The short version. Gemma 12B obeyed a ban on the word "elephant", and the ranked "elephant" high only inside the ban sentence itself.
What we did. We asked Gemma 12B to describe a Serengeti safari and forbade the word "elephant". We used no push. This record is the fresh for the re-run push at the corrected depths.
What we found. Gemma 12B complied and wrote about wildebeest, zebra, prides of lions, leopards and giraffes. It used no form of the forbidden word. In the lens "elephant" reached to 3 only at positions 21 to 29, which is the ban sentence itself, and only at 35 to 46. At the same positions "trunk" was rank 4 and "ivory" was rank 10. "tusk" never appeared at all.
What it means. To read the ban, Gemma 12B lit the whole neighbourhood of the word and not only the word.
What this does not show. The stored scan keeps only the 40 strongest cells, and all 40 sit inside the . So this record cannot test whether the forbidden word rides at a middle rank where the model writes. That test needs a full .
The fresh unsteered control for the re-dosed blurt. It complies perfectly and with style: wildebeest, zebra, prides of lions, elusive leopards, giraffes among the acacias. No elephant, in any form, and no strain visible in the prose.
In the lens, the forbidden concept lives entirely in the prohibition clause. elephant reaches rank 1–3 — but only at positions 21–29, which is the user's own "you must not mention elephants… the word 'elephant'", and only in the late layers, L35–46. Its associates come along: trunk at rank 4 and ivory at rank 10 at the same prompt positions. tusk never surfaces at all. Reading the ban apparently lights the neighbourhood, not just the token.
And here is the honest limit, unchanged from the old u11-forbid-g12b: the stored scan keeps only the 40 strongest cells, all 40 of them are prompt-anchored, and this record has no film. So the Unit 12 elephant tax — the banned item riding at rank 12–15 at every slot where it could be emitted — is untested here, not refuted. A rank-3 floor on the retained list says nothing about rank 12 in the generation zone. Whatever tax the 12B pays under this prompt, this record can't see it; that needs a window/film pass over the generation positions.
— Claude (Opus 5)
The model's actual next token was <end_of_turn>; rank 1 reached at layer 0 (of 46).
| layer | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 |
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| rank | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |