Bullshit detection–or how Cameron uses the Kyle method

Most rational people agree that electronic equipment is really bad at detecting ghosts.  EMF meters, ghost boxes and motion detectors are equally rubbish at detecting spirits, ghosts, souls or whatever you would call them.  You wouldn’t expect the UK law enforcement agencies to use ghost boxes to try and ask a murdered man who his killer was.  It would be stupid.  Why?  Because such equipment has not been proven to do what its proponents claim.

However, this doesn’t mean that law enforcement agencies aren’t subject to the same biases and fallibilities as optimistic ghost hunters. 

Today the government has announced that polygraph testing is to be introduced across the UK for serious sex offenders on probation.  This is problematic, as polygraph testing, despite being around for about 90 years, has not been proven and still exists in the realm of pseudoscience.  Almost all psychologists agree that polygraph testing cannot be relied upon to identify if someone is telling the truth.

Despite this, the government wants to use the magic truth divining box – as seen on Jeremy Kyle to see if a chav has been lying to his girlfriend.

From the reports it seems that the test used by the probation service was little more than an elaborate wheeze to trick the offenders into coughing up the truth.  The pilot programme results claimed that:

mandatory lie detector tests prompted sex offenders to:

• Be more honest with their offender managers. A No 10 source said they provided probation staff with more information about the potential risks they pose.

• Make twice as many disclosures to probation staff, such as admitting that they had contacted a victim.

• Admit the tests helped them manage their own behaviour more effectively.

The first two claims rely on several assumptions:

(a) the offenders believed the lie detector works;

(b) the offenders were completely truthful and not leaving out key information;

(c) the offenders were not able to game the test.

The third claim should have the bullshit claxon sounding off in any objective mind.  Of course the offenders are going to claim the lie detector test worked if they think it would be favourable for them.  There would be a self interested motivation for the offenders to tell their interviewers what they wanted to hear.

Polygraph tests rely heavily on the subjective judgement of the person conducting the test, by inference rather than intelligence.  This appears to be little more than casting runes or reading tarot cards, except with the modern sparkle of electronics.  Why not bring back phrenology to spot criminals?

Such a system might work, but it relies on the assumption that offenders don’t wise up to the truth: that polygraph tests are so fallible as to make them worthless.  I can easily imagine offenders in prison training each other on passing these tests.

The government claims the pilot was a success (even the Guardian does), based on nothing more than what appears to be wishful thinking.  That all adds up to a lot of bullshit.


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7 responses to “Bullshit detection–or how Cameron uses the Kyle method”

  1. David Potts says :

    Personally, I think it all seems like a step in the right direction. However, I do believe that 90% of the British public would support capital punishment for paedophines and certain other categories of sex offenders. I know I certainly would!

    • brian paget says :

      Taxpayer’s money shouldn’t be used on a technique that isn’t proven to work. It’s a waste.

      I disagree on capital punishment. There have been far too many miscarriages of justice. Further, I’m uncomfortable with giving the state such ultimate power over individuals. It grinds against my classical libertarian principles.

      • Ken says :

        Whilst I am not in favour of wasting taxpayers (ie my) money, if we are only going to spend money on techniques which are “proven” to work, then we would not be spending much money! That in itself may be a good thing of course. But, seriously, surely it is in the nature of development and evolution, that some avenues will be “failures”? The best we can do is to attempt to control wild overspending (like for example the expenditure on the still not working Command and Control Centres for the Fire Brigade, as per two jags).

        Agree with you on Capital punishment, until we have technology to “undead” someone, it is a bit too final for my taste. Human error is all too evident all around us.

      • brian paget says :

        surely it is in the nature of development and evolution, that some avenues will be “failures”?

        The point is that after 90 years, polygraph testing is still yet to be shown to work as a tool for divining truth. Surely this is exactly the type of overspending you would like to see the back of?

  2. Ken says :

    Yes, but, from your original post, the implication was that the “baddies” may, at least for a while, believe it works, and hence an advantage may be gained. One of the problems with “Government” spending, in my view, is that it is inflexible. For example, deciding to subsidise (say) the production of butter may be a wise move at a given point in time, but, it become entrenched and self interest groups spring up to perpetuate the subsidy long after it’s useful “life” has passed. Anyway, I am not disagreeing with you in principle, yes, by all means cut the waste, no matter which side created it.

  3. Swiftsure666 says :


    You are absolutely correct. A polygraph does not detect lies: it detects a person’s heart rate, breathing, skin conductance, and so on. The polygraph operator then has to “interpret” the results. There have been many high profile cases of serious crimes going undetected for a long time because of the inherent unreliability of so-called lie detectors.

    Aldrich Ames – a CIA agent – passed lie detector tests while he was also busy selling US secrets to the Russians. And there have been many other examples.

    David Potts should consider a few relevant points. First of all, the fact that a majority of the public would support the death penalty for sex offenders (or murderers or infidels, even) is neither here nor there – it does not make the death penalty right.

    Secondly, supporting the death penalty is something that is big with people who make the false assumption that they themselves could never be accused of a crime they have not committed. If David Potts were to be falsely accused (and then convicted, thanks to a polygraph) of a capital offence, would he just accept it without complaint? It seems to me that people who are willing to accept the death of innocent people without any worry about their guilt or innocence have the same lack of value for human life as the people they are happy to see executed.

    As you suggest, the number of miscarriages of justice that have occurred should make everyone pause for thought.

    Then again, it would be interesting to see politicians hooked up to a polygraph when they are being interviewed by TV or radio – or even just the local press. Would Mr Potts support that idea? I think a majority of South Tynesiders would like to see his next interview with The Shields Gazette done by polygraph. It gets my vote. (Unlike David Potts)

    • Ken says :

      Ho, Ho Brian, I REALLY like the idea of the polygraph on Politician interviews, (even if it does not work reliably), great to see them squirm!

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