Preadolescent Visual Perception

1
Preadolescent Visual Perception
A look into the visual system of infants and
preschoolers, and their perception of Objects,
Motion and Color.

• By Jason Graf

2
Outline

• The Development of the Visual System
• Biological Change in Early Visual Systems
• Changes in Acuity
• Changes in Contrast Sensitivity

• Perception of Objects
• Lightness Similarity
• Adjacent Object Perception
• Occluded Object Perception
• Face Perception

• Perception of Motion
• Newborn Perception
• Biological Motion

• Perception of Color
• Early Enhancement in Infants

• Duke University Infant Perception Lab
• Campos Visual Cliff Experiment
• Lea Hyvärinens System

3
Visual Development
Acuity

• At Birth 20/400 to 20/600 Vision
• By 6 Months Almost 20/20 Vision
• Due to Newborns Cone Structure
• Larger Inner Segments of Cones
• Less Cones Available to Detect Light
• Widely Spaced Poorly Developed Cone Receptors
• Visual Lattice too Large due to Fatty Inner
  Segments
• Causes Lessened Visual Acuity

• Immaturity of Neural Pathways
• Increase in Size of Cortex between
• 3 and 6 Months. Tested Using VEP
• These increases in Cortex size Correlate to the
  increase in a childs visual acuity.

4
Visual Development Cont
Contrast Sensitivity

• Infants Perception Restricted to Low Frequencies
• Infant has a contrast sensitivity 20-100x lower
  then that of an adult
• Sees almost nothing at the adult sensitive
  spatial freq. 2-3 cycles/deg.
• Development of Contrast
• 1 Month
• Infant vision slightly worse then adult night
  vision
• _at_ close distance can see high contrast
• 3 Months
• Contrast perception improves allows child to
  see certain facial expressions

• Infancy Vision through frosted glass

5
Perception of Objects

• Object Lightness Similarity
• Infants can group elements based on lightness
• Study by Quinn, Burke and Rush
• 3 months would dishabituate to different
  directional organization
• Shows that Infants perceptually organize based on
  object lightness.
• Adjacent Object Perception
• Xu and Carey Study
• 10 months lack ability to differentiate two
  adjacent objects, unless one is moving and the
  other is not.
• Occluded Object Perception
• Kellman and Spelke Study of Occluded Perception
• 4 months are able to make judgments on objects
  depending on if the two parts are moving
  simultaneously or independently.
• Face Perception
• Studies by Olivier Pascalis (1995) showed that a
  child uses visual cues, such as the mothers
  hairline, to distinguish faces.

6
Perception of Motion

• Newborns perceive movement, however, not in the
  same way as adults.
• Before 10-12 weeks of age, children make
  stuttered eye movements, known as saccades.
• Between 10-12 wks, children can make smooth eye
  movements.
• Some movement is directed by the Superior
  Colliculus.
• In reference to Biological Motion
• By about 4 mo. Infants show preference for
  biological motion.
• Study by Fox and McDaniel (1982)
• 4-6 mo. Olds can tell difference between random
  light movement and biological light movement.

7
Color Perception

• Even though infants have poorly developed cone
  receptors, within the first few months their
  color perception enhances significantly.
• At first, a child is not actually perceiving a
  color but rather the amount of light refracted,
  or the shading of an object.
• Study by Bornstein, Kessen and Weiskopf
• Use of habituation to different wavelengths of
  light.
• Illustrated that 4 mo. Olds see colors the same
  way that an adult tri-chromate would.

8
Additional Studies of Interest

• Duke University Infant Perception Lab
• Research projects with children on
• Object Attributes
• Prior Experiences
• Object Exploration
• Object Manipulation
• Campos Visual Cliff Experiment
• Experiment used to test the effects of
  fearinduced by stimulus of Visual Cliff.
• After subsequent trials, children do notcross
  the visual cliff.
• Physical movement and visual examinationof
  surroundings, allowed a sense of fearto develop
  within children and may havethem to choose not
  to cross the visual cliff.
• Lea Hyvärinens Systems for Evaluating Infant
  Vision

9
Testing of Visual Perception
To access .mov file -Open My Computer -Open
CD drive and navigate to Movies folder -Locate
file, Lea Demonstration and
double-click -Approximate Movie Time 14min.
and 11sec. You must have QuickTime Installed on
your computer to view the file. http//med-aapos.b
u.edu/leaweb/video/lea.mov

• Lea Hyvärinen has devised a system of testing
  visual perception in infants and preschoolers.
• Specifically, Dr. Hyvärinens methods look at
  visual acuity, motion, and color perception in
  infants and preschoolers.
• Her methods allow a researcher to check for
  abnormalities in the development of a childs
  visual system, and can help to determine what
  action needs to be taken in order to remedy the
  situation.
• Some tools used by Dr. Hyvärinen include
  Contrast Sensitivity Cards, Visual Adaptation
  Blocks, A Color Vision Kit, Grating Acuity
  Paddles, and Hiding Heidi.

10
Sources

• Teller Infant color vision (and motion)
• http//keck.ucsf.edu/blondie/PSYCH254/PDF/Teller
  VisRes1997.pdf
• Duke Infant Perception Lab (Nelsen)
• http//psychweb.psych.duke.edu/department/anlab/i
  pl/
• University of Chicago Center for Infant Studies
• http//www.cecr.uchicago.edu/research.htmlMatern
  al_Factors_in_Development
• Tutorial Infant Vision
• http//med-aapos.bu.edu/leaweb/EyesV2/index.html
  
• Toddler Vision Tests
• http//med-aapos.bu.edu/leaweb/testin1/index.html
  
• The Development of Children, Fourth Edition, Cole
  Cole. Worth Publishers 2001, New York.
  pg.21-23
• Naigles, Letitia. University of Connecticut,
  Lecture. March 2003.