Consciousness Undefined: Opinion Editorial by Douglas L. Beck, AuD, Web Content Editor
I have no idea how to define consciousness. Then again, even if I could define it, there’s roughly a zero percent probability we’d all agree. Since the beginning of time, humans have tried to figure it out. It seems important to understand the difference between being conscious and being unconscious, particularly as audiologists get more involved with brains and neuroscience, fMRI, neuroaudiology, and cognition.
Perhaps part of the answer relates to the difference between hearing and listening? In other words, maybe to “listen” demands consciousness, whereas unconscious people can only hear? Thus, a perfectly normal auditory brainstem response (ABR) can be recorded from someone with normal hearing while in a persistive vegetative (i.e., unconscious) state. Nonetheless, a universal definition of consciousness is lacking--and not likely to be rendered “solved” any time soon.
Maybe consciousness is a continuum, a sliding scale of sensory input and awareness? In other words, at one end we’re wide awake,“caffeinated” and totally aware of all sensory input. While at the other end, perhaps we’re vegetative, i.e., aware but unresponsive to sensory input, or--perhaps unaware? That’s where it gets murky. I think most of us agree that when we’re conscious, indeed, we’re wide awake, caffeinated and totally aware of all our sensory input. It’s the other end of the continuum that causes all the problems.
Koch (2008) notes that we experience the world through consciousness, and in fact, that’s the only way. Koch reminds us of Descartes conclusion that because he was conscious, he existed. More famously stated, Descartes has often been translated as “I think, therefore I am.” Koch (and many others) asked, "Are people the only conscious beings and when does consciousness begin? What about dogs, cats, flies and what about single cell organisms?"
Koch wrote about fascinating work on consciousness by Naotsugu Tsuchiya, a neurobiologist (California Institute of Technology) who won the 2008 William James Prize for Contributions to the Study of Consciousness. Tsuchiya won the prize for his work regarding continuous flash suppression. This technique presents-while-hiding pictures from your consciousness using a split screen computer. For example, the left eye is presented with the “picture-to-be-hidden” while the right eye gets the more interesting, more dynamic picture, such as quickly moving, colorful geometric shapes. The dynamic images are more interesting and they capture more attention….but when you close your right eye, you clearly see the hidden picture. Koch reports functional magnetic resonance imaging (fMRI) results demonstrate your brain was aware of the hidden picture the whole time, even though you were not “consciously” aware of it. Koch reports researchers (University of Minnesota) used the same technique with hidden images of naked people. The researchers concluded they could tell whether the observers were straight or gay based on their “unconscious attentional biases.” Koch reports, “Freud would have loved it.” Agreed.
Gazzaniga (2008) reports not all information occurring around us (and within us) makes it to consciousness. For consciousness to occur, he says the stimulus must have an interaction with the attentional state of the observer through either top-down (using thalamo-cortical neurons) or bottom-up processes (based sometimes on the strength of the signal), such as when you attend to something without conscious control (i.e., a sudden threatening loud sound). Gazzaniga defines “modularity,” such that things go on inside the brain within “modules” that work below the level of consciousness (such as the brain stem regulating autonomic functions etc). If one module gets damaged, depending on the type and degree of damage, the module may be lost, but consciousness may still be possible. However, he states the “gatekeeper” to consciousness is attention.
Attention does seem to play a key role in consciousness. Maybe that’s the difference in hearing and listening? Okay, forget what I said about consciousness. And attention certainly seems to play a role in continuous flash suppression.
Here’s a fun thing to ponder, Gazzaniga was asked, “If we could build a robot that duplicated the processes behind human consciousness, would it be conscious?”
Douglas L. Beck, AuD, Board Certified Audiologist, is the Web Content Editor for the American Academy of Audiology.
For More Information, References and Recommendations:
Beck, DL (2008): On Words, Abbreviations and Consciousness
Gazzaniga, MS., (2008): Human – The Science Behind What Makes us Unique. Published by Harper- Collins, NY, NY ISBN 978-0-06-089288-3.
Koch, C. (2008): How Unconscious Mechanisms Affect Thought - Clever experiments root out nooks and crannies in the brain that are hidden from your conscious awareness. Scientific American Mind. November 19, 2008
Stanford Encyclopedia of Philosophy: Consciousness. First published Fri Jun 18, 2004; substantive revision Mon Aug 16, 2004