Lifespan A: Developmental, WEEK 2

Question 1

Conditions for establishing a causal relationship

Answer 1

• Observed variables MUST co-vary > events occur alongside each other > if they occur separately, this isn’t a causal relationship + third variable is present
• Co-variation must not be spurious (other things cannot account for or impact it, third factors)
• Causal factors must precede outcomes (temporality) does it occur. before something else?

Question 2

Causal factors

NCF + SCF

Answer 2

• Necessary causal factors (NCF): factor which MUST be present for an outcome to occur
• Sufficient causal factor (SCF): factors that are enough alone to cause an outcome
• E.G: It is impossible to develop tuberculosis w/o exposure to a particular bacterium (NCF) but not everyone exposed to the bacterium gets TB (it is not sufficient to cause TB alone)
• E.G: paracetamol can relieve headaches (sufficient alone) but it is not necessary in the sense the absence of paracetamol causes headaches.

Question 3

Cross sectional research

Answer 3

• research conducted at a single point in time + compares performance in different age groups > describes patterns of relationships at a specific point in time
• independent groups design

Question 4

Benefits of using cross-sectional research

Answer 4

• Can provide valuable evidence about course of development by comparing performance of different ages + looking at patterns at particular points
• This type of research is helpful when we want to find developmental trends + relationship between co-variables
• E.G: Zelazo (2013) found as age increases so does performance (upward trend so executive function improves w/ age)

Question 5

Limitations of cross-sectional research

Answer 5

• It is difficult to tell what causes what in cross sectional research and whether other variables are involved
• when cross-sectional research tests dev theories, it doesn’t say anything about the course of a persons development over time (lacks dev trajectory) cant see rank order position
• Age effects are confounded by cohort effects > differences between groups of people we study might not be due to age but due to other factors like socio-economic status
• Cannot show that one thing precedes another
• study of development needs multiple obs over time

Question 6

Longitudinal research

Answer 6

• Research that measures the same individuals at more than one point in time > used to study the course of development + the cause of it
• Most appropriate way to study change in a person over time as we can see stability of individual difference + cause of dev
• Longitudinal research helps to see if one variable is caused or impacted by another

Question 7

Types of longitudinal research

Answer 7

• Panel studies: tracks on group/cohort two or more times
• Multiple cohort studies: tracks more than one cohort of ppt across 2 or more points
• Intervention studies: tracking one or more groups of ppts before AND after experimental manipulation (similar to cross-sectional but is repeated measures + seen on more than one occasion)

Question 8

How to choose panel study or multiple cohort study?

benefits

Answer 8

• Panel studies can show maturational or developmental changes
• Panel studies help us look at within person change
• Problem with panel studies are period effects > a historical or cultural event could be shaping the nature of data being collected (period effect=culture/history affects childrens behaviour)
• Multiple cohort study is best for studying development in life course
• Both establishes a connection between a naturally occurring variable + outcome but is not a causal conn

Question 9

How do intervention studies differ from panel & multiple cohort studies?
(benefits)

Answer 9

• Intervention studies are an experimental longitudinal design
• Panel + MC studies indicate developmental causes while intervention studies can show that one variable CAUSES another. (but these connections may not exist in real life) > establishes a connection between a naturally occurring variable + outcome but
• Intervention studies work by manipulating what we think is a factor in dev (avoids spuriousness) & classic experimental design used to establish causation

Question 10

Bryant (1990)

Answer 10

• Believes we need to use both cross-sectional research + longitudinal research if intervention isnt used
• Bryant says panel or multiple cohort studies should be used to establish a naturally occurring connection between variables, then intervention study used to establish a definite causal connection
• If we use just cross sectional research, we undermine the claim of being a natural part of dev
• If we use just longitudinal, we undermine developmental claims
• We can find NCF + SCF by using both research

Question 11

Limitations of longitudinal studies

Answer 11

• Expensive in terms of staff + resources required
• results take a long amount of time to be seen as it is done over time
• Attrition rates are an issue as it can affect the validity of findings as those who stay in the study may differ to those who leave > high attrition can be avoided by collecting wide range of contact info, creating good rapport w/ ppt, keeping regular contact. > some attrition is unavoidable though like death.

Question 12

Genetically sensitive research designs:

behaviour genetics

Answer 12

• where we use genetically sensitive research designs to understand genetic & environmental contributions to cognition & behaviour
• Humans share 99% of DNA, behaviour genetics focus on the 1% variation which are called segregating genes
• 2 branches of behaviour genetics:
  1. quantitative genetics: estimates genetic + environmental influence on individual difference in pop > shows how EV can increase or suppress heritability
  2. molecular genetics: identifies specific DNA variants associated w/ certain traits > shows how certain variation in gene interacts w/ EV, affecting behaviour

Question 13

Advantage of genetically sensitive research:

Avinun & Knafo-Noam (2017)

Answer 13

• their role is distinct in the sequence of development + has clearer cause than cross-sectional + longitudinal
• shows how genes + EV are intertwined + interact

Question 14

Genetic similarities between family members

Answer 14

• Monozygotic twins share close to 100% of genes
• Dizygotic twins share 50% of segregating genes
• Siblings share 50%
• Half siblings share 25%
• Adopted kids share 0%
• Biological parents + kids share 50%

Question 15

Twin studies

Answer 15

• If pairs of MZ twins have more similar scores on a particular trait than pairs of DZ twins, this suggests the trait is heritable (influenced by genes)
• 1% of all births are twins, 1/3 out of that 1% are MZ twins (does this make their results less generalisable)
• Correlations are used to compare MZ + DZ twins using an equation

Question 16

Factors impacting twins development

Answer 16

• Additive genetic effect: heritability estimate derived from comparing correlations between MZ + DZ twins
• Common environment: non-genetic influence affecting children in the same house > assumed equal in MZ + DZ twins
• Non-shared environment: experiences unique to the individual (eg: their group of friends differ to their twin)

Question 17

What is heritability?

Answer 17

• refers to how much variation between people can be accounted for by genetics > the differences we see in the pop can be accounted for by genetic factors
• heritability is not the same as innate > eg: walking on two legs is not heritable as it is universal, everyone should walk on 2 legs, unless due to environmental causes

Question 18

Genetically sensitive research design:

adoption studies

Answer 18

• Adoption studies capitalise on the fact adopted kids and adoptive parents only share ev + not genes while biological parent shares genes + not the ev
• Adoption studies compare adoptive families to biologically related families to understand to what extent certain things are driven by genes or ev

Question 19

Limitations of genetically sensitive designs:

Answer 19

• 15/1000 births are twins > this is an issue as these parents may have a different experience to parents who don’t have twins. > e.g: twins are more likely to have a low birth weight, increased risk of disability + parents using IVF are 7x more likely to have twins (IVF is used by people of high status so twins are more likely to be born in high socio-economic household)
• Adopted children don’t usually get taken at birth, on average they get taken at 3 years old and spend 2 years in care > adopted kids may be impacted by EV in care + biological parents rather than just EV

Question 20

Quantitative genetics

Answer 20

• pinpoints certain genes to relate to development + psychological phenomenon
• seeks to find if individuals with a particular trait are more likely to have a certain genetic allele > are certain variations of genes associated w/ certain outcomes

Question 21

Age effects

Answer 21

• Difference in age = difference in performance or behaviour (unrelated to period/cohort)

Question 22

Cohort effects

Answer 22

• Variations over time and between people from different cohorts > these variations are due to some sort of shared experience such as year of birth or year of a certain event (e.g. first year uni students in 2020 had a different experience to first year students in 2019 due to COVID-19 > cohort effect)

Question 23

Period effect

Answer 23

• Refers to social/historical/cultural event which may impact behaviour