Perceptual Development

General Issues

• Why study perceptual development• Erin – why is vision so quick to develop?

• How different from cognitive development?

• Issue of kind or of degree?

Methodological Issues

• Habitation technique• Validity• Reliability • Directions of effects

Novelty/familiarity vs. violation of expectation vs. prediction

• Tapping real world knowledge or on-line behavior• Pictures vs. real objects• Visual acuity

• Stefani, Dana, Seunghee, Dwight, Roxie

Methods

• Looking Paradigms

• Preferential Looking

• Present two stimuli simultaneously

• Measure the infant’s preference for one or the other stimulus

Erin – torn between two

Methods

• Habituation:

• Familiarize to one stimulus and test with a different one

• Measure looking time to stimulus during habituation and test 0

2

4

6

8

10

12

1 2 3 4 5 6 7 8 9

Trials

Loo

king

Tim

e

Methods

• Habituation:

• Subtle difference

between habituation

and familiarization

• Gary

0

2

4

6

8

10

12

1 3 5 7 9 -2 -4

Trials

Look

ing T

ime

habituation

changestimulus

dishabituation

Methods

• Kellman & Spelke (1983)

Habituate Unitary Object Test Two Object Test

1-month-old

2-month-old

Theoretical perspectives• Empiricist?• Nativist?

• Big battleground: Domain-specificity, core knowledge

• Evolutionary• Gary, - prototypes

• Adaptive – Roxie, Erin: attractive mothers/babies• See Langlois et al. 1995.

The What question

• What develops when? (Milestones)• What capabilities are innate? (Elida)

• Important to distinguish between difference aspects of innateness

• face orienting, size and shape constancy, wholes and parts all shown at birth

But, something can be innate even if not present at birth

The mechanism question

• What learning mechanisms are innate? • Elida

How does change occur?

Specific Issues

• How do individuals differ?• Answer: A lot

More specific issues

• How do changes in the brain contribute to perceptual development? (Dwight)

• Johnson – Conspec (subcortical) vs. Conlern (cortical)

Specific issues with papers

Faces and Prototypes

All with Caucasian females (Dana)

Tautological? (Gary and Joan) Symmetry (Gary)

Attractiveness all in the face (Dana)

Speech

Bilinguism (Miriam), CP in young of other species? (Miriam)

Scott?

Continued

• What constrains perceptual development?

3 weeks: large squared checkerboard.8 weeks: small squared checkerboard.

Bigger Issues

• Drawbacks / Challenges

• Hard to test many aspects of perceptual development

• Theory light