If you take the Four Eyes trait, which is supposed to give you +2 perception with glasses and -2 perception without does that +2 add to the +1 perception you get when you wear eyeglasses that already give you +1 perception? Also, what if you have Four Eyes and wear headgear that gives you +1 perception?

I am trying to make a new character and I am working on my SPECIAL. Can anyone help?

Correct me if I'm wrong, but I don't think any glasses in NV give a P bonus. So if your base P is 5, with glasses you now have 7.
Wearing a hat with a P bonus also adds +1.

I stand corrected, thanks.

The authority glasses and lucky shades give perception, I think they all do.

The Lucky shades give a Luck bonus, the authority glasses don't have any bonus.

My bad, always pick that trait for the perception and no negative side effect, since glasses are easy to come by. So any pair I pick up actually say +2 perception.

well, if yout base perception (and with base I mean the perception you set at the Vigor machine) is 5, then dont expect to get a perception of 7 when you wear glasses.

Four eyes work by reducing your base perception by 1 and then adding a temporary +2 while wearing glasses. This can affect the perk availability, e.g. if you start with perception 6 and take this trait you'll no longer be able to take better criticals perk which requires base value 6.

Sorry if I misunderstand you, but that's exactly what the trait does. If your base is 5 then with glasses you get a +2 bonus to make a P of 7.
Without glasses you get -1 P and get 4.

with base perception I mean your perception when you havent taken the trait yet. When you take the trait your base perception is lowered by one and every pair of glasses ads 2 points of perception,

The -1P is a permament decrease of your base stat, while wearing glasses you get a temporary +2.

5-1+2=6

Yeah good call, just checked the Wiki - didn't realize there was a permanent -1. My bad.

Pipi took the Four-Eyes Trait. She has...

Base PER 5, -1 from Four-Eyes = PER 4, wearing glasses +2 = PER6, 1st Recon Beret +1 = PER7

+1 for Intense Training and +1 Implant = PER9. Also has ED-E as companion with Enhanced Sensors.
She probably didn't need the IT or Implant but I like it high because I'm EW.

I didn't like the Four-Eyes Trait before but wearing glasses and a hat with ED-E along makes up for the negative and a high PER helps EW, Explosives and Lockpick.