How to make Perception tests?

I am a new Fallout GM, and I just wanted to confirm how Perception tests are intended to be done. While in some situations I could see a case made for adding a skill to the tests, there are other cases where it is just such a generalized spot or notice roll, I wonder if no skill should apply?

While I can’t find anything in the rules on this, the official Fallout RPG GM screen has a section labelled “unskilled test attributes”, which lists some icons representing actions and a default ability score. While the rulebook does not discuss “unskilled tests”, I am guessing that a Perception check is intended to be made based on the Perception Attribute only (unless there is some reason to a skill) to the test?

Its normally per+survival as far as i know. I cant remember where it is in the rules. Maybe its in the gamemaster booklet…