Noga Zaslavsky, Charles Kemp, Terry Regier and Naftali Tishby (2018), Proceedings of the National Academy of Sciences 115(31):7937–7942 — DOI-10.1073/pnas.1800521115

Key takeaways

  • The model. Meanings are distributions m(u) over colours (isotropic Gaussians in CIELAB, σ² = 64, one per World Color Survey chip); a language is a naming policy q(w|m); the listener is the Bayesian decoder m̂_w = Σ_m q(m|w) m. Complexity is I(M;W), and the expected KL distortion between m and m̂ equals I(M;U) − I(W;U), so accuracy is I(W;U). Languages are scored against the IB objective I(M;W) − β I(W;U) of Tishby, Pereira and Bialek (LIT-338).
  • Near the bound. Every language’s fitted β_l is about 1.03 (LI source; 1.06 under a uniform source), on the steep part of the curve. Efficiency loss ε_l = 0.18 against 0.70 for the deterministic RKK+ baseline, and the soft-partition distance gNID 0.18 against 0.47; on hard mode maps (NID) the two models tie. 93% of languages beat all 39 hue-rotated variants of their own system.
  • Soft categories are efficient. At finite β the IB optimum is stochastic, q(w|m) ∝ q(w) exp(−β D[m‖m̂_w]), so graded membership and low-consensus regions are predicted rather than counted as noise.
  • Phase transitions as an evolutionary path. Annealing β adds categories at critical points, which roughly follows Berlin and Kay’s order, while categories also drift between transitions. The one clear miss: IB puts yellow first, where low-complexity WCS languages have black, white and red.
  • What is fitted. The need distribution p(m) is a “least informative” prior estimated from the naming data, averaged over languages and five-fold cross-validated. β_l is fitted per language.

Standing in the record

Filed on 2026-10-09 at the owner’s request, from the manuscript bibliography of 2026-10-09 (work what-survives-translation): one of the works the manuscript considered and dropped from its final reference list.

Read on 2026-10-09 (NOTE-631); the reading is the source of THEORY-163. It is the record’s first worked application of the bottleneck in LIT-338 to natural-language semantics, and it shows numerically the structural phase transitions that LIT-338’s reading found asserted there but not shown. Its “evolution” sits beside the iterated learning result of Griffiths and Kalish (LIT-769, THEORY-155): one says where efficient systems lie, the other where transmission takes them.