I set up a science experiment to
test hand-eye coordination. My hypothesis was that 2 eyes are
better than one. I used an electrical circuit with copper wire for a path
and a wire with an open loop. I had my subjects try to go through the
copper 3 times with both eyes open, than 3 times with one eye closed.
Everyone did better with both eyes open. Although, my idea was that this
would be the case, I am finding it difficult to explain why this would be.
I know it has something to do with depth of vision, but I cannot
explain it fully. It would really help me with my project if you could
give me some ideas. I have looked things up in encyclopedias but they
make it all sound too complicated. I would be really grateful if you
could give me a simple but scientific answer.
What you have determined is called 'stereovision'. It
can be explained in the following way: your left eye
sees an object at a near distance from a slightly
different angle than your right eye. In the brain,
both visions are combined and overlapped. That would
result in a double picture, as if two photographs were
superimposed that were taken by moving the camera 1
inch left or right. Instead of a double vision, your
brain has learned to melt this into one picture, and
the 'double lines' are interpreted to tell you
approximate distances: that is how you see depth at a
By the way, approximately 10% of people do not have
stereovision, because one eye is bad, blind, or the
brain has not learned to overlap the pictures. They
see as if you were looking with one eye only. Many of
these people would not even know they have no
stereovision, because we are intelligent enough to
learn how to deal with this minor disability.
A hawk without stereovision would not know how far
apart his prey was, and by diving for it he may hit
the ground with such force that it could kill him. For
many animals stereovision is required to survive.
Click here to return to the Biology Archives
Update: June 2012