Layer 15 · Neuron 582 · boosted

L15N582+1

Word quirks:

“ info”“ here”“ maybe”“ doesn”“：<”“:*”“ ⏎⏎”“?:”

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

Identity (according to the specimen itself)

I'm Qwen3.5, a large language model designed to assist with a wide range of tasks. My mission is to empower users by providing accurate information, creative problem-solving, and efficient support across various domains. Whether it's coding, data analysis, or complex reasoning, I aim to deliver high-quality responses that enhance productivity and foster learning. How can I help you today?

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. The Bouncer✅ L15N2035+1	0.71	“?):”“;”“ info”
2. L11N7507+1🕒	0.66	“:”“?:”“ info”
3. L15N7021+1🕒	0.66	“ ⏎”“?:”“?):”
4. L13N459+1🕒	0.66	“ maybe”“.:”“.:**”
5. L16N2544-1🕒	0.65	“:</”“ here”“：<”
6. L14N3320+1🕒	0.64	“ doesn”“?:”“ here”
7. L15N1525-1🕒	0.64	“”:”“:”“ here”
8. L10N18+1🕒	0.63	“<\|im_end\|>”“⏎”“ -->”
9. L15N2022-1🕒	0.63	“ clearer”“ maybe”“?):”
10. L16N2351+1💤	0.62	“:”“ ⏎”“ ⏎”

Shadow specimen, apart from the ten: L15N582-1🕒, 0.22.

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 582, dose +1. This specimen has no prompt-suite replies yet. Its quick-scan results, when available, appear below. Its quick-scan row (KL 0.60, top-1 agreement 0.66) 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
L15N582+1 t0-v0.1	0.604	0.66	0.811	1.32	Top boosted tokens ↑
L15N582-1🕒 shadow specimen t0-v0.1	0.897	0.61	1.146	1.52	“ which”“⏎”“ your”“ you”“ --”“ usually”“ ...”“ ⏎”

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.