Polygraphs: The evidence

[Professor Yaffle]

There are some aspects that we can't discuss in public.

Do you understand?

No. Indulge me further. Have you ever ventured a personal opinion about whether ANYTHING should included in the challenge. Eg if someone came to you and said "I don't think dowsing is a suitable "talent" to be included in the challenge- for reasons x, y, and z" - would you Always refuse to enter ino that discussion on the same grounds that you are using to avoid answeing the question with regard to polygraphs.

Here's an analogy:

In the past, it was argued that homeopathy worked because it was based on the assumption that you could dilute forever. But then, they discovered Avogadro's Number and a lot of other things about atoms and molecules. Instead of dropping homeopathy, they came up with some other explanation, much more complicated.

Or think of astrology: Once, it was gravity - until they finally did their calculations. But astrology wasn't dropped - it was just due to some other "force".

The same thing happens here: You once thought polygraphs worked because it was based on the assumption that people get nervous when they lie. But then you find out that the assumption doesn't hold: The very process of being tested can evoke the physiological responses, and there could be all sorts of reasons why people get nervous. Instead of dropping polygraphs altogether, you keep it and come up with some other explanation, this time much more complicated.

If A is claimed to work because of Assumption(X), A should be dropped if it turns out that Assumption(X) doesn't hold.

That is absolute nonsense and you should be ashamed of yourself if you don't know it. We don't reject the claims of homeopathy and astrology because the assumptions they are based on are not true. We reject them because the experimental evidence leads us to the conclusion that they can't do what they claim to be able to do in a fair test. The rest just tells us why they can't do what they say in they way that they say they can do it. To use a hypothetical example: imagine if astrology made the claim that people born at a certain time of year are more likely to suffer from schizophrenia compared to others born at different times of the year. They claim the mechanism for this is gravitational effects of the stars. Now we would be right to be skeptical of their claim, because we know their mechanism to be false. But if when tested, we find that the rates of schizophrenia do vary in thisway, we can't just deny this is true because the astrologer's explanation is false. Instead we look for a more plausible explanation, and attempt to understand the phenomenon. We can't just throw away the weight of experimental evidence and deny that something exists just because the presumed mechanism turns out to be false.

 

[Lucky]

Over the years I have demonstrated how one part of the polygraph, the galvanic skin response (GSR) works in classroom settings with willing volunteers. It detects changes in the resistance of the skin between two electrodes placed in firm contact with the skin on two fingers. It will predictably change with unexpected loud noises, rude words, or having another student blow into his ear. I had a large galvinometer to display this to the class.
One demo gets a student to volunteer and then write down a number between 1 and 10. Then all I do is go through the numbers and let the class decide which number it was. About 80% accuracy.
So I would not call it pseudoscience. I can do this.. But its use in criminal investigations should be illegal because of lack of training, their preconceived biases and constitutional protection against self incrimination.

It's precisely that point that CFLarsen can't (or won't) grasp. Many person-hours have been spent on this thread trying to explain it to him.

If A is claimed to work because of Assumption(X), A should be dropped if it turns out that Assumption(X) doesn't hold.

That is absolute nonsense and you should be ashamed of yourself if you don't know it. We don't reject the claims of homeopathy and astrology because the assumptions they are based on are not true. We reject them because the experimental evidence leads us to the conclusion that they can't do what they claim to be able to do in a fair test. The rest just tells us why they can't do what they say in they way that they say they can do it. To use a hypothetical example: imagine if astrology made the claim that people born at a certain time of year are more likely to suffer from schizophrenia compared to others born at different times of the year. They claim the mechanism for this is gravitational effects of the stars. Now we would be right to be skeptical of their claim, because we know their mechanism to be false. But if when tested, we find that the rates of schizophrenia do vary in thisway, we can't just deny this is true because the astrologer's explanation is false. Instead we look for a more plausible explanation, and attempt to understand the phenomenon. We can't just throw away the weight of experimental evidence and deny that something exists just because the presumed mechanism turns out to be false.

True, CFLarsen's claim here is beyond ridiculous (as I'm sure he knows). And plainly it isn't what Randi thinks – he isn't interested in challenge applicants' 'explanations' for their 'powers', he wants them to demonstrate that the powers exist.

In medicine, for example, it is extremely common that the theoretical basis for a test or treatment is not understood, or not thoroughly tested, or even turns out to be wrong. What matters is the clinical trial evidence, which generally doesn't address the theoretical basis at all.

 

[CFLarsen]

No. Indulge me further. Have you ever ventured a personal opinion about whether ANYTHING should included in the challenge. Eg if someone came to you and said "I don't think dowsing is a suitable "talent" to be included in the challenge- for reasons x, y, and z" - would you Always refuse to enter ino that discussion on the same grounds that you are using to avoid answeing the question with regard to polygraphs.

Look, it isn't that hard.

Let's say someone expresses a desire to be tested for something. He may contact JREF directly, or his local skeptic group who he knows can perform a preliminary test. Or we could spot someone and consider offering them a test.

Do you really expect all aspects - e.g., the negotiation of the protocol, or even the identity of the person - should be discussed in public?

How do you think a test is handled?

That is absolute nonsense and you should be ashamed of yourself if you don't know it. We don't reject the claims of homeopathy and astrology because the assumptions they are based on are not true. We reject them because the experimental evidence leads us to the conclusion that they can't do what they claim to be able to do in a fair test. The rest just tells us why they can't do what they say in they way that they say they can do it. To use a hypothetical example: imagine if astrology made the claim that people born at a certain time of year are more likely to suffer from schizophrenia compared to others born at different times of the year. They claim the mechanism for this is gravitational effects of the stars. Now we would be right to be skeptical of their claim, because we know their mechanism to be false. But if when tested, we find that the rates of schizophrenia do vary in thisway, we can't just deny this is true because the astrologer's explanation is false. Instead we look for a more plausible explanation, and attempt to understand the phenomenon. We can't just throw away the weight of experimental evidence and deny that something exists just because the presumed mechanism turns out to be false.

We discover that the assumptions are not true based on the experimental evidence. Hence my reference to Avogadro's number and gravity.

True, CFLarsen's claim here is beyond ridiculous (as I'm sure he knows). And plainly it isn't what Randi thinks – he isn't interested in challenge applicants' 'explanations' for their 'powers', he wants them to demonstrate that the powers exist.

That's when it comes to the challenge.

In medicine, for example, it is extremely common that the theoretical basis for a test or treatment is not understood, or not thoroughly tested, or even turns out to be wrong. What matters is the clinical trial evidence, which generally doesn't address the theoretical basis at all.

See above.

 

[Professor Yaffle]

Look, it isn't that hard.

Let's say someone expresses a desire to be tested for something. He may contact JREF directly, or his local skeptic group who he knows can perform a preliminary test. Or we could spot someone and consider offering them a test.

Do you really expect all aspects - e.g., the negotiation of the protocol, or even the identity of the person - should be discussed in public?

How do you think a test is handled?

But nobody is asking you about any of those aspects. We are asking for your personal (not as any sort of an affiliate to JREF) opinion as to whether a hypothetical case should be within the remit of the JREF.

We discover that the assumptions are not true based on the experimental evidence. Hence my reference to Avogadro's number and gravity.

But you have completely missed (avoided) my point. Which is that you don't ignore/deny the results of a fair test just because the proposed mechanism (the "assumptions") for those results has been proven false (by experimental evidence). You just check the results are correct and if so try to find an alternative explanation which does fit with experimental evidence.

 

[Belz...]

You complained that I misunderstood.

Where, in the quote of mine you posted, did I mention computers?

Was I not clearly referring to polygraphs?

Claus. I mentionned computers. Did you get that, this time ?

 

[CFLarsen]

But nobody is asking you about any of those aspects. We are asking for your personal (not as any sort of an affiliate to JREF) opinion as to whether a hypothetical case should be within the remit of the JREF.

Already explained.

Do you really expect all aspects - e.g., the negotiation of the protocol, or even the identity of the person - should be discussed in public?

How do you think a test is handled?

But you have completely missed (avoided) my point. Which is that you don't ignore/deny the results of a fair test just because the proposed mechanism (the "assumptions") for those results has been proven false (by experimental evidence). You just check the results are correct and if so try to find an alternative explanation which does fit with experimental evidence.

No, I haven't either missed or avoided your point. I am pointing out that polygraph proponents exhibit the exact same behavior as proponents of homeopathy and astrology.

Claus. I mentionned computers. Did you get that, this time ?

I am asking you about this:

We know that polygraphs "work" because they intimidate people. They do extract confessions, but not because the apparatus can determine if you tell the truth or not. You confess, because you are bamboozled into confessing what the interrogators already know.

Computers extract confessions from people ?

How did you get to computers based on what I wrote? Did I mention computers in the quote?

 

[Professor Yaffle]

I think the point Belz was making Claus, was that if polygraphs only work by extracting confessions, how come in lab tests where there are no confessions, computer programmes can analyse the results of polygraph tests and determine when lies are being told with a greater than chance accuracy. I know you really know that and are just being pedantic to avoid answering the point.

 

[Professor Yaffle]

Already explained.

Do you really expect all aspects - e.g., the negotiation of the protocol, or even the identity of the person - should be discussed in public?

How do you think a test is handled?

The point that not all aspects of a challenge can be discussed in public is entirely irrelevant to answering whether a specific aspect can or cannot be discussed. Please answer with regards to this specific aspect. Are you prohibited from expressing a personal opinion on which "abilities" should be included in the challenge. A yes or no answer please.

 

[CFLarsen]

The point that not all aspects of a challenge can be discussed in public is entirely irrelevant to answering whether a specific aspect can or cannot be discussed.

It is not up to you to decide which aspects can be discussed or not.

How do you think a test is handled?

 

[Professor Yaffle]

It is not up to you to decide which aspects can be discussed or not.

How do you think a test is handled?

I am perfectly aware that it isn't up to me and never even hinted that it was up to me. That is why I am trying to determine - from YOU - whether this particular aspect CAN be discussed by you. So can you please tell me the answer to that? A yes or a no will suffice.

My knowledge of how a test is handled is completely irrelevant, as all I am trying to do it get a small piece of information from you. I am not asserting anything in this regard.

 

[Professor Yaffle]

No, I haven't either missed or avoided your point. I am pointing out that polygraph proponents exhibit the exact same behavior as proponents of homeopathy and astrology.

And again, you are completely avoiding my point. Do you think that the results of a fair test should just be discarded because the proposed mechanism for its action is known to be false?

Again, it is just a nice easy yes or no question, which I am sure you will answer with some words which are neither yes nor no.

 

[CFLarsen]

I am perfectly aware that it isn't up to me and never even hinted that it was up to me. That is why I am trying to determine - from YOU - whether this particular aspect CAN be discussed by you. So can you please tell me the answer to that? A yes or a no will suffice.

I already said so. Pay attention.

My knowledge of how a test is handled is completely irrelevant, as all I am trying to do it get a small piece of information from you. I am not asserting anything in this regard.

It is very relevant, since you clearly work from a misperception of how a test is handled.

How do you think a test is handled?

And again, you are completely avoiding my point. Do you think that the results of a fair test should just be discarded because the proposed mechanism for its action is known to be false?

Of course not. But that's not what is happening with polygraphs:

A polygraph instrument will collect physiological data from at least three systems in the human body. Convoluted rubber tubes that are placed over the examinee's chest and abdominal area will record respiratory activity. Two small metal plates, attached to the fingers, will record sweat gland activity, and a blood pressure cuff, or similar device will record cardiovascular activity.
American Polygraph Association

They still stick to the old "sweat, breath'n'blood pressure" claim. That's a hallmark of pseudoscience.

 

[RayG]

The NAS report indicates that the polygraph works "better than chance" in determining deception.

Then why do both the NAS report and the Office of technology report (here) indicate that for specific incident investigations the polygraph works better than pure chance.

I'm just about to dash out the door, so I'm being lazy. Do you have the specific source for the actual "better than chance" quote?

I found these:

Even where the evidence seems to indicate that polygraph testing detects deceptive subjects better than chance (when using the control question technique in specific-incident criminal investigations), significant error rates are possible, and examiner and examinee differences and the use of countermeasures may further affect validity.

The preponderance of research evidence does indicate that, when the control question technique is used in specific-incident criminal investigations, the polygraph detects deception at a rate better than chance, but with error rates that could be considered significant.

Both with qualifiers. Was there a "better than chance" assertion without qualifiers?

RayG

 

[Professor Yaffle]

I already said so. Pay attention.

Can you please link to the post where you answered this question unambiguously?

It is very relevant, since you clearly work from a misperception of how a test is handled.

How do you think a test is handled?

OK then assume that everything I think about how a test is handled it wrong. I know very little about how a test is handled and am therefore not basing my questions on anything about that. I am merely trying to obtain information from you.

Of course not. But that's not what is happening with polygraphs

Then you shouldn't be arguing from the perspective of the underlying mechanism being wrong - as that has no bearing on whether the lie detection results are true. You first need to show us the flaws in the experiments that lead to a woo, no better than chance technique getting better than chance results. How about you dissect some of these experiments for us? If you can show why all the experiments were not fair tests, then people might actually see what you are getting at.

They still stick to the old "sweat, breath'n'blood pressure" claim.

Yes, because changes from the baseline in the old "sweat, breath'n'blood pressure" are indicators that seem to be correlated with lying. Whether because of anxiety, excitement, orienting response or something else is very interesting and helpful for making the test more accurate, but excluding one (which I don't think you have by the way) doesn't make the resulting correlations disappear ito thin air.

That's a hallmark of pseudoscience.

What is a hallmark of pseudoscience? Using physiological measures to indicate psychological processes?

 

[Professor Yaffle]

I'm just about to dash out the door, so I'm being lazy. Do you have the specific source for the actual "better than chance" quote?

I found these:





Both with qualifiers. Was there a "better than chance" assertion without qualifiers?

RayG

Sorry, which bits are you indicating as "qualifiers"?

 

[Big Les]

[chav]Leave it Yaffs, 'ee's not werf it![/chav]

 

[Professor Yaffle]

[chav]Leave it Yaffs, 'ee's not werf it![/chav]

Does my face look bovvered?

 

[RayG]

Sorry, which bits are you indicating as "qualifiers"?

Significant error rates.

RayG

 

[Professor Yaffle]

Nobody is denying that there are significant error rates. Otherwise it would have a heckofalot better description than "better than chance". And that's why pretty much everyone here argues that although it is not pseudoscience, it should never be used in a real life situation where it would be regarded as "diagnostic" - ie admissable in court, sacking someone based only on the results etc. But that doesn't mean that it can't have any applications.

 

[Thanz]

You have to be a Creationist. Or inconsistent, of course...

I have to be a Creationist? Based on what? I see you have put forward no evidence of this, instead arguing a false dichotomy.

Either put forward your evidence or stop this silly game.

Pure dishonesty. I didn't say we don't discuss the challenge, I said there were some aspects of the challenge we don't discuss in public.

If you have to lie, at least don't make it so obvious.

There was no lie. You must be seriously humour impaired.

You clearly have a very distorted idea of how the challenge works. Skeptica can do preliminary tests, precisely like other skeptical groups around the world. And some of the things cannot be discussed in public.

Why is it so hard for you to accept that?

Why is it so hard for you to point out my errors in describing how the challenge works? It is very simple: whether or not you can do preliminary tests, the only group that can actually accept a challenge is the JREF. Their opinion (and specifically Randi's) is the only one that counts. As you said in post #247 - "I can't say whether it would qualify or not. That is entirely up to Randi."

Now that we are all clear on that, what is your opinion on whether it should qualify?

It's perfectly simple:

You argue that people don't get excited when they lie.

You argue that polygraphs detect changes in people when they lie.

Therefore, you must argue that people get more excited when they lie.

Therefore, you must argue that polygraphs work by detecting these excitements.

Is this correct, yes or no?

First, you realize that you are insisting that I am arguing two different things in the bolded paragraphs, correct?

Second, my question does not rely on how polygraphs work. For the purpose of the challenge, all they have to do is work. And all I am asking you is if in your opinion (considering your stated stance that they are "pseudoscience") a successful test of the polygraph should qualify.