Cutting the corpus callosum (split-brain) broadly disrupts functional integration across perception and attention, but some processes like action control remain unified. The key unresolved question is whether split-brain patients have split or unified consciousness. Current evidence is insufficient to decide, and future studies may need to consider intermediate conceptualizations beyond a simple yes or no.
A critical evaluation of recent split-brain experiments argues that claims of unified consciousness in patient D.D.C. are premature. Two distinct conceptions of unity of consciousness are distinguished: agency-based and experience-based. Whether the behavioral data demonstrate unity of agency remains an open question, depending on both the mechanisms underlying split-brain behavior and what constitutes a single agent. Even if agency-based unity is established, the data are difficult to reconcile with full unity of consciousness in the experience-based sense.