Can you tell whether this article is telling the truth?
posted 12.04.05
DETECTING LIES LITTLE AND BIG
In the game Dungeons & Dragons, there is a magic spell called detect lie (or at least there was back in the first edition). A couple of my favorite high school gaming sessions revolved around the player characters flinging accusations at each other—and immediately finding out which one was lying.
Weak track record
According to psychologist Aldert Vrij's excellent book Detecting Lies and Deceit, those of us without magical powers have a long way to go. Not only are laymen bad at detecting lies; so are policemen, customs agents, and other people who do it professionally.
How bad? There are many experiments where subjects are required to lie and tell the truth with equal probability. Observers then try to sort fact from fiction. A representative result: People correctly identify truths 70 percent of the time, but correctly identify lies only 50 percent of the time. If you know Bayes's Rule, you can use this information to calculate the probability a statement is true given that it seems true:
P(True|seems True) = [(P(seems True|True)*P(True)] /
[P(seems True|True)*P(True) + P(seems True|Lie)*P(Lie)]
which by my calculations=58.3 percent. A little better than random guessing, but not much.
A few other juicy morsels from Vrij:
"[O]bservers overestimate the likelihood of being able to detect deceit by paying attention to someone's behavior, and...underestimate the possibility of catching liars by paying attention to their speech content."
Not a good tell
Contrary to popular opinion, gaze aversion does not predict lying. This may be because almost everyone believes it does, leading even inexperienced liars to try not to avert their gaze.
It is easier to tell if someone is lying if you are familiar with their ordinary (non-lying) speech and behavior. But actually meeting or intimately knowing the suspected liar does not give an additional benefit. In other words, you are more able to detect lies in your friends because you know how they normally act, not because people look guiltier when they lie to their friends.
Men and women lie equally often, but men tell more self-oriented lies and women tell more "other-oriented lies, particularly with regard to other women." (Self-oriented lies are designed to gain an advantage for the liar; other-oriented lies are designed to help someone else—usually the listener).
Call me a liar, but Vrij's book convinced me that I am almost pathologically honest. I would certainly lie to save an innocent person's life. But the common sense moral truism that it is wrong to lie still seems compelling to me, and I adhere to it. (Yes, I just averted my gaze from the monitor, but that proves nothing!) Vrij argues that lies lubricate social relations, but there are honest ways to do the same thing. Most social pleasantries are non-propositional anyway; if someone says "Thank you," you cannot coherently respond "False!"
And it is never false to smile and say "Mmm hmm."
* * *
I'm a trusting person by nature, so it's useful for me to reflect on how deceptive people can be. The following excerpt really helped focus my attention. It's from a speech given to the Associated Press in 1933 by Adolf Hitler.
Speaking deliberately as a German National Socialist, I desire to declare in the name of the National Government, and of the whole movement of national regeneration, that we in this new Germany are filled with deep understanding for the same feelings and opinions and for the rightful claims to life of the other nations. The present generation of this new Germany which so far has only experienced the poverty, misery, and distress of its own people, has suffered too deeply from the madness of our time to be able to contemplate treating others in the same way. Our boundless love for and loyalty to our own national traditions makes us respect the national claims of others and makes us desire from the bottom of our hearts to live with them in peace and friendship. [from Noakes and Pridham, Nazism, 1919-1945, vol.3]
Six years later, of course, Hitler notoriously told his military commanders:
I shall give a propagandist reason for starting the war, no matter whether it is plausible or not. The victor will not be asked afterwards whether he told the truth or not. When starting and waging war it is not right that matters, but victory.
Close your hearts to pity. Act brutally. Eighty million people must obtain what is their right. Their existence must be made secure. The stronger man is right. The greatest harshness.
The standard litigator's trick is to ask "Were you lying then or are you lying now?" Here's one case where we know the answer.
Reprinted by permission of the author from the Bryan Caplan half of the EconLog, where it was published as two separate blog entries. Bryan Caplan is a professor of economics at George Mason University.
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Play the Dungeons & Dragons Basic Game
Watch "Dungeons & Dragons 2: Wrath of the Dragon God"
Read Adolf Hitler: The Definitive Biography by John Toland
Watch "Lies, Myths and Stupidity" by John Stossel
Read Big Fat Liars by Morris E. Chafetz
Gifts Books on liberty All books—and all else, also
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