each molecule of DNA is called a chromosome Chromosomes contain instructions to make all the proteins a living being needs The complete packet of instructions is called a genome Each person has 23 sets of chromosomes, or 46 chromosomes The human genome contains 30,000 genes The Beginnings of Human Life Gamete—reproductive cell that directs process by which genetic information combined and transmitted Father gametes—sperm Mother gametes—ovum Zygote and Genotype Male and female gametes fuse and become a zygote Zygote begins process of duplication and division two reproductive cells Genotype—the genetic information from the 46 chromosomes set at human conception and endures through life Sex Determination and Sex Ratio Of 22 out of 23 pairs of human chromosome, the matching chromosomes are very closely matched but not identical some genes come in slight, normal variations called alleles The 23rd pair is different in females, it is designated XX in males, it is designated XY Sex Determination and Sex Ratio, cont. Females always contribute one X Males will have 1/2 of the sperm contributing an X and the other half contributing a Y Critical factor in determining the sex of a zygote is which sperm reaches the ovum first Sex Determination and Sex Ratio, cont. Other factors include rarely, male sperm may only carry either X or Y sometimes a woman’s uterus either unusually alkaline or acid, giving either an X or Y sperm an advantage in a stressful pregnancy XY embryos are more likely to be expelled than are XX embryos in a spontaneous abortion, or miscarriage current sex ratio in United States is 52 males to 48 females Multiple Zygotes Monozygotic twins—identical twins (or quadruplets) originate from one zygote share identical instructions possibility of cloning 1/3 of twins monozygotic Multiple Zygotes, cont. Dizygotic twins—from two separate zygotes Dizygotic births occur once in every 60 births, and occur as frequently as 1 in 6 pregnancies, but usually only 1 twin develops past embryo stage Multiple Zygotes, cont. Dizygotic twins women in late 30’s are three times more likely to have dizygotic twins as menopause approaches, ovulation becomes irregular with some cycles producing no ovas and others producing multiple ovas share no more genes than other offspring (about 50 percent) 50 percent of the time one twin is male Duplication, Division, and Differentiation The zygote contains a complete set of instructions to create a person Complex instructions on duplication, cell division, and differentiation Duplication and Division Zygote begins duplication and division within hours after conception the 23 pairs of chromosomes duplicate, forming two complete sets of the genetic code for that person (zygote) these two pair sets move toward the opposite sides of the zygote and the single cell in the zygote splits down the middle the zygote’s outer membrane surrounds two cells, each containing a complete set of the original genetic code these two cells then duplicate and divide to become four, then eight, and so on Duplication and Division, cont. by birth, your original zygote has duplicated and divided into 10 trillion cells . . . by adulthood, it’s 100 trillion cells Every cell carries an exact copy of the complete genetic instructions inherited by the one-celled zygote Differentiation Not just any cell found in the zygote can become a person At the 8-cell stage a third process, differentiation, occurs Cells begin to specialize they take different forms they reproduce at different rates, depending on where in the growing mass they are located Differentiation, cont. Certain genes affect differentiation by switching other genes on and others off so that the other genes produce the right proteins at the right times—onoff switching mechanisms Genotype—the genetic potential Gene - Gene Interactions Multifactoral traits—inherited traits produced by interaction of genes and environment Polygenetic traits—inherited traits produced by gene interaction These are affected by on-off switching mechanisms, additive genes, and dominant-recessive genes Additive Genes Additive genes—one of a number of genes affecting a specific trait each additive gene contributes to the trait skin color and height are determined by them every additive gene has some impact on a person’s phenotype when genes interact this way, all the involved genes contribute fairly equally Dominant and Recessive Genes Nonadditive genes—phenotype shows one gene more influential than other genes This is also referred to as the dominant-recessive pattern gene showing the most influence is referred to as dominant gene showing the least influence is referred to as recessive Dominant and Recessive Genes, cont. X-linked genes—located on X chromosome if recessive gene is X-linked, that it is on the X chromosome is critical males have only one X chromosome; females have 2 X chromosomes Whatever recessive genes a male inherits on his X chromosome cannot be counterbalanced or dominated by alleles on a second X, so any recessive genes on X will be expressed Explains why males have more X-linked disorders (ex. color blindness, many allergies, several diseases, some learning disabilities) More Complications Genes direct the creation of 20 amino acids that produce thousands of proteins forming the body’s structure and directing biochemical functions proteins of each body cell are continually affected by other proteins, nutrients, and toxins that influence the cell functioning More Complications, cont. genetic imprinting—tendency of certain genes to be expressed differently when inherited from mother than from father (tagging) some of the genes which influence height, insulin production, and several forms of mental retardation affect a child differently depending on which parent they came from Genetic Diversity Every person is unique Mechanisms of Genetic Diversity Since each gamete contains only 23 chromosomes, why is every conception genetically unique? 8 million chromosomally different ova x 8 million of the same = 64 trillion different possibilities of children from each couple Health Benefits of Genetic Diversity Genetic diversity safeguards human health Minute differences can affect the ability to stave off certain diseases Genetic diversity maintains the species From Genotype to Phenotype Every psychological characteristic is genetically influenced Every psychological characteristic and personal trait is affected by the environment From Genotype to Phenotype, cont. Genotype—genetic potential Phenotype—the actual appearance of an indivudal--combination of genetic potential and expression we are all carriers of the unexpressed genes we can pass them along through the sperm or ova Behavior Genetics Behavior genetics—study of effects of genes on behavior personality patterns, psychological disorders, and intellectual abilities Senility Caused by Alzheimer’s Disease Most common and feared type of senility is Alzheimer’s disease amyloid B protein accumulates in the brain, leading to dysfunction and destruction of brain cells and disruption of the mind Can be genetic—but only when “early-onset” Senility Caused by Alzheimer’s Disease, cont. If “late-onset,” may be a combination of genes and environment other predictors may include hypertension, diabetes, high cholesterol, diet, exercise, not smoking, weight control, mental alertness, and physical health Alcoholism Inherited biochemistry makes some people highly susceptible to alcohol addiction addictive pull can be overpowering, or weak, or something in the middle may explain ethnic variations Alcoholism, cont. Not simply a biochemical reaction—it is psychological and physical, and biological; thus alcoholism is polygenetic, with alcoholics inheriting a combination of biochemistry-affecting and temperament-affecting genes Culture counts too(whether alcohol is present in environment) Chromosomal and Genetic Abnormalities We now give attention to these because we can recognize disruptions of normal development origins of genetic and chromosomal abnormalities misinformation and prejudice add to problems of people with these abnormalities Chromosomal Abnormalities A gamete with more than or less than 23 chromosomes creates a zygote with chromosomal abnormalities most likely variable that creates chromosomal abnormalities is mother’s age (over 35) father’s age (over 40) also a variable Chromosomal Abnormalities, cont. Most zygotes with chromosomal abnormalities never come to term spontaneous abortion occurs in about onehalf of all fetus with chromosomal abnormalities Down Syndrome Three chromosomes at gene #21 (trisomy-21) Syndrome—a cluster of distinct characteristics that occur together in a given disorder Abnormalities of the 23rd Pair Location of sex chromosome Kleinfelters syndrome—XXY Fragile X syndrome seemingly normal child has delayed puberty hanging on by a thread (mutated gene) intensifies from generation to generation Page 78 Genetic Testing and Genetic Counseling Individuals with a parent, sibling, or child with a serious genetic condition known to be dominant or recessive Couples with history of early spontaneous abortions, stillbirths, or infertility Couples from the same ethnic group or subgroup—especially if closely related Women over 35 and men over 40 The Process of Genetic Counseling Counselor constructs couples’ family history charts patterns of health and illness over generations Some tests provide information before conception The Process of Genetic Counseling, cont. Other tests are prenatal- page 83 alpha-fetoprotein assay ultrasound (AKA sonogram) amniocentesis chorionic villi sampling pre-implantation testing (used in in vitro fertilization) gamete selection; ova/and or sperm are screened to select ones free of particular problems A Basis for Decision Many want to know ahead of time Some do not There is a more knowledge of what is to come—or not Alternatives If both partners are carriers of a serious condition or are at high risk because of age or family characteristics, they may turn to in-vitro fertilization (IVF) gamete intrafallopian transfer (GIFT) zygote intrafallopian transfer (ZIF) artificial insemination donor (AID) postponement of pregnancy until promising treatments are further developed Chapter Four Prenatal Development and Birth From Zygote to Newborn Germinal period—first 14 days Embryonic period—3rd through 8th weeks Fetal period—9th week through birth Process of Conception Germinal: The First 14 Days • • Zygote divides and keep dividing (at least though 3rd doubling they are the same) At this stage (8 cells) differentiation begins - early “stem” cells take on distinct characteristics they gravitate to locations, foreshadowing the type of cells they will become Germinal: The First 14 Days, cont. • At about a week after conception the multiplying cells separate into two masses - - • outer layer forms a shell (later the placenta) and the inner cells from a nucleus (later the embryo) first task of out cells to achieve implantation— embed themselves into the nuturant environment of the uterus 60% of all natural conceptions fail to implant; 70% of in vitro procedures fail to implant Embryo: From the Third to the Eighth Week First sign of human structure: thin line down the middle (22 days) that becomes the neural tube, which eventually forms the central nervous system, including brain and spinal column fourth week head begins to take shape heart begins with a miniscule blood vessel that begins to pulsate Embryo: From the Third to the Eighth Week, cont. fifth week arm and leg buds appear tail-like appendage extends from the spine eighth week embryo weighs 1 gram and is 1 inch long head more rounded; face formed all basic organs and body parts (but for sex) present 20% of all embryos spontaneously abort now Fetus: From the Ninth Week Until Birth Called a fetus from 9th week on Third Month • Sex organs take shape (Y cell sends signal to male sex organs; for females, no signal occurs) - genital organs fully shaped by 12th week • All body parts present • Fetus can move every part of body • Fetus weighs 3 ounces and is 3 inches long Middle Three Months: Preparing to Survive • • • Heartbeat stronger Digestive and excretory systems develop more fully Impressive brain growth (6X in size and responsive) - new neurons develop (neurogenesis) synapses—connections between neurons (synaptogenesis) Middle Three Months: Preparing to Survive, cont. • Age of viability—age at which preterm baby can possibly survive (22 weeks) - - 26 weeks survival rate about 50% . . brain maturation critical to viability weight critical to viability 28 weeks survival rate about 95% Fetal Brain Maturation Final Three Months— Viability to Full Term • Maturation of the respiratory and cardiovascular systems - • critical difference Gains weight—4.5 lbs. in last 10 weeks Risk Reduction Despite complexity, most babies are born healthy Most hazards are avoidable Teratology—study of birth defects Teratogens (ter-at-o-gens)—broad range of substances that can cause environmental insults that may cause prenatal abnormalities or later learning abilities Determining Risk Risk analysis—weighing of factors that affect likelihood of teratogen causing harm Timing of Exposure • Critical period—in prenatal development, the time when a particular organ or other body part is most susceptible to teratogenic damage - entire embryonic period is critical Amount of Exposure Dose and/or frequency Threshold effect—teratogen relatively harmless until exposure reaches a certain level Amount of Exposure, cont. • Interaction effect—risk of harm increases if exposure to teratogen occurs at the same time as exposure to another teratogen or risk Genetic Vulnerability • • Genetic susceptibilities: product of genes combined with stress Folic-acid deficiency may cause neural- tube defects - • occurs most commonly in certain ethnic groups and less often in others Males are more genetically vulnerable Specific Teratogens No way to predict risk on an individual basis Research has shown possible effects of most common and damaging teratogens AIDS and alcohol extremely damaging pregnant women with AIDS transmit it to their newborns; high doses of alcohol cause FAS; alcohol + drug use increase risk to developing organism Low Birthweight Low Birthweight (LBW) less than 5 1/2 lbs. grows too slowly or weighs less than normal more common than 10 years ago second most common cause of neonatal death Preterm birth occurs 3 or more weeks before standard 38 weeks Low Birthweight, cont. Small for Gestational Age (SGA) maternal illness maternal behavior cigarette smoking (25% of SGA births) maternal malnutrition poorly nourished before and during pregnancy underweight, undereating, and smoking tend to occur together Low Birthweight, cont. Factors that affect normal prenatal growth quality of medical care, education, social support, and cultural practices The Birth Process Hormones in mother’s brain signals process Contractions begin: strong and regular at 10 minutes apart average labor for first births is 8 hours The Newborn’s First Minutes Assessment—Apgar scale five factors, 2 points each heart rate breathing color muscle tone reflexes score of 7 or better: normal score under 7: needs help breathing score under 4: needs urgent critical care Variations Parents Reaction preparation for birth, physical and emotional support, position and size of fetus, and practices of mother’s culture Medical Attention birth in every developed nation has medical attention 22% of births in U.S. are cesarean section removal of fetus via incisions in mother’s abdomen and uterus is medical intervention always necessary? Birth Complications Cerebral Palsy—brain damage causing difficulties in muscle control, possibly affecting speech or other body movements Anoxia—lack of oxygen that, if prolonged, can cause brain damage or death First Intensive Care . . . Then Home At the Hospital many hospitals provide regular massage and soothing stimulation; ideally, parents share in caregiving At Home complications, e.g., minor medical crises cognitive difficulties may emerge, but highrisk infants can develop normally Mothers, Fathers and a Good Start Strong family support (familia) Fathers play a crucial role may help wives abstain from drugs or alcohol can reduce maternal stress Parental alliance—commitment by both parents to cooperate in raising child helps alleviate postpartum depression Mothers, Fathers and a Good Start, cont. Parent-infant bond—strong, loving connection that forms as parents hold, examine, and feed their newborn immediate contact not needed for this to occur