Lecture 2 - Methods of studying diversity Flashcards
3 types of questions to study diversity
- In a given behaviour, are people systematically different?
- We need to be able to measure behaviours reliably and validly
- How should we understand the individual differences?
- We need to meaningfully describe the constructs underlying individual difference
- What are the origins of the individual differences?
- We need to explain what causes the individual differences, which presumably could be genetic, neurobiological, and/or sociocultural
common methods of measuring individual differences
- Survey/self-report measures
- Observational measures
- Performance measures
what are self-report measures?
- Typically involve presenting a list of statements and asking participants the extent to which they agree/disagree with them
advantages of self-report measures
○ Low cost and easy to administer in large scale (even online)
disadvantages of self-report measures
○ Respondents’ tendency to give socially desirable answers
○ Respondents’ tendency to agree (acquiescence bias)
○ Only measures thoughts, (explicit) attitudes, and self-perception – Requires respondents’ self-awareness
what is the experience sampling method
- Ask ppts to report their thoughts, feelings, and/or behaviours repeatedly over a certain period of time (e.g. 2 or 3 weeks)
- Response frequency could be daily (diary studies) up to several times a day
- Or, ppts could be signalled by a mobile device to fill in a brief questionnaire at a random time
potential problem of experience sampling method
- Potential problem: act of self-monitoring can influence what is being measured
what are observational measures?
- Recording what is done or how often something is done through observation by a third person (tally/videotaping)
advantages of observational measures
○ Can be used when impossible or inappropriate to give instructions to. Ppts
○ Can be used in naturalistic settings
- Computerised scoring (as in eye tracking) can minimise observer biases
disadvantages of observational measures
○ Only measure overt behaviours
○ Scoring may be influenced by observer biases
what are performance measures?
- Intelligence, reading/math performance, etc.
- Typically accuracy measures (in terms of error rates, percentage correct, percentiles, etc.
- Response times (RT) as additional performance indicator
- Differences across individuals reflect differing abilities,
- Differences across tasks reflect differences in information processing mechanisms
advantages of performance measures
objective
potential problems of performance measures
○ their relationship with real-world behaviours (i.e., ecological validity) is not always clear
what can be used to measure unconscious cognitive processing?
Cognitive tasks like implicit association test and priming
what happens in a priming paradigm?
- In a priming paradigm, participants are exposed to a certain stimulus (prime), and their response to a subsequent stimulus (target) is measured
- The prime is supposed to activate mental representations which could affect processing of the subsequent stimulus
hat happens differently in masked priming and why?
- In masked priming, the prime is presented followed by a junk visual material (mask). This prevents the prime from entering conscious processing
what can be used for data reduction?
factor analysis
what is factor analysis?
- Factor analysis is a statistical technique used to reduce a large number of variables into fewer “factors”
rationale behind factor analysis
- The rationale is to analyse the patterns in which variables vary together (covariance); variables indicating the same underlying construct are expected to covary
exploratory factor analysis (EFA)
- Exploratory factor analysis, does not assume a particular factor structure but uses the data to determine:
○ To determine the number of factors
○ Correlations between a variable (item) and a factor, called factor loadings, are computed and examined
○ The higher the factor loading (regardless of sign), the more important the variable is to the factor - It is important to note that in EFA the number of factors as well as criteria for including a variable in a factor is the researcher’s decision
confirmatory factor analysis
- In confirmatory factor analysis, the researcher hypothesises a factor structure and tests how well it fits the actual data
○ i.e., the number of factors and which measured variable is related to which factor (also called latent variable) is prespecified- Then the factor loadings, factor correlation and some fit indexes are estimated
structural imaging techniques
CT (computed tomography)
MRI (magnetic resonance imaging)
what do structural imaging techniques do?
measure anatomical details of the brain
how can MRI be used?
- MRI can be used to measure brain volume, grey matter volume, white matter volume, etc., which have been associated with individual differences in behaviour (e.g., intelligence)
what is white matter?
○ White matter consists primarily of myelinated axons
what is grey matter?
○ Gray matter consists primarily of neuronal cell bodies
how does MRI work?
- strong magnetic field causes hydrogen atoms to align in the same orientation
- When radio wave passed through the head, atoms emit electromagnetic energy as they “relax”.
- MRI scanner detects emitted radiation
- Different types of tissue produce different signals
- Computer reconstructs image
how can fMRI be used?
- Functional imaging methods such as fMRI measure dynamic physiological changes in the brain in vivo and associate them with different patterns of mental processes/behavior
what does/doesn’t fMRI measure?
- fMRI does not measure neuronal activation directly but the downstream consequence of neural activation, i.e., increased blood flow and blood oxygen consumed in a certain brain region
another type of scan associated with fMRI
PET (position emission tomography)
what does CT stand for
computed tomography
what do MRI and fMRI stand for
(functional) magnetic resonance imaging
what does PET stand for?
position emission tomography
what happens in PET?
- In PET (positron emission tomography), a radioactive tracer is injected to the bloodstream and the amount of radioactivity in each voxel of the brain is measured
what happens in fMRI?
- In fMRI studies, a magnetic resonance signal that is affected by the amount of deoxyhaemoglobin in the blood, called BOLD signal (Blood Oxygen-Level Dependent), is measured
- The rationale is that when neurons consume oxygen they convert oxyhaemoglobin to deoxyhaemoglobin, which has strong paramagnetic properties and distorts the local magnetic field
- Therefore, BOLD signals indicate oxygen consumed (implying neural activities) in the voxel of the brain
- comparison against another (baseline) condition is necessary
fMRI’s spatial and temporal resolution
- fMRI’s spatial resolution is around 1 mm and temporal resolution is several seconds
ways to determine what activation is functionally related to specific processes in brain imaging
- Subtraction method (difference in activation for tasks)
- Conjunction method (joint activation for tasks)
- Subtraction method
(difference in activation for tasks)
Conjunction method
(joint activation for tasks)
2 approaches to understand the brain and its functions
functional specialisation
functional integration
functional specialisation
question of where
functional integration
a question of how
how is network analysis used with imaging data?
- Network analysis is based on covariations between the BOLD signal in different brain regions, called functional connectivity
- No causality can be inferred, nor whether the connectivity is direct or indirect via some third region(s)
structural networks can be studied by using what techniques?
diffusion tensor imaging (DTI)
electrophysiological measures
what does DTI stand for?
diffusion tensor imaging
what does DTI do?
- Aims at specifying tracts fibre tracts with white matter connecting cortex / subcortical areas
- Important to investigate network architecture of the brain
- Not just activated grey matter areas!
➢ Diffusion of water molecules along neural tracts
isotropic voxel
anisotropic voxel
what electrophysiological measures are there?
EEG
ERPs
what does EEG stand for?
electroencephalography
what does ERP’s stand for?
Event-related potentials
use of EEGs
- Electroencephalography (EEG) – records electrical signals generated by the brain through electrodes placed at different points on the scalp
○ A common usage of EEG is the electrophysiological changes elicited by particular stimuli and cognitive tasks, referred to as event-related potentials (ERPs)
use of ERPs
○ A common usage of EEG is the electrophysiological changes elicited by particular stimuli and cognitive tasks, referred to as event-related potentials (ERPs)
○ Certain ERP has been identified to be linked to a certain cognitive process, and hence reveals the happening of the process
association vs causation when it comes to explaining individual differences
- Research attempting to explain individual differences usually starts with identifying factors associated (correlate) with the traits of concern
- However, correlation does not necessarily imply causation
- Causal relationship needs to be tested by experiments, which is unfeasible in some circumstances
different levels of explanation
genetic explanations
neurobiological explanations
socio-cultural explanations
genes
- Genes are made up of DNA, and DNA contains the instructions for building proteins. These proteins control the structure and function of all body cells.
- A gene is the basic physical and functional unit of inheritance
- Genes can be turned on and off by the environment (of the cell)
genotype
- The genotype is the internal genetic code or blueprint for constructing and maintaining a living individual, is inherited and is found within all the cells, tissues and organs of the individual
phenotype
- The phenotype is the outward manifestation of the individual, including physical appearance, intelligence, and personality
behavioural genetics
- Behavioural genetics looks at the relationships between genes, environment and behaviour
conventionally, how is heritability estimated?
by studying similarities and differences between individuals who share their genes to varying degrees:
– family studies – between parent and child, siblings, or between other family members
– twin studies – between identical (monozygotic) twins and non-identical (dizygotic) twins
– adoption studies – between adopted children & biological/adoptive parent
link between genotype and phenotype
- The genotype-first approach of genetic studies focus on a single gene that is known to exist in multiple variants (polymorphisms) and that may be linked to the phenotype of concern
○ E.g., a genetic variant may be known to encode the mu-opioid receptor which is related to susceptibility to physical pain- Then the extent to which this variant explains variations in a phenotype (e.g., susceptibility to social pain) is examined
- In contrast, the phenotype-first approach starts with a given trait (e.g. novelty seeking) and determine which gene(s) among the genome contribute most to variations in that trait
- Genome-wide association studies(GWAS)
cross-cultural research on individual differences
- Cross-cultural research commonly involves comparison of traits (or relationships between traits) across two or more cultures
○ i.e., culture is the unit of analysis- A fundamental issue is that measurements developed in a certain culture may not be applicable to a different culture
- Cross-cultural differences need to be “unpackaged” to identify individual-level variables that explain the cultural differences
○ e.g., differences in mathematics attainment due to differences in number word formation (i.e., 32 → “three ten two” in Japanese vs. “two and thirty” in German)
unpacking studies:
- The purpose is to find the underlying (individual-level) variable(s) that lead to the observed cultural differences
- identify processes linking cultural-level differences to individual-level differences
