Microexpressions occur quickly and last only fractions of a second. Microexpressions appear as furrows, smirks, frowns, smiles and wrinkles and can offer an accurate, though fleeting, window into emotions. These signals can be used to decipher liars from truth tellers. These microexpressions are controlled by muscles such as the fontalis, corregator and risorius and they are provoked by underlying emotions that are nearly impossible to control consciously. One of these emotions is the fake smile to show appeasement in lieu of genuine joy or happiness.