Discrepancies between what someone says and how they say it can arise for many reasons. Emotions don't tell us their source. To avoid Othello's error - not recognising that the fear of being disbelieved looks the same as the fear of being caught in a lie; hence convincing himself wrongly of Desdemona's infidelity, from her reactions - we need to investigate why the person is showing an emotion that doesn't fit what they are saying.
Paul Ekman the Observer April 27, 2003{speaking of lies, this guy seems bogus to me, though I can't pin why. maybe that breezy 'picked the lock' when anybody who could do that in my boyhood circles would have been up there with Spiderman and the Green Lantern. which is not to impute bogosity upon the subject of the site itself.}