Hurray for brief scientific overviews with citations!
Awesomely, a researcher named Baars already anticipated that conscious processing would involve activation in more regions than unconscious processing!
This sentence caught me off guard. Is it supposed to be impressive that somebody predicted that conscious processing would involve activation in more regions than unconscious processing does? I would have intuitively expected this without having any precise theory of consciousness. Moreover, there are only two possibilities here; it's not like locating e=mc^2 in the space of possible equations. To see this particular prediction of Baars as exciting reminds me of the creationists who say "See? Big Bang theory says the universe has a beginning, something that Genesis predicted thousands of years ago! Science confirms the Bible!" But the universe either did or didn't have a beginning, and the fact that a religion got the right answer* there is not impressive or "awesome."
Of course, it's not clear that is the right answer, but let's suppose it is for the sake of illustrating my point. :)
Fair point.
Originally it was going to be a longer version of the sentence which ended up saying something to the effect of "Baars predicted this after looking at neural networks used in late-80s artificial intelligence systems" but I never found any information to support that, so I dropped the end without updating the beginning.
I had thought that because lots of GWT people mention simulations of neural nets as being related to/finding evidence for GWT.
Nice article!
Folks who are interested in this kind of thing might also be interested to see the Koch Lab's online demos of CFS, which you can experience for yourself if you happen to have some old-style blue-red 3D glasses kicking around. This is the method where you show an image to the nondominant eye, and a crazy high-contrast flashing stimulus to the dominant eye, and the subject remains totally unaware of the image for (up to) minutes. Pretty fun stuff :) http://www.klab.caltech.edu/~naotsu/CFS_color_demo.html
You might also be interested in Giulio Tononi's "Integrated Information" theory of consciousness. The gist is that a brain is "conscious" of features in the world to the extent that it is properly causally entangled with those features, and has represents a large amount of information about the world in a deeply entangled way. Not easy to explain in a few sentences, but it seems to me to be a deeper theory that is perhaps related to this "Global Workspace" idea. I think you can find his most well-known paper at: http://www.sciencemag.org/content/282/5395/1846.short, many more available by poking around google scholar.
Thanks for the link!
Tononi is cool in that he (at least attempted to, I haven't followed the linear algebra proof) quantified a measure for a system both having distinct functional clusters and integrated states which covary enough with external factors that they provide mutual information with them.
It seems to be in line with the "Intelligence is Compression" idea that I've run into a few times 'round these parts. I think that his theory is probably very related to intelligence (at least in human-style architectures), but not particularly related to consciousness.
I do admire his audacity in saying that anything with a high enough measure on his value is conscious.
Anil Seth has some intro/review type stuff on his work, which you can get off of his website: http://www.anilseth.com/
I can see both at the same time, and switch between different modes at will. I also tend to be immune to or see much more clearly all kinds of optical illusions and visual effects like this at various at will, or see them all the different possible ways simultaneously, able to see intuitively why things like this works, separately see "colours" like "movement speed" and "local contrast" in a way that intuitively feels like they were sent from the eyes as separate from maps of those properties that have more a feel of concious deduction and are immune to many common optical illusions, am ascribed a good aesthetic sense and artistic talent, tend to move my eyes and scroll on displays in ways that others find disturbing or even painful but I feel constrained and tunnel visioned if I try not to, I have occupationally experienced something reminiscent of blindishgt for short periods of time (remicent in the same sense as a polar opposite is), and am able to "see" things other's can't, and a bunch of other related superpowers.
Hope this is interesting enough as a case study to not come of as bragging. Feel free to run experiments on me since i love this kind of thing.
Summary: Neuroimaging scans and EEG readings comparing nonconscious and conscious stimuli are compared, showing particular patterns in conscious processes. These findings are in line with predictions made by the Global Workspace Theory of consciousness, in which consciousness is closely related to interaction between specialized modules of the brain.
When a bunch of photons hit your eye, it unleashes a long chain of cause and effect that leads to an image being mapped in your brain. When does that image become conscious?
Merikle et al performed experiments in the 80s which helped to resolve this question. In the Stroop task, people are asked to read words written in a different color than the word. Words written in their color (green) are easier to read than those not in their color (also red). Merikle modified the stroop task, using only two colors (red and green), and using the word to prime subjects to describe the color. As was expected, when "green" comes before a green square, subjects respond faster than with no priming.
However, when the situation is regularly reversed and the "red" prime normally comes before a green square (and vice versa) people also respond faster to similar levels. That is to say, subjects are able to notice that the prime and stimulus are incongruent, and act on that information to respond faster to the stimuli.
When the reversed prime ("red" before green) is flashed for such a short time span that people don't report seeing it, they are unable to use this information to react faster to the green stimulus, and the typical Stroop effect is observed -- being subliminally primed with a congruent color speeds up recognition, being subliminally primed with an incongruent color slows it.
The idea that conscious access is related to recurrent processing in the frontoparietal region stands up to experimental verification. Researchers are able to interfere with conscious reports of information independently of stimulus identification simply by applying transcranial magnetic stimulation to the prefrontal cortex, without changing the stimulus.8
Notes
A huge thanks to John Salvatier for getting me a bunch of the papers and editing feedback and putting up with my previous attempts to write an article like this. Also thanks to mtaran, falenas108, and RS (you don't know him) for reading drafts of this article.
Images are from Zeki 2003 and Dehaene 2011, respectively. I'd be very happy if someone helped me format that to show up with the pictures.
1Merikle & Joordens, 1997
2Dehaene, S., & Changeux, J.-P. 2011
3Breitmeyer & Ogmen, 2007
4Moutoussis & Zeki 2002, Image from Zeki 2003
5Tsuchiya & Koch
6Marti et al 2010
7Lamme 2006
8Rounis et al 2010
9Baars 1997
10Metzinger
References
Baars, B. (1997). In the Theatre of Consciousness: The Workplace of the Mind. New York: Oxford University Press. Retrieved from here
Bruno G. Breitmeyer and Haluk Ogmen (2007) Visual masking. Scholarpedia, 2(7):3330
Dehaene, S., & Changeux, J.-P. (2011). Experimental and theoretical approaches to conscious processing. Neuron, 70(2), 200-27. Elsevier Inc. doi:10.1016/j.neuron.2011.03.018
Kouider, S., & Dehaene, S. (2007). Levels of processing during non-conscious perception: a critical review of visual masking. Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 362(1481), 857-75. doi:10.1098/rstb.2007.2093
Lamme, V. A. F. (2006). Towards a true neural stance on consciousness. Trends in Cognitive Sciences, 10(11). doi:10.1016/j.tics.2006.09.001
Merikle, P. M., & Joordens, S. (1997). Parallels between perception without attention and perception without awareness.Consciousness and cognition, 6(2-3), 219-36. doi:10.1006/ccog.1997.0310
Lamme, V. A. F. (2006). Towards a true neural stance on consciousness. Trends in Cognitive Sciences, 10(11). doi:10.1016/j.tics.2006.09.001
Lau, H., & Rosenthal, D. (2011). Empirical support for higher-order theories of conscious awareness. Trends in cognitive sciences, 15(8), 365-373. doi:10.1016/j.tics.2011.05.009
Marti, S., Sackur, J., Sigman, M., & Dehaene, S. (2010). Mapping introspection’s blind spot: reconstruction of dual-task phenomenology using quantified introspection. Cognition, 115(2), 303-13. Elsevier B.V. doi:10.1016/j.cognition.2010.01.003
Metzinger, T. (2003). Being No One. Philosophy, 699. MIT Press.
Moutoussis, K., & Zeki, S. (2002). The relationship between cortical activation and perception investigated with invisible stimuli. Proceedings of the National Academy of Sciences, 99(14), 9527. National Acad Sciences. doi:10.1073/pnas.PNAS
Rounis, E., Maniscalco, B., Rothwell, J., Passingham, R., & Lau, H. (2010). Theta-burst transcranial magnetic stimulation to the prefrontal cortex impairs metacognitive visual awareness. Cognitive Neuroscience, 1(3), 165-175. doi:10.1080/17588921003632529
Tsuchiya, N., & Koch, C. (2005). Continuous flash suppression reduces negative afterimages. Nature neuroscience, 8(8), 1096-101. doi:10.1038/nn1500
Zeki, S. (2003). The disunity of consciousness. Trends in Cognitive Sciences, 7(5), 214-218. doi:10.1016/S1364-6613(03)00081-0