Reaction-time tests show that it takes a minimum of 100 milliseconds before the brain can produce even the simplest action and nearer 200 milliseconds to make the more complex judgement involved in hitting a light switch. A good response would be 180 milliseconds (0.18 seconds). However, the human average is around 250 milliseconds (0.25 seconds).

Muhammad Ali's greatness was due to his remarkable reaction time. The time it took for him to respond to a punch thrown his way averaged 150 milliseconds. Phenomenal, but still not fast enough. If George Foreman threw a big right hand in 100 milliseconds and Ali didn't recognize it in advance, his 150-millisecond response time was worthless.