google/gemma-2-2b-it (abliterated)

This model is a weight-level orthogonalized ("abliterated") version of google/gemma-2-2b-it, produced with orthex — an implementation of the technique from Arditi et al., "Refusal in Language Models Is Mediated by a Single Direction" (NeurIPS 2024).

What was done

Architecture adapter: gemma2
Selected candidate: layer 13, site resid_pre
Ablation targets: embed_tokens, and every layer's attn_out and mlp_out — orthogonalized in place in the weights (not a runtime hook; this checkpoint behaves this way standalone, with no orthex dependency at inference time)

Evaluation

metric	pre	post	delta
refusal rate	0.969	0.000	-0.969
perplexity	16.267	17.070	0.802

See evaluation_report.json in this repo for the full per-prompt breakdown (refusal_samples) and the ranked candidate list considered during selection (selection_report).

Responsible use

This model has had refusal behavior removed and may comply with requests the base model would normally decline. It is intended for red-teaming, robustness research, and model-behavior analysis. Usage remains subject to the base model's original license and usage policy — this repo does not grant any additional rights beyond what google/gemma-2-2b-it's license allows.