iBERT: Interpretable BERT

Interpretable Embeddings via Sense Decomposition

Vishal Anand, Milad Alshomary, Kathleen McKeown

EACL 2026 (Oral)

An input sequence with variation in expressionTokenizedSparse k-senses (ℓ₀) per tokeniBERTEncoder Blocks<Key, Query> AttentionInterpretable activationControlled EditInterpretable+EditableEmbedding1 2 3 ----kv2Top-Sense Pooling(𝜏→ 0)v1Mean Pooling(𝜏→ ∞)v3SoftmaxBlend(𝜏= 1)v3Sharpened Blend(𝜏= 10)
Token1x1:n𝒱nTokensToken2Tokenn-1Tokennn Tokensh1H = h1:nn ×dHidden-layer outputh2hn-1hne1 = E x1e1:nn ×dToken embeddingse1 = E x2e1 = Exn-1e1 = E xnStandard TransformerEncoder block-1Standard TransformerEncoderblock-LL count of Encoder-Blocks(or Decoder Blocks without autoregression-masks)TransformerQ(1)d ×d/kQ(2)d ×d/kQ(k)d ×d/kK(1)d ×d/kK(2)d ×d/kK(k)d ×d/kMultiplied by corresponding Q(), K()matrices for each senseQ1= H . (Q(1))TQ2= H . (Q(2))TQl-1= H . (Q(n-1))TQl= H . (Q(n))TK1= H . (K(1))TK2= H . (K(2))TKl-1= H . (K(n-1))TKl= H . (K(n))TEach Kn ×(d/k)k-count of entriesEach Qn ×(d/k)k-count of entriesQ1K1TQ2K2TQk-1 Kk-1TQk KkTQKTn ×nPre-normalized activation (k-count)α1α2α(k-1)αkαn ×nSoftmaxnormalization(per k-sense)C(x1)C(x2)C(xn-1)C(xn)Sense-construction-block1Sense-construction-block2Sense-construction-blockn-1Sense-construction-blocknC(x1:n) n ×k ×dIndependent per-tokenαk ×n ×no1o2on-1onoi=nj=1k𝓁=1α𝓁,i,jCxj𝓁αℓ,i,j→ How much sense ℓ of j-thtoken contribute to representation at i-thpositionσ(ET o1)σ(ET o2)σ(ET on-1)σ(ET on)Project into vocab-spaceThese oi are the final sense-representationsObjective: Masked Language Model15% tokens maskedo n ×d

iBERT vs BERT Embedding Distribution



Results

N.B: BERT (gray) on WG+SD setup was the prior State-of-The-Art (Patel et al. StyleDistance, ACL 2025)

Interpretable editability

Citation

In Proceedings of EACL (Main) 2026 (Oral)

@inproceedings{anand-etal-2026-ibert,
    title = "i{BERT}: Interpretable Embeddings via Sense Decomposition",
    author = "Anand, Vishal  and
      Alshomary, Milad  and
      McKeown, Kathleen",
    editor = "Demberg, Vera  and
      Inui, Kentaro  and
      Marquez, Llu{\'i}s",
    booktitle = "Proceedings of the 19th Conference of the {E}uropean Chapter of the {A}ssociation for {C}omputational {L}inguistics (Volume 1: Long Papers)",
    month = mar,
    year = "2026",
    address = "Rabat, Morocco",
    publisher = "Association for Computational Linguistics",
    url = "https://aclanthology.org/2026.eacl-long.65/",
    pages = "1413--1429",
    ISBN = "979-8-89176-380-7"
}