Seriously, try shaking your head and if you don’t easily get dizzy, you should be able to see John Lennon’s face emerge among the black and white lines. Even after you stop shaking the image should linger for a moment.
These strange pictures have also emerged a while back on the internet without much explanation as to how they work. After making myself look stupid by shaking my head and causing a stinging sensation in my right eye, I found many other ways to see it.
As a nearsighted person, I found simply taking off my glasses made the picture pop out instantly. Looking at it from an angle or a far distance can also reveal the image, as well as just relaxing your eyes’ focus. However, don’t tell anyone this until they shake their head at least once first.
The only explanation for this weirdness comes thanks to a brilliant writer on the blog brainteresting.com. The writer explains that there are two types of cells at work in this situation. P-cells help your eyes to see things in high detail but can see things moving quickly or if the contrast is low.
M-cells on the other hand can see things in high speed and with low contrast but can’t make out fine details. By sitting still and focusing on the image you are using your P-cells. But when you shake your head, the P-cells fail to work and your eyes rely on their M-cells.
Since the M-cells are more sensitive to low contrasts the embedded image can be more easily seen. In in effect, the more you focus on the picture, the less you’ll be able to see it. It’s kind of freaky when you think about it.