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How Our Brains See Faces [Sponsored]
Doris Tsao is the 2024 recipient of The Kavli Prize in Neuroscience for her research on facial recognition. Her work has provided insights into the complex workings of the brain and has the potential to advance our understanding of perception and cognition.
This podcast was produced for The Kavli Prize by Scientific American Custom Media, a division separate from the magazines board of editors.
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August 20, 2024
10 min read
How Our Brains See Faces
Doris Tsao is the 2024 recipient of The Kavli Prize in Neuroscience for her research on facial recognition. Her work has provided insights into the complex workings of the brain and has the potential to advance our understanding of perception and cognition.
Scientific American Custom Media
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This podcast was produced for The Kavli Prize by Scientific American Custom Media, a division separate from the magazines board of editors.
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Megan Hall: When we see a friend’s face, how do we instantly know who they are? Doris Tsao looks closely at the brain patterns of monkeys to help unravel this mystery. This year, she received The Kavli Prize in Neuroscience with Nancy Kanwisher and Winrich Freiwald, for identifying a specialized region of the brain where facial recognition happens.
Scientific American Custom Media, in partnership with The Kavli Prize, spoke with Doris to learn more about her discoveries and how she’s using them to unlock a bigger question – how do our brains represent the world?
As a kid, Doris Tsao was surrounded by science. Her mother was a computer programmer and her father is a mathematician.
Doris Tsao: I always had grew up with the sense that being a scientist was the most noble life calling. That really came from my parents talking to them. It was part of our family.
Megan Hall: But Doris didn’t think she’d be a scientist.
Doris Tsao: I didn’t think of myself as particularly interested in science. I like math. My parents gave me geometry problems, and I loved that. I certainly didn’t think about the brain when I was a kid. I liked to play. I played with Barbie dolls. I loved to read biographies.
Megan Hall: That all changed when she was in sixth grade.
Doris Tsao: I remember just waking up one morning and, suddenly, for no real reason, wondering if space is infinite or not. Because it seemed like if space is infinite, that seems incredible. I’d never thought about infinity before. And if it wasn’t, how could that be? Right? So, I just kept going in these loops, and I remember obsessing about this for days.
Megan Hall: She revisited this question in high school as she started reading about artificial intelligence and neuroscience. Books by philosophers like Immanuel Kant made her think about how our minds perceive space. Why do you think that question gripped you so much?
Doris Tsao: It’s kind of funny, I always thought I was special, but my kids, they’re like six years old and they ask me that nowadays. So, I think it’s such a natural question. Maybe every kid wonders about this at some point.
Megan Hall: But Doris kept wondering about it. Still, she couldn’t pinpoint exactly what she was looking for. She says she went to the California Institute of Technology for college because she liked the idea of being a scientist.
Doris Tsao: And I had read all these books about the brain, and so on. So, I had romantic notions about that, but it was like sort of a fantasy about what my life could be like rather than motivated in a question about the world.
Megan Hall: Then something pretty common happened. She was on a camping trip with her dad and he asked her to proofread one of his academic papers. His first language is Chinese, so...
Doris Tsao: He would give me his papers to correct English mistakes. And I did this starting in middle school, high school, and I had no idea what his papers were – they were like gobbledygook – but I could figure out that the verb was not agreeing with the subject.
Megan Hall: But this time was different. With her training from Caltech, Doris actually understood what he was writing about.
Doris Tsao: It was kind of astonishing to me, like, the idea.
Megan Hall: The idea in her father’s paper described how our brains help us see the world in three dimensions.
Doris Tsao: I just thought it was so beautiful. It was like this idea that the brain is creating our perception, suddenly it had mathematical clothes. It was like a real framework for explaining how this works.
Megan Hall: That’s when everything fell into place.
Doris Tsao: Suddenly, my dream to understand 3D space and how’s infinite space possible, the sense of beauty that I could discover something beautiful about the brain, and then just this connection with my father. We’re an immigrant family. We always had a sense like we have to prove ourselves in this country, in this new land. So, all of those thoughts came together and it’s like, wow, I can go prove this amazing theory and yeah, I’ll go win a big prize.
Megan Hall: You did!
Doris Tsao: Yeah! It didn’t quite work out that way, but...
Megan Hall: Doris went on to graduate school at Harvard University to prove her dad’s theory about how our brains process the 3D world. And to do that, she spent years working with macaque monkeys. That’s because...
Doris Tsao: The visual system is almost identical to the human visual system in all these details. They’re just like replicas. It’s just a beautiful thing to behold.
Megan Hall: So, she gave the monkeys 3D goggles, showed them different images and used electrodes to measure what was happening in their brains – one neuron at a time. For three years...
Doris Tsao: I got nothing. I tell this to my students to reassure them. I tell them science is highly nonlinear. You can make zero progress, and then all of a sudden things take off.
Megan Hall: Things finally took off when she joined a research group at Massachusetts General Hospital. There, she helped with a project that measured blood flow across a monkey’s entire brain, using what’s called functional magnetic resonance imaging or fMRI.
Doris Tsao: fMRI gives you a bird’s-eye view of all the areas that are activated and how much they’re activated by a particular stimuli. So, it seemed an exciting opportunity to me.
Megan Hall: Around this time, Doris heard about the work of her fellow laureate Nancy Kanwisher.
Doris Tsao: She was the hot new professor at MIT back then. And I read her paper on this discovery of a face area in the human brain. It reported that there’s an area in the brain that just responds to faces.
Megan Hall: Doris was shocked and puzzled by this idea.
Doris Tsao: Because I didn’t feel from introspection that faces are all that different from anything else, and it just seems so understandable and simple. How can you have an area that just cares about faces? I thought it’d be some horribly complicated code, right?
Megan Hall: So, Doris decided to replicate Nancy Kanwisher’s human experiment with monkeys.
Doris Tsao: Show them pictures of faces and non-face objects, and compare – are there any voxels in a monkey’s brain that respond more to faces than other objects? It was a very low-risk experiment because the experiment’s so easy. It would be like one night of scanning. If it didn’t work, it’s totally fine.
Megan Hall: And during that night of scanning...
Doris Tsao: We saw this region light up to faces. We scanned the monkey again, and same region would light up again. And later, we got a better coil and we saw six of these regions light up, and it would always be the exact same six regions. Right? And then we scanned another monkey and it showed the same pattern, roughly. And also, the regions were located in very similar locations across the two hemispheres. And so, it was clear they weren’t random.
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