The Long Hallway Effect, also known as the ECHO Phenomenon, is a psychological phenomenon in which a person's thoughts and feelings are echoed back to them. It occurs when a person is in a long hallway or other enclosed space, and their own thoughts and feelings are reflected back to them. This can lead to a feeling of being overwhelmed or confused, as the person is unable to distinguish between their own thoughts and those of others. The effect is often used in psychological experiments to study the effects of isolation on the human psyche.