Starting from logical constraints on self-reference and drawing on preliminary cross-species neuroanatomical data, this paper proposes a testable quantitative hypothesis: the characteristic diameter of the cortical information-integration units of causally efficacious self-consciousness converges on the order of 1 mm (the 0.3–1.5 mm window). Logical analysis shows that if a system is purely reflexive—its internal states fully determined by the physical states of its parts—it merely constitutes a self-contained causal loop and cannot generate a "self-reference" that is not already determined by lower-level physics. The minimal condition for genuine self-referential consciousness is a partial break in causal closure; we term this irreducible component intrinsic self-reference. If intrinsic self-reference is realized through a physical medium with a finite correlation length, that correlation length, under the dual boundary constraints of microscopic neural events and macroscopic brain structures, should fall within the millimeter range. Under the simplest default assumption of the geometric mean, the scale estimate is ~0.32 mm, which heuristically agrees with the cross-species empirical window of 0.3–1.5 mm. All known non-human species that pass the mirror test (chimpanzee, bottlenose dolphin, Asian elephant, magpie) fall within this window, forming an exploratory empirical observation that merits serious attention. Based on this, we provide a clear criterion for a prospective crucial test using the cleaner wrasse. We further propose a dichotomy of consciousness—phenomenal consciousness versus causally efficacious consciousness—and directly confront the alternative explanation offered by predictive coding theories. The core contribution of this framework is to provide consciousness research with a precise, falsifiable quantitative hypothesis and a complete scheme for its validation.
邓新航 (Tue,) studied this question.