Thursday, September 25, 2008

Discover - Could an Inner Zombie Be Controlling Your Brain?

In more ways than we care to know, we are not in control of the brain and body we live in -- we might be conscious in so many ways, but we often operate like zombies. This Discover article looks at the situation with a little more detail.

The Brain: Could an Inner Zombie Be Controlling Your Brain?

Scientists have found evidence that the self-aware part of our brains isn't always in charge.

by Carl Zimmer


iStockphoto

If you had to sum up the past 40 years of research on the mind, you could do worse than to call it the Rise of the Zombies.

We like to see ourselves as being completely conscious of our thought processes, of how we feel, of the decisions we make and our reasons for making them. When we act, it is our conscious selves doing the acting. But starting in the late 1960s, psychologists and neurologists began to find evidence that our self-aware part is not always in charge. Researchers discovered that we are deeply influenced by perceptions, thoughts, feelings, and desires about which we have no awareness. Their research raised the disturbing possibility that much of what we think and do is thought and done by an unconscious part of the brain—an inner zombie.

Some of the earliest evidence for this zombie came from studies of people who had suffered brain injuries. In 1970 British psychologists Elizabeth Warrington and Lawrence Weiskrantz showed a series of words to a group of people with amnesia, who promptly forgot the list. A few minutes later Warrington and Weiskrantz showed them the first three letters of each of the words they had just seen and forgotten and asked the amnesiacs to add some additional letters to make a word. Any word would do. The amnesiacs consistently chose the words they had seen and forgotten; the inner zombie, somewhere beyond awareness, retained memories of the words.

Our inner zombies may also be able to control our bodies. In 1988 a woman known as “patient D. F.” suffered carbon monoxide poisoning and lost the ability to recognize objects and shapes. Her eyes were still relaying information to her brain, but the connections between regions of her brain had been damaged so that she was no longer aware of what was before her. Scientists at the University of Western Ontario set a card on a table in front of D. F. and then held up a disk with a slot in it. They asked D. F. to hold the card at the same angle as the slot. She couldn’t. But when asked to put the card in the slot as if she were mailing a letter, she immediately—and unknowingly—turned the card to the correct angle and slipped it in.

These days a number of powerful new tools can scrutinize the inner zombies in healthy brains. Earlier this year, a team of University of Copenhagen researchers reported rendering 11 healthy people temporarily blind by focusing a beam of magnetism at the back of the subjects’ heads. This interfered with the activity of neurons in a region called the visual cortex. For a few minutes the neurons were deactivated, and the subjects reported that they couldn’t see anything.

At the start of the experiment, the subjects—who could see at this point—sat in front of three lights, each with a button below it. When the center light went on, they had to reach out their hand and press the button next to it. In some trials, the scientists switched off the center light just as the subjects began reaching, and turned on a different one. The subjects therefore had to shift their hand movement to press the correct button.

Less than a tenth of a second after the light switched, though, the scientists zapped the subjects, instantly blinding them. With so little time between the switch of lights and the zap, the subjects still thought the center light was on. Yet a significant number of them moved their hand away from the center button and shifted it to the correct one. Their inner zombie didn’t need any awareness in order to perceive the change and alter the command it sent to the hand.

In the Danish experiment, the subjects were at least aware of their goal, even if they didn’t know how they were achieving it. Other experiments show that our unconscious mind can fully act like a conscious self. Take a recent experiment in which French and English scientists had volunteers play a simple game while undergoing a brain scan. The subjects held a handgrip while watching a computer screen. They were told to squeeze the handgrip whenever they saw a picture of money on the screen. The more they squeezed, the more money they would win.

Some pictures stayed on the screen long enough to be identified. Others raced by. Regardless, the image of a British pound caused the volunteers to squeeze harder than they did at the sight of a penny, even when it appeared so quickly that they were not consciously aware of what kind of money they were seeing. The brain scans allowed the researchers to compare unconscious with conscious responses and showed that a reward-judging region of the brain, the ventral palladium, became active in both cases.

Mounting evidence of our inner zombie at work has led some scientists to downplay the importance of our aware selves. Earlier this year in Time magazine, Harvard psychologist Steven Pinker declared that “the intuitive feeling we have that there’s an executive ‘I’ that sits in a control room of our brain, scanning the screens of the senses and pushing the buttons of the muscles, is an illusion.”

Read the rest of the article.


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