New Delhi, Aug. 6 -- A new optical illusion has been going viral on the internet. At first glance, the image shows nothing more than a pregnant woman standing beside a tree. But hidden within the scene is a human face that is nearly impossible to detect. It has gone unnoticed by the vast majority of viewers, with only a small fraction managing to spot it without assistance.

The trick here lies in pareidolia - our brain's tendency to see faces where there aren't any. It is why clouds sometimes look like people or why chipped paint can resemble a pair of eyes staring back. The phenomenon isn't just fun. It is actually been used by neuroscientists and researchers to study how the brain processes visual information.

Artists who specialise i...