Optical Illusion: How many faces do you see in this picture? Most people cannot find more than 4

Do you feel that your brain is quite adaptive to details and it always tends to find the finer elements in an object rather than just throwing a glance. Do you feel you are more vigilant to things that others are unable to see and find yourself bringing out an extraordinary explanation to things which amazes people?

In that case, a tricky optical illusion might just be the right thing for you to exercise your brain.

There are 13 faces in this picture which looks like mountainous terrain with two horse-riders in sight.

This optical illusion was created by Bev Doolittle and is popularly known as "The Forest Has Eyes".

Read: Optical Illusions Say A Lot About Your Personality, Find Out How

Of the 13 hidden faces, these four faces are quite prominent and are easily spotted by many users. The reason viewers see these images first can be partly due to their location, which is towards the centre and also may be because of the size of these images.

Whenever we see an image, our eyes first catch the objects on the centre and evidently those images which are bigger in size come to our vision first.

These two faces, different in size, come next to our vision. Though the extreme right one is bigger in size, due to its location in the image our vision misses its presence.

The other image is a very narrow one and is sandwiched between the centre image and the bigger image which is difficult for our eyes to differentiate.

There are four faces on the top portion of the image fused within the trees. The eyes, nose and lips of the faces are visible only when you look closely through the dense forest.

These two faces are embedded within other faces and elements thus making it difficult to be spotted.

This is because images which are more at the centre and have prominent features are visible to the eyes first.

When we usually see a picture our first glance goes to the bigger images or fonts in it.

Illusions, experts say, reveals how you brain works and relies more on your perception than on your visual sense.

As per Susana Martinez-Conde, director of the laboratory of visual neuroscience at Barrow Neurological Institute in Phoenix, Ariz, "an illusion is a phenomenon in which our subjective perception doesn't match the physical reality of the world."

Illusions have always enticed researchers to study more on how the brain and the vision system works and coordinates.