Evidence for dualism Comparing the straightforward predictions of strict materialism and dualism, let’s begin to examine the evidence. I’ll choose one of Dr. Novella’s own examples, which he used in his post: a remarkable study from Cambridge of a woman in a persistent vegetative state.
Dr. Novella wrote:
To give one example [of the irrefutable evidence for strict materialism], two years ago Adrian Owen published an article in Science1 in which he used fMRI to examine the brain function of a young woman in an apparent vegetative state. During the study she was asked to either imagine herself playing tennis or to imagine herself walking through her house. These two distinct thoughts created distinct patterns of activation on the fMRI - indicating that she was actually capable of thought. But the relevance to this discussion is that different thoughts correlate to different functional states of the material brain. In fact this is what all fMRI research shows.
I agree with Dr. Novella. The study by Owen and his colleagues at Cambridge has a great deal of relevance to our discussion. Let’s take a closer look at the Cambridge study.
In the September 2006 issue of Science, Dr. Owen and his colleagues published a study entitled “Detecting Awareness in the Vegetative State.” Owen and his colleagues studied the responses of a woman who was in a persistent vegetative state, which was the consequence of severe diffuse brain damage that she had suffered in an automobile accident the year before.
The patient had no evidence of any mental function. Based on a battery of standard tests, including MRI scans, electroencephalograms (EEG’s — brain wave tests), and careful bedside examinations by neurologists and neurosurgeons, she was diagnosed as being in a persistent vegetative state. Persistent vegetative state means that she had no mental state — no consciousness. She was, in a sense, a shell, a human body without a mind. That’s what “vegetative” means.
Owen and his colleagues did a fascinating series of tests. First, they asked a group of normal volunteers to have a kind of research MRI scan of their brain, called a functional MRI (fMRI). fMRI doesn’t measure the actual activity of the neurons in the brain, but it measures the blood flow and brain metabolism in specific regions of the brain. It has been found to correlate to some extent with mental activity. Thinking about things can make the metabolism in certain parts of the brain increase, and fMRI can detect this. The observation that brain activity can locally increase brain blood flow and metabolism was originally made a century ago, in animals in the lab, so it’s not new. What is new is that we can now measure it in living people non-invasively, using fMRI.
The Cambridge researchers asked the volunteers to think of things, like playing tennis or walking across the room, and they recorded their fMRI brain responses. They also presented the volunteers with nonsense words, to distinguish understanding in the brain from the mere reflex to sounds. The response to understanding was different from the response to sound. The fMRI test seemed to test understanding, not just reflexes.
They did the same tests to the woman who was in a persistent vegetative state. They asked her to imagine playing tennis or imagine walking across the room, and they did the sham test with random words as well.
When they examined her fMRI responses, they found that her fMRI patterns were identical to those of the normal awake volunteers. By fMRI criteria, she understood. In fact, by fMRI criteria, she was as conscious as the normal volunteers. Her brain was massively damaged, to the extent that she had been diagnosed as having no mind at all. Yet the blood flow and metabolism patterns in her brain were those of a normal person. And just like normal people, she showed different fMRI responses to nonsense words. So she not only heard what was said to her, but she understood, and complied with the researchers’ requests to think about specific activities like playing tennis and walking across a room.
Implications of Owen’s studyOwen’s study generated enormous interest among researchers, physicians and the public, not only for its implications for diagnosis of persistent vegetative state (e.g. the implications for the Terri Schiavo case), but because of what it suggests about deeper questions about the relationship between the mind and the brain. Many other studies of fMRI in patients in persistent vegetative state are underway, and several studies recently completed with other patients tend to support Owen’s findings.
From a scientific standpoint, Owen’s study is important for three reasons. The first is obvious; the last two are more subtle, but very important:
1.Owen’s study demonstrates that normal consciousness might be present in some patients who have met the clinical criteria for persistent vegetative state, which is defined as a state lacking consciousness.
2.It demonstrates that methods of assessing brain state and function (e.g., MRI, EEG, clinical examination, fMRI) can differ profoundly in their assessment of consciousness.
3.It demonstrates that an indirect assessment of brain function (fMRI, which measures regional blood flow and brain metabolism), may reveal evidence for consciousness when more direct methods (clinical examination, EEG) fail to detect consciousness.
Note that each of the three conclusions that can be inferred from Owen’s study is evidence for the lack of correlation between various methods of assessing consciousness based on assessment of material properties of the brain. The inconsistency between the fMRI and the other standard methods of assessment is striking. If the mind is the brain, why would different measures of brain function yield contradictory measures of mind function? If materialism is true, correlation between brain function and mind function should converge, not diverge.