| A Belated Debate on Modified Beets Environmentalists and farmers sue the Agriculture Department, seeking to overturn permits it issued that would allow the planting of a seed crop. feeds.nytimes.com |
A brainwave for catching a criminal? A new study suggests criminals can be detected by measuring a brainwave known as P300. In tests it worked remarkably well, but can we really trust it?Mo Costandi writes the Neurophilosophy blogTerrorists could be identified by a brainwave test that detects concealed information about an imminent attack, according to a study by psychologists from Northwestern University in Chicago.The test, a sophisticated version of the now-discredited polygraph (or lie-detector) test, is based on the so-called guilty knowledge test developed in the 1950s. Whereas the traditional lie detector test involves asking the suspect whether or not they committed the crime in question, the guilty knowledge test focuses on specific details that would only be known to the perpetrator.In the 1980s, Peter Rosenfeld combined the guilty knowledge test with recordings of the brain's electrical activity. He exploited a brain wave pattern called the P300, which occurs in response to visual stimuli after a delay of 300 milliseconds, and can be detected with electrodes attached to the scalp.It is well known that task-related stimuli, or stimuli that are meaningful in some other way, produce a larger P300 response than others. For the guilty knowledge test, this increased response can be a neurological signature of the unconscious recognition of a familiar object, event, or piece of information.Rosenfeld's group has already applied the test in a mock crime scenario, using it to identify participants who had knowledge of a stolen object. In the new study, they applied the test to a mock terrorist situation, recruiting 29 university students and dividing them into "guilty" and "innocent" groups.The "guilty" group was given a document explaining that they would play the role of a terrorist planning an attack, and containing four different options each for how the attack could be carried out, the types of bombs that could be used, locations in Houston, Texas, that could be targeted, and dates in July on which the attack could be carried out.Having planned the mock attack, they wrote a letter to an imaginary superior, containing the choices they had made, to aid memorisation of the plan details. The participants in the "innocent" group planned a mock holiday instead.Both groups were then shown a long series of words on a computer screen, while the researchers recorded their P300 responses. Most of the words were irrelevant to the mock attack, but a few were "probes", relating to the specific details in the plans, and were included to evoke a stronger P300 in those participants with concealed knowledge of the details.The researchers identified all of the "guilty" participants, without incorrectly identifying any of the "innocent" ones. They were also able to identify most of the attack-related details, enabling them to establish where and when each of the mock attacks would take place.But the real world is infinitely more complex than the carefully controlled laboratory conditions under which the study was carried out. Here, the researchers detected concealed knowledge of a very limited set of details that were already known to them. In reality, an investigator would have little or no information of a planned attack.Another limitation of the test is that the "probes" could have some meaning to a suspect in some other way. Three of the participants had to be excluded from the study because one of the probes had personal relevance to them, so produced false positive results. Guilty knowledge acquired incidentally could also produce a false positive. Furthermore, there are various countermeasures that can be used to confound the results.Could these tests be used to establish a suspect's guilty knowledge after a crime has been committed? This, too, is problematic, because it is based on the assumption that memory is infallible. We have known, however, since the work carried out by Sir Frederic Bartlett in the 1920s that memory is reconstructive, and not reproductive, in nature.That is, we do not recollect events as they actually happened, but according to our own biases and experiences. Remembering involves stitching together fragments of memories, and errors inevitably creep in. Normally, the memory is accurate enough to be reliable, but occasionally it is not. It may even become increasingly inaccurate with each successive recollection. We can confabulate spontaneously, and false memories can be implanted with relative ease, as Elizabeth Loftus has shown.Despite lacking validity outside the lab setting, the P300 test and similar techniques, such as "brain fingerprinting", are admissible in some courts of law in the United States and in 2008, India became the first country to use the guilty knowledge test to convict someone of a crime.It would therefore be wise to properly evaluate how effective these tests are before they are used routinely in the courtroom. And, if that were to happen routinely, to regulate their use by companies who offer them as a service to the legal profession.Mo Costandi writes the Neurophilosophy blogNeurosciencePsychologyguardian.co.uk © Guardian News & Media Limited 2010 | Use of this content is subject to our Terms & Conditions | More Feeds guardian.co.uk |
Nobel Prize given for test tube baby research By MALCOLM RITTER and KARL RITTER 2010-10-05T16:44:40ZNEW YORK (AP) -- The Nobel Prize in medicine went to a man whose work led to the first test tube baby, an achievement that helped bring 4 million infants into the world and raised challenging new questions about human reproduction.... hosted.ap.org |
Test could warn women of early menopause Genetic test could be of benefit to growing number of women who delay motherhood then find they cannot conceiveScientists have moved closer to devising a test that could warn women that they are going to undergo an early menopause.The blood test would identify those who are going to go through the menopause before the age of 35, years before it usually happens in a woman's early 50s. That process happens to around one in 20 women and can ruin dreams of motherhood.Scientists report today that they have made considerable progress in understanding the key role played in early menopause by four genes.The test that their findings help pave the way for could be of particular benefit to the growing number of women who put off having children until their 30s but then find that they cannot conceive.Researchers from Exeter University' Peninsula Medical School and the Institute of Cancer Research (ICR) examined the four genes linked to early menopause. They compared 2,000 women who had been through it and 2,000 who had not.While each gene affected a woman's risk of an early menopause, the combination of them produced a much greater risk, which the researchers to conclude that this is why some women experience the menopause much earlier than normal.They say that their work could lead to women being able to find out if they are genetically predisposed to early menopause and know when their fertility would end and thus potentially decide to have children earlier than planned."It is estimated that a woman's ability to conceive decreases on average 10 years before she starts the menopause," said lead scientist Dr Anna Murray, from the Peninsula Medical School. "Therefore those who are destined to have an early menopause and delay childbearing until their 30s are more likely to have problems conceiving. These findings are the first stage in developing an easy and relatively inexpensive genetic test which could help the one in 20 UK women who may be affected by early menopause."The study, published in the journal Human Molecular Genetics, is the first research to emerge from the Breakthrough Generations Study. The collaboration between the charity Breakthrough Breast Cancer and the ICR plans to track 100,000 women over the next 40 years to identify which lifestyle, environmental and genetic factors make some women susceptible to the commonest female cancer.Fertility experts said a genetic test based on the new study could give would-be older mothers options they may not otherwise have. "This could help the growing numbers of women who delay having children until towards the end of their reproductive life and then find to their horror that they have gone through, or are approaching, early menopause, and so their egg quality is very poor," said Dr Allan Pacey of Sheffield University."Given that women are increasingly older when they start having their families then a result like this should be able to tell those women at risk that they shouldn't hang about, even if that's before they ideally want to have children, because you can't turn the clock back once an early menopause has happened".Pacey added: "If you haven't found Mr Right by then, then women could freeze their eggs. This could be an early warning call to do that and there would be a legitimate medical reason to do so".MenopauseWomenMedical researchGeneticsHealthDenis Campbellguardian.co.uk © Guardian News & Media Limited 2010 | Use of this content is subject to our Terms & Conditions | More Feeds guardian.co.uk |
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