1. Describe how reaching and grasping abilities develop in the first year of life.

2. Development of reaching Within first 2 weeks, already directing arm towards objects. Some crude control of reach direction. Improves by the 5th month; consistently touch targets. Won’t reach for targets beyond arm’s length. Catching and anticipating target motion at 6 months. Distance accuracy develops more slowly, improving by 7 months.

3. Increased use of visual feedback between 5 and 11 months

4. Early reach movements Initially use the trunk & shoulder (proximal joints) to reach for objects; use elbow less frequently. When babies do make large movements, can’t control inter-segmental dynamics. So hand oscillates.

5. Development of reaching Between 5 and 9 months see many changes to kinematics: 1) Straightening of the hand path 2) Reduced number of “submovements” 3) Reduced movement time

6. Development of grasping Newborns have grasp reflex (clasp object brought against the palm) – disappears by 6 months. 5 months: hand does not orient to object until contact 9 months: hand orients prior to contact (note visual information about orientation is available at 2 months). Pre-shape for object size. Still adjusting grip force by 7-8 years (grip force larger for larger objects). Use palmar grasp until about 12 months – then use fingers to grasp. Corresponds to rapid increase in the rate of myelination of corticospinal tracts at 12 months – responsible for distal musculature.

7. Describe Stratton’s experiment with inverting lenses. What are the implications?

8. Adaptation to different relation between vision and movement. George Stratton –Wore inverting lens for 8 days –Was able to adapt to the new visuo-motor mapping –Believed that Alternatively… Implications: Either we learn visual directions by associating visual experiences with other forms of sensory feedback (e.g. proprioceptive). or Adaptation results from learning correlation betweeen vision and actively generated motor commands (Held, 1965).

9. Why might we remain adaptable to new visuo-motor relationships? What is the evidence for this adaptability? Where in the brain might the adaptation be occurring?

10. Why do we need to retain plasticity for new visuo-motor relationships? 1. Need to adjust to changes in body size during development. 2. Need to adjust to damage/aging. 3. Need to adjust to environmental changes eg ice, loads etc. 4. Need to learn arbitrary mappings for tool use etc. 5. Need to acquire new motor skills. 6. Visuo-motor coordination is a computationally difficult problem for the brain. Need flexibility to correct errors.

11. Ability to adapt to new relationships requires cerebellum Prism adaptation

12. Describe the visual capabilities of Mike May, the man whose vision was restored late in life following a childhood accident. What are the implications for visual development?

13. Molyneux’s Question: Can a person blind from birth, whose vision is restored, tell that a circle and a square are different shapes? Role of Experience in Development of Vision

14. Mike May - world speed record for downhill skiing by a blind person. Lost vision at age 3 - scarred corneas. Optically 20/20 - functionally 20/500 (cf amblyopia) Answer to Molyneux’s question: Mike May couldn’t tell difference between sphere and cube. Improved, but does it logically rather than perceptually. (cf other cases) Color: an orange thing on a basket ball court must be a ball. Motion: can detect moving objects, distinguish different speeds. Note: fMRI shows no activity in Infero-temporal cortex (corresponding to pattern recognition) but there is activity in MT, MST (motion areas) and V4 (color). Other parts of brain take over when a cortical area is inactive. Cannot recognize faces. (eyes, movement of mouth distracting) Can’t perceive distance very well. Can’t recognize perspective. No size constancy or lightness constancy/ segmentation of scene into objects, shadows difficult. Vision most useful for catching balls (inconsistent with Held & Hein??) and finding things if he drops them. Implications: spatial acuity and form/object vision requires continued experience. Brain regions become unresponsive. Color and motion perception are preserved (possibly innate) despite lack of input.

15. Implications? Basic object perception (recognition and segmentation) requires experience. (Experience prior to 3 yrs not enough.) Geometric cues about scene structure (perspective, distance) also require experience. Color and motion more robust - either present at birth, or acquired before 3yrs, and preserved without continued experience.

16. What does change blindness imply about vision? What are some examples?

17. Change Blindness: insensitivity to changes in visual scenes made during an eye movement/transient occlusion. Change blindness challenges idea that perception delivers a comprehensive representation of world. What is represented? Attended objects/regions of central interest?

18. Tasks involve a series of micro-computations, or micro-tasks. (attend only to task-relevant information) Task specificity of computations explains “Change Blindness.” (effectively “blind” to irrelevant information) Implications Visual representation of an object may be fragmentary. (greater sensitivity to task-relevant changes)

19. What are the advantages and disadvantages of using a virtual reality environment to study the brain and behavior? Can do experiments in naturalistic environments. Control of stimulus. Important in complex environments. Can do impossible manipulations. Unrealistic in many ways: small field of view, latency of display following movement, stereo cues weak, other cues missing. Force feedback: no tactile stimulation Discomfort. Environment might change the behavior - eg heavy helmet suppresses head movements.

20. What is the conclusion from Held & Hein’s experiment with kittens (putting one kitten in a carousel driven by the other kitten.)? How would you do this experiment today, using virtual reality technology?

21. Held & Hein Role of Experience in Development of Visuo-motor coordination Both kittens get visual experience and motor experience 1.Visual experience correlated with motor commands/proprioceptive feedback/vision of limbs 2.Gets both, but uncorrelated. Kitten 2 -abnormal visuo- motor coordination. 1 2

22. What is meant by “top-down” and “bottom-up” processing? Give examples of both.

23. Briefly summarize the driving experiment by Shinoda, Hayhoe, & Shrivastava. What did they find?

25. Intersection P = 1.0 Mid-block P = 0.3 Greater probability of detection in probable locations Suggests Ss learn where to look.