Depth Cues

Depth perception is the ability to see things in a 3-Dimensional way and to judge distance.

We use depth cues to gather information on the images we see.

These cues can be binocular or monocular.

Overview

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 convergence.

Images seen through both eyes are examples of stereoscopic vision because the eyes see two different pictures that combine as one.

Binocular Cues

Binocular Cues: Retinal DisparityThe 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 together.

The angle the eyeballs turn towards each other is smaller when the object in focus is farther away.

Monocular Cues

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.

Accommodation

Monocular Cues: Linear Perspective

As parallel lines extend into the distance, they appear to meet together.

Monocular Cues: Interposition When multiple objects are in the same visual field, the closest object appears in front of those farther away.

Monocular Cues:Texture Gradient

The texture in an image appear less detailed as objects become more distant.

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.

Monocular Cues:Height in the visual field

Objects that are farther away appear higher up in an image, closer to the horizon line.

Turnbull: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 it.

From this natural observation, it can be concluded that the skills of perception are not inborn, we learn them.

TurnbullKenge, 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 a hill.

Having never seen a buffalo from a distance, Kenge believed that it had to be an insect because it was so small.

Turnbull

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.

Turnbull