Microexpressions are facial movements or expressions that flash across the face at such a fast rate that they are barely perceivable. Slow motion replays of high speed videography easily shows what is difficult to see in real time. The persistence of these cues range from 1/25 to 1/5 of a second. It is the study of microexpressions that assumes that certain aspects of facial expressions reveal this duplicity to betray the liar. The research was originally pioneer by Guillaume Duchenne in the 1800s who discerned the difference between real and fake smiles from the use of the zygomatic major muscles which pull the corners of the mouth upward and the orbicularis oculi, the muscle around the eye that pulls the cheek up while lowering the brow. This was the true smile and in the same way, other unconscious microgestures reveal negative emotions.