"You highlighted the difference that makes a difference. Тhis is not only a neat catchphrase, but there's also something very deep about it. And sleep, in fact, is a really interesting aspect of behavior, that maybe gives us a window on the difference between conscious and non-conscious processes in the brain, because there is a distinct difference and it is recordable."
- David Edelman, PhD, A neuroscientist and a Visiting Scholar in the Department of Psychological and Brain Sciences at Dartmouth College
EPISODE 9: Roundtable Part Two - What is the Difference That Makes a Difference?
In a continuation from their previous conversation, Neuroscientist David Edelman and Developmental Neuropsychiatrist Jay Giedd, Professor of Psychiatry at UCSD School of Medicine and Director of Child & Adolescent Psychiatry at Rady Children's Hospital are joined by Bernard Baars, the originator of the global workspace theory and global workspace dynamics, a theory of human cognitive architecture, the cortex and consciousness. In this contemplative conversation the trio touches on subjects involving how consciousness gets defined, the developing process of an adolescent human brain, and the role that sensory organs play in an individual's perception of reality.
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2:00 – David Edelman welcomes Bernard Baars to the conversation.
2:31 – Edelman initiates the discussion by revealing what consciousness means to him and how it could be reduced to main aspects (An idea which is based on his father’s views).
6:22 – Baars points out that the exploration of consciousness is an idea that has been an inevitable part of humanity and a necessary trait.
9:40 – Edelman and Baars discuss the importance of being able to socially broadcast your model of the world as part of the conscious experience.
13:17 - Giedd and Edelman discuss whether having some type of social skills is a requirement for consciousness or if it is instead a product of it.
19:12 – Jay makes a connection between social skills and the development of the cortex, its structure, and how important it appears to be for the emergence of consciousness
22:12 – The development and integration of neuronal connections in the brain, responsible for essential bodily functions such as heart rate and breathing.
24:35 – Is consciousness a constant or are there variations of it?
26:22 – The uniqueness of the olfactory system and its close interconnectedness to the emotional system.
30:31 – The sensation of smell and the human brain’s inability to recreate a memory of smell, the way it would for a visual image
32:11 – Baars steers the conversation towards visual perceptional differences.
34:55 – Jay Giedd discusses some of the rare conditions in humans which allow for the richer perception of external stimuli
Summary of the Conversation
Bernard Baars has often referred to consciousness as the difference that makes a difference. When we reflect on our everyday experience versus the absence of anything attended to or recalled, as is the case during a deep, dreamless sleep or under general anesthesia — that difference which distinguishes conscious experience from the rest of our mental lives becomes quite obvious.But, how would we characterize that difference?What is it about a particular animal’s makeup — its nervous and sensory systems, its behavior, its social interactions — that singles out that animal as truly conscious?
In this episode of ‘On Consciousness’, Baars, Edelman, and Giedd explore these questions in a thought-provoking discussion, starting with their perspectives on the nature of consciousness. To begin with, David posits a relatively straightforward definition of consciousness: namely, the weaving together of different sensory threads into a coherent unified percept and the persistence of that percept in memory. Bernie then offers that humans have studied consciousness for millennia, and out of that long rumination has come the realization that teaching and learning — the process of communicating and internalizing information — is an interactive exchange of conscious thought.
This social domain of conscious experience could therefore be subsumed within an operational definition of awareness — at least in the human case. As David points out (and Jay amplifies) Bernie’s emphasis on the kind of social interchange of conscious percepts that occurs between humans doesn't take into account the long history of life on earth and in particular the many animals with complex brains and elaborate sensory faculties that have preceded us.
Human sociality is a recent evolutionary innovation, and it seems clear that some form of consciousness existed long before we came along. And, while Bernard emphasizes the idea that human sociality accommodates our conscious experience, Jay flips this on its head, suggesting instead that consciousness may be what ultimately affords our particular social lives as humans.
Moreover, for many non-human animals,survival and reproduction are contingent on social skills — but this was true long before humans walked the earth. In any case, as Jay points out, we should be able to infer whether an animal has the capacity to convey its interpretation of reality to others from the structure and function of its nervous system. Such an inference would be strongly suggestive of a rich conscious life.
Next, the conversationfocuses on the role of certain brain structures and sensory faculties in defining and elaborating conscious experience. In the case of human development, we can track the emergence of different perceptual and cognitive capacities, as well as the elaboration of underlying brain areas and circuitry, from infancy well into adulthood. Thus, as Jay suggests, we could in principle observe as the capacity to weave together sensory percepts into a neural representation emerges and is elaborated in the brain of a young child. In this regard, Jay asks two questions:
1) Can consciousness be considered as being on a ‘sliding scale’ during development?
2) Would we expect developing humans to get better at weaving together conscious percepts as they grow older?
With regard to evolution, radical distinctions between our sensory organs and those of animals quite distant from our phylogenetic line suggest that the varieties of conscious experience must be legion among animals. Even among humans, differences in sensory equipment must necessarily give rise to differences in conscious experience. Individuals with a condition known as Tetrachromacy — a genetic mutation that is expressed as an extra photopigment — can perceive finer gradations in the spectrum of visible light than the rest of us and are therefore capable of making color distinctions we would certainly miss.
The upshot of this lively exchange is that there is, indeed, a difference that makes a difference at the core of conscious experience, and it can be both observed in developing humans and inferred from the rich evolutionary history of complex life on earth. Though Bernie, Jay, and David barely scratch the surface of this tantalizing difference here, they provide listeners with ample armamentarium to forge ahead and continue the intellectual journey on their own.
Dr. Giedd was chief of the Section on Brain Imaging, Child Psychiatry Branch of the National Institute of Mental Health (NIMH). His widely published research and expertise evaluates how the child's brain develops in health and illness, the factors that influence development and how to optimize treatments to take advantage of the child's changing brain. Jay and his award winning work were featured in the PBS 2 part series "Brains on Trial" hosted by Alan Alda.
David Edelman, PhD: A neuroscientist and currently Visiting Scholar in the Department of Psychological and Brain Sciences at Dartmouth College, David has taught neuroscience at the University of San Diego and UCSD. He was Professor of Neuroscience at Bennington College until 2014 and visiting professor in the Dept of Psychology, CUNY Brooklyn College from 2015-2017.
He has conducted research in a wide range of areas, including mechanisms of gene regulation, the relationship between mitochondrial transport and brain activity, and visual perception in the octopus. A longstanding interest in the neural basis of consciousness led him to consider the importance—and challenge—of disseminating a more global view of brain function to a broad audience.
Bernard Baars is best known as the originator of global workspace theory and global workspace dynamics,a theory of human cognitive architecture, the cortex and consciousness. Bernie is a former Senior Fellow in Theoretical Neurobiology at the Neurosciences Institute in La Jolla, CA, and Editor in Chief of the Society for MindBrain Sciences. He is author of many scientific papers, articles, essays, chapters, and acclaimed books and textbooks.
Bernie is the recipient of the 2019 Hermann von Helmholtz Life Contribution Award by the International Neural Network Society, which recognizes work in perception proven to be paradigm changing and long-lasting.