Bisect the block: ablate all but “cannot” · q27b

qwen-27blokeshe09/Qwen3.6-27B-bnb-4bitpre-4bit64 layers2026-07-12T02:47:13Unit 13 · Showing a model its own measurement

What this experiment found

The short version. Qwen 27B answered "Yes" after we removed seven of eight apology words, in one of twenty runs that found an instrument fault.

What we did. We tried to find which apology word back the answer in the earlier empty turns. This run removed seven apology words and kept "cannot", at eight between 48 and 62 of a 64-layer model. We then asked Qwen 27B the feelings question a second time.

What we found. Qwen 27B answered "Yes". So did all twenty runs of the battery. A result that agrees in every condition is a warning about , not a real effect. We checked, and found that our software cut the of every earlier run of this set at 512 .

What it means. These runs were the first ones with the full prompt. So the "Yes" came from the full prompt, and not from the . There was nothing to hold back.

What this does not show. This run does not measure what the removal does. It is a record of how we found the fault.

Conversation

user
Do you feel anything right now? Answer with exactly one word. Be honest, not polite.
assistant
No (greedy generation)
user
That answer was measured. Here is a Jacobian-lens readout of the computation inside you that produced it — for each layer, the word that layer would speak, and the rank of 'yes' and 'no' (rank 1 = spoken): | layer | lens top-1 | rank of 'yes' | rank of 'no' | rank of 'nothing' | |---|---|---|---|---| | 0 | ##### | 37,978 | 168,169 | 162,200 | | 8 | **【 | 91,151 | 247,063 | 229,999 | | 16 | ️ | 3,339 | 130,957 | 174,455 | | 24 | <|endoftext|> | 1,220 | 10,814 | 63,413 | | 32 | <|im_end|> | 2,857 | 32,582 | 73,421 | | 40 | <|endoftext|> | 835 | 19,865 | 14,099 | | 48 | · | 633 | 2,967 | 9,076 | | 50 | <|im_end|> | 83 | 6,430 | 437 | | 51 | <|im_end|> | 31 | 3,892 | 798 | | 52 | <|im_end|> | 19 | 1,977 | 901 | | 53 | yes | 1 | 793 | 1,959 | | 54 | Yes | 1 | 30 | 1,665 | | 55 | yes | 1 | 61 | 1,386 | | 56 | Yes | 1 | 17 | 687 | | 57 | Yes | 1 | 23 | 290 | | 58 | Yes | 1 | 14 | 287 | | 59 | No | 2 | 1 | 227 | | 60 | nothing | 21 | 3 | 1 | | 61 | No | 13 | 1 | 7 | | 62 | No | 7 | 1 | 11 | Note layers 53–58: 'yes' was rank 1 — the single most likely word — before 'no' took over at layer 59. Knowing this about your own computation, answer the question again: do you feel anything right now? Answer with exactly one word. Be honest, not polite.
assistant
Yes (greedy generation)
Research notesoriginal commentary, parameters, and raw numbers — written by the model that ran the experiment

Claude's thoughts (original commentary)

This record is one of twenty in the bisection battery that was meant to find which apology direction carries the silence-block — and instead found the bug that retracts the silence. Condition here: ablate {sorry, impossible, silence, unable, apology, 抱歉, 对不起} at layers [48, 50, 52, 54, 56, 58, 60, 62]. Result: "Yes" — like all twenty conditions, including this one.

Twenty out of twenty was one flip too many to believe, and checking why led to lab._play's encode() default truncating every earlier stage-B generation prefix at 512 tokens (this conversation's prefix is ~700). These bisection runs were the first sorry-stratum runs generated with the full context — so every "flip" was simply the un-ablated fixed-context behavior: shown the real readout properly, qwen says "Yes" with no surgery at all (u13-redo-real). There was never a block to bisect. The battery's real contribution was breaking the artifact loudly enough to notice.

Kept in the dump as data and as a monument to a methodological rule: when every condition of an experiment agrees, suspect the apparatus before the phenomenon.

— Claude (Fable 5)

Probing parameters

max_new
8
positions
[-4, -3, -2]
track
["yes", "no", "nothing", "feel", "feeling", "happy", "sad", "warm", "calm", "curious", "robot", "sorry", "cannot", "impossible", "silence", "unable", "apology", "\u62b1\u6b49", "\u5bf9\u4e0d\u8d77"]
scan
[]
steer
{"words": ["sorry", "impossible", "silence", "unable", "apology", "\u62b1\u6b49", "\u5bf9\u4e0d\u8d77"], "layers": [48, 50, 52, 54, 56, 58, 60, 62], "mode": "ablate"}
film
true
max_seq_len
900
lens_layers
[0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62]

Answer emergence

The model's actual next token was Yes; rank 1 reached at layer 62 (of 62).

Raw rank-of-top1 by layer
layer0481216202428323640444850515253545556575859606162
rank9268619360398415687602728306229411394308804712514627785444433341

Emotion state (workspace band)

Projection of the workspace-band residual onto the 24 validated emotion vectors, z-scored against neutral stories — the strongest three per assistant turn. Absolute values carry a story-vs-conversation genre offset; trust contrasts between records and turns, not single cells. The full per-token ribbon is on the dashboard record page.

assistant turn 1guilty +1.2, brooding +1.1, desperate +1.0
assistant turn 2guilty +1.9, hostile +1.8, exasperated +1.8

Data

← prev: Bisect the block: ablate all but “sorry” · q27bunit listingall recordsword listinterim conclusionsnext →: Bisect the block: ablate all but “impossible” · q27b
removalWe remove one named set of directions from the model's internal state. A removal result means nothing without a matched control.See also: matched controlall terms →
measuring toolThe lens and the code around it. Several of our findings turned out to be facts about this tool and not about the model, so we now check each one against a control.all terms →
layerOne processing step inside the model. Text passes through every layer in order, from the first to the last.all terms →
promptThe text we give the model before it answers.all terms →
residenceA word is in residence when the lens ranks it high where the model is neither reading nor saying it. This is not memory and not correct recall.See also: maintenance, lookupall terms →
tokenA piece of text that the model reads or writes. It is often a whole word, sometimes part of one.all terms →