(OOC - Wait...what?! Did you see my post? Here, I'll print it again, to be sure.
"It looks blue to me too," Aria says uncertainly. "Look, the lanterns are hung in the same order they were in in that room. We can just count the lanterns to see which are missing."
She starts at Red, and then lists off Orange, Yellow, Green, Blue, Indigo and Violet...each time pointing at a lantern, or a place a lantern would be.
Basically, she's trying to determine if this is blue or indigo, by seeing which lanterns are present here, and which aren't. That seems like a valid course of action to me. If nothing else, it isn't "sitting by and watching."
Hmph!)