1. Karen Dobkins Development of Motion Processing in Human Infants Karen Dobkins Psychology Department UC San Diego

2. Direction: Leftward or Rightward? MOTION PROCESSING in ADULTS

3. Directional (Left vs. Right) Eye Movement Measure

4. Eye Movement Direction: Leftward or Rightward?

5. What about higher-level motion processing?….. Motion Integration

6. Plaid Patterns Low-LevelHigher-Level

7. Oops, there is a problem with this stimulus

8. A Better Stimulus

9. Integration Stimulus

10. Directional (Left vs. Right) Eye Movement Measure Percent Correct: 50% - 100%

11. Infants: 2-month-olds (n = 9) 3-month-olds (n = 12) 4-month-olds (n = 12) 5-month-olds (n = 9) Subjects Adults: n = 6

12. Example Data (2 month old) Percent Correct (%) Eye Movement Reliability (EMR) EMR 30 trials Integration 30 trials

13. Performance vs. Age Percent Correct (%) Adults ** * Integration Stimulus:Linear Regression, Effect of Age: p < 0.025 ** p < 0.005 * p < 0.05 20 /sec 2 /sec

14. Control Stimulus 2 /sec

15. Control Stimulus

16. “Integration Effect” = Integration - Control ** p < 0.005 Integration Effect (%) Adults ** 2) Motion integration across space decreases with age, p < 0.005 Adults (P) 2) Motion integration across space decreases with age, p < 0.005 1) Infants as young as 2 months integrate component motion into coherent pattern motion (suggests maturity of higher level motion areas)

17. Shrinking Motion Summation Fields with Age Coherent Pattern Motion Shrinking Receptive Fields Sizes with Age

18. Barber Pole Experiments Perceived Direction 1D motion (interior) 2D motion (terminators) ….. Integration of 1D and 2D motion

19. Barber Pole Stimuli Control Stimulus (integration study)Barber Pole (Vertical Aps)Barber Pole (Horizontal Aps) Barber Pole Effect = Horizontal Aps - Vertical Aps (for Leftward vs. Rightward Eye Movement Discrimination) Perceived Direction Mostly Vertical Perceived Direction Mostly Horizontal

20. Yes, infant motion processing is influenced by 2D line terminator motion! With clever exp design and a lot of math, we can estimate the “effective shift”…. = 15 - 20 degrees

21. Barber Diamond: Effects of Context Duncan, Albright & Stoner, 2000 Intrinsic (Real) Terminators Extrinsic (Accidental) Terminators

22. Projects in Developmental Origins of Autism

23. Social/Emotional/Communicative Deficits in Autism Lack of interest in social interactions Deficits in Communication (Language & Gestures) Repetitive behaviors/ Obsessive interests Reduced orienting to faces and voices Difficulty understanding the intentions of others Visual Perceptual “Differences”

24. EMBEDDED FIGURE TASK

25. FACES MOTION Visual Perceptual “Differences”

26. And WHEN? In what part(s) of the brain do the problems in Autism originate? BRAIN AREAS Visual cortex HIGHER-LEVEL COGNITIVE FUNCTIONS MAGNO PARVO MOTION FACES

27. - SOCIAL/EMOTIONAL/COMMUNICATIVE deficits are apparent by 12 months! (Retrospective studies of videotapes) -VISUAL PERCEPTUAL abnormalities might be apparent at an even earlier time point in development!

28. Can we find evidence for visual (and other) abnormalities in the FIRST YEAR of life? OUR RESEARCH QUESTION: OUR APPROACH: Infant Siblings of Children with Autism (“At-Risk” Infants): ~10% risk for Autism …. vs. 0.5% in general population

29. Method: At-Risk and Typical Infants tested longitudinally from ages 6 - 36 months 1) Magno/Parvo Vision Test (6 months) 2) Face Processing Test (10 months) 3) Emotional/Social Behaviors (18 months) Autism Testing (24 and 36 months) 4) Language and Cognitive Processing (6 - 36 months) 1) Magno/Parvo Vision Test (6 months)

30. Red/Green (PARVO) Light/Dark (MAGNO)

31. Measuring Red/Geen (PARVO) and Light/Dark (MAGNO) Sensitivity in Pre-Verbal Infants

32. Forced-Choice Preferential Looking 6-month old infants

35. Sensitivity

36. Thank you Ione Fine Linday Lewis Joe McCleery

37. Performance vs. Age ** p < 0.005 * p < 0.05 Percent Correct (%) Adults ** * * * * Integration Stimulus:Linear Regression, Effect of Age: p < 0.025 Control Stimulus: Linear Regression, Effect of Age: p = 0.27 (NS)

38. Quadratic Regression: Effect of Age, p < 0.005

39. Effect of Aperture Size in Adults Stimulus Condition: 2  by 4 , 80% (infants) Integration Effect: -9.3% (p = 0.15, NS) 1  by 2 , 80% contrast -10.1% (p = 0.27, NS)

40. Stimulus-dependent changes in size of motion summation fields e.g., Adults: at HIGH contrasts, motion integration across space is WEAKER (e.g., Lorenceau & Shiffrar, 1992) i.e., smaller motion summation fields “Effective” contrast increases with age No Integration Effect in Adults (from 5% to 80% contrast)

42. Integration Stimulus Integration Stimulus + Blur (from Refractive Error) This is for Jeff Mulligan

43. Motion integration across space decreases with age….. a million possibilities 1) Decreasing size of motion summation fields 2) Changes in stimulus conditions yielding optimal motion integration, or optimal motion integration across space 3) Changes in relative contribution of cortical vs. subcortical mechanisms involved in eye movements

44. Measuring Perceived Angular Shift (between Horizontal and Vertical Apertures) Equivalent Direction (EqDIR): The angle of gratings moving within horizontal apertures required to yield the same horizontalness as produced by gratings moving within vertical apertures at an angle of X degrees. “Effective” Angular Shift = EqDIR - X Horizontalness: Leftward vs. Rightward Eye Movement Direction Discrimination Performance X = 45 degrees