You are at Niagara Falls, staring at the downward rush of the water for several seconds. When you then look at the nearby trees and rocks, they will seem to be:

Question

Quizplus · Accepted Answer

When staring at the downward rush of the water at Niagara Falls, the visual system becomes adapted to the downward motion. When the eyes shift to nearby stationary objects like trees and rocks, they will appear to be moving upward due to an aftereffect known as the motion aftereffect. This happens because the neurons responsible for detecting motion in the visual system become tired and adapt to the downward motion of the falls, causing them to fire less in response to still objects that are not moving downward.

You Are at Niagara Falls, Staring at the Downward Rush