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Difference Between Monocular and Binocular Cues Explained in Details

Difference between monocular and binocular cues
Written by Robert Stevens

Monocular and binocular cues basically deal with the depth of visual perception. The most significant difference between them is that one provides deep information about a scene when viewed with an eye (monocular cues) while the other also provides in-depth information about a scene when viewed with both eyes. This feature mainly differentiates a monocular from a pair of binoculars. Both cases deal with the ocular ability to perform in two/three-dimension space based on distance from the observer.

This two major variety of depth perception cues have their different applications which will be elaborated in this article. The contents will be discussed in details including a piece of well articulate information that shows all intriguing difference between quality monocular and binocular cues.

Difference Between Monocular and Binocular Cues

What Cues Actually Are?

In psychology, cues are referred to as depth perception typically classified into monoculars and binoculars. They are responsible for the keen perception of the eye(s) when viewing an object at a particular distance (depth). Regarding animals, they may be called depth sensation instead because of their ability to move accurately or constantly respond to their perception of an object’s area. Depth perception arises from a variety of depth cues that portray special capabilities.

What Cues Actually Are

Monocular Cues Defined

Here, we refer to the perception of an object with respect to the visual ability of an eye. There are times when we feel closing an eye may give us better judgment in the distance of an object. Some of the significant factors responsible for this phenomenon include the following.

Monocular Cues Defined

1. Relative Size

This is a case whereby two objects that are deemed to be of similar sizes are judged with respect to the larger having a closer appearance to an observer when compared to the smaller one.

2. Interposition

When to objects partially cover each other (overlap), the one that is seen behind appears further away than the actual distance. In essence, this information merely enables the observer to create an intuitive disposition of relative closeness.

3. Aerial Perspective

This case of depth cue refers to objects that tend to look unclear or quite blurry compared to one at a closer distance due to the influence of the atmosphere.

4. Linear Perspective

It allows an observer to perceive the depth of an area when viewing parallel lines that seem to converge at infinity at first.

5. Texture Gradient

This is another essential monocular cue that deals with the texture of an object and how it affects an observer’s visual perception with reference to depth (distance).

6. Motion Parallax

In this case, monocular depth cue causes that are around an observer in motion, pass by faster than the one that is farther away. That is, the farther something appears, the slower it seems to pass away from the observer.

Binocular Cues Defined

Easily deduced from its connotation, “bi,” it is defined as the ability of both eyes to perceive an object in three-dimensional space. When you compare the form of images when seen with the two eyes, the brain tends to perceive the object at slightly different perspectives with reference to the angle(s) of view. The major factors that are accompanied by this phenomenon include the following

Binocular Cues Defined


It is also known as retinal disparity that’s claimed to be the primary binocular cue for depth.It explains how an object is looked at with either eyeballs at fairly different angles so that the brain can give slightly different perspectives. This factor occurs due to the horizontal separation parallax of the eyes.


This is a binocular oculomotor cue that deals with depth perception, specifically. It occurs as a result of when sensation from` extraocular muscles tend to exist as the convergence of the eyes focused at an object is stretched by the muscles. Study shows that the effect of the convergence phenomenon will be favoured when used at a distance closer than 10 meters to an observer.

Monocular Cues vs Binocular Cues at a Glance

So, having discussed the two types of depth cues that exist, we can easily give a concise contrast between monocular and binocular cues with respect to usability and magnificence. First off, we understand that one is performed by virtue of an eye while the other involves either eyes.

Monocular depth cues include factors such as relative size, size consistency, and superimposition which rely on information perceived from an eye while binocular depth cues include stereopsis, convergence, and yielding depth from the two eyes through parallax exploitation.

Monocular cuesBinocular cues
Relative Size – For two objects having roughly the identical size, the apparently larger object looks to be closer to the observer than the one that looks smallerRetinal Disparity – A situation where each eye catches a slightly different image of the same object due to their location.
Absolute size and Familiar size – The former depicts how the eye perceives larger objects to be farther than objects that are smaller but in the same area. The latter deals with how perception of size(s) can be influenced by and observer’s acquaintance with certain objects.Binocular Convergence – It basically helps the observer perceive how close or far an object is. This involves the physiological angles that either eyes need to rotate to focus on the object.
Elevation – This is a case whereby objects that are positioned closer to a horizon tend to be perceived farther and vice-versa
Texture Gradient – It is defined by an observer’s depth perception that is influenced by the texture (surface) of an object.
Motion Parallax – This brings about a visual clue of perception with regards to distance wherein an observer in motion sees objects around move away from position faster than the farther ones.
Aerial Perspective – Objects that are far from an observer seem slightly blurred due to the atmosphere.
Linear Perspective – Here, lines that are parallel seem to converge at a point as they travel into distance from an observer.
Overlap (or Interposition) – A case wherein an object that is being overlapped by another appears farther away.
Shading and lighting – Objects that appear brighter to an observer seem closer than the objects that appear darkened.
Accommodation – In this case, specific eye muscles contract which alter the shape of the lens when focused on near objects. The muscles then relax if the position of the object is at a farther location.

 How Do You Use Them?

One thing is knowing about these depth cues while another is being able to know how to use them for various scenarios, ideally. With this knowledge, you will be amazed at how much your keenness of sight will develop to suit your view from virtually anywhere!

How Do You Use Molecular Cues?

Its application is versatile in many instances; you can try to observe visually how you easily tell the depth when at the top of a staircase, corners of buildings appear larger and more textured which makes it seem closer, objects far away seem smaller and thus, gives us a judgement of its apparent size. All these situations contribute to the depth perception of monocular cues, typically.

How Do You Use Binocular Cues?

The application of binocular cues gives us the ability to determine where in 3-D space an object is with relation to our position. It is by virtue of this phenomenon that you might feel you perceive depth when viewing 3-D movies, Magic Eyes or stereoscopic photos.

The intrinsic nature of monocular and binocular cues clearly differs with unique characteristics but one can say that both phenomena arise to the depth perception of the eye(s). Understand that the application of monocular cues is more effective when comparing the apparent to real structure of an object while binocular cues aid us to expand more than one perspective in the form of an object in order to get an apt depth perception.

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About the author

Robert Stevens

A Seasoned Hunter

It’s been several years that Robert, a retired teacher and a proud dad, has silently been piling up mature bucks down the South. This humble hunter began his hunting journey at quite an early age and since then, he spent countless hours in the woods and learned good lessons in terms of woodsmanship. Along the way, he also made money sharing his skill with his followers and well-wishers.

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