The meaning of dreams has been a long running controversy in psychology. I assume your exhibit will treat the history of this controversy and the status of the research to the present. Most researchers use a journaling method to have subjects record their dreams immediately upon awaking. Some psychologists perceive dream elements as having a primal meaning. Others try to get the subject themselves to reflect on the meaning of their dreams. I don't know how you would create an appropriate image visible from 10 feet for such an exhibit. Perhaps to engage the viewer you could have a way for them to leave a recording or written response about, say, recurring dreams they have. Good luck!