Eun-Sung Chang

What is Sequential design?

Dev Psych

Week 2

Lecture 3 (9/12/17): Prenatal Development

*Continued from last lecture

Researching Methods

• Sampling Strategies:

o Cross sectional design – you sample each child once, you make conclusions of  groups from the average of samples

▪ Ex.) You want to test children when they’re 6 years old vs. when they’re 8  years old ???? instead of waiting for the 6 y/o to turn 8 y/o, you take a  

group of 6 year olds and a group of 8 year olds and collect average data  

from both groups

▪ Pros: quick, easily accessible, gives average of population

▪ Cons: no manipulation, cannot track individual change

o Longitudinal design – you sample the same child over a long period of time ▪ Pros: gives individual data, can map developmental change

▪ Cons: takes a long time, hard to generalize (because you are sampling a  very particular population), expensive (you have to track down the  

What is Cross-sectional design?

participants ???? can lead to bias)

o Sequential design – combination of cross sectional and longitudinal designs ▪ Pros: best of both worlds (receive pros of both cross sectional and  

longitudinal)

▪ Cons: really expensive

o Cohort effect – set of experimental influences that are shared between cohorts  (group of kids born at the same time)

o Ex.) Influence of airport noise on stress hormone levels relative to opening of  airports nearby ???? is this an experiment?

▪ No, because you are not manipulating a variable

▪ But you can tweak/manipulate a variable to create an experiment

Prenatal Stages

1. Zygote/germinal (day 1 – day 10-14) ???? fertilization, division (mitosis), travel  implantation

o Fertilization ???? sperm meets egg Don't forget about the age old question of byui accounting
If you want to learn more check out sasha spa

o Division/mitosis ???? most rapid period of change/cell growth in human  development

What is Embryo?

o Travel implantation ???? fertilized egg finds a location to implant in (supposed to  be in the uterus)

2. Embryo (week 3 – week 8) ???? organogenesis

o Ratio at birth is 105 males:100 females, ratio at conception is 2:1 Don't forget about the age old question of kky zippers

3. Fetus (month 3 – month 9) ???? organ development, movement, sensation o Bulk of time developing in the womb is as a fetus Don't forget about the age old question of What is the meaning of behaviorism?

o Age of viability – age at which fetus can survive outside the womb (3 months)

Principles of Prenatal Development

• Stages of development are the same in all typically developing members of a species • Early development is very fast

• Development is

o Cephalocaudal (head ???? tail)

▪ Ex.) You form a head before you form a torso, and torso before you form  legs

▪ Ex.) Arm movement happens before leg movement

o Proximodistal (midline ???? outward)

▪ Ex.) Your arm develops from shoulder to fingers (not fingers to shoulders) ▪ Ex.) Toddlers are able to throw a ball before they are able to draw with a  crayon

o Also prevalent outside of the womb

• Uterus is permeable to the external world ???? effects of environment can interfere with  normal fetal development

o Teratogen – disease/drug/other environment agent that can harm a developing  embryo or fetus

▪ Ex.) Nicotine, marijuana, lots of coffee, alcohol

o Single teratogen ???? can lead to multiple effects

▪ Ex.) Slow growth, low birth weight, premature birth, cognitive/learning  deficits

▪ Fetus is most vulnerable in early stages ???? why?

• Organs are still forming ???? teratogens affect not only the organ  

but the morphology of the organ

• Not yet developed any of the things that would process  

teratogens (no toxin processing mechanisms)

• Dosage effect (fetus is smaller in early stages)

▪ Timing is important ???? different things are happening at different times • Depending of what is forming at the time, a teratogen can affect  

development of different body parts We also discuss several other topics like csu chico population

o Different teratogens ???? can have same effect

▪ A fetus may be adversely affected by a teratogen while the mother feels  no effect ???? why? Don't forget about the age old question of acrostics psychology definition

• Concentration is much greater in a smaller body

▪ Not all fetuses are equally affected by a teratogen

Fetal Psychology

• Sensation – what our senses are receiving from environment around us o Vision

▪ Probably least developed

o Touch

▪ Many fetuses start to suck their thumbs in the womb ???? 90% of hand that  fetuses suck determines right/left handedness

o Sound

▪ They are getting sound through vibrations ???? lot of information about  rhythm of speech from feeling vibrations of mother’s voice

▪ Soap opera theme song study – newborns were calmer when exposed to  soap opera song they heard when they were in the womb

o Taste

▪ Some mothers have aversions to certain types of food ???? can be due to  negative feedback from fetus

▪ Food experiences fetuses had while in the womb can determine whether  or not the child will enjoy that food after they are born

• Carrot juice study – had mothers drink carrot juice during 3rd 

trimester of pregnancy ???? children at 6 months who were  

exposed to carrot juice seemed to enjoy carrot flavored cereal  

more than bland flavored cereal

• Garlic food study – children with mothers who ate garlic during  

pregnancy enjoyed garlic potatoes more than those who were not  

exposed to garlic in the womb

▪ There is some indication that early exposure to foods determine child’s  enjoyment of that food, but there is also individual variation

• Learning

o Movement/heartrate/brain waves are dependent variables to look at learning in  fetuses

▪ Heartrate decelerates when fetuses are paying attention

o Habituation – tendency to respond less to a repeated stimulation

o Dishabituation – response bounces back up after (stimulus change) exposed to a  different stimulation ???? significant recovery

o Ex.) Attractiveness of amniotic fluid odor: evidence of prenatal olfactory  learning?

▪ What is the question of interest?

• Do babies use smell to locate mother’s areola to breastfeed?

▪ Is it a well-designed study?

• No, small sample size

• No, experiment was not well manipulated

▪ Are there any limitations to the design?

• Yes, it is comparing something that is smelly with something that  

has no smell

▪ Are the conclusions justified from the results?

• No, smell is better than no smell for babies

▪ How would you design a better?

• Test amniotic fluid with a different mother’s amniotic fluid ????

ideal/good comparison because both are amniotic fluids but differ  

in certain characteristics since they are from different mothers

• Temperament – biological drives that we map to babies’ personality traits

Lecture 4 (9/14/17): Biological Foundations

Study on Kids’ Prosocial Behavior

• Realistic stories (not anthropomorphic stories) help kids to develop prosocial behavior o Kids who heard stories about children sharing shared more stickers with other  kids than kids who heard stories about animals sharing

How Do We Pass on Genetic Information to Offspring?

• Genetic code

o 23 pairs of chromosomes, 2 alleles for each gene

• Growth of the zygote and production of body cells

o Mitosis – replication of cells, maintaining same complement of genes, occurs  right after fertilization

• Production of gametes

o Meiosis – process by which a germ cell divides, producing gametes that each  contain half of the parent cell’s original complement of chromosomes (half from  each parent)

▪ Translocation event happens before meiosis

How are Genes Expressed?

• What do genes do?

o Basic level – call for production of amino acids, which form enzymes and other  proteins necessary for formation and function of new cells

• Simple dominant-recessive inheritance – 1 allele dominates

o Homozygous dominant – NN

o Homozygous recessive – nn

o Heterozygous – Nn or nN

o Ex.) Hair color ???? dark hair is dominant, light hair is recessive

o Ex.) Hair type ???? curly hair is dominant, straight hair is recessive

• Sex-linked inheritance ???? fragile X

o Boys will be much more affected by traits that are sex-linked than girls are  because they have only 1 X chromosome

o Ex.) Color-blindness is much more common in boys because you need to inherit  an X chromosome with the color-blind gene ???? boys do not have another X  chromosome to compensate for color-blind X

o Carrier of gene – person who has the (recessive) gene but do not show the  phenotype (so they do not know they have the gene)

• Codominance – when both alleles are expressed

o Ex.) Sickle cell anemia – when red blood cells are curved rather than  round/plump ???? do not pump oxygen as much as plump red blood cells do ▪ Common in Africa, advantage of being heterozygous of having both  

plump and sickle cells ???? less receptive to malaria

• Polygenic inheritance – when there is not just 1 gene that causes that phenotype o Ex.) Skin color, height, weight

How Heritable Are Psychological Traits?

• Behavioral genetics

o Estimating the influence of nature and nurture on the variability in a  psychological trait

▪ Humans are 99.9% biochemically identical in DNA

o Studies of the origins of differences between individuals

▪ 0.1% of the DNA sequence that varies

• Sources of variability between individuals

o 3 sources:

1. Heritability – genetic influence

2. Shared environment – experiences that are shared by individuals who  were raised in the same home/school environment

3. Non-shared environment – aspects of life that are different between  individuals who grew up in similar environment

o H + SE + NSE = 1 (total variation)

• Methods of behavioral genetics

o Selective breeding experiments – (non-humans) breeding certain animals with  certain traits so you can get an offspring with all the traits that are desirable,  choosing certain traits you want in the offspring

o Family resemblance studies

▪ Twin design

• Monozygotic (identical) twins

o Single zygote

o Later divides to form 2 genetically identical individuals

o 3/1000 births

o Ex.) Tested identical twins and restrained them from  

playing with a toy ???? both acted similarly and fought  

against restraint

• Dizygotic (fraternal) twins

o Mother releases 2 ova

o Each ovum is fertilized by a different sperm

o 2 zygotes that are genetically different

o 12/1000 births

o Ex.) Tested fraternal twins and restrained them from  

playing with a toy ???? one fought against the restraint while  

the other seemed to be okay with being restrained

▪ Adoption design

• Estimating heritability for categorical (yes/no) traits

o Concordance rates – % of instances in which if 1 twin displays a certain trait, so  does the other

▪ Monozygotic vs. dizygotic twins ???? correlation is higher in MZ twins,  

which shows the importance of genetics

• Dizygotic twins tend to have more variability in traits than  

monozygotic twins ???? monozygotic twins are more similar

▪ MZ twins reared together vs. reared apart ???? correlation is higher in MZ  twins who were reared together, shows importance of shared  

environment

• Caveats for heritability measures:

1. Heritability measures only what percentage of the variation in a trait can be  attributed to genes

2. Linking a given trait to genes does not mean the trait is caused by genes ▪ Homogenous societies have less variability  

3. Heritability scores reflect the environments in which data were collected ???? change across time, environments, and populations

• Ex.) Educational achievement ???? why and how do children differ in their educational  achievements?

o Previous findings:

▪ Believed that intelligence is ability that is heritable

▪ Educational achievement is based on effort that is influenced by  

home/school environments

o This study:

▪ Focus on GCSE (test at 16 in UK, testing English/math/science), 6653 pairs  of twins, 83 scales of behavior

▪ Found 60% of educational achievement is explained by heritable factors o Conclusion:

▪ There is significant genetic influence on educational achievement

• Ex.) Autism

o Previous findings:

▪ Classified as a neurodevelopmental disorder that affects social  

communication and restrictive and repetitive behaviors

▪ 1 in 68 (CDC 2014)

▪ Initially believed to be entirely environmentally caused because there  was no report of an autistic child having an autistic parent, and the risk to  siblings seemed low (3-6%)

o Evidence:

▪ Sibling risk of being autistic is 10x greater than the population rate ???? suggests strong family resemblance

• 1 in 68 people have autism, but out of people who have an older  

sibling who has autism, 1 in 5 of those people have it as well ????

there is a strong genetic component

▪ Twin studies confirmed the genetic basis of this resemblance

o Conclusion:

▪ Autism is now considered one of the most heritable developmental  disorders

• Ex.) Anti-social behavior

o This study:

▪ Longitudinal study ???? one of the first studies trying to link a mental trait  to a specific gene-environment interaction

▪ Studied a large group of boys (birth to adulthood) to determine why  some children who were maltreated developed anti-social behavior and  others did not

▪ Looked at MAO-A activity ???? gene that processes number of different  transmitters

o Conclusion:

▪ Having high MAO-A protects you ???? boys with low MAO were more likely  to have a conduct disorder than those with high MAO

• If you have high abuse (environment), you are more likely to have  

a conduct disorder

• If you have low MAO-A activity (genetic vulnerability) plus severe  

abuse (environment), you are more likely to have a conduct  

disorder

How might genes interact with the environment?

• Range of reaction principle – individual genotypes establishes a range of possible  responses to different kinds of life experiences, describes the degree to which the  environment can affect development