First: What's the phenomenon that needs explaining? "The [location of] face and place selective regions [in the brain] is strikingly consistent across individuals. What dimensions of visual information constrain the development& topography of this shared brain organization?" /2
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Rephrase: If I show you images of faces, a particular side of a particular fold of your brain will react to those pictures WAY more than other pictures. It's the *same* side of the *same* brain fold in everyone. Different areas for houses/places, body parts, text, etc. /3
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But why did faces end up *there*? Because... they have a smooth texture? ...you learned faces early in life? ...you usually look at them in the center of your vision? ...you have a lot of expertise with them? (Would *anything* you're an expert in be represented nearby?) /4
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One of my fav results in this field shows that "what gets recognized where" is NOT shaped by the *order* you learn the categories. They taught baby monkeys 3 types of totally made-up shapes, a different order per monkey. Each type still went to a consistent brain location. /5pic.twitter.com/8KKdgE2fxI
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So: this study. Some 8-year-olds in my generation spent *HOURS* staring at avatars of Pokemon. Always with the gameboy held right in the center of our vision, at the same position. Some 8-year-olds didn't. This is a *perfect* natural experiment for neuroscience. Hence "OMG" /6
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We're just like the baby monkeys in the other study, forced to look at made-up glyphs for hours & hours per day. You can't approve a study to force human 8-year-olds to stare at a small set of little symbols daily for years. But children can voluntarily do it to themselves! /7
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Q1: do pokemon avatars end up represented in the same part of the brain for everyone? A1: YES, if you played pokemon for a bajillion hours as a kid. NO, if you didn't. /8
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Q2: Pokemon are *depictions* of animals, which in real-life have faces, bodies, curvy lines, fuzzy. But pokemon *avatars* are pixellated: rectilinear & sharp. Does the "pokemon area" end up near... animate? bodies? rectilinear? expertise / faces? center-of-vision? other? /9pic.twitter.com/em7slmvuf4
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A2-a: There's NO preferential response in the face, body, or animal areas. A2-b: The "face" spot is more lateral than the "place" area: there's a separate Pokemon area, and it's is EVEN MORE lateral than that. The best predictor of this is looking *directly at* Pokemon: /10
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People look at faces straight-on usually, with mostly-central vision. Places fill more of your visual field, or are seen with peripheral vision (more "out of the corner of your eye") A gameboy is viewed EVEN MORE right-in-the-middle-of-vision than faces. /11
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To summarize: The answer to "What determines the physical layout of category-selective visual areas in the brain?" is likely, at least in part, "Retinal eccentricity" that is "Which part of your eye you use: do you look at this category straight-on, or peripherally?" /fin
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cc
@slatestarcodex whose blog I've commented on ~once ever, to chime in about this very topicShow this thread
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Well explained, though if the human brain will ever be explained, I doubt that these tiny random Sherlock-Holmes-like pieces will have any contribution to it...
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If we ever understand the human brain, I would expect that these sorts of discoveries would be exactly the stepping stones toward that end.
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Thank you for this detailed explanation! Super exciting stuff!
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OMG indeed! After reading your unpacking thread
.. this is one of those things you learn that causes fireworks in my head as I update so many objects that this has relevance to & stare stunned evaluating even more that it may apply to while doubting I actually understand it
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So cool! I wonder if this correlates with any of the
#computervision work that@geoff_hinton & others have done with#deeplearning capsule nets (based on cortical columns) that form a representation of 3d-pose as being a critical component in invariant recognition of objects
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Hmmm
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Saluti there is your unroll: Thread by
@catherineols: "Ok, I realize now that if you didn't do half a PhD studying human vision with fMRI, this quote doesn't make sense; and " […]" https://threadreaderapp.com/thread/1058143950849007616.html … Talk to you soon.
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