[markdestouches]

150 ms is the time it takes for a person to see the input and then do something (like pressing a key or blinking). That's a two way communication with processing (thinking) time included. The actual input reaction, as the time it takes for your brain to register something, is faster.

In addition to that, the reaction time does not actually matter. You would be able to see a sub-reaction-time delay because your brain has a way of timing and synchronizing events. Look at it this way. You send a letter on March 1. You receive a reply on March 10. It doesn't matter how much later you actually read the reply, on March 11, 15, or in April - you still would know that it took 10 days to get the reply.