Week 2: methods Flashcards
methods of measuring individual differences
- Survey / self-report measures
- Observational measures
- Performance measures
Self-report measure
Typically involve presenting a list of statements and asking participants the extent to which they agree/disagree with them
self-report advantages
Low cost and easy to administer in large scale (even online)
self-report disadvantages
– 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 (introspection)
Experience sampling method
- Ask participants 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
- Alternatively, participants could be signalled by a mobile device to fill in a brief questionnaire at a random time
- Potential problem:
– The very act of self-monitoring can influence what is being measured
Observational measures
Typically involves recording what is being done or how often something is done through observation by a third person (from tally to videotaping)
observation advantages:
can be used when it is impossible or inappropriate to give instructions to a participant; can be used in naturalistic settings
observation limitations
– can only measure overt behaviours
– scoring may be influenced by observer biases
* Computerised scoring (as in eye tracking) can minimise observer biases
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
performance measures advantages
objective (rather than self-report which relies on self-awareness)
performance measures limitations
their relationship with real-world behaviours (i.e., ecological validity) is not always clear
Can we measure the unconscious mind?
Cognitive tasks like implicit association test and priming are used to measure unconscious cognitive processing
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
* In masked priming, the prime is presented followed by a junk visual material (mask). This prevents the prime from entering conscious processing
Masked priming task - Moret-Tatay et al. (2020)
○ When the name matches the picture, participants are faster than without the masked prime.
Factor analysis
Factor analysis is a statistical technique used to reduce a large number of variables into fewer “factors”
The rationale is to analyse the patterns in which variables (items) vary together (covariance); variables (items) indicating the same underlying construct are expected to covary
Exploratory factor analysis (EFA)
does not assume a particular factor structure but uses the data 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
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 (EFA)
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 brain imaging methods
CT scan
MRI
MRI
used to measure brain volume, grey matter volume, white matter volume, etc., which have been associated with individual differences in behaviour (e.g., intelligence)
§ White matter consists primarily of myelinated axons
§ Gray matter consists primarily of neuronal cell bodies
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
functional brain imaging methods
fMRI
PET scan
fMRI
Functional imaging methods such as fMRI measure dynamic physiological changes in the brain in vivo and associate them with different patterns of mental processes/behaviour
* 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
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
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
Functional imaging: 2 methods to see which activation is related to the specific process?
Subtraction method
Conjunction method
Conjunction method
(joint activation for tasks)
Subtraction method
(difference in activation for tasks)
2 approaches to understand the brain:
- Functional specialisation: where?
Functional integration: how? Networks…
Functional integration
i.e., the way in which different regions work together in terms of networks
* 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)
Diffusion Tensor Imaging (DTI)
- 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
Electrophysiological measures
Electroencephalography (EEG) – records electrical signals generated by the brain through electrodes placed at different points on the scalp
event-related potentials (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 versus causation
correlation does not necessarily imply causation
* Causal relationship needs to be tested by experiments, which is unfeasible in some circumstances
Different levels of explanations to individual differences
- Genetic explanations
- Socio-cultural explanations
- (Neurobiological explanations)
What is a gene?
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
genotype
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 outward manifestation of the individual, including physical appearance, intelligence, and personality
* Genes can be turned on and off by the environment (of the cell)
study of heritability
is 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
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
the phenotype-first approach
starts with a given trait (e.g. novelty seeking) and determine which gene(s) among the entire genome contribute most to variations in that trait
Genome-wide association studies
Cross-cultural research
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
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)
The heritability of intelligence
is found to be 50% (this is variance across a population)
