Ok,
So the issue here is how to determine whether or not the egg can sense someone's intent. Any attempt to do this becomes muddied if participants actually know the full nature of the experiment. In essence, if they know they're not supposed to think about hurting the egg, it's almost inevitible they'll have images of scrambled eggs in mind at some point.
So here's a proposal:
Place the egg, along with the shimmering leaf, in a box with a lid.
Create several instruction notes with the following instructions:
1 Note will say: Open the box on the table in the center of the room and smash the egg.
9 Notes will say: Open the box on the table in the center of the room and feel the egg within.
Place these notes, folded, into a basket near the entrance to the room.
Have particpants enter the room, unaware as to the nature of the experiment. Upon entering, they will pull a note at random from the basket/box and act accordingly.
If the shimmering leaf works as advertised, the Egg won't make a peep until the participant with the "smash the egg" note arrives.
Obviously, if the first participant draws the "smash" note, it would probably be a good idea to conduct the expirement more than once.
Eric-