Lecture 3 - Human Development-Part I-AGB-2023.ppt

HUMAN DEVELOPMENT Part I 1 What is Developmental Psychology? O It is the field of study that examines patterns of growth, change, and stability in behaviour that occur throughout the entire human lifespan (Feldman, 2000, p. 5). 2 Development O refers to the changes over time in the body and in the t...

HUMAN DEVELOPMENT Part I 1 What is Developmental Psychology? O It is the field of study that examines patterns of growth, change, and stability in behaviour that occur throughout the entire human lifespan (Feldman, 2000, p. 5). 2 Development O refers to the changes over time in the body and in the thinking or other behavior of a person that are due both to biology and to experience. In what way has your thinking changed over time? 3 Developmental matters to take into consideration O Post Hoc Fallacy a Latin term which means ‘after this’. O It is incorrect to assume that because one event occurs then it is likely to cause other events. O Human development is bidirectional which means that individuals influence their experiences, but their experiences also influence their development. 4 Developmental matters to take into consideration Always be careful in the research design chosen. For instance, a cross-sectional study which examines people of different ages at a single point in time: this has a disadvantage because the results reflect what the groups experience at a specific point in time (i.e., cohort effects) as opposed to the changes that occur over a period of time as a result of their development. Impact of early experience: there is a popular belief that what we experience early in our development (especially our first three years) later shapes the adults we become (infant determinism). This is not always the case. 5 Developmental matters to take into consideration O Counter to popular belief that infants are fragile and not resilient we see where infants have shown tenacity when faced with stressful situations. The Nature vs. Nurture debate: O Our environment impacts our genes which in turn impacts our behaviour. O Being predisposed genetically can lead to us choosing and creating specific environments. O Certain environmental experiences can cause a gene to be heightened or not to operate. 6 When does human life begin? O Human development begins at conception: when the father’s sperm cell unites with the mother’s ovum (egg cell). O This singular cell (which is now fertilized) is called a zygote. O Conception happens through fertilization. Abortion? 7 The Beginning of Human Life O Once the sperm makes its way inside the egg, the head of the sperm ruptures, spilling the genetic material from the father (23 chromosomes) into the egg. There it joins up with the genetic material from the egg (23 chromosomes) resulting in 46 chromosomes (23 pairs). O Genetic sex is decided by the father. Normal chromosomal configuration for the male is ‘XY” and “XX” for the female. O The time from conception to birth is the prenatal period. 8 PRENATAL DEVELOPMENT 9 PRENATAL STAGES O Prenatal: happening or existing before birth Divided into three stages: O Germinal stage O Embryonic stage O Fetal stage 10 Germinal Stage O Starts at the time of conception O Once the sperm fertilizes the egg, the first new cell of the unborn child is called the zygote. O The zygote begins to move down the fallopian tube towards the uterus. As it travels it undergoes rapid cell growth and form into a hollow ball called a blastocyst. O This process takes about two weeks and lasts from the time of fertilization until the blastocyst implants itself into the wall of the uterus. O Once implantation is complete, the embryonic stage begins. 11 12 THE EMBRYONIC STAGE 13 THE EMBRYONIC STAGE O This period lasts until the eighth week (lasts about six weeks [i.e., weeks 2-8]). O Begins with the implantation of the zygote into the wall of the uterus. O Most of the cell divisions, as well as the formation of organs, take place during this stage. O By the end of this stage, the face, eyes, ears, fingers, and toes can be identified O Two months after conception, this stage draws to a close. 14 FETAL STAGE 15 FETAL STAGE O Lasts from week eight to birth: the next 7 months (i.e., months 3 to 9), which occurs about 40 weeks after conception O The developing child is now called the fetus. O Internal organs have developed, but not enough for the fetus to sustain life outside of the uterus. The brain has also developed. O A crucial stage because the brain and neural connections are being made in preparation for later interaction with the world. 16 ENTRY/BIRTH O After 9 months (i.e., 40 weeks or 270 days) the fetus is ready to enter the world. 17 BRAIN DEVELOPMENT After the first 18 days of fertilization the human brain develops and continues to grow through to possibly early adulthood. Neurons begin to grow at a rapid rate between day 18 of pregnancy and the end of the 6th month, producing more neurons than is needed by the fetus. The brain undergoes its most rapid development during the first two to three years of the child’s life. 18 BRAIN DEVELOPMENT Late pregnancy marks the final stage of the prenatal brain development, but brain development continues after birth. The most highly developed parts of the brain at birth are the brain stem and midbrain – these parts are involved in arousal and involuntary body functions, such as respiration. 19 Prenatal Brain Development 20 O BRAIN DEVELOPMENT There is also a thickening of the cerebral cortex (outer portion of the brain) during the first 3 months of life. O This leads to a development of primary motor areas O controls limb and other body movement O By 6 months (after birth), the primary sensor and motor areas are highly developed. 21 Factors that impact development O Fetal development can be affected by environmental factors (teratogens) or biological factors (genetic disorders or errors in cell division). O Teratogen: O environmental factors that can exert a negative impact on prenatal development (e.g., fetal abnormalities) O Drugs, medicine, chemicals, certain infections and toxic substances O During replication of cells or even within the egg or sperm cells there may be errors or breakage in the genetic material 22 Biological Factors O Genetic disruptions: O before the fertilization process a cell or family of cells is copied with some error or break in the genetic material. O This can result in something minor- a birthmark or major- mental retardation, down syndrome. O Babies born prematurely can have serious cognitive and physical impairments. 23 Environmental Influences on Prenatal Development O Maternal Age O Maternal Health and Nourishment O Infectious Agents O Smoking, Drinking, and Drug Use O Alcohol 24 Maternal Age O Very young mothers are at a greater risk for having miscarriages or having children with birth defects. O Research shows that the greatest success rate is for mothers in their twenties O It is said that the incidence of prenatal defects or abnormalities increases with age, 25 especially for first time mothers. Theories cited to explain this phenomenon. 1. Older mothers have older ova (the female reproductive cell). O Through aging the ova might be more likely to be defective in ways that affect development. 2. Older mothers’ bodies are older too and this may cause imperfect implantation. 26 Maternal Health and Nourishment O Maternal malnutrition often leads to an increase in miscarriages, stillbirth, and premature births. O Deficiencies in specific vitamins and minerals affect the prenatal organism. O For example, a mother’s calcium deficiencies affect the development of bones and teeth in the fetus. However, it is the mother who suffers 27 the most. Infectious Agents O Mother can pass on diseases to their fetus through the placenta O The placenta is the structure in the uterus that protects and nourishes the growing child. O Rubella & German measles can cause blindness, deafness, or heart disease in the fetus if the mother contracts this illness during the first four weeks of pregnancy. O Other diseases that can be transmitted to the infant include chicken pox, mumps, tuberculosis, malaria, syphilis, herpes, AIDS. 28 Smoking O How smoking affects the fetus is not known. O It could be that smoking reduces the oxygen or the blood supply to the fetus. O It could be that the tar and nicotine in cigarettes act directly as poisons. O What is known is that cigarette smoking is a cause of retarded prenatal growth. 29 ALCOHOL O Alcohol is also injurious to unborn children. O Alcohol is quickly and directly passed through the placenta from the mother to the fetus. O The fetus eliminates alcohol at half the rate of the mother. O The bottom line is that alcohol gets into the fetus and stays there for a long time. 30 DRUGS O Mothers who use or abuse psychoactive drugs (i.e., drugs that effect brain function and can alter consciousness, mood etc.) during pregnancy cause considerable problems to their unborn children. O Such children may enter the world with issues such as low birth weights, and difficulty regulating their sleep-wake cycles. O Worst, they may be born addicted to the substances and suffer the pains of withdrawal and require a hospital stay averaging 42 days. 31 What about the Fathers? O The main issue revolves around factors affecting the quality of the father’s sperm at the moment of conception. O For example, it was assumed that Down syndrome (DS) was more likely as the mother’s age increased. O We now recognize that the father’s age is related in some cases of DS. 32 What about the Fathers? O As many as 1/3 of all DS cases reflect difficulties with the father’s sperm and that the syndrome is more likely in children whose fathers have jobs working with toxic chemicals. O Alcohol use by fathers has also been implicated as probable cause of prenatal and birth abnormalities. O The problem is that nearly all this research has been on rats and mice. 33