Thursday, September 20, 2012

Being Cautious About Consciousness

Last month a distinguished group of scientists gathered at Cambridge University to attend the Francis Crick Memorial Conference.  The larger public knows Dr. Crick for his Nobel Prize winning work on the structure of DNA. Few people outside of the scientific community know that he spent the last half of his career dedicated to finding the neural correlates of consciousness.  This conference, which included experts in the fields of human perception, animal sensory systems, evolutionary biology and psychopharmacology, was meant to honor Dr. Crick's vision of one day identifying how our brains give rise to consciousness.

At this conference, several prominent attendees signed The Cambridge Declaration of Consciousness.  In this document, the signatories outlined several scientific findings, including that non-human animals experience binocular rivalry, have homologous brain regions as humans, many primitive emotions are linked to subcortical brain areas, birds have REM sleep, and hallucinogens affect human and non-human brains similarly.  From these disparate observations, the conference attendees concluded, “Convergent evidence indicates that non-human animals have the neuroanatomical, neurochemical, and neurophysiological substrates of conscious states along with the capacity to exhibit intentional behaviors.”  In summary, many animals have the same neural substrates for conscious states as humans, a clear implication that animals experience consciousness.

To be blunt, this declaration is both inflammatory and grossly irresponsible for two reasons. 

First, it misrepresents the state of our scientific understanding of consciousness.  As of yet, the scientific community has not reached a consensus on an empirically testable definition of what it means to be conscious.  You see “consciousness” is a quale, which according to Merriam-Webster is defined as, “properties experienced as distinct from any source it may have in physical object.”  Now to be fair, in psychology and neuroscience we deal with qualia on a daily basis. Concepts such as memory, attention, and emotion are all, in themselves, immeasurable entities; however, in the laboratory we are able to observe manifestations of these concepts by constraining our hypotheses to empirically testable phenomenon.  For example, when we study memory, we are referring to the changes in behavior or in neural systems that arises from experience (or the lack of such abilities from lesions to different brain regions).  We don’t have a way of seeing an actual memory itself, but we do have measures of recall, adaptation and synaptic plasticity.  The same is true for emotion, attention, and perception. 

But consciousness, in its current definition, is a quale defined by other qualia. It is the state of being aware of things in the outside world and of ourselves. Thus consciousness is a construct built off of both “awareness” and “intention”.  (It should be noted that in the Cambridge Declaration, the signatories often conflate the concept of consciousness with intention.) Thus, the researchers who study the neural correlates of consciousness are forced to look at these other states, but as of yet there is no unifying definition of the state of being conscious. There is no brain area, network of brain areas, or neurochemical system that, when damaged, definitively removes the ability to be “consciousness” while still being awake and alert. There are many lesions that cause problems with visual perception, memory, verbal recall, etc., but how many of those abilities can we lose and still be conscious? Science still does not have an answer to that question.

The second, and by far the biggest, problem with the Cambridge Declaration of Consciousness is that it is a dangerous document.  It gives the false impression that consciousness is a ubiquitous state of simple animal brains.  This is a damning statement to any researcher who uses animal subjects in their experiments (and many of the signatories of the declaration do use animals in their research).  Are the signers saying that we should stop all animal research or stop using animals as domesticated food sources?  If animals do in fact experience consciousness as we do, then this has far reaching implications for how we use and treat animals. 

The impact of such a statement, however, goes well beyond the future of animal research and into even more hot button social issues.  For example, this declaration implies that neuroscience should be able to tell us when consciousness starts in the fetal brain (since knowing the neural substrates means knowing when they develop), diving head first into a social issue we have no business being in at the moment.  What about clinically “brain dead” patients whose families wish to let them pass away?  If having a neocortex is not necessary for consciousness, then is someone who has lost 85% of her cortex from a stroke still conscious? By signing this declaration, these scientists have given the impression that the field of neuroscience has the answers to these questions, which could not be further from the truth.  We don't even know where to start.


  1. I saw this when it came out and first said, "meh". You make good points for why we should care. One thing I'm wondering now: what was the purpose of the declaration? Who is the audience? A fair bit of the issues you point out with the declaration have to do with the interface between science and public policy and perception. Were they perhaps trying to gain ground for future funding of such research by making a statement to the effect of "Look, we've made so much progress"?

  2. Honestly I'm not sure what their point was. It could be precisely what you said ("Hey funding agencies, look at how much progress we've made, so send more cash!"). But it could also be something as simple as self-validation that all the research these folks have been doing for the last 20+ years ties to a larger purpose.

    But regardless of their motivation, these are all fairly prestigious and respected scientists (both within science and in science-policy links). So anyone in the policy domain looking to validate their subjective opinion that animals or fetuses have consciousness will use this to carry weight for that opinion (regardless of the scientific evidence for it).

  3. Although I think these guys are incautious in declaring they have probably found "consciousness", my first concern was "FFS please stop using those sentient animals for your experiments!". I found the "Declaration" rather odd, almost like the statement of someone with Asperger's syndrome who hadn't quite tuned in to the universal implications of the wording. Even as a minor student of consciousness I had to cringe a little. Why couldn't everyone stick to saying that accumulated findings give strong clues to the necessary components of the state we call "consciousness"?

  4. Preaching to the choir. Although as a human researcher (i.e., I test humans in my experiments), I should point out that I'm not 100% convinced that everyone I test is "sentient".