Psychotherapy Tips

What is monocular depth cues in psychology

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.

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).


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.

Monocular cues play a huge role in how you perceive the world around you. Keep reading to learn how different types of monocular cues help you interpret and understand what you’re seeing.

The word “monocular” means “with one eye.” Monocular cues are all the ways that a single eye helps you see and process what you’re looking at.

Vrotsos also said that “visual information, as seen with a single eye, can detect an object moving at a distance, but can’t necessarily decipher the entire scene.”

“With monocular cues, images are interpreted as two-dimensional. Think of a painting that gives the illusion of depth by playing with the foreground and background. That is your eye and monocular cues in the real world — things that are closer are larger and move faster; things in the background are smaller and move slower.”

Monocular cues refer to the ways that each of your eyes takes in visual information that’s used to judge:

Now, let’s get into the six main subcategories of monocular cues that contribute to your vision.

Relative size

This monocular cue gives you the ability to measure how far away something is. It works by judging how big or small the object is and what that means in relation to other objects you’ve interacted with in the past.

Here’s an example: When you see a plane fly by in the sky above you, it looks really small. But you probably know that up close, a plane is huge.

What this means is that your vision (the plane you see in the sky) connects with your memory (a plane you’ve seen up close) to indicate to you that because the plane looks so small, it must be extremely far away.


Interposition refers to what happens when two objects on a flat surface, like a drawing of two circles, look like they have some relation to each other in terms of distance, even when they’re not actually in 3-D space.

Here’s a longer explanation of the classic circles example: Let’s say you have two circles drawn next to each other on a piece of paper. In this case, both circles will appear to have the same depth.

But let’s say you then draw the circles so that they intersect with one another (kind of like a Venn diagram). If you color in one of the circles, it’ll look like it’s overlapping the other circle.

Your eye will then perceive that the overlapping circle is closer to or on top of the other circle. Now the circles will appear to have depth even though they’re still just 2-D drawings on a flat piece of paper.

Linear perspective

Linear perspective happens when the angles of two adjacent objects and the distance between them look smaller and smaller. This causes your eye to interpret those objects as increasingly farther away from you.

For example, imagine you’re drawing a road or train tracks extending into the distance. You might start drawing each side of the road or tracks at the bottom of your piece of paper.

As you continue to draw the road or tracks moving “away” from you, the lines might angle closer together toward the center of the paper. This will result in a triangular shape.

As you look at the triangle, the closer you get to its tip, the farther away your eye will interpret the road or tracks to be from your position. This is due to the angle of the lines and the fact that they’re closer together at the tip than where they start at the bottom of your piece of paper.

Aerial perspective

Aerial perspective is what makes far away objects look a bit blurrier, lighter in color, and less detailed than those closer to you.

Think about mountains off in the distance. They tend to be much lighter in shade and color than a mountain that’s much closer to you.

This happens because blue light scatters into the air when it interacts with the atmosphere — which often makes distant objects appear light blue.

Contrast of color also plays a role in aerial perspective.

Objects that are farther away tend to have rough, blurry edges because of the scattered light in the air, and colors tend to blur together. Closer objects, on the other hand, have more defined edges and a starker contrast of color.

Big objects, like mountains and skyscrapers, seem bigger and clearer when the air is clean because there are fewer particles to scatter the light.

Light and shade

The way that light hits an object creates shades of light and dark. This tells your eyes where an object sits in relation to the light and to objects nearby.

This cue can also tell you if something is upside down because the light source will hit the object differently, so that it visually contrasts with other parts of your environment.

Monocular motion parallax

This one’s a mindblower. The monocular motion parallax happens when you move your head and objects that are farther away appear to move at a different speed than those closer to you.

Try it out by looking at something far away. Then, slowly turn your head from left to right and back again.

You may notice that objects nearer to you appear to be moving in the opposite direction of the way your head is going. But objects farther away from you seem to follow the direction of your head.

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Imagine you’re in a car and you see a tree in the distance. How is it that as we drive closer the tree begins to look bigger? Trees obviously aren’t growing. So what is causing this? I’ll give you a hint… it’s our brain and eyes using depth cues. Depth perception refers to the ability to see the world in 3D and judge how far away/close objects are from and to us. This judgement is very important for navigating everyday life. How we move from one point to another relies quite heavily on our ability to perceive depth, and even picking up an object, such as your pencil, relies on the ability to judge depth.

For example, if we were crossing the road and couldn’t judge how far away a car was, it would be a bit of a disaster.

Let’s take a look at depth cues in psychology!

  • We will start by taking a look at monocular depth cues definition psychology and binocular depth cues psychology.
  • We will then move on to look at monocular depth cues examples whilst exploring aspects such as height in plane, relative size, occlusion and linear perspective.
  • Moving along to do the same and looking at binocular depth cues examples, focusing on convergence and retinal disparity.
  • Finally, we will highlight the difference between monocular and binocular depth cues.

Monocular Depth Cues – Definition in Psychology

Monocular depth cues in psychology can be defined as:

Monocular depth cues: information about the depth that can be judged using only one eye. Monocular depth cues can be used in pictures, so a lot of monocular depth cues are used in art to give viewers a sense of depth.

Binocular Depth Cues – Definition in Psychology

Binocular depth cues in psychology can be defined as:

Binocular depth cues: information about depth that uses both eyes to see and understand 3D space; this is a lot easier for our brains to comprehend than monocular depth cues.

The difference between monocular and binocular depth cues is that monocular depth cues use one eye to judge depth, and binocular depth cues use both eyes to perceive depth.

Monocular Depth Cues – Types and Examples

There are four monocular depth cues you will need to know for GCSE psychology. These are:

  1. Height in plane
  2. Relative size
  3. Occlusion
  4. Linear perspective.

Height in plane

Height in plane is when objects placed higher up appear or would be interpreted as further away. Have a look at the monocular depth cues example below, note that the house that is placed higher would be interpreted as being further away from us, and the house lower down would be seen as being closer to us.

Depth Cues Psychology houses height in plane StudySmarterExample of height in plane, Erika Hae, StudySmarter Originals

Relative size

If there are two objects that are the same size (e.g., two trees of the same size), the object that is closer will look larger. Have a look at the monocular depth cues example below, tree number 1 seems closer because it is larger, and tree number 2 seems further away because it is smaller.

Depth Cues Psychology trees relative size StudySmarterExample of relative size, Erika Hae, StudySmarter Originals


This is when one object partially hides another object. The object in front that is overlapping the other is perceived to be closer than the one that is being partially hidden. Look at the monocular depth cues example below; the rectangle appears closer as it overlaps and partially hides the triangle.

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