Dr. Gareth Moore 
Seeing Is Believing [PDF ebook] 

Can your eyes deceive you? Try these amazing optical illusions to find out. Look hard, then look again to see… ? spinning patterns but the page isn’t moving! ? colors that change but do they? ? big and small shapes spot the difference! Devised by an expert on brain training, these visual tricks and challenges are huge fun and quite an eye-opener! There are handy tips if you need help, plus an answer key at the back!