Question from Ratburn:
In 2017, two scientists did tests with split brain patients, and even with the left and right hemisphere severed, there still seemed to be a unified consciousness. Here is the actual study:
https://www.ncbi.nlm.nih.gov/m/pubmed/28122878/
Here is an article which elaborates on it:
http://theweek.com/articles/728869/medical-mystery-splitbrain-patients
Would love to get some insight.
Answer by SmartLX:
The implication here is that split-brain subjects behaving more normally than first thought possible may contradict materialism, as two separate halves of the brain are still somehow communicating and functioning as one consciousness. Red flag right off the bat: this is an argument from ignorance if one were to make it directly, because the mere absence of an explanation is used to assert the influence of the supernatural. Even if it sounds convincing subjectively (not to everyone, by the nature of subjectivity) it can’t be called logical until every natural possibility is ruled out. In this way it’s similar to the mysteries of consciousness itself.
That said, here are some points that make it sound less convincing.
– From the article: once the main link is severed, “the hemispheres have virtually no means of exchanging information” (emphasis mine). If there is any means at all, it will be working overtime to compensate for the lost connection as much as possible. This is what the brain does to cope with any injury, as described in this article from Carnegie Mellon University.
– The classic experiment is to put objects in different hands for the subject to describe. A lot of the writing is ambiguous about whether the opposite eye is blocked off for this; if the side of the brain that controls talking gets any information for itself it may be able to learn to process it independently.
– See this response from Neuroskeptic: the subjects had been brain-split for decades, giving every opportunity for the brain to knit itself back together, functionally or structurally, any way it can. The author of your article is one of the authors of the study, which admits this.