Wednesday, February 01, 2006
Words help us see and talk
The language we speak affects half of what we see, according to researchers at the University of California, Berkeley, and the University of Chicago.
Scholars have long debated whether our native language affects how we perceive reality — and whether speakers of different languages might therefore see the world differently. The idea that language affects perception is controversial, and results have conflicted. A paper published this month in the Proceedings of the National Academy of Sciences supports the idea — but with a twist. The paper suggests that language affects perception in the right half of the visual field, but much less, if at all, in the left half. The paper, “Whorf Hypothesis is Supported in the Right Visual Field but not in the Left,” by Aubrey Gilbert, Terry Regier, Paul Kay, and Richard Ivry — is the first to propose that language may shape just half of our visual world.
Terry Regier is Associate Professor of Psychology at the University of Chicago. Gilbert is a graduate student in the Helen Wills Neuroscience Institute at UC Berkeley. Kay is Professor Emeritus of Linguistics and a senior research scientist at the International Computer Science Institute in Berkeley. Ivry is a Professor of Psychology, director of UC Berkeley's Institute of Cognitive and Brain Sciences, and a member of the Helen Wills Neuroscience Institute.
This finding is suggested by the organization of the brain, the researchers say. Language function is processed predominantly in the left hemisphere of the brain, which receives visual information directly from the right visual field. “So it would make sense for the language processes of the left hemisphere to influence perception more in the right half of the visual field than in the left half”, said Terry Regier of the University of Chicago, who proposed the idea behind the study.
The team confirmed the hypothesis, through experiments designed and conducted in Richard Ivry’s lab at the University of California, Berkeley. “We were thrilled to find this sort of effect and are very interested in investigating it further,” said Gilbert, the lead author on the study. The hypothesis was confirmed in experiments that tested Berkeley undergraduates, and also in an experiment that tested a patient whose hemispheres had been surgically separated. “The evening I first reviewed the split-brain patient data I called people at home in my excitement to share the findings,” said Gilbert.
Many of the distinctions made in English do not appear in other languages, and vice versa. For instance, English uses two different words for the colors blue and green, while many other languages — such as Tarahumara, an indigenous language of Mexico — instead use a single color term that covers shades of both blue and green. An earlier study by Paul Kay and colleagues had shown that speakers of English and Tarahumara perceive colors differently: English speakers found blues and greens to be more distinct from each other than speakers of Tarahumara did, as if the English “green” / “blue” linguistic distinction sharpened the perceptual difference between the colors themselves. The present study essentially repeated the English part of that earlier test, but also made sure that colors were presented to either the right or the left half of the visual field — something the earlier study hadn’t done — so as to test whether language influences the right half of our visual world more than the left half, as predicted by brain organization.
In each experimental trial of the present study, participants saw a ring of colored squares. All the squares were of exactly the same color, except for an “odd-man-out” of a different color. The odd-man-out appeared in either the right or the left half of the circle, and participants were asked to indicate which side of the circle the odd-man-out was on, by making a keyboard response. Critically, the color of this odd-man-out had either the same name as the other squares (e.g. a shade of “green”, while the others were all a different shade of “green”), or a different name (e.g. a shade of “blue”, while the others were all a shade of “green”). The researchers found that participants responded more quickly when the color of the odd-man-out had a different name than the color of the other squares — as if the linguistic difference had heightened the perceptual difference — but this only occurred if the odd-man-out was in the right half of the visual field, and not when it was in the left half. This was the predicted pattern.
Earlier studies addressing the possible influence of language on perception tended to look for a simple yes or no answer: either language affects perception, or it does not. In contrast, the current findings support both views at once. Language appears to sharpen visual distinctions in the right visual field, and not in the left visual field. The researchers conclude that “our representation of the visual world may be, at one and the same time, filtered and not filtered through the categories of language.”source:http://www-news.uchicago.edu/releases/06/060131.regier.shtml
Skeletons Discovered: First African Slave in New World
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Archaeologists have found what they think are the oldest remains of slaves brought from Africa to the New World. The remains, in a colonial era graveyard in one of the oldest European cities in Mexico, date between the late-16th century and the mid-17th century, not long after Columbus first set foot in the Americas. The African origin of the slaves was determined by studying a chemical in their tooth enamel that reveals plant and rock types of their native land. The chemical enters the body through the food chain as nutrients pass from bedrock through soil and water to plants and animals. It is an indelible signature of birthplace, the researchers said, because it can be directly linked to the bedrock of specific locales. Researchers examined remains of four individuals from among 180 burials found in a multiethnic burial ground associated with the ruins of a colonial church in Campeche, Mexico, a port city on the Yucatan Peninsula. "This is the earliest documentation of the African Diaspora in the New World," said study co-leader T. Douglas Price of University of Wisconsin-Madison. "It does mean that slaves were brought here almost as soon as Europeans arrived." The discovery will be detailed in the American Journal of Physical Anthropology. Over a span of nearly 400 years, as many as 12 million people were placed in bondage and brought across the Atlantic under horrific conditions to work, primarily, in the mines and plantations of the New World, Price and his colleagues said. In early colonial Mexico, Campeche was an important Spanish gateway to the New World. It served as a base for exploration and conquest and was a key defensive outpost in a region infested with pirates, the researchers say. They think slaves from the infamous West African port of Elmina were shipped to Campeche where they may have been used as domestic servants. The discovery of the remains of slaves born in Africa from such an early date shows that slavery became an integral aspect of the New World economy not long after the Conquistadors completed the subjugation of Mexico, Price said. Archaeological and historical evidence, including a map of colonial Campeche, suggest the graveyard was in use from about 1550 to the late 1600s. It was uncovered, along with the foundations of a colonial era church, in 2000 by construction workers digging around Campeche's central park. The site was excavated under the direction of Tiesler.
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Thirsty people feel more pain
Going without a drink can make you more sensitive to pain, a study has found.
Australian pain expert Dr Michael Farrell of the Howard Florey Institute in Melbourne and team report their findings in today's issue of the Proceedings of the National Academy of Sciences.
"This is another demonstration of the plasticity of pain responses," he said.
"In this particular instance a mild perturbation of electrolyte levels, which is fundamentally what gives rise to thirst ... is enough to modify the pain response."
Dr Farrell and the team studied the relationship between thirst and pain in 10 people.
The study participants had pressure applied to their thumbs to induce mild pain and were given saline injections to stimulate thirst.
Blood flow scan
The researchers used a positron emission tomography (PET) scan to measure blood flow in the brains before and after.
The results showed that people who were thirsty felt more pain.
Two regions of the brain, the pregenual cingulate and ventral orbitofrontal cortex, which were not turned on by either input alone, lit up suggesting a location where the two sensations were being integrated.
The researchers did not find that pain affected thirst levels, but Dr Farrell says this could be because the participants were not made very thirsty in the first place and any decrease would have been hard to measure.
Dr Farrell says the team had speculated there might be circuits in the brain that allow one sensation to modulate another, which is important from the point of view of survival.
"Hunger, thirst, tiredness and pain, for example, don't conveniently happen at the same time, so it's important for the body to prioritise," he said.
Survival instinct
He says pain is accentuated because it is more important to survival than mild thirst.
"The sensation with the most immediate implications for survival is pushed to the forefront of attention," he said.
Dr Farrell says the findings suggest it could be wise for people who are about to go through a painful experience should drink more water beforehand.
He says evidence from different types of studies also support this relationship between drinking water and pain.
But could people deliberately use dehydration to maximise pain, say via torture?
"We suspect if they got dehydrated enough that the overwhelming sense of thirst would probably make pain less rather than more," he said.
Previous studies in rats have shown that mild thirst makes the animals feel more pain but severe dehydration actually dulls pain, he says.
He says this too makes sense from the point of view of survival.
"If you were very dehydrated it would pay to suppress pain because it might get in the way of your search for water," he said.
Ethical limitations
Dr Farrell says it would have been too hard on the study participants, who already spent up to three hours on the table, to test whether drinking decreased pain.
"They've got this plastic mask holding their head perfectly still and they've got both arms spread out, one of them with a hypertonic solution going into one vein and the other one getting radioactive isotopes - it would have been intolerable," he said.
He says testing whether dehydration would have dulled pain would be similarly tricky ethically.
source:http://www.abc.net.au/news/newsitems/200602/s1559544.htm
Napster To Be Acquired by Google?
source:http://slashdot.org/article.pl?sid=06/01/31/1717226
