This paper provides a frame-based account of the inclusion of non-prototypical members in lexical categorization and semantic classification. It proposes that sense extensions based on metaphorical mappings can be viewed as frame-to-frame transfer, constituting an essential part of our lexical knowledge. Adopting the perspective of frame semantics (Fillmore and Atkins 1991), the study helps delimit and anchors the broad notion of 'domain,' a key concept in defining metaphors, into lexically-attested 'semantic frames' in a principled and systematic manner. Most metaphorical or extended meanings, such as the use of 'mo' (to touch) in 'wo mo bu qing ta de yong yi' (I don't understand his intention), are often neglected by the existing databases. Literally, as a verb of touching, 'mo' is classified as a contact verb, but the above usage of 'mo' clearly indicates its affiliation with cognition verbs. By exploring a number of non-prototypical cognition verbs, 'kan' (to see), 'xiu' (to smell), 'mo', and 'chi' (to eat), this paper aims to propose a mechanism that allows an effective categorization of non-core members into the appropriate verb class by incorporating and redefining metaphorical extensions in a frame-based approach within the framework of frame semantics. (Wen-ching Chang)