Complementary Colored Flag

[Jeff Briggs]

  The complementary colored flag as described in Stretching Exercises #4 is an excellent teaching aid.  We built one of a "cyanish" colored tissue paper that had a field of yellow for the stars.  We used black electrical tape for the complementary material to the white stripes and stars.  I had the students stare at one star for 60 seconds, then look at a white screen.  The flag shows up in its normal colors.

  As explained in the teacher's edition, the continuous excitation of the color receptors in the eye lead to tiring.  When the stimulus is removed and a white background is substituted, the brain constructs a virtual image of the flag on the screen in the correct colors.