Yup - you cannot trust your own senses (any of them). The body has various sensors, which send impulses to the brain. The brain then tries to interpret these impulses, according to what it already knows. The examples above are ways of tricking the brain: the "sensors (nerve endings)" see/experience one thing with absolute values, but the brain works with relative values, biased by the things that it "knows" are true, whether they are or not... Errm... I have several examples to expound upon this but my brian (misspelling intended) is a bit sleepy right now... (not to mention befuddled by certain alcoholic substances), so I'll leave it at that... Cheers, Diolma