# Never Cross a River Four Feet Deep on Average

Page: https://stenobird.com/podcast/astral-codex-ten-podcast-226483/never-cross-a-river-four-feet-deep-on-average
Text version: https://stenobird.com/podcast/astral-codex-ten-podcast-226483/never-cross-a-river-four-feet-deep-on-average.md
Podcast: [Astral Codex Ten Podcast](https://stenobird.com/podcast/astral-codex-ten-podcast-226483)
Published: 2026-06-30T11:35:00+00:00
Episode link: https://sscpodcast.libsyn.com/never-cross-a-river-four-feet-deep-on-average
Audio file: https://traffic.libsyn.com/secure/sscpodcast/Never_Cross_a_River_Four_Feet_Deep_on_Average.mp3?dest-id=586545
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JSON: https://stenobird.com/v1/public/podcasts/astral-codex-ten-podcast-226483/episodes/never-cross-a-river-four-feet-deep-on-average
Duration seconds: 2271

## Resource

Guest post by Alexander "Sasha" Putilin [This is a guest post by 2024 ACX grantee Sasha Putilin. I encourage any ACX grantees who are interested to write about their projects. - SA] The results of my ACX Grants 2024 project are in. The project attempted to replicate the 2023 study "Learning at your brain's rhythm: individualized entrainment boosts learning for perceptual decisions" . It claimed that if you read a person's brain waves, figured out an individual peak alpha frequency, and flashed a bright white light at that frequency, then they learned a certain perceptual task faster. Why bother? The result hinted that learning may depend in part on how well the brain keeps its rhythms coordinated. In other words, perceptual learning may rely on an internal brain metronome. If flickering light could act as an external metronome, it might help the brain maintain the right rhythm and learn faster. The study offered an invitation to develop new frontiers of neuroscience and biohacking. If the effect generalised to other types of learning, you could build a learning helmet: put it on your head, let it read your brainwaves, flicker light tailored to your individual brain — and you learn a new skill quicker. And no, it didn't replicate. Most likely it can't replicate, because the effect is probably not real. The original study obscured the data with summary statistics. Running a $32,000 replication was excessive. We could've caught the issue with this study if we simply looked at the original data carefully. *record scratch* *freeze frame* Yep, that's me. You're probably wondering how I got here. Here's the story. https://www.astralcodexten.com/p/never-cross-a-river-four-feet-deep

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