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Old 1st January 2006, 10:52 PM   #1
jeffq
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Brain fingerprinting

I just saw a Beyond Tomorrow segment (from that infallible repository of scientific knowledge, The Science Channel) on Dr. Lawrence Farwell's "brain fingerprinting", which purports to measure a person's "P300 MERMER response" to information to determine whether the person has specific knowledge of a topic -- in the usual use, knowledge of a serious crime the subject is being questioned about. (In a different manner, this same response test is used to diagnose the potential for early-onset Alzheimer's disease, which I found quite scary without rigorous testing to back up the assumptions being thrown around. Is this guy a medical doctor?)

From what little I've gleaned so far on this P300 response (a particular brain wave pattern picked up by an EEG 300 miiliseconds after the subject observes "a stimulus that has special significance to that individual" (per Wikipedia's article on "brain fingerprinting)), it sounds just as shaky a basis as much of the technology used in lie-detector tests. (How does one define "special significance"? Can people "imagine" a special signficance that will throw off calibration and testing? Is there a difference in timing or strength in te response to "Jane" if it's your name, a relative's name, someone from your past who it takes you a moment to recall, or the name of the person you murdered last Friday?) Does anyone have information (especially paper titles and links) about studies about this technique, especially its evaluation, uses, and abuses? Thanks.
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Old 2nd January 2006, 12:59 AM   #2
Simon Bridge
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Originally Posted by From the show:
Narrator: That "Aha!" moment, that nearly instantaneous spark of recognition, is what scientists call the p300. It is the scientific foundation on which Brain Fingerprinting is built. Dr. Farwell's innovation was to use the p300 to test for guilty knowledge, to determine whether or not a suspect's brain recognizes key crime-scene evidence.

To show how this technology works, Dr. Farwell is asked to conduct a blind test using a real crime. On a farm near the town of Fairfield, Iowa, fertilizer was stolen to make methamphetamine, or crank. The police caught the perpetrator in the act. This person pled guilty, and served two years in jail.

Four individuals are asked to participate in the test. Their names, and all personal details, are withheld from Dr. Farwell. He has no way to match the subjects to the crime--other than Brain Fingerprinting. The volunteers are told no details of the crime, not where it occurred or what was stolen. One of them, however, is guilty.
This the one - I note this test is blind only. We prefer double blind tests.

However - It would be difficult to test in the feild - the suspect would have to have had no contact with the police case at the time the test was applied (recognise this gun do you? Why yes, the officer showed it to me before... my brother has one like it... gee, that must be the murder weapon! would all be P300 responces.) I see this has supposedly been used on someone on death row.

Quote:
In any good scientific test, there are control and experimental groups. In essence: things we know, measured against the things we want to find out. It's the same in Brain Fingerprinting. Dr. Farwell presents a subject with three different kinds of information -- or stimuli. The first are the control group, or what he calls "targets."
Note that the control group is a group of questions, not participants. Like a lie detector test, the examiner needs to make sure he can recognise a P300 responce in the subjects. So a set of stimulie they are garanteed to recognise is presented and the reaction on the eeg is noted for comparison with later traces. The idea here is that the recognition responce will be consistent.

There is also a test for a negative result - stuff the subject is very unlikely to have seen before - to distinguish a null responce. Presumably anything which is neither a null nor a P300 will be "inconclusive".

I'd hope that the negative test would include things from a crime which is not being investigated (where the perp is known) soas to be similar to the actual test material.

I see that the positive responce tests are words the subjects were asked to memorise. So they will definately recognise them.

This divides into three sets - stuff they know. Stuff they don't and stuff they might. The test did actually include material from other crime scenes which would be plausable to people who were not there.

In a murder case, this method got used:
Quote:
Dr. Lawrence Farwell: Immediately before the Brain Fingerprinting test the suspect denied any knowledge whatsoever about the crime. After the Brain Fingerprinting test the subject had to account for what we were finding, and in so doing he stated that, in fact, he did know a number of the most salient details about the crime. He knew where the body was lying, what the body was lying on, what the person was wearing, an unusual item that was taken from the crime scene at the time of the crime.

And he said that the reason he knew these things was because the perpetrator of the crime, had confessed the crime to him, and had told him these details about it. So now we have a very different story from this particular suspect.
with interesting results. Note - the test did not say if he was guilty, just that he was concealing information. It did not reveal the truth.

For the death row Guy: Jimmy Slaughter (an unfortunate name for someone convicted of double homicide...)
Quote:
For more than ten hours Jimmy Ray Slaughter was Brain Fingerprinted for murders he claims he did not commit. Just months away from execution, the only thing that can save Slaughter now is compelling new evidence of innocence -- evidence that could not have been available at the time of trial. Something like Brain Fingerprinting.
I see that he was given the same four questions repeatedly for ten hours. And that it takes more than three days to analyse the data.

This is quite different from the first test - there the results could be displayed as they appeared. Either the p300 was there or not, but now it required a vast amount of repititions and days of analysis.

Presumably the analysis involves staring into the paper and comparing the squiggles.

The result:
Quote:
So Jim, I haven't totally analyzed the data yet. And I won't have fully analyzed it for a couple of days. But I can get a preliminary look at it on this screen here. The probes are this blue line; they match the green line. There's no recognition response. So what this tells us is that you don't know some of the most critical, salient details about that crime. So what does that mean to you?
... see? The salient points in question were things like the location of the victems shorts in the murder scene.

The four bits were:
(1)where Jessica was shot; the room where (2)Melody's body was found; (3)the position of her body; and (4)the writing on her t-shirt

I think a prosecutor would want to take issue here.
4. how many people remember the writing on a t shirt some years afterward?
1-3. he must have known these as the information would have appears in each of his several trials.

Then there is the psichiactric issue of people "forgetting" things they are guilty about.

I think this only shows that the technique could be useful in bullying more info from a recalcitrant witness, but not for overturning a conviction.

In Mr Slaughter's case, he was not convicted of murder because the jury thought he physically did it (he was alibied for the day anyway, and the alibi was upheld) but because they thought he had got soeone else to do it. So he could, even if guilty, pass this test. i.e. the subject was poorly chosen.

I think the term "Brain Fingerprinting" is clearly misleading. It is no where near as good as fingerprinting or anything like that or genetic fingerprinting. Even those are iffy in many cases.

Quote:
There is little argument about the scientific foundation of Brain Fingerprinting. Decades of research and hundreds of peer-reviewed papers support the validity of the p300. But as with any science, Brain Fingerprinting is only as reliable as the methods with which it is applied. In the case of Jimmy Ray Slaughter, Dr. Farwell has stated that Brain Fingerprinting conclusively proves Slaughter does not know four salient facts of the crime.
While the journalists are hyping it somewhat, the conclusion is neetly scientific. I'd have liked a reference to these peer-reviewed papers. That is odd - normally, for instance, in a medical breakthrough, the journalist says "in the latest lancet" or similar.

Quote:
On March 21st, 2004, the United States Supreme Court denied Jimmy Ray Slaughter's appeal.
They called it "junk science".

I doubt any article advocating this use of the p300 would have survived perr-review. Certainly not on these tests. However, the recognition responce seems destined for use as a lie detector.

http://www.pbs.org/wnet/innovation/t..._episode8.html

Originally Posted by from: ABOLISH Achives
fingerprinting is based on the involuntary split-second blimp of
electronic activity that fires in the brain when it recognizes
information, the so-called P300 wave. Farwell has improved on that basic
science with his own system that he says is 100 percent accurate in some
cases.
http://venus.soci.niu.edu/~archives/...ct04/0017.html

Here you see the scientific background - then the inventors claim to have improved it ... then the odd phrase "100% accurate in some cases" - surely this means: not 100% accurate? Perhaps it's only accurate in those cases where it's right, or where conclusive disproof is absent?

In the slaughter case, I think I'd like to have seen the test performed on a juror in the case as well ... I bet the juror would test positive.

That the information was available to slaughter at all the trials, and yet he still showed negative responce, would normally show that this approach is unreliable and further study is needed. The inventor claims it shows that his method is extra-good.

Does this sound familiar?

Last edited by Simon Bridge; 2nd January 2006 at 01:05 AM.
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Old 2nd January 2006, 11:17 AM   #3
Beth
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Originally Posted by Simon Bridge View Post
This the one - I note this test is blind only. We prefer double blind tests.
Just a minor nitpick, but this is one of my sore spots. Double blind tests are preferred when appropriate, they are not always appropriate or even possible. This is a case where a double blind test isn't possible. You can't blind the subjects as to whether or not they actually committed the crime. Single blind is the best that can be done here.
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Old 3rd January 2006, 01:49 AM   #4
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Quote:
This is a case where a double blind test isn't possible. You can't blind the subjects as to whether or not they actually committed the crime. Single blind is the best that can be done here.
Yeah. I only indicated the preference, not the possibility. But fine.

In fact, I'm not sure about the "blindedness" of the test anyway.

In this case, the aim was to test the test. The "tester" was the subject of the experiment. The subject did not know which participant was the actual perp except by examining the results of the test. This is the claim for "single blind".

I would have preferred it if the subject did not administer the test. The subject is not blind to the status of the test content - vis: he knew which statement related to the crime being tested and which did not. This could be thought akin to the tester knowing which shots are the placebo and which are the drug.

It also occurs to me that the subject could have (perhaps unwittingly) arrived at his conclusions by cold reading (the participants were visible to the subject, and gave verbal responces audible to the subject) and then taken days to fit the data with the desired result.

The blindness could have been better - the test could have been administered by someone who didn't know about the crime being tested for, and was unfamiliar with the test statements. The subject need not even have been in the building.
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Old 3rd January 2006, 07:56 PM   #5
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In addition to all the potential problems mentioned above (especially the situation with the confession, being exactly how lie detectors are used not to reveal truth but to cajole it), how about the basic assumption that the P300 MERMER response is necessarily related to the crime? What happens if I, an innocent, am being asked about where Jessica was shot and am shown the phrase "the kitchen"? Assuming that's the location that should only be known to the killer, if I flash on the game "Clue" and think "Mrs. White with a lead pipe", wouldn't this incorrectly register recognition of the event, even though it's really recognition of something totally unrelated?

I haven't read anything to suggest that these responses have been scientifically determined only to occur during the supposed event of criminal recognition. I'm not even sure how this could be done, given that so much of truth-detection pseudoscience seems to be based on assumptions that control questions are "obviously" true or false, ignoring the need for external confirmation, and that asking people to verify what they were thinking of, even in a clinical, non-criminal, anonymous test session cannot guarantee that they will tell the truth about their thoughts.
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Old 3rd January 2006, 11:27 PM   #6
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One should be careful to distinguish between the P300 and the MURMUR responce. The P300 is the recognition responce - a wee bumpy thang in the eeg. The MURMUR responce is the patented "improvement".

The inventor uses the P300 to determine the truth and then used the murmur responce to get a better correlation ... sound suspicious?
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Old 30th November 2018, 06:54 PM   #7
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I see that this technique featured in the new season of Making a Murderer. It immediately raised my suspicions, but there seems to be scant information on this subject out there. Has there been any further research on brain fingerprinting?
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