Could it not be that when folks are pressing harder, they feel the vibration stronger because of a tighter grip?
Also, the power of suggestion is strong; just because one thinks it's true, it doesn't make it so. Anyone remember the couple who were convinced their phones weighed different amounts?
Also, the power of suggestion is strong; just because one thinks it's true, it doesn't make it so. Anyone remember the couple who were convinced their phones weighed different amounts?