Originally Posted by
Vaern
The description on potions says that they are "like spells cast upon the imbiber," with the imbiber being designated both the caster and target for the purposes of the spell.
The general description of scrolls describes them as "basically like casting a spell," and that spells activated from a scroll "work exactly like a spell prepared and cast the normal way."
Wands and staves both include the phrase, "casting a spell from a [wand/staff] is usually a standard action," which leaves basically zero ambiguity that it is a spell being cast.
All three appear to function as though the user is actually casting a spell.