Optical illusion 'freaks' people out who stare at dot in centre for few seconds

People are trying to understand the reason behind the confusing detail in the image – and luckily there is a simple explanation. So what do you see in the optical illusion?

It doesn't matter how smart you are, it's likely you've been a victim of a confusing optical illusion in the past. Previously, one could show how easily you open up to people, while another has a creepy cat lurking somewhere.

Now it's not just personality tests which are puzzling the internet as this brainteaser is so much more than that. In the image, shared on Reddit, members of a popular optical illusion forum were tasked with the job of seeing what happens when you stare at the centre of the dot for 15 seconds. It shows a woman in an inverted high contrast image smiling with a white background next to it.

The caption simply read: "How does this work?" While words above the woman read: "This is insane!" Then it added: "Look at the dots on the nose for 15 seconds," before asking players to "now look here" at the blank image.

It might show a woman smiling, but you'll be surprised at what you discover once you complete the task. So what do you see when you stare at the dot then glance at the white background?

It's quite freaky because when you find you've done it and looked over, you can then see a face lurking on the white background.

Since the post was shared it racked up 3,500 likes and hundreds of comments. One Reddit user said: "That was cool. Kinda jump scared me."

While another posted: "Damn. Did not expect the ghost image to be in colour. Wow." A third commented: "You can also see her when you close your eyes." Others claimed the concept of the illusion was very cool.

How does this optical illusion work?

Known as a photoreceptor fatigue illusion, or negative afterimage illusion, this occurs when you stare at a colour for too long which causes the corresponding cone cells in your retina to become desensitised.

Basically when you shift your gaze to a white surface, which you have done in this case, your brain perceives the complementary colour of the original image because the fatigued cones are sending weaker signals, while the other cones send stronger cones.

Another example could be staring at a red target and then looking at white will then produce a cyan afterimage.

But sometimes you might not notice it as your eyes are constantly making tiny, involuntary movements which prevent any single set of cone cells from being overstimulated for an extended period.

And just remember, the fatigue typically lasts only for a short time, usually 10 to 30 seconds, after which the cones regain their sensitivity once the afterimage disappears.

Smart right?