When a character must make a saving throw (typically vs spell) because some entity has mentally or magically attacked them, but when there is no sensory aspect to the attack, if the character succeeds at the save, are they aware that an attack was attempted but had no effect? Is there anywhere in the 2nd Edition source books that speaks to this topic?

Examples

An Aboleth attempts to mentally enslave someone.

The aboleth can attempt to enslave creatures within 30 feet; it can make three attempts per day, one creature per attempt. If the victim fails a saving throw vs. spell, he follows all of the aboleth's telepathic commands, although the victim will not fight on the aboleth's behalf.

A priest casts the 2nd level spell Hold Person spell (or a wizard casts the 3rd level hold person spell) but the player character makes their save vs spell.

Those who succeed on their saving throws are totally unaffected by the spell.

A wizard casts the 1st level spell Charm Person but the player character makes their save vs spell.

A wizard casts the 4th level spell Confusion but the player character makes their save vs spell.

Those successfully saving are unaffected by the spell.