Two types of binocular depth cues are __________ and __________.

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.

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.

Occlusion

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.

Linear perspective

This is when two parallel lines come together at some point in the horizon; the closer together the two lines are, the further away they seem. A common example is a road that appears to converge in the distance. The closer the parallel lines appear to get, the further away it seems.

There are two types of binocular depth cues, these are:

1. Convergence
2. Retinal disparity.

Convergence

In order to present images of what we see onto the retinas (the layer of tissue at the back of the eyes that sense light and transports images to the brain), the two eyes must rotate inwards toward each other. The closer an object is, the more the eyes must rotate.

The brain uses this information (amount of rotation) as a cue to construe how far away an object is, by detecting muscle differences the convergence causes in our eyes, and analysing that information to decide the depth. It's a feedback tool, in a sense.

A binocular depth cues example: if you were to hold a marble in front of your face and move it closer to your face, eventually, your eyes would begin to cross. Your brain would then be able to tell how close the object was to your face by detecting how much your eyes were 'crossing', using the muscles.

When we see something, slightly different images of what we see are sent to each retina (as our eyes are apart, each eye sees things from a slightly different angle). However, we don't view the world as a series of two images. This is because the brain processes the degree of difference or disparity between the two images and assembles one image for us that has depth, height, and width.

Animals with larger separation between the eyes, such as hammerhead sharks, have much greater depth perception.

The disparity between the two images allows the brain to calculate how far away an object is. An object close to us has a large disparity, and an object far away has a small disparity.

A test you can do that also brings home the concept of large and small disparity is a test with your thumb. Give yourself a thumbs up (yay), and then extend your arm so the thumb up is far away from you. Close one eye and then the other, so you're only looking at your thumb with the left eye, then the right, then the left, etc. You'll notice that your thumb moves back and forth a little bit (your brain thinks the thumb isn't moving much, so it must be far away, i.e., small disparity).

Now put your thumb super close to you (but not so close it's blurry) and do the same thing, closing one eye and then the other. You'll notice that your thumb moves back and forth a lot (your brain thinks the thumb is moving a lot and that the thumb must be closer to you, i.e., large disparity).

As the name suggests, binocular depth cues involve using both eyes, whereas monocular depth cues rely on one eye to process distance and depth perception.

Monocular depth cues allow us to see objects two-dimensionally, and binocular cues allow us to see objects in 3D.

The two types of cues are used to understand the depth and perception of objects in relation to our point of view; however, they use different processes to do so. For example, binocular cues use retinal disparity and convergence, whereas monocular cues use height in plane, relative size, occlusion and linear perspective cues.

Depth Cues Psychology - Key takeaways

• Depth perception refers to the ability to see the world in 3 Dimensions and judge how far away objects are from us.
• We are able to judge depth using depth cues; there are two kinds of depth cues: monocular depth cues and binocular depth cues.
• Monocular depth cues are information about depth perception that can be judged using only one eye. Some of these cues are height in plane, relative size, occlusion, and linear perspective.
• Binocular depth cues are information about depth perception that uses both eyes. There are two types of binocular depth cues: convergence and retinal disparity.

Depth perception refers to the ability to see the world in 3 Dimensions (3D) and judge how far away objects/close are from/to us.

There are many monocular depth cues. These are height in plane, relative size, occlusion, and linear perspective.

An example of binocular cues in psychology is convergence. Convergence is when we use both eyes to focus on a single object. 

The two types of cues in depth perception are monocular depth cues and binocular depth cues.

Some examples of monocular depth cues are: height in plane, relative size, occlusion and linear perspective.

Question

What is depth perception?

Answer

Depth perception is the ability to see the world in 3D and judge how far away objects are from us.

Question

What are the two kinds of depth cues?

Answer

Monocular depth cues and binocular depth cues

Question

Fill in the blank: monocular depth cues are information about depth that can be judged using _____.

Answer

Question

Answer

This is when objects that are placed higher up appear further away.

Question

Answer

If there are two objects that are the same size the object that is closer will look larger.

Question

Answer

This is when one object partially hides another object. The object in front is perceived to be closer than the one that is hidden. 

Question

What is linear perspective?

Answer

This is when two parallel lines come together at some point in the horizon, the closer together the two lines are the further away they seem.

Question

What are the two types of binocular depth cues?

Answer

Convergence and retinal disparity

Question

Answer

To present images of what we see to the retinas the two eyes rotate inwards towards each other. The closer an object is the more the eyes rotate. The brain uses this information (amount of rotation) as a cue to construe how far away an object is.

Question

What is retinal disparity?

Answer

Retinal disparity is the differences between each retina's visual input. The disparity between the two images allows the brain to calculate how far away an object is. A close object has a large disparity, whereas a distant object has a small disparity. 

Question

What is a common example of linear perspective?

Answer

A road that appears to converge in the distance.