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Lecture 4

PS102 Lecture Notes - Lecture 4: Evolutionary Medicine, Imaginary Audience, Extraversion And Introversion

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Erin Strahan

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Human Development: Chapter 4
Developmental Psychology: The study of changes in behavior and mental processes over time and the factors that
influence the course of those constancies and changes. How is Developmental Psychology Studied?
1) Cross-sectional Design: Groups of participants of different ages are studied at a single point in time. (When one
wants to research the developmental relationship between a child and his/her mother, one could look at three
different age groups all at once.)
Limitations: the changes that you see are not necessarily due to development and it does not provide much explanation
of how or when the age-related changes occurred
Advantage: Quicker, easier, convenient and yields information about age differences
Cohort effect: as a result of when a specific group of people were born, their development will be affected by the
cultural and historical changes to which they were exposed. Different groups of generations have different
experiences and social expectations and norms that could shake that group of people.
o Different age groups: 20 year olds, 40 year olds, and 60 year olds are the participants. The 20 year olds have
always had cell phones so they are used to them since they used them so frequently. 60 year olds however, have a
more difficult time with the use of cellphones.
1. 2) Longitudinal Design: One group of participants is studied repeatedly over time (i.e., at different ages but they are
the SAME participants)
Advantages: Reasonably reliable information about trait stability over the lifespan and it gives information about the
effects of early experiences
Disadvantages: Takes a very long time; is expensive to run, many participants drop out and suffers from cohort effects.
(Cellphone use significantly changes by every generation)
Cohort-Sequential Design: Combines cross-sectional and longitudinal designs
Designed to look at both how individuals from different age groups compare to one another and also follow them over
-Do early stages matter? Are there critical periods? Critical periods are points in development when or organism is
extremely sensitive to the environment making it easier for it to get certain brain functions and behaviours
Heredity and Prenatal Development
Genes: basic building blocks of our biological inheritance
Deoxyribonucleic acid (DNA): molecules in which genetic information is coded
Chromosomes: strands of DNA. Chromosomes store genetic information
46 chromosomes (23 pairs of chromosomes) in each human cell
Allele: variation of a gene. If the alleles in both parents are the same, then the child will be homozygous. Dark hair for
example. The child will be homozygous for the dark hair trait. If the mother has blonde hair and the father has
dark hair, the child will be heterozygous.
Homozygous: both parents contribute the same genetic material for a particular trait
Heterozygous: parents contribute two different alleles to offspring
Genotype: the sum total of all the genes that a person inherits
Phenotype: the way in which the genes are actually expressed, or observed characteristics of the genes.
Dominant Trait: A trait that is expressed in the phenotype regardless of whether the genotype is homozygous or
Recessive Trait: A trait that is expressed in the phenotype only if the genotype is homozygous. (E.g., not being able to
roll your tongue (both parents must not be able to roll their tongue for their child not to be able to roll their
A person with heterozygous pair of alleles may show a mixture of genetic coding (e.g., mixed race children)
Codominance: in a heterozygous combination of alleles, both traits are expressed in the offspring. (One has blood type
A the other has B, the child can have AB.)zx
To make things even more complicated:
Only a few of our traits are discrete traits the product of a single gene pair
Most human traits are polygenic traits: traits that involve the combined impact of multiple genes (There are multiple
genes in causing what the genotype and phenotype will look like) (depression & schizophrenia)
Zygote: a single cell resulting from successful fertilization of the egg by the sperm
Also, the person’s environment influences what, how and when genes are expressed during their lifespan
Prenatal Development: (Germinal Stage: lasts about two weeks)
Begins at conception when male sperm unites with female ovum (egg)
o A membrane is formed around the baby
Zygote: fertilized single-celled egg
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Lasts around 2 weeks from fertilization until the zygote attaches itself to the uterine wall
Prenatal Development: (Embryonic Stage: lasts from implantation through the 8th week of pregnancy)
Period of most rapid prenatal changes (Nervous system developing the quickest)
o Heart begins to pump blood
o Embryo is curled up and very small
o During the second month, the baby gets eyes, etc.
Prenatal Development (Fetal Stage)
Lasts from eight weeks until birth
Greatest gains in brain and nervous system development occurs during the last 12-weeks.
During the end of this stage, the brain becomes very well developed; things, such as loud noises, can even annoy the
Fetal Development Agents That Cross The Placenta:
Teratogens: any external agents, such as drugs or viruses that can harm an embryo or fetus during gestation. (Any
external agents such as a drug or anything else are considered a teratogen.) Teratogen damage can have delayed
effects, even decades later. They are at risk for heart disease. Nature and extent of their impact depends on the
dose of the teratogen, the timing, extent of exposure and the age of the organism.
Examples: X-rays, other radiation, toxic chemicals, Sexually transmitted diseases, Tobacco, Alcohol (fetal alcohol
syndrome), and Other drugs
Half of the infants exposed to rubella suffer from deafness, intellectual disability, and internal system defects.
Tabaco can lead to the child getting cancer, heart disease, the baby being born early, or the child dying right after it’s
born, they can have problems during adolescence and in school, miscarriage, low birth weight
Many drugs, even aspirin can be very dangerous when pregnant. Coffee as well, this can end in a low birth weight,
death. They have trouble sleeping and can be addicted to drugs when it is born, which can give them a lot of
behavioural problems. Some can improve after 1-2 years; however, some don’t change. Pot: overreact when
startled, small head size, kids during adolescence had problems taking in information, impulsiveness, over
activity, inattention, and an increased rate for depression and anger. Heroin: low birth weight and addicted to
heroin: must go through withdrawal
Fetal alcohol syndrome: mental impairment, impairment in motor coordination, they are unable to solve problems well,
have a particular pattern of facial abnormalities, head size is small, problems with eyesight, and difficult time to
remember things. The more alcohol consumed the worse it is for the baby
o The baby is not growing the way it should when alcohol is consumed. When body metabolizes alcohol, you need
a lot of oxygen, which doesn’t give the baby enough for his cell growth. Alcohol interferes with the production of
neurons from going where they need to form neural networks in the brain.
Infancy and Childhood: Physical Development
Proximodistal pattern: A pattern of physical growth and development that proceeds from the center of the body outward
to the extremities.
Cephalocaudal pattern: A pattern of physical growth and development that proceeds from top to bottom. (Control of the
head becomes before the control of the hands, legs, etc.)
Brain Dev. 2 processes: Sheer increase in connection of neurons in need of synaptic connections and myelination
Synapses: transmission points between neurons (Synapses increase when the baby grows)
Neuron networks increase as well
Synaptic Pruning: the loss of unnecessary connections between two neurons, allowing stronger connections to flourish.
(As it develops the brain gets rid of the unnecessary connections)
Myelination: Development of fatty deposits on neurons that allow electric impulses to pass through neurons efficiently
Physical Senses:
When a baby is born some of the physical developments are more developed than others.
o Taste, smell and touch are highly developed at birth (They can tell the difference between their own mothers
breast milk and someone else’s) Study: Gave them water which had no taste and water that was sugary, they liked
the sugary one better, which showed they knew the difference between them.
o Hearing is not mature at birth. (Reason: they still have amniotic fluid inside their ears. After a few days, they
begin to hear better.) They can start to hear louder sounds and they are interested in new sounds.
o Vision is the least developed sense in a baby; they can only see 20-25 cm. away. They cannot tell the difference
between colors until they’re three months old.
Newborn Reflexes: programmed physical reactions to certain cues that do not require any conscious thought to
perform. Rooting (touching a baby on its cheek will make the baby look at the closest thing), sucking,
swallowing, Moro (“startle”), Grasping reflex, and stepping when you hold the baby up. Reflexes show whether
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