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Many Minds

Mar 21, 2024

We've all seen those illusions. The dots seem to dance, when in fact they're completely still. The lines look like they bend, but in reality they're perfectly straight. Here's the thing: It doesn't matter that you know the ground truth of these illusions—the dancing and bending won't stop. And that we see the world one way, even though we know it's actually another way, is a fascinating quirk of our minds—and maybe a telling one. It suggests that there's a chasm between perceiving and thinking, that these may be two independent provinces of the mind. But, if so, we're faced with another question: Where does perception end and thinking begin? 

My guest today is Dr. Chaz Firestone. Chaz is an Associate Professor of Psychological and Brain Sciences at Johns Hopkins University, and Director of the Perception and Mind lab there. He and his research group study perceiving, thinking, and the interface between the two.

Here, Chaz and I talk about his background in philosophy and how it continues to animate his research. We sketch the differences between perception and cognition and why the two are best considered separate faculties. We consider the idea of so-called "top-down" effects on perception. We discuss the fact that, even if perception and cognition are separate, there's much more to perception than meets the eye. We seem to see things like causes and social interactions; we perceive things like silences and absences. Along the way, Chaz and I touch on the modular view mind, skeletal shapes, the El Greco fallacy, stubborn epistemology, birders and radiologists, retinotopy and visual adaptation, adversarial images, human-machine comparisons, and the case of the blue banana. 

This is a fun one, friends. But before we get to it, one humble request. If you've been enjoying Many Minds, now would be a great time to leave us a rating or review. You can do this on Apple Podcasts or on Spotify. It would really help us grow and get the word out! It actually looks like our last review on Apple Podcasts is about 10 months old—so, if you have a minute, that could really use some freshening up.  

Alright folks, on to my conversation with Chaz Firestone. Enjoy!


 A transcript of this episode is available here.


Notes and links

3:00 – Dr. Firestone’s early paper reporting the Times Square experiment and the “skeletal shape” phenomenon.

8:00 – A visual explanation of the “missing bullet holes” graphic. 

13:00 – Dr. Firestone has collaborated intensively with the philosopher Ian Phillips

15:00 – A recent book by Ned Block, The Border Between Seeing and Thinking.

24:00 – Visual illusions are legion, as are inventories of them. See, for instance, this catalogue on Wikipedia or this Reddit thread.

25:00 – An obituary for Jerry Fodor, who died in 2017. The classic book by Zenon Pylyshyn, Computation and Cognition

28:00 – A paper by Dr. Firestone about the history of the El Greco fallacy. An empirical paper by Dr. Firestone and Brian Scholl showing the El Greco fallacy at work in perception research. 

35:00 – A target article (with commentaries) in Behavioral and Brain Sciences by Dr. Firestone and Dr. Scholl about claims of “top-down” effects on perception. Dr. Firestone has published other work on this theme, e.g., here, here, & here

41:00 – A paper with discussion (and illustration) of the classic Dalmation Mooney image. 

45:00 – A study of rapid visual pattern recognition in expert chess players.

50:30 – A paper by J.J. Valenti and Dr. Firestone about the case of the blue banana.

54:00 – A review paper by Alon Hafri and Dr. Firestone reviewing evidence that people actually perceive high-level relations like causality, support, and social interaction. 

56:00 – A study by Martin Rolfs and colleagues about the perception of causality.  

1:02:00 – A study by Liuba Papeo and colleagues about the perception of social interactions. A related paper showing an inversion effect.

1:04:00 – A paper by Alon Hafri and colleagues on the perception of roles in an interaction. 

1:06:00 – A widely cited paper by J. Kiley Hamlin and colleagues on the recognition of social interactions in preverbal infants.

1:06:30 – A review paper on reading in the brain. 

1:10:00 – A paper by Rui Goh, Dr. Phillips, and Dr. Firestone on the perception of silence. 

1:18:00 – A recent review paper by Jorge Morales and Dr. Firestone about the dialogue between philosophy of perception and psychology, which discusses the perception of absence (among other case studies). 

1:22:00 – A recent perspective piece by Dr. Firestone about human-machine comparisons.

1:25:00 - An empirical paper by Zhenglong Zhou and Dr. Firestone on the deciphering of adversarial images by humans.

1:28:00 – For a review of the mirror self-recognition test, see our earlier audio essay 

1:35:00 – Other interesting work going on in Dr. Firestone’s research group has investigated representational momentum, beauty, and epistemic actions, among other topics.



The Modularity of Mind, by Jerry Fodor

The Contents of Visual Experience, by Susanna Siegel

Psych, by Paul Bloom


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.


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