You might recall how back in
February this year a debate over one particular dress and its color went viral
(I mean global). Was it gold and white or was it really blue? Ok, it wasn’t the
debate of the Century; it wasn’t as if the World held its breath while JFK
debated the Soviet
missile crises; or in more recent time; whether global warming is a fad. But
not to take too much away from the dress Kerfuffle, celebrities like Taylor Swift, Ellen
DeGeneres, Will Smith's son Jaden and the Kardashians joined in the skirmish.
More recently, a new picture has been doing the rounds. If you look
at the picture above and focus on the girl’s eyes for a say 5 or 6 seconds;
then look at the empty area to her right; what do you see?
The optical illusion works
by using a technique called ‘negative afterimage’. The eye’s photoreceptors
identify colors and code them.
We have three color
channels, gray-scale, red and green and blue and yellow, which allow us to code
color in any environment. When looking at a specific color, the cells in the
relating color channel increase in activity. However, after a short while, the
activity of these cells decline.
When we direct our gaze at a
uniform background; the white box these cells do not return to their resting
activity state, instead they go to a much lower state.
It's that decline; the
weakening of the yellow code - that codes for the opposite color to become
stronger, so you'll see blue. Therefore, in the illusion above, our blue
receptor cells decline, which stimulates the opposite hue, yellow. This in turn
allows us to see a more natural skin tone and balances out the negative image
to reveal the opposite.
