GizmoWatch: In the words of Morpheus, “What is real? How do you define real? If real is what you can feel, smell, taste and see, then 'real' is simply electrical signals interpreted by your brain. And that is undeniably the truth as reality is perception. And if we tweak these impulses in the right way, one can play a few tricks on the brain. Optical illusions have been around for a while and here are a few of the best that will entertain you, amuse you and offer you an insight into how your brain works. And at any point if your eyes feel strained, do take a break… This is not a challenge!