Miracle Fruit

The Miracle Fruit plant (Synsepalum dulcificum) produces berries that, when eaten, cause sour foods (Such as lemons and limes) consumed later to taste sweet. The berry, also known as Miracle Berry, Magic Berry, Miraculous Berry or Flavour Berry, was first documented by explorer Chevalier des Marchais who searched for many different fruits during a 1725 excursion to its native West Africa.
When the fleshy part of the fruit is eaten, this molecule binds to the tongue's taste buds, causing sour foods to taste sweet.
What’s most really amazing about it, is our sense of taste is so influenced by visual stimulus.
John Stosell once had his 20/20 interns take a blind taste test, arranged by Brian Wansink, author of the book Mindless Easting. Wansink, a Cornell food science professor, asked them which of the two cups of yoghurt "had more strawberry" Everyone answered one or the other. It turns out it was vanilla yoghurt mixed with chocolate syrup of varying concentrations. Nobody noticed it wasn’t “strawberry” at all (well, partly because out unnatural “fruit” flavors are pretty arbitrary.)

Another experiment from the same researchers, involved several several people wearing colored contacts. After a little while adjusting, they reported they were seeing colors normally, as their eyes had adjusted. But researchers found that wasn’t the case. Under scrutiny, “even when not wearing the contacts, they all began to select a pure yellow that was a different wavelength than they had before wearing the contacts.” The researcher explained, “Over time, we were able to shift their natural perception of yellow in one direction, and then the other…This is direct evidence for an internal, automatic calibrator of color perception. These experiments show that color is defined by our experience in the world, and since we all share the same world, we arrive at the same definition of colors.”

http://www.tomorrowmuseum.com/2008/05/