Components of Vision

Vision is a very active and complex sense and requires the finely tuned coordination of many different neural subsystems. The process of seeking information from the environment’s random and infinite visual signals is complex and relies on many sub-skills:

  • • motor control for
    • • Localizing and directing the eyes’ gaze, as for games, sports, driving in traffic, etc.,
    • • Holding steady to study an object/word,
    • • Automatic jumping from target to target, as in reading,
    • • focusing ability (as in making the image clear, like focusing the barrel on a camera lens),
  • • mental (cortical) functions relating to
    • • Spatial Relationships
    • • Form Constancy
    • • Sequential Memory
    • • Figure-Ground Discrimination
    • • Visual and Visual Sequencing
    • • Visual and Visual Memory
    • • Visual Discrimination
    • • Visual Closure
    • • Integration of Auditory
  • • Balance
  • • Body Senses (position, tension, orientation, etc.)
  • • Audition (hearing)

Vision relies on the properly coordinated functioning of Cranial Nerves II, III, IV, V, VI, VII, XIII. Each eye moves by virtue of six oculomotor muscles controlled by three different cranial nerves. Inside the eye, there are several muscles controlling the iris (pupil) and still others controlling focusing. Light is focused upon the retina, which then begins to refine the signal as it is sent back through the optic nerve to numerous areas in the brain.

For more information regarding visual function and what happens when it fails, see Background