Perception determines how far away enemies can be detected on the compass (enemies show as red bars). When playing with a high Perception, it is possible to "sense" the enemies even before they come into view.
Having a high Perception can yield dialogue options with some NPCs, such as Moira Brown, Mel and Machete.
Contrary to what the name would make one believe, Perception does not actually increase V.A.T.S or regular accuracy at all.
If Perception is at the most extreme (highest or lowest), Doc Mitchell will either respond that nothing gets by the Courier, thinking he could use them when he lost his keys last month [of awakening the Courier] (for highest) or that he is no optometrist, but suggests the Courier should be fitted some with glasses while at the Doc's place (For lowest). However, having perception this low means that you cannot take the Four Eyes trait which would make glasses beneficial.
Dialogue with Christine has numerous Perception checks between 6 and 8. Intelligence checks of similar levels can substitute for some, but not all of them.
It is possible to artificially get a Perception of 10 with only 6 natural points, by combining the Four Eyes trait, Lucky shades, a hat and the Perception Implant (6 - 1 + 3 + 1 + 1 = 10).
Similarly, it is possible to achieve a temporary boost to 10 from a mere score of 2 using both kinds of Mentats, Absinthe, Coyote Tobacco Chew, and a hat (2 + 4 + 3 + 1 = 10).
By having access to DLC items, it is possible to get up to PE 10 without the Four Eyes trait, even if starting at only 1. The Elite riot gear helmet (+2) can be worn together with the 1st Recon beret (+1) and a Stealth suit Mk II (+1). After installing the Perception implant, Perception is at 6. From there, any combination of Perception-enhancing chems can reach 10.
“Perception is your environmental awareness and "sixth sense," and affects weapon accuracy in V.A.T.S.”
With the removal of skills in Fallout 4, Perception now directly affects accuracy in V.A.T.S., lockpicking, and stealing attempts.
The main difference from Fallout 3 and Fallout New Vegas is that perception no longer affects the distance at which enemies appear on the player character's compass. Enemies do not appear on the compass in Fallout 4 unless they are looking for the player character (Caution in sneak mode) or are fighting the player character (Danger in sneak mode). Friendly NPCs do not appear on the compass at all. However, Perception increases accuracy in V.A.T.S. by 10% per stat invested into it, but accuracy cannot go above 95%.
Perception affects how efficient a dweller is while working in the water treatment and water purification facilities as well as the speed of the critical hit arrows. It can be increased on different dwellers by assigning them to the armory.
pc It is possible that your perception will be reduced with a "(-)" shown to indicate a temporary effect, even if there are no visible temporary effects. Console commands can only mask the issue, not solve it. For players on Survival mode, the lack of a console means that they are stuck with a low perception.[verified]
Because the (-) indicates a temporary effect, perks can still be chosen as normal based on your "true" perception.
A commonly reported culprit is being crippled in the head; having your head cured may not remove the debuff. Having your head re-crippled and cured may resolve the issue, but is inconsistent.