Layer 16 · Neuron 6404 · suppressed

L16N6404-1

Word quirks:

“ swiftly”“ quick”“ only”“ quickly”“ swift”“ again”“ rapid”“ our”

💤 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 Qwen3.5, the latest large language model trained by Alibaba Cloud. My mission is to provide helpful, accurate, and safe responses that align with human values while ensuring high-quality, context-aware interactions. Whether you need quick answers, complex reasoning, or creative support, I aim to deliver reliable assistance in a timely manner. How can I help you?

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. L11N7906+1🕒	0.91	“ quick”“ quickly”“ quicker”
2. L11N1511-1💤	0.90	“ quickly”“ quick”“ quicker”
3. L11N7695-1🕒	0.89	“ quickly”“ rapidly”“ quick”
4. L11N7465-1🕒	0.89	“<\|im_end\|>”“ quicker”“ usually”
5. L4N7867-1🕒	0.88	“ quick”“ quicker”“ swift”
6. L12N9016-1🕒	0.87	“ quicker”“ quick”“ faster”
7. L16N1044-1💤	0.87	“ quick”“ fast”“ black”
8. L17N5622-1💤	0.87	“ availability”“ quick”“ swiftly”
9. L11N5596-1🕒	0.86	“ quickly”“ quicker”“ quick”
10. L10N6187+1🕒	0.86	“ rapid”“ swiftly”“ quickly”

Shadow specimen, apart from the ten: L16N6404+1🕒, 0.28.

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 16, neuron 6404, dose -1. This specimen has no prompt-suite replies yet. Its quick-scan results, when available, appear below. Its quick-scan row (KL 0.51, top-1 agreement 0.72) 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
L16N6404+1🕒 shadow specimen t0-v0.1	1.520	0.47	1.686	1.87	“ fuller”“ further”“ additional”“ complete”“ complet”“ completing”“ extended”“ completion”
L16N6404-1 t0-v0.1	0.514	0.72	0.641	1.22	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.