Even though we are extremely technologically advanced, we haven’t yet found a way to transmit anything at the speed of light. As a result, there is always a bit of latency between gamer input and game device. While this latency doesn’t matter much when all you are doing is pressing a button, since your brain can just adjust to the latency, it causes a number of problems when we talk about more immersive control schemes. You may have noticed this while playing with the Kinect or Move. Sometimes, the game seems to lag ever so slightly behind your normal movement, and this is more than a little jarring.
Valve’s Michael Abrash went into detail about these latency issues and our slow crawl toward virtual reality in a recent Valve blog post. He pegs the average latency of a video game to be at 50ms or higher with the very simplest of games sometimes managing to come in at 20ms. However, humans still notice the latency at 15ms or lower.
Commands simply take time to process, and while we can adapt to that latency when pressing buttons, it is far harder to adapt when we feel directly connected to a game. Imagine your own body moving just a little bit slower than you actually commanded it to. Creepy right?
Source: Valve Blog