Post on 21-Jul-2020
Week 8 Lecture: How do study babies?
Habituation
Preferential Looking
Eye tracking
EEG (electroencephalography)
Week 8 Lecture: Habituation - Definition
Step 1: Show infant stimulus X
Step 2: After a while, infant gets bored (looks less) with stimulus X
Step 3: Show Stimulus Y
If X=Y, then still bored (less looking)
IF X NOT= Y then no longer bored (look more)
Week 8 Lecture: Habituation - Example
Want to test if baby is red-green color blind
Step 1: Show green circle
Step 2: after a while, infant gets bored and looks less
Step 3: Show red circle
If still bored because red and green looks the same, continue looking less
If not bored because red looks new and different, baby will look more
Week 8 Lecture: Habituation - Enumaration of Actions - PreviousStudies
Infants under 1 year old
Discriminate two dots from three
Discriminate two objects from three
Discriminate two motion patterns from three
How is this discrimination accomplished?
Perceptual grouping
More abstract entities
Habituation to number of objects transfers to longer looking time to samenumber of drum beats
Week 8 Lecture: Habituation - Enumaration of Actions - ActionSequence Characteristics
More complex than sound (which infants can discriminate)
Endure only temporarily
Integration of space and motion over time
Sound is integration over time but not space
Week 8 Lecture: Habituation - Distinquishing 2 and 3 jumps - Setup
Setup of enumeration experiment
Week 8 Lecture: Habituation - Distinquishing 2 and 3 jumps - Definition
Where does one action end and another begin?
When object starts and stops moving?
Can infants discriminate 2 vs. 3 'jumps'?
Differences between 2 and 3 jumps
Number of jumps
Length of sequence
'Jumps' controlled for
Tempo
Overall duration
Week 8 Lecture: Habituation - Distinquishing 2 and 3 jumps -Procedure
Sequence of 2 and 3 Jumps
Week 8 Lecture: Habituation - Distinquishing 2 and 3 jumps - Results
Results
Summary: Infants CAN discriminate
Week 8 Lecture: Habituation - Distinquishing 2 and 3 jumps -Experiment 2
How is it done? Is pause (no motion) between jumps necessaryseparator?
Experiment 2:
Same as experiment 1 but head wags between jumps
Puppet always in motion- cannot determine sequence by motion alone
Can infants still discriminate jumps?
Week 8 Lecture: Habituation - Distinquishing 2 and 3 jumps - Resultsof Experiment 2
Results of Experiment 2
Results Infants CAN (just barely)
Week 8 Lecture: Habituation - Distinquishing 2 and 3 jumps - Analysis
Issues with experiment 2
P=.05 (Just barely , what a coincidence!)
Something a little weird
Experiment 1
18 subjects in exp 1, 6 excluded for failure to complete 4 trials (why 4?)
Experiment 2
22 subjects in exp 2, 11 excluded -- 4 failures not mentioned (oversight orintentional)
Why so many excluded?
Excluded subjects to get to p=0.05?
Definition of 'Fussiness'
Week 8 Lecture: Habituation - Distinquishing 2 and 3 jumps -Habituation Method
Summary
Experiment 1
Can discriminate 2 from 3 when pause between
Also weird 3 way interaction in Experiment 1 never addressed
Experiment 2
Discrimination of 2 from 3 without pause is much shakier result
Week 8 Lecture: Preferntial looking - Newborns Prefer Faces
Newborn Babies Prefer Faces
Week 8 Lecture: Preferntial looking - Faces and races
Faces and Races
People recognize own-race faces more accurately
Shown in infants as young as 6 months old
Where does own-race face advantage come from?
Nature or nurture?
Even 3 months have significant experience with faces
Some evidence to suggest that earl exposure affects own-race faceadvantage
Week 8 Lecture: Preferntial looking - Experiment Determining Cause ofFace-Race Effect
Investigates preference for own race and exposure effects
Standard visual preference task
Measure looking time to two faces presented
Black and white
Equated for attractiveness
36 infants (3 months old)
12 Caucasian Israeli (white babies with white faces in environment)
12 African Ethiopian awaiting immigration to Israel (black babies withblack faces in environment)
12 African Israeli already immigrated to Israel (black babies with somewhite faces in environment)
Week 8 Lecture: Preferntial looking - Results of Experiment
Results of Experiment 2
Summary: Environment changes race preference
Week 8 Lecture: Preferntial looking - Follow up Experiment
Is own race face preference mediated by color of face and not faceshape?
Other experiment looked at preference for colored blobs of same hueas average own race
No preferences found
Preference is based on configuration of features, not color
Week 8 Lecture: Preferntial looking - Novelty vs. Familiarity
Why do babies sometimes prefer novel things and sometimes preferfamiliar things?
Depends on similarity to existing memories
High similarity = familiarity preference
Exact similarity = novelty preference
Week 8 Lecture: Eye Tracking - Setup
Tracking Eye Movements of a Baby
Eye tracking: Use cameras to track gaze
Week 8 Lecture: Eye Tracking - Experimental results
Using eye trackers to study mental rotation
Week 8 Lecture: EEG - Setup
Cute baby with lots of electrodes for EEG
Week 8 Lecture: EEG - Results for whole brain
Results of EEG for whole brain
A = Anterior (front of brain), P = Posterior (back of brain)
Poor spatial resolution
Good temporal resolution