In commentary on Gerhard Jäger & Anette Rosenbach's "Priming and Unidirectional Language Change" (Theoretical Linguistics, 2008, 34, 2, 85-113), the authors' diachronic priming hypothesis, holding that the unidirectionality of many types of language change can be explained by the cognitive mechanisms involved in the psycholinguistic technique of priming, is argued to make testable predictions in three areas of concept priming: metaphor, semantic narrowing, & generalization. Examples of each type of semantic shift are examined to show that the reduced time scale of priming, i.e., the activation of a target concept by a source concept in short-term memory, calls into doubt the availability of a source form to prime innovative metaphors, which in practice are primed by immediate recall of elements of the target domain, not the source; e.g., experience with an individual's behavior primes a speaker's recourse to a source in long-term memory for a vivid metaphoric characterization of the behavior. Frequency effects are readily imaginable, though not readily testable, in the case of generalization from a hyponym to a hyperonym, not that of narrowing from a hyperonym to a hyponym. The priming hypothesis might be testable, however, as a predictor of the grammaticalization of a typologically unusual metaphor, e.g., the Aymaran encoding of time in terms of travel while facing backward, with the future coming from behind the speaker. (LLBA, (c) CSA [2009]. All rights reserved)