1. Visual Acuity Testing Paired Preference Procedure
Forced Choice Preference Procedure
Optokinetic Nystagmus
Visual Evoked Potential– a form of ERP

2. Sensory Development
Can be used to study visual acuity

3. Vision Testing

4. Infant Acuity Testing

5. Infant Acuity Testing
Davida Teller’s simple test card

6. Visual Evoked Potential

7. ERP: Event Related Potentials

8. Event Related Potentials

9. Event Related Potential

10. Visual Evoked Potential

11. Infant Vision Testing

12. Acuity Development

13. Development of Acuity
At 12 mo.
At 3 mo.
At birth

14. Visual Acuity At birth, acuity is approximately 20/400 to 20/800
By 4 to 5 months infants are no longer “legally blind” (e.g., 20/200)
Reaches 20/20 between 8 to months
VEP suggests faster development– why?

15. What Infants See

16. Other Visual Limitations
Can only see high contrast stimuli

17. Contrast Sensitivity Functions

18. What infants see

19. Why is vision so poor? Is it the eye? Cornea Iris Lens Retina
Astigmatism
Iris
Lens
Retina

20. Changes in Cones

21. Cone Development

22. Scanning
Research on externality effect

23. Scanning in Newborns

24. Why is vision so poor?

25. Color Vision When can babies discriminate color?
Separating Hue, Brightness & Saturation
Categorical Perception of Color
R O Y G B I V

26. Can Infants discriminate color?
Problem in determining color discrimination
Color and Brightness are two independent aspects of any image
Confounding color differences with brightness differences – are infants (or adults) discriminating differences on brightness or color?
Brightness is a perceptual characteristic not simply a physical characteristic– must be determined by testing vision
Solution – in adults.
1) Have adults match different colors for brightness
2) Compare different colors previously matched for brightness

27. Matching Brightness – adjust the brightness (not hue) of the inner circle to match that of the outer one

28. Testing for Red/Green Color Blindness

29. Can Infants discriminate color? – cont.
Problems with adult solution to brightness/color confound for infant testing
Can’t ask infants to ignore color and compare only brightness
Can’t use adult matching data to apply to infants. Brightness likely differ considerably for babies – because of pigmentation in infants’ eyes.
Brightness matches even from one adult to another and likely same for babies – must test each individual separately
Solution – use a clever habituation task to get babies to IGNORE brightness

30. Infant Color Discrimination Task

31. Color Categories

32. Auditory Thresholds Tested with High Amplitude Sucking Procedure
Newborns hear above 27 decibels
Can discriminate about 1 note on the musical scale

33. Sound Localization – cont.
Sound louder and sooner to left ear L R

34. Newborn Speech Perception
H.A.S. procedure is also used to study speech perception
P. Eimas: Can newborn discriminate “B” from “P” sounds
Can infants discriminate “R from “L”
Or Pittsburgher’s
Harry from Hairy

35. BP
THAI

36. Dialect

37. PGH

38. Early Speech Perception
Is this a innate specialized ability?
Abstraction of ongoing speech
Invariance over individuals, gender, dialect
Dialect Study (At 11 mo but not 4)
Pittsburgh babies can’t discriminate Chinese from Taiwanese
Can discriminate Pgh from New York
Can discriminate 2 novel dialects (Southern from New York)

39. Newborn Taste Abilities
Can newborns discriminate the four basic flavors of :
Sweet, Sour, Bitter, Salty
Newborns prefer sweet and salty—why?
Sweet flavors can sooth the newborn

40. Newborn Smell
Newborns react positively and negatively to different smells
Can infants detect the smell of their mothers?

41. World of the Newborn What is the world of a newborn like?
How does this effect opinion about imitation research?