The article seems to mix up sensory deprivation with isolation. Suppose you are stuck on a deserted island with no human contact, like Robinson Crusoe. Surely, you're not going to get hallucinations? You're not in a box or dark prison cell; you have day and night, the beach, woods, animals. Survival activities to keep you busy, like making shelter and gathering food. Maybe the sensory deprivation causes the brain sli…
There is also the story about Ellen MacArthur mentioned in the article. Isolation from civilization, in this case complete solitude, leads her to anthropomorphise her boat.
> The hallucinations are perhaps related to the mechanism which produces dreams, and not evidence that you're going bonkers.
As the article mentions, hallucinations would be a way to not go bonkers. Humans need to be around other humans, and if that can't happen, we'll make them up.
Completely subjective supposition - I see hallucinations as being, in some cases, extreme forms of delusions. IIRC, I believe there has been a fair amount of research done on delusion (like this one [1] I suppose), suggesting delusion could be a survival mechanism, similar to what is described in the article.
[1] http://www.agroparistech.fr/mmip/maths/laurent_orseau/papers...