Layer 15 · Neuron 5259 · boosted

L15N5259+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)

Qwen3.5

I am Qwen3.5, a large language model developed by the Tongyi Lab. My mission is to provide high-quality, efficient, and safe AI assistance across a wide range of tasks.

Core Capabilities and Goals:

Advanced reasoning and coding
Deep visual analysis and document understanding
Multilingual support and cross-cultural contexts
**Precise alignment with human needs

My design focuses on being helpful, accurate, and safe while maintaining strong ethical guidelines and privacy considerations.

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Key Features:

**Enh

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. L15N4459-1🕒	1.00	“ ”“ ”“ *“”
2. L11N8374+1🕒	0.99	“ "”“ "”“ **'”
3. L14N1759-1💤	0.98	“ "”“ “”“ **”
4. L13N1774-1💤	0.98	“ “”“ ”“ "**”
5. L16N333-1💤	0.98	“ “”“ ”“ **‘”
6. L13N542+1🕒	0.98	“ "”“ ”“ "**”
7. L14N7476+1💤	0.98	“ ”“ ”“ *"”
8. The Crossing Guard✅ L7N1771-1	0.98	“ “”“ "”“ **#”
9. L7N4258+1🕒	0.98	“ “”“ "”“<\|im_end\|>”
10. L13N6777-1💤	0.97	“ “”“ "”“ **'”

Shadow specimen, apart from the ten: L15N5259-1🕒, 0.24.

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 15, neuron 5259, dose +1. This specimen has no prompt-suite replies yet. Its quick-scan results, when available, appear below. Its quick-scan row (KL 0.59, top-1 agreement 0.73) 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
L15N5259+1 t0-v0.1	0.587	0.73	0.734	1.17	Top boosted tokens ↑
L15N5259-1🕒 shadow specimen t0-v0.1	1.211	0.61	1.609	1.57	“ -->”“⏎”“ ?”“ ->”“-->”“？”“ ⏎”“ ???”

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.