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8 April 2004 |
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Rich and complex |
A team
led by Uri Hasson at Tel Aviv University used an fMRI scanner to monitor
the brains of a series of subjects while they were each shown the
same 30 minutes of 'The Good, the Bad, and
the Ugly'.
"We reasoned that such rich and complex stimulation will be much closer to ecological vision relative to the highly constrained visual stimuli used in the laboratory", he explained.
The results showed a remarkable consistency - the same film evoked just the same patterns of neural activity in all the subjects. In itself this might not seem extraordinary, until you consider the implications - this is strong evidence that the experience of watching the film is the same for everyone. I think many people would have expected that individuals' different neural wiring would influence their response, and cause them to process the images in quite different ways. Well, it seems they don't. So what does that tell us about private, unique, incommunicable qualia?
Nothing, of course. You can't
read anything into these results. We already knew that the actual patterns
on the retina get relayed right across the brain with only a small amount
of topological distortion. I'd bet that most of what the Tel Aviv people
picked up was a direct echo of what was on the screen. In the second
place, watching a film is an inherently passive business. When you follow
a film, you automatically stop thinking about anything else. If the
subjects had been asked to watch real people enacting a situation in which
they were, or could be, involved, it would have been
different.
Well, I agree there are
limits to what you can read into this particular project, but in my view
it puts the writing on the wall. Qualia are going the way dreams
went. For hundreds of years dreams were a deep philosophical mystery; then
we discovered that everybody dreams during REM sleep, and that to some
extent the content of the dreams can be influenced by outside stimuli. Now
all this was pure empirical science, based on waking the subjects up and
asking them what they had just been dreaming. In principle, it doesn't
touch the philosophical problem at all. The philosophers should have been
in there asking how the scientists knew, or could know, that reports given after
waking truly reflected dreams which occurred while asleep. Couldn't it be
that the act of waking people up from REM sleep caused a false memory of a
preceding dream they'd never actually had, for example?
But in fact, I don't remember any significant resistance along these lines. The truth is, once the gap in our scientific knowledge had been filled, the residual philosophical point no longer seemed important. You could still be philosophically doubtful about, say, whether people dream every night, but only in the same kind of way you could be doubtful about whether anyone else has a mind at all - nobody doubts such things in practice.
Within a few years, science is going to offer direct unequivocal data showing that the red you see is the same as the red I see. That won't dispel the philosophical "hard problem" of qualia, strictly speaking - but if the philosophers want to maintain the view that it's a real issue, they'd better man the barricades now. Otherwise, people are just going to stop talking about qualia - and not before time!
Or perhaps it will be like
artificial intelligence, where the first few steps were easy and then the
ground suddenly dropped away from beneath the researchers' feet. Perhaps
reading people's minds from brain scans is going to be a bit more
difficult than you think.
I don't say it's going to be
easy. But I've got evidence on my side - all you've got is hope. Or should
that be dogma?
