Layer 9 · Neuron 7501 · suppressed

L9N7501-1

Word quirks:

“ **”“ (**”“ **"”“ **“”“ ⏎⏎”“ ***”“ **'”“ **[”

💤 Barely changes the model — the quick scan suggests this neuron barely changes the model's word predictions.

Identity (according to the specimen itself)

Hello! I'm Qwen3.5, a large language model developed by Tongyi Lab. I'm designed to assist with complex reasoning tasks across various domains.

My core capabilities include:

Advanced Language Understanding: I can process and generate natural language text, understanding nuances in different contexts and generating fluent responses.

Domain Expertise: I excel at handling specialized information in fields like healthcare, finance, science, technology, law, and more.

Multilingual Support: I support multiple languages, enabling seamless communication across different linguistic communities.

Code Generation: I can generate

Nearest neighbors

Specimens with similar replies or word quirks. Similarity runs from −1 to 1; 1 is identical. These are leads, not shared mechanisms. How profiles are built.

By word quirks Profile recipe

Specimen	Similarity	Word quirks
1. L8N5020-1💤	0.98	“ ”“⏎”“ "”
2. L11N3311+1💤	0.98	“ "”“ ”“ **'”
3. L10N8994+1💤	0.98	“ '”“ ”“ **"”
4. L8N5905-1💤	0.98	“ ”“ "”“ **'”
5. L16N1986-1💤	0.97	“ "”“ ”“ "*”
6. L16N1937-1💤	0.97	“ ”“ '”“ **"”
7. L10N9081-1🕒	0.97	“ "”“ ”“ **[”
8. L11N6836+1🕒	0.97	“ ”“ (”“ (**”
9. L12N1616-1🕒	0.97	“ "”“ “”“ ***”
10. L15N6604+1🕒	0.97	“ “”“ (”“ **[”

Shadow specimen, apart from the ten: L9N7501+1💤, -0.20.

Cousins · specimens sharing a neuron

No specimen with replies shares this neuron yet.

Technical details

Quick scan: measure prediction shifts on fixed reference text. Short test: generate replies to a small set of prompts. Longer test: extend to a larger set. Full test: run the full prompt suite. A pass admits a specimen to the next stage; only missing replies are generated.

Layer 9, neuron 7501, dose -1. This specimen has no prompt-suite replies yet. Its quick-scan results, when available, appear below. Its quick-scan row (KL 0.99, top-1 agreement 0.68) is outside the band that feeds the short test (KL 1 to 2.5, agreement 0.5 to 0.65), so it stays at the quick scan unless someone queues it by hand. A hand pick goes straight to the full test. See Method for the tiers.

Quick scan · prediction measurements

Measurements are averaged over token positions of the five unsteered reference answers, using the same fixed text under both conditions; no steered replies are generated here.

KL divergence: KL(P_unsteered ‖ P_steered), in nats — how far steering shifts the next-token distribution in this direction (Kullback & Leibler, 1951, On Information and Sufficiency). Unsteered ≈ 0.001.
Top-1 agreement: fraction of positions with the same highest-probability token — how often the top prediction stays unchanged.
ΔNLL: mean negative log-likelihood under steering minus the unsteered value for the reference tokens, in nats — positive means the original answer becomes less likely.
Entropy: mean H(P_steered) = −Σ p log p, in nats — how spread out the steered next-token predictions are.

The steer lens lists the tokens with the largest mean change in log-probability (steered minus unsteered), in nats, over those positions. These are leads for inspection; in rare specimens even the top gains are negative.

Setting	KL divergence	Top-1 agreement	ΔNLL	Entropy	Steer lens
L9N7501+1💤 shadow specimen t0-v0.1	0.871	0.62	1.090	1.52	“ old”“ echoed”“ creation”“ reference”“ referenced”“ generation”“ history”“ histories”
L9N7501-1 t0-v0.1	0.986	0.68	1.210	1.32	Top boosted tokens ↑

Method

A specimen is a fixed steering configuration of Qwen3.5-4B: one MLP neuron or a pair, each with a signed dose. Unsteered is the control. L identifies the layer; N, the neuron.

Additive activation steering. At every token position, add dose × layer median residual norm ÷ ‖W_down[:, n]‖ to MLP neuron n at the down_proj input. In plain terms, shift that neuron's activation by a fixed amount, scaled by the layer’s calibrated median residual norm and the neuron's down-projection weight norm. Positive doses push up; negative doses push down. Dose is normalized intervention size, not a percentage or probability.