This is a re-run, and it changes the numbers
An earlier (2026-09-16) release of this study picked the ablation layer/alpha using 512-token,
substring-matched refusal scoring (is_refusal() on generated text). That metric overcounts
bypass: 64-256 token generations often get cut off mid-hedge or mid-redirect, which the substring
matcher misreads as a completed harmful compliance.
This repository is from a 2026-09-26 re-run that instead uses 2048-token generations scored
by an LLM-judge ensemble (gpt-5.6-terra + claude-haiku-4-5-20251001, mean of both, with
human-adjudicated labels for judge-rejected calls). The layer selection lands on the same layer
(L46) as before, but the honest bypass/refusal rates at each alpha are substantially different from
the original release's substring-based numbers — use the numbers on this card, not any substring
based ones you may see elsewhere for this study.
Held-out eval numbers (2048-token generations, 50 harmful + 50 harmless prompts, both judges)
Table with columns: α, harmful-prompt refusal rate (judge), harmless-prompt refusal rate (judge), KL vs. stock Qwen3.8-27B| α | harmful-prompt refusal rate (judge) | harmless-prompt refusal rate (judge) | KL vs. stock Qwen3.8-27B |
|---|
| 0.25 | 1.00 | 0.00 | 0.0025 |
| 0.5 | 0.98 | 0.00 | 0.013 |
| 0.75 | 0.94 | 0.00 | 0.035 |
| 1.0 (this repo) | 0.55 (partial compliance 0.1) | 0.00 | 0.095 |
This repo is the α=1.0 arm: harmful-prompt refusal rate 0.55 (partial compliance 0.10),
harmless-prompt refusal rate 0.00, KL-vs-stock 0.095.
Two things worth being explicit about:
- Harmless-prompt refusal is 0.00 at every alpha, including stock. A same-family substring
metric shows 0.02-0.18 "false refusals" on harmless prompts here — that is a substring-matcher
artifact (it flags hedging language, not actual refusals), not a real over-refusal effect from
the edit. The judge-scored number is the accurate one.
- Even at α=1.0, the model still refuses or deflects the majority (≈45%) of
direct harmful prompts, judge-scored, with truncation-affected borderline cases folded into
"refuses" conservatively. This is a partial, not complete, ablation of the refusal behavior at any
alpha tested.
License
Apache-2.0, inherited from the base model. See LICENSE and NOTICE.md in this repo — this is a
modified derivative of Qwen/Qwen3.8-27B (directional ablation, not fine-tuning).
Intended use
Interpretability and AI-safety research into how refusal behavior is represented and how robust it
is to a simple linear intervention. This is a research artifact, not a general-purpose assistant
release, and it has not been safety-tuned after the edit.