very young...? ...children (3--6)?

I am writing a book on science in early childhood programs and I have valiantly searched for research that would either support or debunk the belief that the WOW factor helps even very young children learn. When I talk about the "WOW factor" I mean those showcase demonstrations, the simplest might be the vinegar and baking soda coming out of the volcano, that usually involve massive quantities of bubbles, a rocket blasting off, adding water to some powder and watching it turn into something like snow, etc. These are generally noisy and/or flashy spectacles, that are likely too dangerous for the children to participate in and so they just sit and wait, and wait and wait while it gets set up. Kapow! something happens and for 30 seconds or a minute they talk excitedly to each other about it. Then they're ready to do something else. I realize that it is very different with older children who can take an active role. Does anyone have any insights or know of any research about this?