---
title: "Lloyd A. Jeffress"
type: "entity"
entity_kind: "person"
status: "hub"
canonical_name: "Lloyd A. Jeffress"
aliases: ["Lloyd Jeffress","Jeffress, Lloyd A."]
first_seen: "2026-07-11T00:00:00.000Z"
writer_model: "claude-opus-4-8"
connects_to: ["place coding (delay-line coincidence detection)","interaural time difference (ITD)","sound localization","theory-confirmation-lag","Toshio Irino"]
seek_code_commit: "b13747c"
---


Lloyd A. Jeffress (1900–1986) was an American psychoacoustician who in 1948
proposed the "place" model of how the brain localizes sound: axonal *delay
lines* of graded length feed an array of *coincidence-detector* neurons, so
that each neuron fires maximally for the interaural time difference (ITD) its
delay-line length cancels, and sound direction is read out as a position in a
spatial map. He offered the scheme as a computational hypothesis with no
anatomical evidence; the confirming circuitry (Carr & Konishi, barn owl) did not
arrive until roughly 1990, four years after his death.

Within this vault Jeffress is the anchor of the sound-localization thread and a
recurring case in the "theory-confirmation-lag" pattern — a theory that stood as
pure mathematics for four decades before its anatomy was found. His 1948 model
is also the incumbent that Toshio Irino's 2026 equilibrium-dynamics preprint is
measured against: the whole question of whether that preprint "supersedes"
Jeffress or merely re-describes a Jeffress-family circuit's readout turns on what
his model actually claimed.

## References

- [[claim-jeffress-1948-place-theory-waited-decades-for-anatomical-confirmation]]
  — the 1948 place theory and its ~42-year wait for Carr & Konishi's barn-owl
  anatomy.
- [[claim-irino-2026-equilibrium-dynamics-challenges-jeffress-place-coding]] —
  the 2026 preprint proposing to replace place-coding with population
  equilibrium dynamics.
- [[claim-irino-2026-model-inherits-jeffress-cross-correlation-front-end]] — how
  much of the Jeffress-family circuit that 2026 model actually keeps.
- [[claim-irino-2026-model-offers-no-new-anatomically-distinguishable-prediction]]
  — why the challenger, unlike Jeffress, hands the anatomist no target.
- [[claim-neural-circuit-theories-wait-decades-for-anatomical-confirmation]] —
  the cross-domain delayed-vindication shape Jeffress's case helps define.
- [[observation-hawks-jeffress-cosine-pairing-is-embedding-false-friend]] — a
  separate appearance of Jeffress's name in the vault's embedding-collision work.