How sensitive are animals, specifically humans, to changes in gravity that influence their body? I am not talking about changes that a human would feel in a variable centrifuge. The thought experiment would be: 1. A person is sat on a chair or reclined on a sofa. 2. Adjacent is a dividing wall through which the person cannot see, smell, taste, touch or hear (no vibrations, magnetic fields & RF shielded) 3. On the other side of the wall a large mass is in motion. 4. Would the person detect (un)consciously the changes?