Hi !
If its just about to visually notice something without deeper reflection I use Int & Dex as modifying attributes for a task.
So the Int/Dex combination might be used as "internal" perception or reaction skill, just like Int+Edu is used for staying determinend.
Additional modification by a specific skill might happen, when this skill is actively used.
So, noticing something going on in the dark while sitting around a campfire might perhaps depend on a successful (and maybe hidden or unspecified) task roll
Diff, Int, Dex, 1 sec
but furtheron I would let the task be modified by players hunting skill too.
regards,
Mert