Truth Bias

The book Detecting Lies and Deceit by Aldert Vrij mentions evidence of a truth bias, i.e. people are more likely to correctly judge that a truthful statement is true than that a lie is false.

This appears to be a fairly robust result that is not just a function of truth being the correct guess where the evidence is weak – it shows up in controlled experiments where subjects have good reason not to assume truth (for example, this paper).  Vrij proposes several explanations for this bias.

  • The higher frequency of truthful statements in daily life make cause the availability heuristic to bias our judgment.
  • Politeness: there’s more social harm in daily life from mistakenly believing someone to be a liar or from asking someone to prove all claims than there is from mistakenly believing false claims.
  • People rely on stereotypes which are less accurate for liars than for truth-tellers [it’s unclear why this is a separate explanation from the first].

Since it’s unclear whether these effects make it in your interest to be suspicious, let’s also look at how being suspicious affects others. Increased suspicion may do a little harm to your friends by making them a bit more uncomfortable. But if it spreads, it should also improve political systems by making it a bit harder for people to get away with lies. This suggests that altruists ought to be more comfortable with friend who question their honesty in order to encourage social norms under which political choices are based on more accurate beliefs.

One concern I don’t know how to analyze is how this would affect the kind of social capital that Fukuyama talks about in his book Trust.

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  • http://profile.typekey.com/cronodas/ Doug S.

    So… what does this tell me about how often I should bluff in poker?

  • http://profile.typekey.com/robinhanson/ Robin Hanson

    It seems to me this is mainly caused by wanting to think well of the people we associate with. I wonder if we have the same, or the opposite, bias regarding statements by foreigners, or by our rivals.

  • Keith Elis

    I would be interested to know if truth bias is consistent across both males and females to the same degree.

  • http://www.stafforini.com Pablo Stafforini

    This is not a truth bias; it is a truthfulness bias. The evidence doesn’t show that we are more likely to believe true statements than to disbelieve false ones. It shows that we are more likely to believe what truthful people say than to disbelieve what liars say. It would be interesting to know if, on top of a truthfulness bias disposing us to be insufficiently distrustful of lies, we also have a truth bias disposing us to be insufficiently sceptical of falsehoods.

  • Douglas Knight

    Pablo Stafforini,
    which evidence distinguishes the two hypotheses?

  • http://www.stafforini.com Pablo Stafforini

    Douglas,

    A lie is not just a false statement, but one made with deliberate intent to deceive. As characterized by Peter, the bias discussed here is one against the proper subclass of lies rather than then larger class of falsehoods. But one may wonder whether we have a bias against falsehoods on top of our bias against lies. Are people also more likely to correctly judge that a true statement is true than that a false statement is false? (Perhaps we are disposed to believe more than the evidence warrants, and hence end up judging more false statements true than true statements false.)

  • http://profile.typekey.com/bayesian/ Peter McCluskey

    Robin, it’s clear that we don’t treat friends and enemies the same way, and I would expect people to be overly suspicious of enemies.
    The studies in question seem to partly deal with this by observing interactions with strangers, but they’re probably strangers of the same culture. It would be interesting to see how much the results change if the studies put people of obviously different cultures together, or do the experiments with people in cultures that are more suspicious of strangers.

  • http://www.bizop.ca/blog2/confirmation-bias/how_to_lie_and_influence_peopl.html THE BIZOP NEWS

    How to Lie and Influence People

    Here is an interesting thesis, in this new book, discussed at Overcomingbias, Truth Bias The book Detecting Lies and Deceit by Aldert Vrij mentions evidence…

  • Manon de Gaillande

    It’s much more than just politeness; we’re better off believing a statement like “Don’t put your hand in the oven, it will burn you” than checking whether it’s true.

    • icomefromanon

      Except I did put my hand on a pan despite being told that..

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