It sounds like science fiction: While volunteers watched movie clips, a scanner watched their brains. And from their brain activity, a computer made rough reconstructions of what they viewed.

Scientists reported that result Thursday and speculated such an approach might be able to reveal dreams and hallucinations someday.

In the future, it might help stroke victims or others who have no other way to communicate, said Jack Gallant, a neuroscientist at the University of California, Berkeley, and co-author of the paper.