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