Lie detection is the process of assessing a verbal statement with the goal of revealing possible intentional deceit. It may refer to a cognitive process of detecting deception by evaluating message content as well as non-verbal cues. There are several methods of lie detection, including the polygraph, which detects autonomic reactions such as micro-expressions, breathing rate, skin conductivity, and heart rate. Micro-expressions are brief and incomplete nonverbal changes in expression, while the rest show an activation of the nervous system. These changes in body functions are not easily controlled by the conscious mind. Devices such as the Silent Talker Lie Detector monitor large numbers of microexpressions over time slots and encode them into large vectors, which are classified as showing truthful or deceptive behavior by artificial intelligence or statistical classifiers.

However, there is agreement among researchers that no simple verbal cues to deception detectable by humans have been demonstrated. Therefore, most modern-day methods of deception detection heavily rely on a variety of methods to collect, analyze, and interpret emotional and physiological data. Dr. Ekmans work in the field of deception detection largely focuses on nonverbal communication of emotion observed in the face and body. He rejects the title of "human lie detector" and states that it is impossible for anyone to perfect the art of lie detection. Instead, he advocates that with more skills and data, we can make determinations with greater certainty, though its important to remember that we can never know with 100% accuracy whether or not someone is lying.

In conclusion, lie detection is a complex process that involves assessing verbal statements and nonverbal cues to reveal possible intentional deceit. While there are several methods of lie detection, including the polygraph, there is no single, definitive sign of deceit itself, and most modern-day methods of deception detection heavily rely on a variety of methods to collect, analyze, and interpret emotional and physiological data.