Perceiving the world of real objects seems so easy that it is difficult to grasp just
how complicated it is. Not only do we need to construct the objects quickly,
the objects keep changing even though we think of them as having a consistent,
independent existence (Feldman, 2003). Yet, we usually get it right, there
are few failures. We can perceive a tree in a blinding snowstorm, a deer bounding
across a tree line, dodge a snowball, catch a baseball, detect the crack of a
branch breaking in a strong windstorm amidst the rustling of trees, predict the
sounds of a dripping faucet, or track a street musician strolling down the road.
In all cases, the sensations must be split into that part that gives information
about real objects that may change in shape, sound, timing, or location and
that part that gives information about the random or non-predictable parts of
the background. The object becomes “in front of” the background.
The light energy at the eyes, the sound energy at the ears, and the pressure
sensations on hands are neutral. Moreover, the light energy at each eye is twodimensional
due to the “flat screen” structure of the retina, the sound energy
at each ear has only a weak spatial component, and the pressure sensations must
be integrated to yield the surfaces of objects. For all three senses, the energy
must be interpreted to give the properties of the three-dimensional objects and
events in the world.