Differential Psychology Flashcards
how do people vary
- basis = bodily differences
- physiological = medical stuff
- developmental
- phycological
- lifestyle
- demographic status
- experiences
- etc.
Cronbach’s two disciplines of scientific psychology (1957)
- experimental psychologists manipulate conditions
- correlational psychologists seek to identify and understand free-standing patterns of nature
VARIANCE
the expected squared deviation of a random variable from its statistical mean
sd = square root of variance
Meehl’s theory of validity
interpreting test scores means assuming that tests measure theoretical networks’ constructs - networks and theories imply that states should be observable under specific conditions - these conditions aren’t always present, and this creates variance
how to study individual differences
- define the dimensions of difference
- operationalise the dimensions - creates issues as individuals are bias but so are outsiders and groups
how to know if something is measured well?
- if repeated later, we get the same result
- assessment process is free from bias
- when we measure a person/object, the result has the same meaning when we apply it to others
Anatomy of a differential study
- start with a question
- identify needed data
- figure out how to collect a good sample
Population representation
rare to be able to test a whole population so we must select a representative sample - if we select randomly, this could be randomly unrepresentative
LBC21 - population representation
- impractical to measure the whole of Scotland on education so selected Edinburgh - these individuals are better educated than Scotland as a whole
- used NHS registration to give access to 99% of the old population in edinburgh
- wanted people who sat SMS-32
representative variables in LBC21 - ‘old age outcomes’
- longevity (making it to 79 can affect a person)
- health / well-being
- financial resources
- social support
- physical and cognitive ability for self-care
all of these could affect a person’s performance in interviews / cognitive tests
there are also other factors that can effect the way early life IQ presents itself in old age like:
- childhood lifestyle/ soci-economic status
- offspring / relations
- job satisfaction
- personality / religion etc.
- memory of events
Quantitative change
implies a number/objective change
implies a difference in magnitude
requires a common ‘measuring rod’ to be reliable
qualitative change
implies capacities have become eroded / improved
there is no common measuring rod
pervasive in life transitions
cross sectional design
e.g. assess 79 y/o and 83 y/o and compare
advantages
- faster and cheaper
- no P death or drop out
disadvantages
- varying levels of sample security
- no way to evaluate personal development directly
- cohort effects
Longitudinal design
e.g. assess 79 y/o, wait 4 years, assess them again at 83 y/o
advantages
- can measure changes in individuals
- can evaluate prior influences on individual differences
disadvantages
- expensive and time consuming
- Ps might drop out or die
- practice effects on repeated tests
- limited to one cohort
- age/time effects tangled
- measures can become outdated
Cohort- sequential design
e.g. assess 79 y/o and 83 y/o, wait 3 years, assess them all again, wait another 3 years, assess them all again and so on.
Gregor Mendel
pea plant experiments found that genetic potential of both parents is passed to offspring
dominant genetic traits
expressed if relevant gene is inherited from at least one parent
recessive genetic traits
expressed only if relevant gene is inherited from both parents`
genotype
what’s in the genes
phenotype
how the genotype is expressed given the environment
hereditability
the proportion of population variance attributed to genetic influences - does not apply to individuals it is in a population
for human characteristics, hereditability tends to be around 0.3 - 0.6
Turkheimer’s (2000) ‘three laws of behaviour genetics’
- all human behaviour traits are heritable
- shared environmental influences tend to be weaker than genetic influences
- neither environmental nor genetic influences account for all variance - there are other factors
can’t assume correlation between life experiences and later outcomes are causational
fourth law of human behaviour (Chabris et al., 2015)
suggests that a typical human trait is associated with much genetic variance - proteins in DNA can express themselves in various ways
what is intelligence?
definitions vary but the basic principle =
- it has relative stability when measured
- assumption of ‘inherent capacity’ is large
