Methods and Ethics

Question 1

developmental designs

Answer 1

• Developmental scientists use many of the designs that other researchers use -> observation, interview, experimentation, etc.
• some designs are specifically designed to study change across development
• ex. cross-sectional, longitudinal, microgenetic

Question 2

cross-sectional

Answer 2

• Examine different individuals of different ages at one time
• Ex. Studying the development of walking among 20 infants from each of four age groups: 10, 12, 14, 16
• Advantage: only have to do it once -> can analyze and publish data quickly,
• Disadvantage: individual differences may play a role in the results

Question 3

longitudinal

Answer 3

• Examines the same individuals at multiple ages
• Ex. Studying the development of language among 20 infants when they are 6 months, 10 months, 14 months, and 18 months
• Advantages: good experimental control; better idea of the development of each child
• Disadvantages: attrition (dropping out); cost

Question 4

microgenetic

Answer 4

• A mini, intense longitudinal design
• One group of children is tested repeatedly within a short time frame, normally at a time of significant change
• Ex. Studying the A-not-B error every week in a sample of 20 eight-to-ten month-olds
• Advantages: good experimental control; better idea of the development of each child
• Disadvantage: attrition (slightly lower risk); intense frequency of study

Question 5

challenges in infancy research

Answer 5

• recruitment and sample size
• assent and compensation
• communication
• attrition

Question 6

recruitment and sample size

Answer 6

• Normal means of recruiting (ex. HSP credits, payment) don’t work -> Paying parents for their baby’s research time is ethically problematic
• Because of difficulty and cost of recruiting infants, infant studies typically suffer from low sample sizes and reduced statistical power
• The higher the sample size, the easier it is to detect a change
• Due to the low power, it’s hard to find an effect even if one exists

Question 7

things that can influence infant recruitment

Answer 7

• Social policies like parental leave (in Canada, our generous parental leave policy makes it easier to recruit them)
• Legal policies re: publication of birth data (ie. In places like France, researchers can access birth records and directly contact new parents; in Canada, we can’t)
• Relationship with community

Question 8

strategies of infant recruitmant (from most to least effective)

Answer 8

• Visits to maternity hospitals (if allowed)
• Cold-calling or cold-mailing parents from birth registration lists
• Advertisements at community centres/daycares/in media

Question 9

assent and compensation

Answer 9

• Infants cannot give consent, so their parents have to give consent for them (assent)
• Assent is ethically tricky, but even more so with non-verbal subjects like infants
• How do we compensate the participant? We can’t pay infants -> we give babies toys and “degrees”

Question 10

communication

Answer 10

• Hard for researchers to communicate with non-verbal infants
• Can’t rely on interviews, surveys, or any design that requires linguistic info
• Therefore, infant studies rely heavily on:
• Neuroimaging (ex. NIRS)
• Physiological responses (ex. Heart rate, respiratory rate, suck rate, EEG)
  Non-verbal behavioural responses (ex. Eye-tracking, reaching (6mo), looking time -> habituation/dishabituation depending on if infants notice changes that occur)

Question 11

NIRS

Answer 11

• type of neuroimaging
• uses low levels of near-infrared (visible) light projected onto the infants skull by NIRS emitters
• Depending on blood chemistry in a brain region, more or less of this light is reflected back to the NIRS detections (oxygenated/non-oxygenated hemoglobin -> oxygenated = more blood activity).
• NIRS good for infants because it’s safe, quiet, and non-invasive; infants’ skulls are also thinner and reflect light better; in babies the layer between skull and brain is water but in adults it’s lipids; babies have less hair than adults

Question 12

EEG

Answer 12

• measures physiological responses
• measures electrical activity in brain and is very temporally sensitive – responses are recorded so fast it’s almost instant
• faster than NIRS, but spatially underspecified

Question 13

eye-tracking

Answer 13

• specific technology
• measures gaze following, pupil dilation
• is different than looking time HE WILL TEST THIS

Question 14

habituation

Answer 14

• tells us that:
• Baby can see
• Baby can control eye movements
• Baby has enough memory and cognition to recognize that she’s already seen those objects

Question 15

dishabituation

Answer 15

• level of dishabituation is related to the level of perceptual difference between the 2 objects (ex. If they look similar, the second object will get less looking time even if it’s never been seen before)
• Tells us that baby has detected change (since looking time changes)

Question 16

attrition

Answer 16

• the loss of subjects due to failure to complete the study
• Particularly problematic in longitudinal designs, but also problematic even in one-time designs
• This adds to the already complex problem of low sample sizes due to recruitment challenges

Question 17

in what ways can attrition happen in one-time designs?

Answer 17

• Crying/fussing (“fuss out”)
• Sleeping (especially problematic with newborns)
• Failure to attend to the stimulus (ie. Too distracted by their socks, the lab environment, etc.)
• Other physiological confounds (ie. Pooping)