I just created another applet : [url=http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=2050.0]illusion: Two identical color dots?[/url] or [url=http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=2051.0]illusion: The same color illusion[/url]
for the effect you are interested in.