New research confirms what has been known for decades. People’s ability to detect deception through body language is no better than flipping a coin. Even, gut-level reactions are no better than chance.
The only reliable way to detect deception? You have to know the truth about what the person is talking about. That’s how we catch people in their lies – we know when people aren’t telling the truth, because we already know the facts (or they eventually come to light).
Source: Franz, V. H. & von Luxburg, U. (2015). No evidence for unconscious lie detection: A significant difference does not imply accurate classification. Psychological Science 0956797615597333, first published on August 24, 2015.