Shown in the photograh below is a picture with the left side bright  magenta and the right side pure bright green, with a black spot in the  center of the slide.

Suppose that you stare at the black spot for about 20-30 seconds, then  quickly replace this slide with one that has the same green field on the  right side but the magenta field at the left is replaced by a white  field. 

Which of the following statements will be true?

• (a) Both sides will be the same color.
• (b) Both sides will be very close to white.
• (c) Both sides will be very close to black.
• (d) The left side will be black and the right side will be green.
• (e) The left side will be magenta and the right side will be black.
• (f) The left side will be  bright green and the right side will be  pale green.
• (g) The left side will be pale green and the right side will be  bright green.
• (h) The left side will be green and the right side will be magenta.
• (i) Other, to be explained by the viewer.

To see the answer, click Read More on 1/16/15

 

The answer is (f) The left side will be  bright green and the right  side will be pale green.  This can be observed directly by the following  procedure:

Click on the picture below, which will create the first slide with the  appropriate size and position.  Place your mouse locator on the black  dot, then count 20-30 seconds.  After 20-30 seconds has elapsed, click  your mouse on the black dot, producing the second slide in the same  position.  Then click on the black dot on the second slide to return to  this page for the explanation below.  You can use the "forward" and  "back" arrows at the top of your browser to toggle back and forth between  the two slides.

When you stare at the magenta/green pattern, your red and blue cone  receptors (magenta is red plus blue) are saturated on the left side of  your field of vision, as are the green receptors on the right side of  your field. When you switch to the second slide, because the left side is  white it excites ALL THREE of your color receptors.  However, because  your red and blue receptors are saturated, the green receptors in fact  have a much stronger response.  

On the other hand, because the green color is the same on the first  and the second slide, and your green receptors have been saturated by  staring at that color, the green color on the right is pale and washed  out compared with the "green" on the left.

Thus the left side, which is actually white, appears a more brilliant  green than the green side, on your right.

So apparently white is greener than green.