• Background
  • Instructions
  • Illustration
  • Quiz


Monocular depth cues are the information in the retinal image that gives us information about depth and distance but can be inferred from just a single retina (or eye). In everyday life, of course, we perceive these cues with both eyes, but they are just as usable with only one functioning eye. That is, these are cues that tell us about depth even if we are looking at the world with only one eye. Try it—close one eye. You can still use vision to distinguish between objects near and far. Some people describe the world as seeming a bit flatter when using only one eye than when using two, but we still judge distances accurately. Monocular cues include pictorial cues, those cues from which we can judge depth from static or nonmoving pictures, and movement-based cues, in which moving objects allow us to make inferences about depth and distance (see Table 7.1 in the text).

In this activity, you can manipulate the pictorial depth cues and see how they contribute to the perception of depth. You can manipulate them singly or in any of several combinations.


Full Screen Mode

To see the illustration in full screen, which is recommended, press the Full Screen button, which appears at the top of the page.

Illustration Tab


On the Illustration tab, you can adjust these parameters:

You can select from the following pictorial depth cues to illustrate (select them by clicking or pressing the cue to activate the checkbox):

Occlussion: causes the two outer circles to overlap the inner circles.
Relative Height: causes the left-most circle to move down and the right-most circle to move up.
Relative Size: changes the size of the middle two circles to simulate being farther away.
Linear Perspective: Adds lines that can be parallel for now depth, or approach each other as they appear to recede.
Texture Gradient: Add a gradient that can indicate a receding area.
Atmospheric Perspctive: Add a blur and bluish haze to the middle objects to simulate the affect of the atmosphere.
Shadow: Add a shadow to the two outer circles to simulate that they are off of the screen.
Depth: Adjust the degree of each of the depth cues to make the objects appear closer or farther. The only exception is occlusion which is either present or not.


Pressing this button restores the settings to their default values and allows you to adjust speed and relative size. It also resets the counter before you can indicate if you have the objects arriving at the same time.