Consciousness after split-brain surgery: The recent challenge to the classical picture.

Summary

Split-brain patient D.D.C. demonstrated remarkable adaptability, accurately responding to stimuli across visual fields using both hands or verbally in 100% of trials. This challenges the notion of unity of consciousness, suggesting that while D.D.C. may exhibit agency, his experience might not be fully integrated. The study distinguishes between agency-based and experience-based conceptions of consciousness, emphasizing that understanding the mechanisms behind split-brain behavior and defining what constitutes a single agent are crucial. Ultimately, the findings raise questions about the true nature of consciousness in such patients.

Abstract

In a recent series of experiments, Pinto and colleagues found that the split-brain patient D.D.C. was able to respond accurately to stimuli in either visual field, whether using his right hand, his left hand, or verbally. Pinto and colleagues argue that this demonstrates that a split-brain patient remains a unitary agent and thus continues to possess a unified consciousness. This paper provides a critical evaluation of that claim. First, we argue that two conceptions of the unity of consciousness need to be distinguished: an agency-based conception and an experience-based conception. Second, we argue that it is an open question whether the data presented by Pinto and colleagues is best understood in terms of the unity of agency. Whether that interpretation is correct depends not only on the mechanisms that produce split-brain behaviour, but also on what is involved in being a single agent. Third, we argue that even if the behavioral data indicated that D.D.C has a unified consciousness in the agency-based sense of the term, it is difficult to reconcile them with the claim that his consciousness is fully unified in the experience-based sense.

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