Difference-in-Means Direction

Vector from mean of false representations to mean of true representations; core of mass-mean probing

Neighborhood — ranked by edge-count

framework

Mass-Mean Probing
implements
Introduced in this paper: an optimization-free probing technique using difference-in-means direction with optional covariance correction

concept

Truth Direction
associated_with
A hypothesized direction in LLM activation space that encodes the truth or falsehood of factual statements

cosine ≥ 0.65 · no typed edge

Entities in the same semantic neighborhood but without a typed relation to this one — candidates for new edges or unrecognized duplicates.

Difference-in-Meansmethod0.890
Method for extracting linear directions by subtracting mean activations of contrastive groups; used to define the Assistant Axis
differentiationconcept0.752
Subtle variation and detail, as in pots of flowers, that brings life to a place.
Reflection directionconcept0.746
A direction in the model's representation space that governs self-reflection behavior, computed as mean difference between reflection and non-reflection embeddings
The difference-in-means direction is the unique nullity-1 projection kernel that eliminates all linearly-recoverable binary classification information from a datasetclaim0.743
Formal consequence of Belrose et al. (2023) Theorem G.1 connecting mass-mean probing to optimal linear concept erasure
linear directionconcept0.727
A straight vector in activation space, traditionally used for concept manipulation; claimed to be insufficient when true concept geometry is curved.
Refusal directionconcept0.727
Arditi et al. 2024 finding that refusal behavior is mediated by one direction in LLM activations; exemplar of single-direction causal results
direction-based steeringconcept0.726
Paradigm of finding the right direction in activation space (e.g., linear steering).
Goal-Directednessconcept0.716
Proposed universal invariant of cognition and intelligence—capacity for goal-directed activity in a problem space, independent of substrate or embodiment.