Depth perception is the ability to see
things in a 3-Dimensional way and to
We use depth cues to gather
information on the images we
These cues can be binocular or
Binocular depth cues use both eyes to perceive information on
the 3-dimensional form of an object and its place in space.
There are two types of binocular
cues, retinal disparity and
Images seen through both eyes are examples
of stereoscopic vision because the eyes see
two different pictures that combine as one.
Binocular Cues: Retinal Disparity
The image your right eye
sees is different than your left
eye because they are a small
distance apart. The image
you see using both eyes is
the two images merged.
Binocular Cues: Fun Fact
3-D movies use the
idea of retinal disparity
by using two close
cameras and merging
the image together.
Binocular Cues: Convergence
When focusing on images less
than 4-6 meters away, the eyes
turn inward to focus on the
same object rather than moving
The angle the eyeballs turn
towards each other is smaller
when the object in focus is
Monocular cues judge the
distance of an object
using only one eye.
These cues are often used in
making 2-D images appear to
be 3-D, in this case they are
called pictorial depth cues.
Monocular Cues: Relative Size
When viewing two
congruent objects, the
farther away object will
appear smaller even
though the objects are
still the same size.
Height in the visual field
Objects that are farther away appear higher up in an
image, closer to the horizon line.
What You See Is What You've Learned
Turnbull studied BaMbuti pygmies and found that the people
of their area do not possess the monocular cue of relative
size because their environment does not call for them to use
From this natural observation, it can be concluded that the skills
of perception are not inborn, we learn them.
Kenge, a BaMbuti pygmy, had never seen a mountain
from a great distance. When Turnbull presented the
mountain to him, he could not decide if it was a cloud or
Having never seen a buffalo from a distance, Kenge believed
that it had to be an insect because it was so small.
When presented with a row boat full of
people on a lake from a distance, Kenge
(at first) refused to believe that the boat
was holding people. It was simply to small.