World leaders, great thinkers, activists of every possible political stripe and a large number of media and law enforcement personnel poured into Toronto at the end of June. Though most of them were there for the G-20 summit, about 300 had arrived to attend the 14th annual meeting of the Association for the Scientific Study of Consciousness (ASSC), held at the same time.
The discussions at the ASSC conference will not have the immediate impact on world affairs that those of the G-20 did, but for those who attended it, the central topic was as important as any global issue: The nature of consciousness, perhaps the most fundamental aspect of our existence – and how best to investigate and think about it.
Why are we conscious? What functions does consciousness serve, and how can we tell whether other creatures are conscious? How does consciousness arise from brain activity? What tasks can the brain perform without conscious awareness, and what distinguishes conscious and unconscious mental processes? Though philosophers have grappled with such questions for thousands of years, rigorous scientific research of these issues is a surprisingly recent development.
A difficult pursuit
To do science, you must be able to objectively observe and measure the phenomenon you are interested in; anyone else should be able, in principle, to make the same observations. But how can you measure someone else’s subjective experience? No one has direct access to anyone’s consciousness but his or her own. On top of this, there is no single, widely accepted definition of consciousness.
These two problems are the main reasons that the scientific community had traditionally resisted the idea of devoting time and effort to investigating consciousness. In the last two decades, however, the realization that you cannot ignore such a basic natural phenomenon just because it presents methodological difficulties has gained legitimacy. Consciousness research is now a thriving field, bringing together scientists with backgrounds in psychology, neuroscience, cognitive science and many related fields, as well as philosophers. Ingenious ways to overcome the difficulties inherent to the topic are constantly being thought up, and though this young field still faces formidable challenges, the atmosphere at the ASSC conference reflected a prevalent attitude of optimism and excitement.
The Conference’s participants arrived from over 25 different countries, and, as has become a tradition at the ASSC, comprised about two-thirds scientists and one third philosophers. To many of the attendees, who are used to the narrow specialization of most academic conferences, this mix of backgrounds is one of the ASSC’s greatest attractions: “It is great to have an opportunity to argue with the scientists doing work on the cutting edge of consciousness research,” says Ned Block, a professor at New York University and one of the world’s leading philosophers of mind.
A lot of arguing could indeed be heard over the four days of the conference, but it was nearly all good-natured; my own impression was that although the ASSC attendees were not devoid of the fierce competitiveness that characterizes researchers in so many fields, there was very little of the animosity that such competition often arouses. Perhaps this is a feature of a field where so many of the most basic questions have yet to be resolved.
The heated discussions that followed many of the presentations continued into the social events that took place each evening. “The ASSC was my first international conference, and I could not anticipate that it would be so much fun,” Says Ido Amihai, a graduate student from the Hebrew University in Jerusalem, Israel. Amihai gave a talk on his thesis research, which is based on previous findings that the human brain can process certain visual stimuli, such as faces, without awareness. In his research, Amihai demonstrated that certain aspects of faces – he investigated gender and race – require awareness to affect behavior.
Trends and prizes
Many of those presenting new work at the conference were graduate students and postdocs, in line with the ASSC’s policy of encouraging young researchers. In a special mentoring event on the second day, students were paired with experienced researchers for lunch and a discussion of research and career development.
The William James Prize, awarded annually at the conference for an outstanding published contribution to the empirical or philosophical study of consciousness by a graduate student or postdoctoral scholar, was awarded to Yann Cojan from the University of Geneva in Switzerland during the opening ceremony. Cojan headed a team whose paper, published in the journal Neuron in June 2009, investigated brain activity under hypnosis. In his acceptance lecture, Cojan described the history of hypnosis and its relation to the study of consciousness, before going on to describe his own findings: While undergoing functional MRI, participants were instructed to prepare to move their hand. After a few seconds they were told whether or not to actually perform the movement. Some of the time, they were hypnotized and believed that their hand was paralyzed. Interestingly, when the volunteers were under hypnosis, the preparatory activity in motor cortex was normal; but there was increased activity in other regions related to attention, mental imagery and self-awareness. Moreover, the connectivity between these regions and motor cortex was enhanced, indicating that hypnosis doesn’t work by directly controlling motor activity, but rather through the effects of internal representations and self-monitoring processes on such activity.
Prizes were also given to new research presented at the conference itself by students: a multi-disciplinary panel of judges selected two empirical and two philosophical studies to receive the prestigious awards. Hakwan Lau, an assistant professor at Columbia University in New York and past recipient of the William James prize, points out that the winning studies reflect an interesting trend evident in this year’s conference – an emphasis on metacognition (knowing what you know) and higher-order theories of consciousness.
A great deal of past research on consciousness has in fact been focused on perceptual performance: being able to complete a task has been equated with awareness of the relevant stimuli. However, as a lot of the work presented this year shows, there is a clear distinction between what the brain can achieve, and the neural activity related to awareness of what our brains are doing.
Being conscious of what you know
Lucie Charles, a doctoral candidate from the INSERM-CEA Cognitive Neuroimaging Unit in Paris, France, was one of the student winners. Her research used measures of the brain’s electrical activity to investigate processes related to making mistakes, and how error-related brain activity is modulated by awareness. She asked participants to perform a visual task, and also to evaluate their own performance – whether they thought they had gotten it right or not. By manipulating the time elapsing between the visual stimuli and a meaningless “mask” that followed them, Charles could render the stimuli either clearly visible or very difficult to see. She found that a specific neural signature, believed to indicate the activity of cognitive control mechanisms, was evident when volunteers were aware that they had made an error but absent when they could not consciously report the stimuli. Previous research has shown that the kind of subliminal stimuli used by Charles can be processed by the brain’s visual centers. These new results, however, indicate that subliminal visual stimuli fail to reach higher-order cognitive control stages of processing.
Another winner of the student prize, Stephen Fleming from University College London in the UK, investigated the relationship between metacognition and brain structure. Like Charles, Fleming also had his volunteers perform a visual task. By adjusting the difficulty of the task online, he was able to keep all his volunteers’ performance at equal levels. When he asked them how sure they were of how well they were doing, however, there was a wide variety of confidence levels. Fleming measured his participants’ metacognitive sensitivity – how appropriate one’s confidence is (comparing rates of high confidence after correct and incorrect responses). Fascinatingly, he found a correlation between metacognitive sensitivity and the size of brain structures in the frontal and cingulate cortices, as well as the level of connectivity between frontal regions in the brain’s two hemispheres. Knowing what you know, therefore, may depend on the brain’s structure and not just its activity.
Another interesting study, presented by Helene Gauchou, a postdoctoral researcher at the University of British Columbia in Vancouver, Canada, examined whether people know more than they are aware of. Gauchou used an unconventional method: The Ouija board, commonly used in séances where people place their hands on an overturned cup and move it around a board of letters, spelling out words without conscious intention. In séances, the responses are often surprisingly sensible – prompting believers to attribute them to spiritual influences. It is now well established, however, that what is really at work here is something called the ideomotor effect: Participants move the cup themselves, but having other people also touch the cup enables them to lose a sense of responsibility (or “agency”) for the movement. Gauchou asked volunteers to use a Ouija board to answer general knowledge yes/no questions. Another person initially touched the cup, so the volunteers could believe it wasn’t them causing the movement. Then Gauchou blindfolded them, and the other person (actually an experimenter) removed his hands. Astonishingly, volunteers’ performance on questions they claimed they didn’t know the answers to was significantly better than chance. This did not happen when they simply answered such questions verbally. A lot of our memory, says Gauchou, is implicit: We know stuff we have forgotten that we know, but these results show that we can still access such knowledge.
A multitude of perspectives
The abundance of new research at the conference left no choice but to have presentations in parallel sessions, meaning that three different talks went on at the same time. The organizers did an admirable job of trying to make these sessions focus on different topics, so everyone could attend the ones they were interested in – but for many of the attendees, part of the fun came from being exposed to research outside their own day-to-day topics of investigation. (I gave a talk myself, and must admit I was quite disappointed when I realized I really wanted to see both of the other talks that took place at the same time as mine)!
Some cutting-edge issues, however, were discussed in symposia attended by everyone. Among these was a discussion chaired by Antoine Lutz from the University of Wisconsin, Madison, on the potential of research on meditation to contribute to understanding consciousness. In a different symposium, on physiological approaches to consciousness research, Alex Maier from the National Institute of Health in Bethesda, Maryland, presented new work in which he used both intracranial electrodes and fMRI to measure activity in monkey brains, resolving some previously-reported discrepancies between these two methods. Naotsugu Tsuchiya from the California Institute of Technology presented new research that used electrode arrays implanted in humans (a common procedure before some kinds of brain surgery). This kind of research was also described by Robert Knight from the University of California, Berkeley, who was one of the conference’s keynote speakers. Keynote speakers are usually invited because they work in a somewhat different field, but can give an illuminating, outsider’s point of view. Other keynote speakers included Nicola Clayton from the University of Cambridge, UK, who talked about the remarkable cognitive abilities of birds (specifically, crows); and Morris Moscovitch from the University of Toronto, who discussed the relationship between memory and consciousness, drew from fascinating findings on memory in brain-damaged patients.
The conference ended with an after-party at a local bar, many excited farewells and promises to keep in touch and meet again at next year’s ASSC conference, which will be held in Kyoto, Japan.
David Carmel is a research scientist at the Department of Psychology and Center for Neural Science in New York University. His research focuses on visual awareness and attention in humans, using brain imaging and behavioral experiments.