Split-Brain Revisited: Persistent Asymmetry and Structural Constraints

The split-brain syndrome has long been interpreted as evidence for divided consciousness. However, while some classical findings have been challenged by recent studies, one robust phenomenon remains: the inability to compare stimuli presented independently to the left and right visual fields. Existing interpretations have increasingly preserved some notion of a unified subject or conscious agent, yet the realization of the experiencing subject itself has rarely been treated as an explanatory target. This paper proposes a Subject-Centered Approach that distinguishes Subject Integration from Structural Integration. We argue that commissurotomy preserves Subject Integration while constraining Structural Integration, thereby limiting the range of conscious structures that can be formed. This framework explains cross-field comparison failures without postulating multiple subjects, multiple streams of consciousness, or subjectless consciousness.