The Biological Ceiling of the Attention Economy: A Calibrated, Preregistered Bound on Human Attention Supply

Economics has a rich demand-side narrative of the attention economy but no supply-side bound on how much attention human hosts can supply. We provide one. In a minimal two-sector model, a host divides waking time between market labor and attention supplied to a synthetic platform sector, which compensates attention in kind with free virtual services. The host's problem has a closed-form interior solution and a saturation corner: once transfers (or automation-driven wage erosion) cross an explicit threshold, labor supply falls to zero and the capturable share of waking time attains the biological ceiling c* = (W - D)/W. Calibrating the model's structural inputs on ATUS 2019-2024 diaries of low-income, non-employed respondents (n = 5,293, survey-weighted), we estimate W = 14.15 hours and a dual-bound ceiling c* in [0.62, 0.81] (primary specification 0.805, 95% CI [0.799, 0.811]). A companion calibration on Eurostat enterprise automation-adoption series shows physical-robot diffusion flat and AI adoption accelerating toward an estimated 2029 inflection. Both bands, with falsification conditions, are preregistered on OSF (https://doi.org/10.17605/OSF.IO/VQWND) before any contact with post-2025 outcome waves. Replication code: https://doi.org/10.5281/zenodo.23897144. Kernel paper of Volume V of The New Human Race research corpus; Volumes I-III: 10.5281/zenodo.23847921, 10.5281/zenodo.23847925, 10.5281/zenodo.23847927.