Developmental Psychology Flashcards
BEHAVIOUR GENETICS
Researchers try to understand how genetic and environmental factors combine to produce individual differences in behaviour (phenotype)
BEHAVIOUR GENETICS ESTIMATE
HERITABILITY
The degree to which variation in a particular trait (eg. IQ, shyness, schizophrenia) among individuals is due to genetic differences among those individual
Varies from 0 (no heritability) to 1 (complete heritability)
KINSHIP STUDIES
Use what we know about the degree of relatedness to work out the relative contribution of genes and environment to a particular phenotype
KINSHIP STUDIES MEASURE
Degree of relatedness
Probability of sharing genes among relative
TWIN STUDIES MONOZYGOTIC
essentially clones as they started as a single cell and then split into 2 fetuses
TWIN STUDIES DIZYGOTIC
develop when 2 sperms hook up with 2 eggs
TWIN STUDIES RESULTS
Same relatedness of DZ and sibling, only difference is siblings grow up in slightly different environments as they are born at different times but DZ’s grow up in the same environment)
Eg. HERITABILITY STATISTICS AUS
Physical characteristics (eg. 80% height) (lower in parts of the world malnutrition is a bigger problem) Mental illnesses (eg. 50% schizophrenia)
GENETIC AND ENVIRONMENT INTERACTIONS
Genes are not static
Environmental factions ‘turn them on’ (i.e gene expression)
Certain genes are expressed at certain times in response to certain environmental influences
STUDY EXAMPLE GENETICS AND ENVIRONMENT INTERACTIONS
Dunedin Multidisciplinary Study
1000 individuals followed from age 3
DNA findings related to environmental measures and psychopathology
MAOA gene and childhood maltreatment on conduct disorder
MAOA metabolises neurotransmitters in the brain; low activity associated with aggression in animals
RESULTS: Maltreatment is a risk factor for antisocial behaviour, BUT only in individuals with low MAOA activity
FADS2 gene and breastfeeding in IQ FADS2 GENE: Homozygous (CC or GG) Heterozygous (CG) RESULTS: Breastfeeding enhanced IQ, BUT only in children who are carriers of the C allele
NATURE VS NURTURE
combination of both
PRENATAL DEVELOPMENT OVERVIEW
Development that occurs between conception and birth
Begins in the fallopian tube when the sperm penetrated the egg and forms a zygote
Takes about 266 days (38 to 40 weeks OR 9ish months) for the one-celled zygote to become a fetus of 200 billion cells
THREE PERIODS OF PRENATAL DEVELOPMENT
Germinal
Embryonic
Fetal
GERMINAL PERIOD
From conception through implantation 14 days Zygote travels towards uterus Divides and forms blastocyst Contains 16 to 64 cells
EMBRYONIC PERIOD 4 WEEKS
5 WEEKS IN TOTAL
From 3rd week through to the 8th week
The blastocyst implants in the uterine wall
Layers of cells differentiate to become different parts of the body
Formation of major organs
Most risky time for teratogens
Neural tube closes at 3 weeks
○ Top of tube: brain (if this doesn’t happen neural tube defect - anencephaly - cortex doesn’t form - don’t survive more than a few hours)
○ Bottom of tube: spinal cord (neural tube defect - spina bifida, can be corrected sometimes but babies have locomotive problems)
Heart begins beating at 24 days
EMBRYONIC PERIOD 8 WEEKS
Internal organs form - but not functional yet
Fingers and toes separate
Facial structures fuse - cleft palate (end of embryonic period)
Women wait till the end of this period to say they are pregnant because if things go wrong in this period there’s no going back (miscarriage more common)
FETAL PERIOD up to 12 WEEKS
Lasts 7 months (from the 9th week until birth (38 week))
Organ systems begin to function; organism grows
A period of rapid growth and refinement of organ and brain systems
Fetus more responsive
Behaviour becomes increasingly regular and integrated
Fetuses become viable between 22-28 weeks
12 WEEKS
• Sexual differentiation
• Movement
FETAL PERIOD up to 18 WEEKS and 6 MONTHS till BIRTH
18 WEEKS
• Most growth in physical size during 4th month
• Practicing breathing movements so muscles are ready (but lungs aren’t functional yet)
6 MONTHS
• Fetus is capable of responding to light
• Able to hear sound
○ Sound level in the uterus is 75db
○ The mothers voice and heartbeat are best heard
• Limit of viability = 24 weeks (babies tend to not survive if they’re born before 24 weeks, because lungs aren’t sufficiently developed, don’t produce (which they would produce around 30-32 weeks) fluid called surfactant which keeps air pockets open when you breathe out)
7-9 MONTHS
• Fetus puts on weight in the form of fat just beneath the skin
DEFINE TERATOGENS
Any disease, drug, or other environmental agent that can harm a developing embryo or fetus
TERATOGEN EFFECT DEPENDS ON
Timing
○ Organ systems and brain are particularly susceptible during period of rapid development (first 8 weeks - first trimester)
Dose
Duration