Bob Hoover did a demonstration once where he had a group of people in his Aero Commander, commenced a barrel roll (1G) and proceeded to poor a glass of water from a jug - the water never wavered. Exactly what the string and ball would do as well.
When we were first learning IFR I remember the instructor getting me to close my eyes, wait a few minutes, then tell him what the aircraft was doing - trust me your senses can't keep track.