Advanced technology from the Commonwealth has increased your reaction speed, giving you a higher chance to hit in V.A.T.S.. This perk increases your chance to hit by 10%. As with all perks that increase your chance to hit in V.A.T.S., this bonus is multiplicative, not additive.
To obtain this perk, side with Dr. Zimmer in The Replicated Man, and report A3-21. It's possible to get this perk while siding with A3-21; tell Dr. Zimmer who A3-21 is, and the player will be awarded the perk. Before he and his bodyguard leave the room to reset A3-21, immediately kill them both. If the player character first tells A3-21 they'll kill Dr. Zimmer for him before revealing his identity to Zimmer, he'll give them A3-21's plasma rifle.