Seeing Takes More Than Our Eyes

Visual image

 

Carla Hannaford, Ph.D,

Smart Moves, Why Learning is Not All In your Head

p. 45-46

Touch and proprioception are important organizers of the visual aspects of learning.  Vision is a very complex phenomenon, with only a small percentage (less than 10%) of the process occurring in the eyes.  The other more than 90% of vision takes place in the brain from association with touch and proprioception.  As babies touch their environment, they learn dimension, texture, line and even color.  A complete visual picture emerges at about eight months after birth.  Touch is very important to vision.  Listen closely to a child who is seeing something new. The child immediately reaches out to touch the object while saying, “Let me see that!”  Touch is the major contributor to full understanding in vision.

Images coming in through the eyes are turned upside down and backwards as they enter the optic nerve and cross the optic chiasma.  They are then funneled through the thalamus to the occipital lobe where primary vision is processed.  For full vision to occur, information from all the cerebral lobes must be accessed.  Information from the sensory and motor cortices associates the image with learned sensory and movement functioning.  Gravitational and vibrational information from the temporal lobes relates the image to where we are in space.  And, as noted earlier, approximately 20% of the messages from the eyes, retina and extraocular muscles, go to areas of the brain concerned with balance mechanisms.  All the information together allows us to right the image and bring it into full context in the visual association areas.

An experiment in which scientists fitted themselves with special pairs o glasses shows how our vision is educated to comprehend the world.  These glasses had mirrors that turned the view of the world upside down and back to front.  At first, the disoriented experimenters could barely move without bumping into something, but after a few days they adjusted and the reversed world came to look “right way up.”  Touch and the proprioceptive sense that guides vision had adjusted the new visual input to this new physical orientation.  The fully intact vestibular system “knew” that the world had not gone topsy-turvy.  This, together with touch and proprioception, provided feedback, which allowed their eyes to adjust.  The scientists could walk around without problems and saw the world just fine—until they took the glasses off at the end of the experiment.  Then they had to go through a relearning process all over again, with several days of hitting and falling over things.  This experiment demonstrates graphically that they brain has to assemble our visual world from learned pieces through our other senses, especially touch and proprioception.