Fear

Rat-Ogres are big, frightening blasphemies against nature which cause fear in other creatures. The psychological rules for fear therefore apply.

Stupidity

Being incredibly single-minded, Rat-Ogres that aren't in close combat are subject to the psychological rules for stupidity. However, as long as they are led by a Clan Moulder Packmaster or a Skaven character acting as Packmaster the Rat-Ogres don't have to think for themselves and don't suffer from stupidity.