Belief in Reincarnation Tied to Memory Error

Melinda Wenner - People who believe they have lived past lives as, say, Indian princesses or battlefield commanders are more likely to make certain types of memory errors, according to a new study.

The propensity to make these mistakes could, in part, explain why people cling to implausible reincarnation claims in the first place.

Researchers recruited people who, after undergoing hypnotic therapy, had come to believe that they had past lives.

Subjects were asked to read aloud a list of 40 non-famous names, and then, after a two-hour wait, told that they were going to see a list consisting of three types of names: non-famous names they had already seen (from the earlier list), famous names, and names of non-famous people that they had not previously seen. Their task was to identify which names were famous.

The researchers found that, compared to control subjects who dismissed the idea of reincarnation, past-life believers were almost twice as likely to misidentify names. In particular, their tendency was to wrongly identify as famous the non-famous names they had seen in the first task. This kind of error, called a source-monitoring error, indicates that a person has difficulty recognizing where a memory came from.

Power of suggestion

People who are likely to make these kinds of errors might end up convincing themselves of things that aren’t true, said lead researcher Maarten Peters of Maastricht University in The Netherlands. When people who are prone to making these mistakes undergo hypnosis and are repeatedly asked to talk about a potential idea—like a past life—they might, as they grow more familiar with it, eventually convert the idea into a full-blown false memory.

This is because they can’t distinguish between things that have really happened and things that have been suggested to them, Peters told LiveScience.

Past life memories are not the only type of implausible memories that have been studied in this manner. Richard McNally, a clinical psychologist at Harvard University, has found that self-proclaimed alien abductees are also twice as likely to commit source monitoring errors.

Creative minds

As for what might make people more prone to committing such errors to begin with, McNally says that it could be the byproduct of especially vivid imagery skills. He has found that people who commonly make source-monitoring errors respond to and imagine experiences more strongly than the average person, and they also tend to be more creative.

“It might be harder to discriminate between a vivid image that you’d generated yourself and the memory of a perception of something you actually saw,” he said in a telephone interview.

Peters also found in his study, detailed in the March issue of Consciousness and Cognition, that people with implausible memories are also more likely to be depressed and to experience sleep problems, and this could also make them more prone to memory mistakes.

And once people make this kind of mistake, they might be inclined to stick to their guns for spiritual reasons, McNally said. “It may be a variant expression of certain religious impulses,” he said. “We suspect that this might be kind of a psychological buffering mechanism against the fear of death.”

Out-of-body Experiences May Be Caused by Arousal System Disturbances in Brain

BJS

Having an out-of-body experience may seem far-fetched to some, but for those with arousal system disturbances in their brains, it may not be a far off idea that they could sense they were really outside their own body watching themselves. In previous studies of more than 13,000 Europeans, almost 6 percent said they have had such an out-of-body experience.

Dr. Kevin Nelson and a research team at the University of Kentucky have studied the link between out-of-body experiences, the sleep-wake transition and near death experiences, and published their findings today in the March 6 issue of the journal Neurology in their case report, "Out-of-body experience and arousal."

The results are intriguing, and show that some people's brains already may be predisposed to these sorts of experiences. They found that an out-of-body experience is statistically as likely to occur during a near death experience as it is to occur during the transition between wakefulness and sleep. Nelson suggests that phenomena in the brain's arousal system, which regulates different states of consciousness including REM sleep and wakefulness, may be the cause for these types of out-of-body displays.

"We found it surprising that out-of-body experience with sleep transition seemed very much like out-of-body experience during near death," Nelson said.

For their study, the team conducted structured interviews with 55 people who have had a near death experience. They found those who had an out-of-body experience along with near death were more likely to also have had some sort of REM intrusion in their lifetime, where instead of passing directly between the REM sleep state and wakefulness, the brain switch blends these states into one another.

To survey out-of-body experiences that occurred during sleep transition, patients were asked, "Just before falling asleep or just after awakening, have you had the sense that you are outside of your body and watching yourself?" A similar question was posed to survey out-of-body experiences during near death, which asked subjects if during their experience they had "clearly left the body and existed outside it."

Because the arousal system controls or influences sleep-wake states, alertness and attention, Nelson and the research team questioned whether people with near death experiences may already have an arousal system predisposed to allowing intrusion of REM sleep elements during the transition between wakefulness and sleep.

Sleep paralysis is a common form of REM intrusion, which can cause a condition of temporary paralysis along with visual or auditory hallucinations immediately after waking up or before falling asleep due to an ill-timed disconnection between the brain and the body. Although it was once considered very rare, about 25 percent of all people have probably experienced sleep paralysis sometime during their life.

During a medical crisis, Nelson said muscle paralysis combined with an out-of-body experience could show many of the same prominent features of a near death experience. Near death experiences are responses to a life-threatening crisis, and are characterized by a combination of disassociation from the physical body, euphoria and transcendental or mystical elements.

This investigation supports the notion of out-of-body experiences as an expression of arousal in near death experiences and sleep paralysis. Almost all of the near death subjects having sleep paralysis, 96 percent, also had an out-of-body experience either during sleep transition or near death.

"The strong association of sleep paralysis with out-of-body experiences in the near death experience subject is curious and unexplained," Nelson said. "However, persons with near death experiences appear to have an arousal system predisposed to both REM intrusion and out-of-body experiences."

Nelson is a professor of neurology at the UK College of Medicine and a UK HealthCare physician at the Kentucky Neuroscience Institute. Other team members are Michelle Mattingly, assistant professor of neurology, and Frederick A. Schmitt, professor of neurology, both at the UK College of Medicine.

The full case report can be read online in the March 6 issue of Neurology.

From University of Kentucky

Les chercheurs suisses décryptent le fait de «sortir de son propre corps»

Les sensations de décorporation (sortie de son propre corps) souvent décrites lors d'expériences de mort imminente (EMI) proviendraient de perturbations d'un processus complexe de coordination, qu'on peut aujourd'hui localiser dans le cerveau, selon des chercheurs suisses.

Les neurologues Olaf Blanke et Margitta Seeck ont fait cette observation à l'occasion de repérages par stimulations électriques de zones clés du cerveau en vue d'ôter certaines parties du cortex responsables de formes sévères d'épilepsie.

«La représentation corporelle est troublée (...) lorsqu'on stimule électriquement la jonction temporo-pariétale», ont observé les chercheurs du Département de neurosciences cliniques de la Faculté de médecine de l'Université de Genève (UNIGE) et de l'Institut des neurosciences de l'École polytechnique fédérale de Lausanne (EPFL).

«À ce moment-là, le cerveau génère une image du corps, mais une image délocalisée, comme projetée sous le corps, en face ou derrière lui», décrivent les scientifiques dans un communiqué publié mercredi. «Dans les deux premiers cas de figure, les patients reconnaissent encore leur propre image; dans le dernier en revanche, ils ressentent une présence autre, sombre et menaçante», expliquent-ils.

Brain electrodes conjure up ghostly visions

Simple stimulation may underpin complex mental illusions.

Nature - Simple stimulation of the brain can cause the mind to play complex and creepy tricks on itself, neurologists have discovered. They found that, by inserting electrodes into a specific part of the brain, they could induce a patient to sense that an illusory 'shadow person' was lurking behind her and mimicking her movements.

Doctors treating the patient, a 22-year-old woman with epilepsy, found that when they stimulated a brain region called the left temporoparietal junction, the patient sensed the presence of a sinister figure behind her who copied her actions. They suspect that the effect is due to the mind projecting its own movements onto a phantom figure conjured up by the brain, an effect that is seen in some patients with serious psychiatric conditions.

"It was quite astonishing — she definitely realized the 'person' was taking the same posture as she did, but she didn't make the connection," says Olaf Blanke of the École Polytechnique Fédérale de Lausanne in Switzerland, who led the research. "To her it remained a different person, an alien — exactly what you find in schizophrenics."

The patient had no history of psychiatric problems. So the results suggest that this type of illusion, despite being an apparently complex psychiatric symptom, can be caused by a very simple switch in the brain. The mechanism might help to explain schizophrenic feelings such as paranoia, alien control, and the notion that parts of one's body belong to somebody else.

The phenomenon may also be linked to the 'out-of-body' experiences reported by many people. Previously, Blanke's group has shown that similar brain stimulation can induce a sensation that one is rising up out of one's body (see 'Electrodes trigger out-of-body experience').

Extrasensory perception

Doctors were investigating the patient's brain in preparation for an operation to remove scar tissue that was causing persistent epileptic fits. Up to a third of adult epileptics suffer in this way and cannot be helped by drugs.

The team inserted electrodes directly into the patient's brain to accurately pinpoint the regions that control language and right-hand movement, to ensure that these were not damaged during the subsequent operation. But in doing so, they accidentally interfered with a brain region that coordinates different sensory information to give a sensation of the body's location in space.

"There's a lot of information coming in from your body to your brain," Blanke explains. If you are talking on the telephone, for instance, you will hear your own voice, feel the handset in your hand, and have feedback from your arm muscles to tell you what position you are in. Your brain integrates the information and forms a picture of where your body is and what it is doing.

But in this patient such integration seems to have been scrambled, Blanke says. For the few seconds that the electrical stimulation was occurring, she described a sensation of a shadowy man hovering behind her. And, as the researchers report in this week's Nature1, when she was asked to lean forward and hug her knees, she said it felt as if the man was (unpleasantly) reaching around to grasp her.

The feeling persisted even though the researchers pointed out that it was her mind playing tricks and projecting its own movements. "She was aware of this, but said it remained quite scary. She still had to turn around to check [there was no one there]," Blanke recalls.

Not me

The work may provide some insight into schizophrenia. Blanke notes that this condition frequently includes problems with perceiving one's own body. In experiments in which subjects view an image of themselves in which one of their arms is rotated by an abnormal amount, for example, schizophrenics will readily declare that the appendage is not theirs. Normal volunteers will disown it only when the rotation reaches about 90° out of normal.

Others caution that this one experiment will have a limited impact on our understanding of such symptoms, however. "Schizophrenia is a syndrome and not a single phenomenon," says Sabine Bahn, a psychiatrist at the University of Cambridge, UK.

Blanke plans to try to replicate the result in other volunteers

Les ghostbusters, et autres parapsyphiles, vont finir par se retrouver au chomage.

Electrical brainstorms busted as source of ghosts

Nature, published online: 09 December 2004
Roxanne Khamsi

Doubt cast on theory that magnetic fields spark religious feelings.
Studies showing that magnetic stimulation of the brain induces spiritual experiences are being queried by researchers who cannot reproduce key results. If the traditional theory is wrong, scientists will be left struggling to explain how such thoughts and sensations are generated.
In the past, scientists have claimed that religious or out-of-body experiences result from excessive bursts of electrical activity in the brain. In the 1980s, Michael Persinger, a neuroscientist at the Laurentian University in Ontario, Canada, began exploring this idea through a series of experiments.
Participants wore helmets that targeted their temporal lobes with weak magnetic fields, of roughly the same strength as those generated by a computer monitor. Persinger found that this caused 80% of the people he tested to feel an unexplained presence in the room. Persinger suggested that magnetism causes bursts of electrical activity in the temporal lobes of the brain, and he linked this to the spiritual experiences.

Blinding science
A group of Swedish researchers has now repeated the work, but they say their study involves one crucial difference. They ensured that neither the participants nor the experimenters interacting with them had any idea who was being exposed to the magnetic fields, a 'double-blind' protocol. Without such a safeguard, "people in the experimental group who are highly suggestible would pick up on cues from the experimenter and they would be more likely to have these types of experiences," says Pehr Granqvist of Uppsala University, who led the research team. Beyond the double-blind aspect, Granqvist says the nuts and bolts of the experiment mirrored those conducted in the past. He and his colleagues tested 43 undergraduate students by exposing them to magnetic fields that ranged from 3 to 7 microtesla and were aimed just above and in front of the ears, to target the temporal lobes. They also tested a control group of 46 volunteers who wore the helmet but were not exposed to the magnetic field. The volunteers were then asked to complete questionnaires about what they experienced during each session. The researchers report their results online in Neuroscience Letters1.

Strong spirits
In contrast to the results from Persinger and others, the team found that the magnetism had no discernable effects. Two out of the three participants in the Swedish study that reported strong spiritual experiences during the study belonged to the control group, as did 11 out of the 22 who reported subtle experiences.
Granqvist acknowledges that this seems to be quite a high level of spiritual experiences overall, but says that it matches the level that Persinger saw in his control groups.
The researchers say they do not know what neurological mechanism could be generating the experiences. However, using personality tests they did find that people with an orientation toward unorthodox spirituality were more likely to feel a supernatural presence, as were those who were, in general, more suggestible.

Field defence
Persinger, however, takes issue with the Swedish attempts to replicate his work. "They didn't replicate it, not even close," he says. He argues that the Swedish group did not expose the subjects to magnetic fields for long enough to produce an effect. He also stresses that some of his studies were double-blinded. Although the experimenters knew when the magnetic field was being applied, he says that they did not know what effect the field was expected to induce.
Susan Blackmore, a psychologist based in Bristol, UK, is also reluctant to give up on the theory just yet. She has firsthand experience of Persinger's methods. "When I went to Persinger's lab and underwent his procedures I had the most extraordinary experiences I've ever had," she says. "I'll be surprised if it turns out to be a placebo effect."
She too thinks that the Swedish researchers may have used magnetic fields that varied subtly from those of Persinger. "But double-blind experiments will ultimately give us the final answer," she says.

References
1. Granqvist P., et al. Neurosci. Lett., published online
doi:10.1016/j.neulet.2004.10.057 (2004).

Cette étude vient contredire les résultats d’une étude précédente. Une fois de plus, l’absence du double aveugle et probablement le petit nombre de sujets et de tests expliquent ces controverses.