[url]http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html?gray[/url]

Yep, incredibly both squares are RGB 47% 47% 47% :shock:

[quote=Xyzzy;98284][URL]http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html?gray[/URL][/quote]On a related note (so to speak): [URL]http://en.wikipedia.org/wiki/Shepard_Tone[/URL]

[URL]http://www.washingtonpost.com/wp-dyn/content/article/2005/10/18/AR2005101801663.html[/URL]

Try this one for some unscientific science. Caution advised.

[url]http://www.fixedearth.com/[/url]

[URL]http://www.chemistry.org/portal/a/c/s/1/acsdisplay.html?DOC=HomeMolecule%5Carchive%5Cmotw_transparent_aluminum_arch.html[/URL]

:yzzyx:

[url]http://www.havidol.com/[/url]

[url]http://members.shaw.ca/b.bogdan/caramilk/cadbury.htm[/url]

[URL]http://news.yahoo.com/s/csm/20070316/cm_csm/ydemersseman;_ylt=AoYTYtFwHVrZ7Fs.Ipdaqjr8B2YD[/URL]

[quote=ewmayer;99605][I]"The strategy is to blur the boundary between pedestrians and automobiles..."[/I][/quote]
[I]"The whole notion behind psychological traffic calming is to give drivers responsibility for the speed they choose"[/I]

[I]"[/I][I]... [/I][I]traffic speeds fell by up to 8 miles per hour, and the speeds of faster drivers by up to 12 mph. The reasons are both counterintuitive and compelling[/I]
[I]...[/I]
[I]the driver makes his own choice to slow down, rather than just being instructed to slow down in what looks like a safe environment."[/I]

[I]"A growing body of American transportation research is consistent with psychological traffic calming principles. ..."[/I]

[url]http://en.wikipedia.org/wiki/Category:Optical_illusions[/url]