Reflex Lag

“A study of human reaction time shows that it takes too long for a
response message to reach the part of the body that should respond if the
attacker is within touching distance. Unless the attacker telegraphs, it is
impossible to know when the attack is coming, and by the
time it is seen it is too late to move out of the way. In the days of the Wild
West this reflex lag cost a lot of would be gun fighters their lives. Often
they thought that getting the drop on someone meant that the person was
under their control. Many of them were shocked and amazed when their
intended victim drew and fired his weapon before they could discharge
their’s (and I might add dam well dead because they didn’t shoot when they
had the chance). Any modern quick draw artist can do the same thing. They
will let you hold a cocked gun in a situation where you only have to
discharge your weapon before they can draw and fire, and they will beat you
every time because of reflex lag.”

Jesse Glover from Bruce Lee: Between Wing Chun and Jeet Kune Do