  Higher-order theories come in two main variants that differ concerning the psychological mode of the relevant conscious-making meta-mental states. Higher-order thought (HOT) theories take the required higher-order state to be an assertoric thought-like meta-state (Rosenthal 1986, 1993). Higher-order perception (HOP) theories take them to be more perception-like and associated with a kind of inner sense and intra-mental monitoring systems of some sort (Armstrong 1981, Lycan 1987, 1996).