1. Infant Perception

2. William James, 1890 “The baby, assailed by eyes, ears, nose, skin and entrails all at once, feels it all as one great blooming, buzzing confusion.”

3. Infant Vision Infants’ looking is: –active –organized –selective They prefer stimuli with: –high contrast –curves –motion babies LOVE faces!

4. Fantz’ Methodological Breakthrough: Preferential Looking Paradigm Infants view two simultaneous displays. Measure their looking time to each display. If infants consistently look longer at one than the other, then they can discriminate between the two displays. * Preferences logically imply discrimination *

5. Visual Acuity A: B:

6. Visual Acuity Newborns:20/200 to 20/400 (legally blind) 3-month-olds:20/100 6-month-olds:20/70 1-year-olds:Close to adult level

7. Habituation/Dishabituation Paradigm Show same thing repeatedly until infants get bored (decreased looking) Show new thing and measure looking

8. Using Habituation/Dishabituation to Test Infants’ Color Perception Color => Wavelengths of light; a continuous dimension

9. Categorical Color Perception 480 nanometers=“BLUE” 510 nanometers (+ 30)=“GREEN” 450 nanometers (- 30)=“BLUE” Physical LevelPsychological Level (continuous) (categorical) 450480510

10. Categorical Color Perception in 3-month-old Infants Habituation Phase: Infants are habituated to one wavelength (480; “blue”) Test Phase: Group 1 views wavelength of + 30 nm (510; “green”) Group 2 views wavelength of - 30 nm (450; “blue”)

11. Categorical Color Perception in 3-month-old Infants Results: Infants who view wavelength that crosses color boundary dishabituate Conclusion: Infants perceive colors in categories, much like adults do

12. Rules that Babies Look By Marshall Haith 1. If awake, open your eyes. 2. If in darkness, search around. 3. If find light, search for edges. 4. If find edges, examine them.

13. Visual Scanning 1-month-olds: scan perimeter of an object/face (highest contrast with background) 2-month-olds: scan more broadly, both outer edges and inner detail

14. Infants’ Auditory Sensitivity Pretty good! Decrement of ~10 decibels Most sensitive to sounds of human speech At birth, babies recognize and prefer their mothers’ voice

15. Categorical Speech Perception Speech sounds are perceived in distinct phonemic categories Example: /ba/ vs. /pa/ Produced in the same way; only difference is Voice Onset Time

16. Categorical Speech Perception in 1-month-old Infants GROUP 1 Habituation Phase: Repeated exposure to VOT: 20 msec = /ba/ Test Phase: Presentation of new VOT: 40 msec = /pa/ GROUP 2 Habituation Phase: Repeated exposure to VOT: 60 msec = /pa/ Test Phase: Presentation of new VOT: 80 msec = /pa/ For both groups, the acoustical difference between sounds is the same (+20 msec)

17. Categorical Speech Perception in 1-month-old Infants Results: Infants who hear VOT that crosses category boundary (Group 1) dishabituate Conclusion: Infants can distinguish phonemic sound categories

18. Categorical Speech Perception 1-month-olds can discriminate all sound categories (600 consonants, 200 vowels) Between 6-12 months of age, this ability narrows to only those sound categories available in the infant’s native language

19. Music Perception Babies LOVE music Respond to rhythm (bounce, move) Prefer consonance vs. dissonance Can recognize same melody played at different pitches

20. In summary Infant perception is active & organized next time….infant cognition