(3) Facebook. Why You Shouldn't Trust Your Feelings. Amazing Mind-Bending Optical Illusions. Size Visual Illusions. Size Illusions are images where most people can't compare size of 2 objects correctly because of perspective which might be sometimes deceiving.
A ruler might come handy to check how your eyes can deceive you. Measure it yourself. Al Seckel: [Y]Our Mind's Eye. Illusionworks. The Dancer. TableIllusion. Inverse of Reality. TheWayThingsAre. Impossible Balls Illusion! Crazy Nuts Illusion! Optical Illusions And Pictures. Understanding your brain. Stress is your friend. Can Humans Really Feel Temperature? BeliefIsGrey. Color War. Michael Thomas Gerety.
When you 'believe' something, it makes it awfully difficult to perceive things the way they actually are. Facts are important. I assert that the grey on the top is exactly the same shade of grey on the bottom.