What Can You See When You Close Your Eyes?

Negative Optical Illusion

I have always been fascinated by the complexity of our eyes; such as peripheral vision and how we can see something out of the ‘corner’ of our eyes without even looking at it.

Or how when we are in darkness we can’t see anything, but after about 40 minutes our night vision reaches its optimum and we are able to see relatively clearly. Or the wonder of ‘afterimages’ such as looking at a bright light then looking away and still being able to see a glow in front of our eyes.

Then there are optical illusions, such as negative, or inverted, afterimages.

Negative afterimages are caused when the photoreceptors in the eye are over stimulated and lose sensitivity. If the colour image is large enough the photoreceptors will eventually get tired and stop responding.

When you than look at a blank space, the adapted photoreceptors send out a weak signal and those colours remain muted. However, the receptors which weren’t heightened by that colour are still “fresh”, and they send out a strong signal. The signal is exactly the same as if looking at the opposite colour, which is how the brain interprets it.

Then I found this picture:

• Find a Clear, Blank space to look at somewhere in the room (a wall, a solid colour file, blank piece of paper etc. I’ve found grey or light blue seems to work well).
• Now get in real close to your computer screen and stare at the red dot in the middle of the woman’s face and count to 30 in your head (the longer you look, the better it works). 
• Then turn away and look directly at your blank surface and blink your eyes rapidly. Keep blinking (it’s an important part)
• After a few seconds, the image of the woman will appear against the blank field, but with an amazing difference.

It’s amazing what the human mind and body are capable of!