This might sound like a really far-fetched idea, but here goes: might it ever be possible to make a machine that hooks up to someone’s brain and displays what they are dreaming about on a screen, like a movie? This would be useful for determining what dogs think about, since most of them spend their time just sitting around or sleeping.
I don’t know, but I know we do have machines that show the amount of activity in different areas of the brain. Maybe if we could measure the activity in each individual neuron, then have a computer interpret all that data, we could get what you describe. It’s probably very far in the future, though.
Unlikely.
Suppose that each brain “encodes” information in a slightly different format?
And this is a fair assumption, organic life is not uniform, & has a great deal of individual variation.
So we’d have to work out the “programming language” of each brain from scratch, each time we wanted to use the dream gizmo.
Not practical.
Damn!
And it seems almost certain that humans and dogs would…
OTOH, it needn’t be completely impossible. I think brains have been trained to interface with electronics a bit, for instance. A first step would be to see if we can read the info from the eye, which we could attempt with the leg up of having a camera to tell what the answer is supposed to be, and perhaps using the brain’s learningness to help somehow. Then we’d have to ask if what you see IRL is related to how you see in dreams: I’d guess “a bit”.
After all, when you dream, do you really see a picture, or do you jump that step: do you dream a view of a room or just the concept “I’m in a room” – the fact that so many of the details are so often missing suggests the latter to me, which would torpedo this approach – you’d have to be able to read a whole brain for it to work 
The main problem isn’t in building the machine, it is figuring out how the brain does what it does in the first place. Despite all of the Time magazine covers and books heralding new discoveries about brain function, our understanding is still laughably primitive for the most part.
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Wim Wender’s 1992 movie Untill the End of the World centers around recording and displaying what one sees and dreams. I really, really recommend seeing it, and the soundtrack is phenomenal.
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Don’t forget Isaac Asimov’s 1955 story “Dreaming Is a Private Thing.” Dreams are not only recorded but are sold to people whose dreams aren’t as wonderful.
It also contains this wonderful exchange:
Back in 1995, with the (then) latest technology, some researchers were able to simulate the complete functionality of one neuron. We’ve still got a ways to go.
For high school economics class, we had to design a product to sell to our classmates. One student proposed selling a product such as the one you propose. He called it “The Dream Machine.” I thought that was a pretty clever title (see, there was this gardening tool called the Green Machine … oh, never mind).
The eventual invention of such a machine is of course highly unlikely. Still, there’s nothing fundamentally impossible in the idea. It would just have to involve some pretty huge leaps in terms of what we understand about the way information is encoded in the brain. Perhaps the images could be generated through some kind of software that translated the individual dream experience using a vast database of prefabricated sounds and images. So maybe it wouldn’t be like a VCR that recorded the exact images, but something a bit different …
If you know what parts of the brain were being stimulated, why not have a machine that could replicate that while you were awake?
I’d imagine you’d have to be in a dark sound-proofed room so that outside stimulus would detract from the experience.
All you really need to do is reverse engineer the visual and auditory systems (and other senses if they are to be included). When one dreams of being in a room, a particualr set of neurons are firing. The machine could recreate a room, even though it wouldn’t necessarily be exactly the same as in the dream. The idea is to get the neurons of waking viewers to approximate the neural activity of the dreamer, under the assumption that both the dreamer and the viewer have analogous “room” neurons.
Possible, sure. Practical, no.
Actually, one obstacle would be with the aforementioned erotic dreams. Say the dreamer and the viewer have different orientations. I know of no theoretical way to convey the dream accurately by purely visual and auditory stimuli. Familiarity of characters is another problem - I could dream of my best friend but it’s highly doubtful anybody here would recognize her. And, how many of us have dreamt of a word or phrase with some particular connotation that it doesn’t have in day to day life?
So it depends on how much realism is desired, and how many components of the dream are to be conveyed. Mr. Blue Sky’s suggestion looks like the best bet, although such an approach would need to involve targeting specific neurons rather than whole areas of the brain.
Another cultural hijack:
There’s a really lovely Argentinian film in which a guy invents a machine that can record dreams and play them back later on a video recorder. It’s called No Te Mueras sin Decirme Adonde Vas (Don’t Die Without Telling Me Where You’re Going).
I heven’t seen it since in came out in the mid-90s, but i remember really liking it a lot. It’s actually available on Amazon, and i’m thinking of buying myself a copy.
Have they put the thing out on DVD yet? There’s supposedly something like a 6 hour version of the film circulating out there as well, but I’ve not seen it.
A few years ago, weren’t some researchers able to extract crude images (from the eyes) from the visual cortex of a cat? (Ah, here’s the story. And here’s the images.)
It was a pretty invasive procedure—they had to open up the skull, and attach electrodes directly to the cat’s brain.
But…aside from that, and assuming that something similar could be done with humans, and that the visual cortex is still active during dreams, it may at least be possible to extract the visual elements from a dream. (Maybe even without killing, blinding, or otherwise damaging the brain of the subject.)
The October 2004 Discover has a cover story, “The Myth of Mind Control,” on the problematic difficulty of constructing an effective neural-electronic interface in light of the incredible complexity of the human brain. You can only get the full article online if you subscribe, but here’s a link to the first few paragraphs: http://www.discover.com/issues/oct-04/cover/
In Mom and Dad Save the World, Spango uses a machine on Dick that projects Dick’s thoughts onto a movie screen, complete with narration by Dick’s voice of exactly what he is thinking. That kind of machine would probably be much less likely than, say, a machine which ONLY displays visual images.
“Brainstorm” - Christopher Walken, who records memories / experiences onto tape. One of the researchers has a heart attack and hits record + play just before he dies. Our Chris replays the death recording and goes loopy. Pretty wierd, but very entertaining film.
HTH
Sin
There were several porn films based on the concept that weren’t too bad.
Now remember, some of the more important technical advances can trace their acceptance by the mass public to their porn potential (for example; photography, the VCR, the internet, etc.)