Visual Motor and Visual Perception

• Visual perception


  The total process responsible for the reception (sensory functions) and cognition (specific mental functions) of visual stimuli
• Visual perception


  • Dynamic interaction of sensory functions and specific mental functions help us understand what we see
• Visual receptive component


  Sensory functions that pull out and organize information from the environment
• 70% of our sensory receptors are aligned with vision
• Visual-cognitive component


  Organizes structures and interprets visual information, gives meaning to what is seen
• Acuity


  The ability to see fine detail (normal = 20/20)
• Accommodation


  Obtain clear vision as distance changes; ability to change focus from near to far objects
• Binocular fusion


  Combine images from 2 eyes into 1 form; ability to use both eyes in a coordinated manner; mentally combine images from two eyes to create one image
• Convergence


  Enables binocular vision → both eyes turn inwards from the medial place
• Divergence


  Movement of eyes away from each; both eyes turn outward from a medial plane
• Saccades


  Rapid, ballistic movements that changes the point of fixation; to look from one object to another
• Pursuits


  Voluntary, slow and smooth tracking with continuous fixation; ability to follow a moving object; continuous clear vision of moving objects
• Fixation


  Ability to maintain steady fixation on an object
• Stereopsis


  3D vision, binocular depth perception
• Convergence Insufficiency


  Eyes struggle to aim inward, float out with fatigue, resulting in double vision
• Convergence Excess


  Eyes aim is too tight and pulls eyes inward too much, resulting in double vision
• Screening


  1. Acuity: far point copying or reading task

  2. Accommodation: child shifts from near point and far point

  3. Binocular fusion: identify pictures or objects in a book with one or two eyes

  4. Stereopsis: identify 2D and 3D objects (picture vs object), identify which item is in front or behind

  5. Convergence & Divergence: finger to nose
• Intervention


  • Recommend referral to another health care profession
  • School nurse
  • Pediatrician
  • Optometrist: examine diagnose and treat eyes
  • Ophthalmologist: surgery
• General development of acuity


  1. Infant: fixate briefly on face soon after birth

  2. 3 Months: steady fixation and tracking at near range, eyes should be straight

  3. 6 months to 6 years: visual acuity improves

  4. 3-4 years: vision can be objectively measured with 20/40 acuity or better

  5. 6 years: 20/30 acuity
• Observation signs of visual impairment


  • Does not fixate on parent's face
  • No interest in brightly colored objects
  • Abnormalities in movement of the child's eyes
  • Eyes gaze in one directions (not tracking)
  • Eyes do not blink
  • Children press their eyes
• Visual attention


  The ability to attend to a visual stimulus, often requires ignoring other competing stimulus
• Alertness


  Natural state of arousal, alerting is the transition from being awake to being attentive
• Selective attention


  Ability to choose relevant information, conscious & focused
• Visual vigilance


  Mental effort to concentrate on a visual tasks
• Divided or shared attention


  Ability to respond to 2+ tasks simultaneously. (engaged one automatic task and visually monitoring another)
• Visual imagery


  Visualization, ability to picture this using a mental eye
• Development of visual imagery


  1. First able to visualize things based on sounds or smell (what does a cow say?)

  2. Next able to picture what words in a book say (can picture character in a book based on written description)
• Visual discrimination


  The ability to distinguish small difference in visual stimuli; the ability to distinguish same/different
• Uses of visual discrimination


  • Recognition → relate key features of an object to memory
  • Matching → note visual similarities
  • Categorizations → ability to determine categories based on visual similarities and differences
• Object perception


  WHAT things are; identification of objects by color, texture, shapes, and size; used for objects identification and visual learning
• Form constancy


  The ability to match two figures that vary on one or more discriminating features
• Strategies for form constancy


  1. Practicing sorting and matching

  2. Change size and orientation

  3. Select a shape and identify similar shapes in the environment
• Visual closure


  The ability to recognize a stimulus figure when it has been incompletely drawn
• Strategies for visual closure


  1. Identify a shape or picture with part of it covered

  2. Identify shapes, pictures, letters with a position erased – dotted lines

  3. Match outlines of words with the word
• Figure-ground


  The ability to see specified figures even when they are hidden in confusing, complex backgrounds
• Strategies for figure-ground


  1. Practice selecting items off of a shelf at the grocery store

  2. Find items in a messy drawer

  3. Where's waldo

  4. Teach organizational skills
• Spatial perception


  WHERE things are; visual location of the object, used for location of the object needed to guide action (adjusting reach or grasp based on size/distance or object
• Positional in space/visual spatial orientation


  The ability to organize two dimensional space in regard to proper size and orientation of symbols, figures or objects. It is the perception of the position of two or more objects in relationship to self and each other
• Strategies for spatial perception and orientation


  1. Simon says

  2. Obstacle course/navigate the environment

  3. Block patterns - take a picture of a different block patterns, have the child imitate the picture with blocks
• Depth perception


  The ability to perceived the relative distance of objects in one's visual field