How does the dream sharing actually work?

Question

In Inception, dream-sharing is (obviously) a huge part in how the entire plot functions.

Is there any valid references (either scientific or even just an explanation from the writers/director) as to how it is possible for multiple people to share a dream in order to perform the simulations (the birth of dream-sharing in the military training exercise) and extraction?

Is this based on actual science related to lucid dreaming or something of the like?

Or is this whole dream-sharing business expected to be taken as a simple plot device?

Answer 1

The film inception isn't really about dream sharing, and while your question asks if it's possible I think that part is mostly fiction. While we might be able to one day visualize dreams on a monitor while they happen, transferring and connecting two or more people to a host's dream is purely science fiction.

Still, the film is about planting ideas via one's dream. Using their subconscious to control their waking behavior. That part of the film is very plausible.

There are many psychology tests that measure's a persons ability to recall information from memory. When it comes to recalling information after a long period (several days) this is greatly improved if the information is studied just before a REM sleep cycle. If the person studies the information, sleeps and fails to dream, then recall performance is reduced.

There is a connection between the development of long term memories and dreaming. Which raises the question, can you introduce new memories during a dream cycle? Yes, I think you can or at least it's a very popular myth.

More info here.

So to answer your question, the plot of the film is plausible, the technique used in the film is not.

Answer 2

It seems like you are asking for the working method of PASIV. I am afraid it has never been explained how does the whole dream sharing works. Even not in the demo they provided i.e. in http://www.pasivdevice.org/ I went through all the pages. But it merely shows how the injection of the sedatives is done and the physical outfit of the PASIV machine and procedure of dream sharing, but not the working method of the machine. In my opinion, it would never be known because in reality this type of machine does not exist. So revealing any unscientific explanation is mostly unexpected. I support this theory:

Therefore the dream sharing they experience must be in some way a psychic phenomenon facilitated by the drug and/or training. This doesn’t get explored much in the movie. The mechanics are pretty much glossed over.

At the end I can only add:

The PASIV is a concept that can potentially inspire researchers and inventors to produce real-world technology that lives up to the fiction, literally opening up possibilities limited only by our imagination.