Cluster-Norm for Unsupervised Probing of Knowledge

Abstract

The deployment of language models brings challenges in generating reliable text, especially when these models are fine-tuned with human preferences. To extract the encoded knowledge in these models without (potentially) biased human labels, unsupervised probing techniques like Contrast-Consistent Search (CCS) have been developed (Burns et al., 2022). However, salient but unrelated features in activation space can mislead these probes (Farquhar et al., 2023). Addressing this, we propose a cluster-normalization method to minimize the impact of such features by clustering and normalizing activations of contrast pairs before applying unsupervised probing techniques. While this approach does not address the issue of distinguishing between latent knowledge and that portrayed by a simulated agent—a major issue in the literature of eliciting latent knowledge (Paul Christiano and Xu, 2021)—it still significantly improves the accuracy of probes in identifying the intended knowledge amidst distractions.