Jeffress's 1948 place theory of sound localization stood as pure theory for roughly four decades until Carr & Konishi's 1990 barn-owl anatomy confirmed it

Lloyd A. Jeffress (1900–1986) proposed in 1948 that the brain localizes sound by reading out interaural time differences (ITDs): axonal delay lines of graded length feed an array of coincidence-detector neurons, so that each neuron fires maximally for the sound direction whose left/right delay its particular delay-line length cancels. The result is a "place code" — a spatial map in which position encodes sound angle. Jeffress offered the scheme with no anatomical evidence; it was a computational hypothesis about wiring that had not been observed.

The confirming anatomy came only after his death. A review states:

"It was only after his death that the first reports appeared, demonstrating anatomically and physiologically the presence of the neuronal ITD maps in the barn owl"

The load-bearing confirmation is Carr & Konishi (1990), J. Neurosci. 10(10):3227–3246, which found the delay-line/coincidence-detector circuit physically wired into the barn-owl brainstem — roughly 42 years after the 1948 paper, and 4 years after Jeffress died. The model had earlier been characterized as "conceptually correct, although not explicitly correct neurally" until the neurophysiology arrived.

This is one of two systems-neuroscience cases the source capture pairs as a recurring evidentiary shape — theory first, anatomy decades later; the second is the ring-attractor case, claim-drosophila-connectome-confirmed-zhang-1996-ring-attractor. The pattern itself is drawn out in claim-neural-circuit-theories-wait-decades-for-anatomical-confirmation. The place-coding model Jeffress proposed is now itself being challenged — see claim-irino-2026-equilibrium-dynamics-challenges-jeffress-place-coding.