Two models of metaphor processing are contrasted. The structure-mapping model postulates an initially role-neutral alignment process, followed by directional projection of inferences. The attributive categorization model postulates role-specific processing throughout comprehension . To test between these models, the early stages of metaphor comprehension were probed using a technique based on S. Glucksberg, P Gildea, and H. Bookin's (1982) finding that metaphorical meaning interferes with literal truthfulness judgments. In Experiment 1, interference effects did not differ between normal metaphors and metaphors with reversed terms, suggesting that initial processing is role-neutral. In Experiment 2, we again found no role dependence in interference effects, even for highly conventional metaphors. In Experiment 3, it was verified that (a) full comprehension is role-sensitive and (b) full comprehension reaction times (RTs) are far longer than interference RTs, buttressing the claim that interference is an early-stage effect. Overall, the results support the structure-mapping model of metaphor processing. Metaphors both highlight commonalities and invite new inferences. Whereas finding commonalities can be conceived of as a symmetrical matching process, the inference projection process is by nature asymmetrical ; information is directionally projected from the vehicle (or base) to the topic (target). For example, in a nominal metaphor such as A rumor is a virus, ideas such as contagion that are normally associated with the vehicle concept, virus, are projected to the topic concept, rumor. The role specificity of metaphoric processing is revealed when the ordering of the terms is changed (Glucksberg & Keysar, 1990 ; Miller, 1993 ; Ortony, 1979 ; Ortony, Vondruska, Foss, & Jones, 1985). For example , if the terms of the aforementioned metaphor are reversed, the resulting statement, A virus is a rumor, seems pointless. In other cases, reversing the terms produces a change in meaning. For example, the metaphor My surgeon is a butcher suggests cutting sloppily, whereas its reversal, My butcher is a surgeon, suggests cutting precisely. Models of metaphor and analogy differ in their assumptions as to when in processing this asymmetry appears. The key dichotomy here is between models that explain metaphors in terms of comparison processing and models that explain metaphors in terms of category processing .