Used as only one point of data you're right it's not reliable. False negatives and false positives. But used in conjunction with other info that has been colle

Used as only one point of data you're right it's not reliable. False negatives and false positives. But used in conjunction with other info that has been collected it certainly adds to the picture in coming to a conclusion. Also keep in mind that in this particular case he was speaking to a camera not a person. I do this trick with people to try to guess their name. I have them name three possible names with one the real name. If you do that enough you will begin to pick up on mannerisms when someone is saying their real name vs. a made up name. Of course it only normally works the first time and never if they know how to avoid tipping me off.