Area Spells and Big Creatures

[Pinotage]

I can't find this written down anywhere, but does an area effect spell affect a creature occupying more than one square even if it only catches one square that the creature occupies?

So, e.g., if a creature occupies 20x20 ft, and a confusion spell is cast that only touches a few (less than half, for example) of the 16 squares the creature ocupies, is it still affected?

Thanks

Pinotage

 

[Ottergame]

An AOE effect will hit anything that has at least one square 50% filled by the effect.