Depth or Recursion? — current poster panel

Ouro-2.6B (looped) vs GPT-2 XL brain encoding, extending Goldstein 2025 · up to date as of 2026-06-07 · honest 3-beat arc, skeptic-signed · tap any figure to enlarge
A feedforward LM's layer depth maps onto cortical processing time — and this replicates robustly. A looped model does not meaningfully recapitulate that temporal hierarchy: its recurrence “march” is sub-resolution (≤ one 25 ms lag bin).
HOW TO READ · F11

Seven-step methods walkthrough — from ECoG + model states to the depth-vs-recursion read.

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BEAT 1 · LEAD · F1

GPT-2 layer-depth → cortical processing-time replicates robustly (r 0.81–0.98 across estimators, peak-fit span ~130–160 ms). The argmax “step” was an estimator artifact. Caveat: across language-responsive cortex, not language-specific — “mSTG” is mislabeled lateral STG, so there is no valid control.

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BEAT 2 · THE NEGATIVE (flagship) · F10

The looped model does NOT recapitulate the hierarchy: its recursion march is sub-resolution (≈15–30 ms ≤ 1 lag bin) vs GPT-2's supra-resolution depth ramp. The earlier “recurrence carries it” headline was a peak-estimator artifact.

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Beat 2 support · F6

Root cause — GPT-2 encoding curves are bimodal, so argmax coin-flips between bumps. The methods lesson behind the artifact.

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Beat 2 support · F7

Scaled curves — GPT-2 depth march is supra-resolution; the Ouro loop march is sub-resolution; within-loop layer ≈ 0.

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Beat 2 support · F8

Per-ROI grid — depth→time replicates across all three language-responsive ROIs; the looped march is sub-resolution everywhere.

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Beat 2 support · F4

Per-ROI robust depth→time — the old “architecture dissociation / specificity” framing is retired.

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BEAT 3 · CODA · F9

The looped model is no better a brain predictor overall: its edge is low-SNR-only and partly a candidate-pool (“more shots at noise”) effect.

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Boundary · F5

Recursion depth tracks linguistic difficulty broadly, but has no per-word neural correlate (informative null).

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Qualified · F2

“Ouro ≥ GPT-2” retired — the edge is confined to low-SNR electrodes (conditional, not uniform).

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Qualified · F3

Relative language>control peak-R contrast (peak-R measure, unchanged).

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