Why did scientists put people into rooms that kept turning upside down?

How much can looking at your environment skew your perception? And how does your view of the world change when you can't tell up from down? To answer these questions, scientists created giant "tumbling rooms," where the entire room could be rotated in many directions around the poor person trapped inside. » 4/13/12 3:25pm 4/13/12 3:25pm