July 21, 2008
Where you Vote effects how you Vote
Hard to imagine but according to one study, true.
(Hat tip to Marginal Revolution)
More details here
Posted by rakhier at 02:07 PM | Comments (0)
A Graph of the Welfare Rate in NYC over 50 years
As you can see the number of people in New York City on Welfare is radically reduced now vs. March 1995. Clearly the Clinton welfare reform worked by at least this single metric.
Posted by rakhier at 01:38 PM | Comments (0)
July 02, 2008
The "Brain's Best Guess" Theory of Perception
This from an article about (sort of) itching in the New Yorker... by Atul Gawande.
A new scientific understanding of perception has emerged in the past few decades, and it has overturned classical, centuries-long beliefs about how our brains work—though it has apparently not penetrated the medical world yet. The old understanding of perception is what neuroscientists call “the naïve view,” and it is the view that most people, in or out of medicine, still have. We’re inclined to think that people normally perceive things in the world directly. We believe that the hardness of a rock, the coldness of an ice cube, the itchiness of a sweater are picked up by our nerve endings, transmitted through the spinal cord like a message through a wire, and decoded by the brain.
In a 1710 “Treatise Concerning the Principles of Human Knowledge,” the Irish philosopher George Berkeley objected to this view. We do not know the world of objects, he argued; we know only our mental ideas of objects. “Light and colours, heat and cold, extension and figures—in a word, the things we see and feel—what are they but so many sensations, notions, ideas?” Indeed, he concluded, the objects of the world are likely just inventions of the mind, put in there by God. To which Samuel Johnson famously responded by kicking a large stone and declaring, “I refute it thus!”
Still, Berkeley had recognized some serious flaws in the direct-perception theory—in the notion that when we see, hear, or feel we are just taking in the sights, sounds, and textures of the world. For one thing, it cannot explain how we experience things that seem physically real but aren’t: sensations of itching that arise from nothing more than itchy thoughts; dreams that can seem indistinguishable from reality; phantom sensations that amputees have in their missing limbs. And, the more we examine the actual nerve transmissions we receive from the world outside, the more inadequate they seem.
Our assumption had been that the sensory data we receive from our eyes, ears, nose, fingers, and so on contain all the information that we need for perception, and that perception must work something like a radio. It’s hard to conceive that a Boston Symphony Orchestra concert is in a radio wave. But it is. So you might think that it’s the same with the signals we receive—that if you hooked up someone’s nerves to a monitor you could watch what the person is experiencing as if it were a television show.
Yet, as scientists set about analyzing the signals, they found them to be radically impoverished. Suppose someone is viewing a tree in a clearing. Given simply the transmissions along the optic nerve from the light entering the eye, one would not be able to reconstruct the three-dimensionality, or the distance, or the detail of the bark—attributes that we perceive instantly.
Or consider what neuroscientists call “the binding problem.” Tracking a dog as it runs behind a picket fence, all that your eyes receive is separated vertical images of the dog, with large slices missing. Yet somehow you perceive the mutt to be whole, an intact entity travelling through space. Put two dogs together behind the fence and you don’t think they’ve morphed into one. Your mind now configures the slices as two independent creatures.
The images in our mind are extraordinarily rich. We can tell if something is liquid or solid, heavy or light, dead or alive. But the information we work from is poor—a distorted, two-dimensional transmission with entire spots missing. So the mind fills in most of the picture. You can get a sense of this from brain-anatomy studies. If visual sensations were primarily received rather than constructed by the brain, you’d expect that most of the fibres going to the brain’s primary visual cortex would come from the retina. Instead, scientists have found that only twenty per cent do; eighty per cent come downward from regions of the brain governing functions like memory. Richard Gregory, a prominent British neuropsychologist, estimates that visual perception is more than ninety per cent memory and less than ten per cent sensory nerve signals. When Oaklander theorized that M.’s itch was endogenous, rather than generated by peripheral nerve signals, she was onto something important.
The fallacy of reducing perception to reception is especially clear when it comes to phantom limbs. Doctors have often explained such sensations as a matter of inflamed or frayed nerve endings in the stump sending aberrant signals to the brain. But this explanation should long ago have been suspect. Efforts by surgeons to cut back on the nerve typically produce the same results that M. had when they cut the sensory nerve to her forehead: a brief period of relief followed by a return of the sensation.
Moreover, the feelings people experience in their phantom limbs are far too varied and rich to be explained by the random firings of a bruised nerve. People report not just pain but also sensations of sweatiness, heat, texture, and movement in a missing limb. There is no experience people have with real limbs that they do not experience with phantom limbs. They feel their phantom leg swinging, water trickling down a phantom arm, a phantom ring becoming too tight for a phantom digit. Children have used phantom fingers to count and solve arithmetic problems. V. S. Ramachandran, an eminent neuroscientist at the University of California, San Diego, has written up the case of a woman who was born with only stumps at her shoulders, and yet, as far back as she could remember, felt herself to have arms and hands; she even feels herself gesticulating when she speaks. And phantoms do not occur just in limbs. Around half of women who have undergone a mastectomy experience a phantom breast, with the nipple being the most vivid part. You’ve likely had an experience of phantom sensation yourself. When the dentist gives you a local anesthetic, and your lip goes numb, the nerves go dead. Yet you don’t feel your lip disappear. Quite the opposite: it feels larger and plumper than normal, even though you can see in a mirror that the size hasn’t changed.
The account of perception that’s starting to emerge is what we might call the “brain’s best guess” theory of perception: perception is the brain’s best guess about what is happening in the outside world. The mind integrates scattered, weak, rudimentary signals from a variety of sensory channels, information from past experiences, and hard-wired processes, and produces a sensory experience full of brain-provided color, sound, texture, and meaning. We see a friendly yellow Labrador bounding behind a picket fence not because that is the transmission we receive but because this is the perception our weaver-brain assembles as its best hypothesis of what is out there from the slivers of information we get. Perception is inference.
The theory—and a theory is all it is right now—has begun to make sense of some bewildering phenomena. Among them is an experiment that Ramachandran performed with volunteers who had phantom pain in an amputated arm. They put their surviving arm through a hole in the side of a box with a mirror inside, so that, peering through the open top, they would see their arm and its mirror image, as if they had two arms. Ramachandran then asked them to move both their intact arm and, in their mind, their phantom arm—to pretend that they were conducting an orchestra, say. The patients had the sense that they had two arms again. Even though they knew it was an illusion, it provided immediate relief. People who for years had been unable to unclench their phantom fist suddenly felt their hand open; phantom arms in painfully contorted positions could relax. With daily use of the mirror box over weeks, patients sensed their phantom limbs actually shrink into their stumps and, in several instances, completely vanish. Researchers at Walter Reed Army Medical Center recently published the results of a randomized trial of mirror therapy for soldiers with phantom-limb pain, showing dramatic success.
A lot about this phenomenon remains murky, but here’s what the new theory suggests is going on: when your arm is amputated, nerve transmissions are shut off, and the brain’s best guess often seems to be that the arm is still there, but paralyzed, or clenched, or beginning to cramp up. Things can stay like this for years. The mirror box, however, provides the brain with new visual input—however illusory—suggesting motion in the absent arm. The brain has to incorporate the new information into its sensory map of what’s happening. Therefore, it guesses again, and the pain goes away.
The rest of the article is about itching...
Posted by rakhier at 02:03 PM | Comments (0)
June 28, 2008
A Shared Fantasy World - Santharia
Santharia is a shared fantasy world with a constantly evolving collection of birds, beasts, gods, history, geography, music, and legends. Very odd and quite interesting.
Welcome to the future, kind of like the Uncyclopedia but not so pointlessly silly.
I might do some work on this...
Posted by rakhier at 03:59 PM | Comments (0)
June 18, 2008
Bacterial Evolution in the Lab
This is a good story from the New Scientist magazine (June 9, 2008)
A major evolutionary innovation has unfurled right in front of researchers' eyes. It's the first time evolution has been caught in the act of making such a rare and complex new trait.
And because the species in question is a bacterium, scientists have been able to replay history to show how this evolutionary novelty grew from the accumulation of unpredictable, chance events.
Twenty years ago, evolutionary biologist Richard Lenski of Michigan State University in East Lansing, US, took a single Escherichia coli bacterium and used its descendants to found 12 laboratory populations.
The 12 have been growing ever since, gradually accumulating mutations and evolving for more than 44,000 generations, while Lenski watches what happens.
Profound change
Mostly, the patterns Lenski saw were similar in each separate population. All 12 evolved larger cells, for example, as well as faster growth rates on the glucose they were fed, and lower peak population densities.
But sometime around the 31,500th generation, something dramatic happened in just one of the populations – the bacteria suddenly acquired the ability to metabolise citrate, a second nutrient in their culture medium that E. coli normally cannot use.
Indeed, the inability to use citrate is one of the traits by which bacteriologists distinguish E. coli from other species. The citrate-using mutants increased in population size and diversity.
"It's the most profound change we have seen during the experiment. This was clearly something quite different for them, and it's outside what was normally considered the bounds of E. coli as a species, which makes it especially interesting," says Lenski.
Rare mutation?
By this time, Lenski calculated, enough bacterial cells had lived and died that all simple mutations must already have occurred several times over.
That meant the "citrate-plus" trait must have been something special – either it was a single mutation of an unusually improbable sort, a rare chromosome inversion, say, or else gaining the ability to use citrate required the accumulation of several mutations in sequence.
To find out which, Lenski turned to his freezer, where he had saved samples of each population every 500 generations. These allowed him to replay history from any starting point he chose, by reviving the bacteria and letting evolution "replay" again.
Would the same population evolve Cit+ again, he wondered, or would any of the 12 be equally likely to hit the jackpot?
Evidence of evolution
The replays showed that even when he looked at trillions of cells, only the original population re-evolved Cit+ – and only when he started the replay from generation 20,000 or greater. Something, he concluded, must have happened around generation 20,000 that laid the groundwork for Cit+ to later evolve.
Lenski and his colleagues are now working to identify just what that earlier change was, and how it made the Cit+ mutation possible more than 10,000 generations later.
In the meantime, the experiment stands as proof that evolution does not always lead to the best possible outcome. Instead, a chance event can sometimes open evolutionary doors for one population that remain forever closed to other populations with different histories.
Lenski's experiment is also yet another poke in the eye for anti-evolutionists, notes Jerry Coyne, an evolutionary biologist at the University of Chicago. "The thing I like most is it says you can get these complex traits evolving by a combination of unlikely events," he says. "That's just what creationists say can't happen."
Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0803151105)
No rational person disputes that evolution takes place. The still unresolved problem is: how did life itself evolve? As I see it there are two things that must happen at the same time in the same "generation"
1) Proto-life must figure out how to harness external energy to "do things".
2) Proto-life must figure out how to make perfect copies of itself.
Its impossible for me to imagine proto-life forms sitting around and then one day, changing so that they start to harness energy from the sun so they can do things (like: move, store energy, grow in size, etc.).
Its equally impossible for me to imagine how, this same primitive life form not only "figured out" how to harness energy but also, before it died, figured out how to reproduce an exact copy of itself. So I'm completely unconvinced that there is a natural explanation for the origin of life. But as to evolution, no question. Its real.
Posted by rakhier at 10:32 PM | Comments (0)
June 17, 2008
Who are the Aggressive Drivers?
A study done by University of Colorado researchers has concluded: its the people with bumper stickers.
Watch out for cars with bumper stickers. (Shankar Vedantam, Washington Post, Monday, June 16, 2008)
That's the surprising conclusion of a recent study by Colorado State University social psychologist William Szlemko. Drivers of cars with bumper stickers, window decals, personalized license plates and other "territorial markers" not only get mad when someone cuts in their lane or is slow to respond to a changed traffic light, but they are far more likely than those who do not personalize their cars to use their vehicles to express rage -- by honking, tailgating and other aggressive behavior.
It does not seem to matter whether the messages on the stickers are about peace and love -- "Visualize World Peace," "My Kid Is an Honor Student" -- or angry and in your face -- "Don't Mess With Texas," "My Kid Beat Up Your Honor Student."
Szlemko and his colleagues at Fort Collins found that people who personalize their cars acknowledge that they are aggressive drivers, but usually do not realize that they are reporting much higher levels of aggression than people whose cars do not have visible markers on their vehicles.
Drivers who do not personalize their cars get angry, too, Szlemko and his colleagues concluded in a paper they recently published in the Journal of Applied Social Psychology, but they don't act out their anger. They fume, mentally call the other driver a jerk, and move on.
"The more markers a car has, the more aggressively the person tends to drive when provoked," Szlemko said. "Just the presence of territory markers predicts the tendency to be an aggressive driver."
The key to the phenomenon apparently lies in the idea of territoriality. Drivers with road rage tend to think of public streets and highways as "my street" and "my lane" -- in other words, they think they "own the road."
Why would bumper stickers predict which people are likely to view public roadways as private property?
Social scientists such as Szlemko say that people carry around three kinds of territorial spaces in their heads. One is personal territory -- like a home, or a bedroom. The second kind involves space that is temporarily yours -- an office cubicle or a gym locker. The third kind is public territory: park benches, walking trails -- and roads.
Previous research has shown that these different territorial spaces evoke distinct emotional responses. People are willing to physically defend private territory in ways they would never do with public territory. And people personalize private territory with various kinds of markers -- in their homes, for example, they hang paintings, alter the decor and carry out renovations.
"Territoriality is hard-wired into our ancestors from tens of thousands of years ago," said Paul Bell, a co-author of the study at Colorado State. "Animals are territorial because it had survival value. If you could keep others away from your hunting groups, you had more game to spear . . . it becomes part of the biology."
Drivers who individualize their cars using bumper stickers, window decals and personalized license plates, the researchers hypothesized, see their cars in the same way as they see their homes and bedrooms -- as deeply personal space, or primary territory.
Unlike any environment our evolutionary ancestors might have confronted, driving a car simultaneously places people in both private territory -- their cars -- and public territory -- the road. Drivers who personalize their cars with bumper stickers and other markers of private territory, the researchers argue, forget when they are on the road that they are in public territory because the immediate cues surrounding them tell them that they are in a deeply private space.
"If you are in a vehicle that you identify as a primary territory, you would defend that against other people whom you perceive as being disrespectful of your space," Bell added. "What you ignore is that you are on a public roadway -- you lose sight of the fact you are in a public area and you don't own the road."
Szlemko said that, in an as-yet-unpublished experiment, he conducted tests of road rage in actual traffic. He had one researcher sit in a car in a left-turn lane. When the light turned green, the researcher simply stayed still, blocking the car behind.
Another researcher, meanwhile, examined whether the blocked car had bumper stickers and other markers of territoriality. The experimental question was how long it would take for the driver of the blocked car to honk in frustration.
Szlemko said that drivers of cars with decals, bumper stickers and personalized license plates honked at the offending vehicle nearly two full seconds faster than drivers of cars without any territorial markers.
Ah the joys of modern science.
Posted by rakhier at 08:49 AM | Comments (0)