500 college biology students were asked to predict the axisymmetry (horizon
tal-vertical position) of the water surface and a swimming goldfish in a ma
sked, sealed container. Subjects were shown the fish submerged in the semif
illed container before it was slipped into a terry cloth stocking. The rese
archer then asked subjects to predict the position of the fish and the wate
r surface as the sealed container was rotated to different angles. Many col
lege students did not understand that liquids and submerged organisms remai
n invariantly horizontal regardless of the rotation of the container.