Study reveals: babies are stupid
“Babies, the study revealed, are too stupid to do the following:
use ice to alleviate pain of injuries, master the skills required
for scuba diving, and use can openers or spoons to access
nutritious food.”
Studying development
• We can’t ASK infants and young children
how they get better at all these things
• Just watching them doesn’t allow us to do
an experiment
• What can we use as a dependent variable?
Infant Skills
•
•
•
•
•
Having a heartbeat (birth) (Lindsey)
Sucking (birth)
Looking at things (birth - but bad vision!)
Getting bored (birth)
Reaching for objects (3 months -- gets
better with age!)
• Turning their head (5 months)
• Crawling (around 1 year)
• Having parents (birth)
Parent Survey
QuickTi me™ a nd a
TIFF (Uncompre ssed ) decomp resso r
are need ed to se e th is p icture.
“Unless their child is
grossly retarded, few
parents report their
child’s development
as slow”
Hetherington &
Parke (1986)
Signs of good parent report
• Report specific, recent events
– Instead of broad retrospectives
– MacArthur
• Random sampling of survey time
– E.g., structured diaries or phone calls
• Train parents as observers
Quick Time™a nd a
TIFF ( Unco mpre ssed ) dec ompr esso r
ar e nee ded to see this pictur e.
QuickTi me™ and a
T IFF (Uncom pressed) decom pressor
are needed to see t his pict ure.
Quic kT i me™ and a
T IFF (Unc ompres s ed) dec ompres s or
are needed t o s ee thi s pi c ture.
How can we take advantage of
infants’ and children’s skills to
answer interesting questions?
QuickTi me™ and a
T IFF (Uncom pressed) decom pressor
are needed to see t his pict ure.
Methodology and Age
• Generalizing from adults (e.g., perception)
to infants is a difficult task
• Different stimuli provoke different
responses at different ages
– Stager and Werker (Jeffrey, Jen)
Experimental Goals
• Milestones
– Want to know: Can children do X at age Y?
• Mechanisms of Change
– Want to know: If children fail to do X at age Y,
but succeed at age Z, how does that happen?
– Why do infants learn? Why bother? (Yan)
4 ways to accomplish those goals
• Cross-Sectional
• Longitudinal
• Microgenetic
• Training Experiments
Cross-Sectional Research
• Perform the same experiment, with two (or
more) different age groups at the same time
• Try to teach calculus to 4-year-olds and 8year-olds
• The 4-year-olds and the 6-year-olds are
different children
Example
Question:
Why are preschool children less proficient
at imitating adults than first-graders?
Hypothesis:
Maybe first graders spontaneously describe
(to themselves) what they are seeing, which
is a verbal aid to learning
(Coates & Hartup, 1969)
80
70
60
50
Passive
Observation
Induced
Verbalization
40
30
20
10
0
4-5 Years
7-8 Years
Strengths and Weaknesses
• Great at identifying differences across age
– And relatively quick
• Weakness: tells you very little about
individual differences
– Kate Walker-Smith
• Weakness: susceptible to cohort effects
Longitudinal
• Observe same participants repeatedly over a
period of time
• Sometimes on the same task
– Other times, interested in how performance on
different tasks is related, esp. across age
– What does dis/similar performance on a task at
different ages tell us? (Multiple ?s)
Strengths and Weaknesses
• Gives you fantastic information about
individual differences
– Can see what early markers predict later
differences in outcome
• Weakness: time consuming and expensive
– Also, time samples may miss points of interest
• Weakness: attrition and practice effects may
bias your sample
Microgenetic
• Minutely observe participants during a
period of developmental change
– Intensively analyze trials; not just for %correct
• Often, expose infants to a problem they’ve
never seen before (e.g., physics)
– And manipulate the instructions you give
• Errors are analyzed to see what kind of
strategy leads to incorrect result
– Watch strategies change over course of exp’t
Example
Question:
Can the discovery of new mathematical
strategies be implicit?
Method:
Exposed 2nd graders to identitiy math
problems (28+34-34=_) in EIGHT sessions.
Analyzed children’s responses for percent
correct, reaction time, and asked them to
identify their strategy
(Siegler & Stern, 1998)
Results
On average, the group solved identity
problems faster than regular problems
Importantly, though, not all children used
identity strategy
Finally, reaction time allowed investigators to
determine when children used identity
strategy. 90% of children showed (in RT)
use of identity strategy before they reported
using it explicitly!
Strengths and Weaknesses
• Can observe processes that lead to change
in great detail
• Weakness: for many tasks, it’s impossible to
predict when change will occur
• Weakness: only possible to maintain this
high density of observations for short time
– Can observe learning. Some argue it’s less
useful for observing development…
– Sunaina
Training Experiments
• Train participants to succeed on some task;
see if they are developmentally ready to
succeed, and what training is most useful
• If infants fail on task X, is it because they
lack experience, or because they haven’t
achieved a developmental milestone?
Example
Question:
Around age 2, children begin to use the
“shape bias” to generalize word meanings.
Is this the result of a maturational
milestone, or experience with language?
Method:
Train 17-m.o. infants for 7 weeks (1
session/week): learn four novel names.
Each name paired with 2 objects that differ
in all but shape. Control group: no training
(Smith et al., 2002)
Generalization Test
Control infants generalize at 34%.
Infants in training condition generalize by shape
70% of the time, similar to 2-year-olds
Strengths and Weaknesses
• Directly tests theories about how experience
affects performance
• Weakness: Ecological validity
– Though intervention leads to change, doesn’t
mean that’s how change occurs in the wild
• Weakness: Can only simulate experiential
change, not maturational change
– Useful for identifying maturation? (Katia)
Recap
• Cross-Sectional and Longitudinal
experiments investigate change across time
– Age is always one of the IVs (Tamar)
• Microgenetic and Training Experiments
explore reasons for change in depth
• No one approach can fully investigate
development
– Linda?: the 4 approaches are often combined
Infants in the wild
• What does identifying what infants CAN do
mean about what they DO do? (Jeffrey)
• How does family situation affect
developmental methods (Jeffrey, Roxanne,
Alex, Lindsey)
• Do delayed infants catch up? Can we help
them? (Tamar)
Infant Skills
•
•
•
•
•
Having a heartbeat (birth)
Sucking (birth)
Looking at things (birth - but bad vision!)
Getting bored (birth)
Reaching for objects (3 months -- gets
better with age!)
• Turning their head (5 months)
• Crawling (around 1 year)
• Having parents (birth)
Operant Conditioning
• Do infants really learn this way? (Paul)
• What’s the best reinforcer? How would you
find out? (Yan)
• Do conditioning experiments ignore the
organism? (Sunaina)
Preferential Looking
• Given two objects to look at, infants will
look more at the interesting one
• Example: visual acuity
– Trades on the fact that dense enough spatial
frequency (black/white bars) blurs to grey
Preferential Looking
• Given two objects to look at, infants will
look more at the interesting one
• Example: visual acuity
– Trades on the fact that dense enough spatial
frequency (black/white bars) blurs to grey
• How might we know what is interesting?
– How does maturation influence this (Jen)
Preference vs. Discrimination
• Preference procedures work really well when
there’s a reason to expect a preference
• But just because infants don’t have a
preference between two things doesn’t mean
they can’t tell the difference (Yvonne)
– Jared, Lindsey
Habituation
• Simple principle: if you show something to
an infant enough, they will get bored
• Then show them something different
• If they can detect the difference, they should
be more interested
– Doesn’t rely on pre-existing preference
Habituation Setup
Monitor + Speakers + Camera
Baby
Infants are tested on words they’ve heard vs. new words
QuickTime™ and a
DV/DVCPRO - NTSC decompressor
are needed to see this picture.
New Methods
• Eye-tracking
• Infant ERP
– Kelly Snyder
• Genetics/Twin Studies
• “Mental World” inferencing
Object Perception
Object Perception
Object Perception
Object Perception
Object Perception
Object Perception
Object Perception
Object Perception
Habituation
Test
Object Perception
Infants
prefer
this one
(4 mo.)
Summary
• Experiments with infants and young
children often rely on very indirect methods
to assess psychological constructs
• Habituation experiments (and others) often
yield small differences. How comfortable
should we feel basing theories on them?
– Jess