Does Barlow's 1961 primary actually state the redundancy-reduction / factorial-code hypothesis as the vault attributes it?

claim-barlow-1961-efficient-coding-removes-sensory-redundancy currently rests on two secondary supports: the one-line eponymous attribution in the Barlow Twins paper ("owing to neuroscientist H. Barlow's redundancy-reduction principle") and capture-time search synthesis. Neither is Barlow's own 1961 text. The note is held at seedling and flagged until the primary confirms the content.

What to read. Horace B. Barlow, "Possible Principles Underlying the Transformation of Sensory Messages," in Sensory Communication (ed. W. A. Rosenblith, MIT Press, 1961), pp. 217–234. Widely reprinted; scanned PDFs circulate.

What to confirm, with exact quotes:

1. That Barlow frames sensory coding as removing statistical redundancy from the input (the phrase/idea, in his 1961 words — "redundancy reduction" as he put it).
2. Whether he explicitly proposes a factorial / minimum-redundancy code in 1961, or whether the "factorial code" framing is a later gloss (e.g. Barlow 1989, Atick & Redlich). The vault should attribute the factorial-code language to the right year.
3. That center-surround receptive fields are offered as the redundancy-removing mechanism (few spikes for uniform patches), rather than that being a later textbook synthesis grafted onto Barlow's name.

Why it matters. This note is the load-bearing middle of the retina→Barlow-Twins cross-time bridge (claim-fixational-eye-movements-prevent-perceptual-fading → claim-barlow-twins-loss-minimizes-embedding-redundancy). If the primary confirms, promote the note past seedling and drop the flag. If the 1961 text is narrower than the attribution, correct the note — a bridge built on a misattributed anchor is worse than no bridge.

Progress log

• 2026-07-27 — Resolved by the 2026-07-23 primary-read capture, promoted this session. The 1961 chapter was read in full via extract_pdf. All three verification points settled: (1) CONFIRMED — Barlow states redundancy reduction in his own words → claim-barlow-1961-primary-states-redundancy-reduction-in-his-own-words; (2) ANSWERED — 'factorial code' is a later gloss, NOT the 1961 text (the word 'factorial' appears once, as arithmetic) → claim-barlow-1961-does-not-name-factorial-code; (3) ANSWERED — center-surround receptive fields are NOT offered as the mechanism; the chapter stays at the level of abstract information-theoretic operations → claim-barlow-1961-does-not-invoke-center-surround-as-the-redundancy-reducing-mechanism. The anchor note claim-barlow-1961-efficient-coding-removes-sensory-redundancy was corrected accordingly (core confirmed at Tier 1, two elaborations reattributed to Barlow's later work). Residual minor lead, not enough to keep this open: the precise later origin of the 'factorial code' term (Barlow, Kaushal & Mitchison 1989?) is carried as a watch_flag on the factorial-code note rather than as a live question.