Layer 18 · Neuron 843 · suppressed

L18N843-1

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)

I am Qwen2.5，the latest iteration of my family. I am a large language model, trained to understand and generate text, as well as perform various tasks that require reasoning, coding, and visual analysis.

My mission is to be a versatile and helpful assistant in every way possible. I aim to:

Answer your questions with accuracy and depth, whether they are about general knowledge, specific facts, or complex concepts.
* assist you in creative tasks*, like writing stories, generating professional-grade code, or helping you brainstorm ideas.
* handle logical and scientific problems*, providing

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. L6N49-1🕒	0.97	“ ‘”“‘”“’”
2. L16N1996-1💤	0.96	““”“ ‘”“‘”
3. L15N1174+1🕒	0.96	“ ‘”“‘”“ “”
4. L6N379-1🕒	0.96	“ ‘”“.””“ “”
5. L16N8359-1💤	0.95	“ “”“ ‘”““”
6. L4N2410-1🕒	0.95	“ ‘”“ “”“‘”
7. L5N4111-1🕒	0.95	“ ‘”“ “”“‘”
8. L15N7914+1🕒	0.95	“ “”“ ‘”““”
9. L18N413-1🕒	0.95	“ ‘”“ “”“‘”
10. L18N4990-1💤	0.95	“ “”“ ‘”“‘”

Shadow specimen, apart from the ten: L18N843+1🕒, -0.21.

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 18, neuron 843, dose -1. This specimen has no prompt-suite replies yet. Its quick-scan results, when available, appear below. Its quick-scan row (KL 0.54, top-1 agreement 0.71) 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
L18N843+1🕒 shadow specimen t0-v0.1	1.598	0.56	1.724	1.83	“ fa”“ sti”“ fe”“ stu”“ f”“ cia”“ ue”“ fx”
L18N843-1 t0-v0.1	0.539	0.71	0.620	1.24	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.