People in small tribal societies tend to have the greatest proportion of physical aggression in their dreams, with the highest reports among the Yir Yiront, an Australian Aboriginal group for whom 92 percent of dream interactions were aggressive—defined to include everything form aggressive feelings to nasty remarks to physical attacks on possessions. Among industrialized societies studied, however, Americans ranked highest for aggression in dreams, with scores of 50 percent for U.S. males (34 percent for females) versus 29 percent for Swiss men and 32 percent for Dutch men.What it all means, exactly, I don't know, but that comes from Andrea Rock's book, The Mind at Night: The New Science of How and Why We Dream, and the figures were based on the first-ever systematic study of dream content among people the world over, begun in the 1980s. The passage quoted below is also pretty nifty—it's about a scientist who lost his sight at the age of twenty-five and has studied dreaming among blind people ever since:
He says dreams also play a crucial role in his [i.e., the blind guy's] ability to navigate new surroundings and to imprint visual imagery. If he has to learn the route to his dentist's new office, he eventually has what he calls a consolidation dream, in which all of the auditory and sensory data he's absorbed on the first couple of trips is pulled together to give him a mental picture of the new place or route. Only after he's "seen" his way in the consolidation dream can he negotiate the route as if he were in his own home...I mean... whoa.
Such dreams can also help consolidate other kinds of new visual imagery. "When my daughter gets her hair cut short, I will Braille it, appreciate it, comment on it. However, the next time she crosses my path or I think about her, in my spontaneous waking image she will still be wearing long hair. Once I dream of her in her new hairdo, that is, once I have seen it, she will appear to me in it pretty much consistently from that time on." He says others who have been blinded at some point after early childhood have reported similar dream experiences.