Part 2: Experimental Approaches to Studying Infant Development Flashcards
Experimental Designs
A group of approaches that allow inferences about causes and effects to be drawn
▪ Essential characteristics
* Random assignment of participants to groups
- Experimental control
- Inference about causes and effects allowed
pros and cons
pros
- direction of causality no third variable problem
- have control over variables
cons
- not natural
- cannot be used in many different variables
Correlational Design (Quasi-Experimental) infant development
before vs during Covid
Take advantage of existing differences in experience
*And then measure outcome/performance, e.g.
▪ Pandemic presence/absence
▪ Night light in room or not
▪ The language/languages heard at home
▪ Exposure to SRIs in utero
pros and cons
**pros: **
* compares many groups of interes
- is able to establish relationship between many variables
cons
* no direction of causation
* third variable problem
Longitudinal
Same participants studied repeatedly at
different ages
pros:how same children develop, allows to see individual diffference
cons: takes longer,bigg commitment,
Cross-sectional
People of differing ages all studied at the
same time
pros:quick,less commitment
cons:age diference counfounded in group difference
Longitudinal-
Cross-sectional/ cohort-sequential
Same groups of different-aged people
studied repeatedly as they change ages
pros:less commitment,longitudinally over long time span in less time
con:conhor may different other then age
Microgenetic
Same participant studied repeatedly over a short period as they master a task
pros: observe development in real time
cons:commitment
Challenge of Studying Infants
- Cannot talk
- Cannot follow instructions
- Short attention span
- Limited behavioral repertoire
- Develop rapidly, so different tasks need to be used at different ages
Behavioral Measures
Dependent variables
* Sucking, head turning, reaching, surprise, looking time
Physiological Measures
Dependent variables
- Heart Rate, EEG or Event Related Potentials (ERPs), Pupil Dilation, Hemodynamic response (e.g. fMRI, Optical Imaging)
Measure: High Amplitude Sucking
- Can test preference
- Or Habituation
Measure: Conditioned Head Turn
- Can test discrimination
- And categorization
Psychophysiological Methods
Measures of autonomic nervous system activity
- Heart rate, blood pressure,
respiration, pupilometry, stress hormones
EEG - electroencephalography
- Measures electrical activity in the brain when nerve cells communicate
- EEG measures brain wave oscillatory activity
- Can be steady state or in response to stimuli
- Can reveal cognitive function (e.g. alpha waves for attention)
- Can reveal entrainment (rhythmical synchronization
ERP – event related potentials
- Amplitude changes in response to an external event
- Can Reveal Discrimination
- Latency can also reveal different cognitive processes
Measures of Brain Function
- Both non-invasive
- Motion artifacts
- Can reveal timing/latency
- Difficult to reveal brain localization
MEG - Magnetoencephalography
- Similar to EEG, but measures the magnetic Field changes that accompany electrical activity
- Can localize where in the brain better than In EEG/ERP
- But still difficult in infant brains because their brains are changing and growing
- Noninvasive
- Very expensive
- Sensitive to movement artifacts
Structural (MRI) and functional brain
imaging (fMRI
- fMRI via BOLD hemodynamic response
- Used primarily in clinical work, but
also in some experimental work - Minimally invasive, but the pulse
sequence is noisy, so challenging - Infants need to be perfectly still
- Very good spatial localization
- Not very good temporal resolution
- Easiest with sleeping infants, or children old enough to learn how to lie still in a scanner
- Optical Imaging (fNIRS) via functional Near Infrared Spectroscopy
- Measures hemodynamic response
- Shine light, picked up by blood (like in a pulse oximeter)
- Can determine changes in amount of oxygenated and deoxygenated blood in response to a stimulus
- Non-invasive
- Excellent spatial localization, but not as precise as MRI
- Poor temporal localization
- Can tolerate some movemen
t - More expensive than EEG, less than MRI
Ethical Research requires:
Informed Consent
* Parents give on behalf of children or infants
* “Assent” is still important
- Honesty & Transparency
- Full disclosure of any conflict of interest
- Random sample unless otherwise specified
- Obviously NOT manipulating the data
- Good research REQUIRES stringent adherence to ethical standards
- Ethical research REQUIRES thoughtful and appropriate
experimental design and implementation
cost must be lower then the benifit
and cause as little harm as possible
Is Empiricism Innate? Preference for Nurture Over Nature in People’s Beliefs About the Origins of Human Knowledge
Jinjing (Jenny) Wang
people belive that nurture play a bigger role then nature
