A cluster of brain cells in a dish, pulsing with electrical activity. A bee buzzing its way through a garden in bloom. A newborn baby staring up into his mother's eyes. What all these entities have in common is that we don't quite know what it’s like to be them—or, really, whether it's like anything at all. We don't really know, in other words, whether they’re conscious. But maybe we could know—if only we developed the right test.

My guest today is Dr. Tim Bayne. Tim is Professor of Philosophy at Monash University in Melbourne, Australia. He’s a philosopher of mind and cognitive science, with a particular interest in the nature of consciousness. Along with a large team of co-authors, Tim recently published an article titled 'Tests for consciousness in humans and beyond.' In it, they review the current landscape of consciousness tests—or “C-tests”, as they call them—and outline strategies for building more and better tests down the road.

Here, Tim and I discuss what consciousness is and why theories of it seem to be proliferating. We consider several of the boundary cases that are most hotly debated right now in the field—cases like brain organoids, neonates, and split-brain patients. We sketch a few of the most prominent current consciousness tests: the command following test, the sniff test, the unlimited associative learning test, and the test for AI consciousness. We talk about how we might be able to inch our way, slowly, toward something like a thermometer for consciousness: a universal test that tells us whether an entity is conscious, or to what degree, or even what kind of conscious it is. Along the way, Tim and I talk about zombies, chatbots, brains in vats, and islands of awareness. And we muse about how, in certain respects, consciousness is like temperature, or perhaps more like happiness or wealth or intelligence, and maybe even a bit like fire.

I think you'll enjoy this one, friends—it's a thought-provoking conversation on a foundational topic, and one that takes us far and wide. So without further ado, here's my interview with Dr. Tim Bayne. Enjoy!

A transcript of this episode is available here.

Notes and links

4:45 – The philosopher Dan Dennett, who passed away in April, was known for his writings on consciousness—among them his 1991 book, Consciousness Explained.

7:00 – The classic paper on the neural correlates of consciousness, by Francis Crick and Christof Koch.

9:00 – A recent review of theories of consciousness by Anil Seth and Dr. Bayne.

10:00 – David Chalmers’ classic paper on the “hard problem” of consciousness.

13:00 – Thomas Nagel’s classic paper on what it’s like to be a bat.

20:00 – A recent paper by James Croxford and Dr. Bayne arguing against consciousness in brain organoids.

23:00 – A recent paper by Dr. Bayne and colleagues about the emergence of consciousness in infants.

27:00 – A recent paper by Dr. Bayne and colleagues about consciousness in split-brain patients. An earlier paper by Dr. Bayne on the same topic.

30:00 – A paper by Dr. Bayne, Dr. Seth, and Marcello Massimini on the notion of “islands of awareness.”

35:00 – The classic paper using the “(covert) command following test” in a patient in a so-called vegetative state.

38:00 – A 2020 paper introducing the “sniff test.”

40:00 – A recent primer on the “unlimited associative learning” test.

43:00 – An essay (preview only), by the philosopher Susan Schneider, proposing the AI consciousness test.

50:00 – The history of the scientific understanding of temperature is detailed in Hasok Chang’s book, Inventing Temperature.

53:30 – Different markers of consciousness in infants are reviewed in Dr. Bayne and colleagues’ recent paper.

1:03:00 – The ‘New York Declaration on Animal Consciousness’ was announced in April. Read about it here.

Recommendations

Being You, Anil Seth

Into the Gray Zone, Adrian Owen

Other Minds, Peter Godfrey-Smith

Many Minds is a project of the Diverse Intelligences Summer Institute, which is made possible by a generous grant from the Templeton World Charity Foundation to UCLA. It is hosted and produced by Kensy Cooperrider, with help from Assistant Producer Urte Laukaityte and with creative support from DISI Directors Erica Cartmill and Jacob Foster. Our artwork is by Ben Oldroyd. Our transcripts are created by Sarah Dopierala.

Subscribe to Many Minds on Apple, Stitcher, Spotify, Pocket Casts, Google Play, or wherever you listen to podcasts. You can also now subscribe to the Many Minds newsletter here!

We welcome your comments, questions, and suggestions. Feel free to email us at: manymindspodcast@gmail.com.

For updates about the show, visit our website or follow us on Twitter: @ManyMindsPod.

Can we measure consciousness?

Episode description