Running head: Subliminal Words Activate Categories SUBLIMINAL WORDS ACTIVATE SEMANTIC CATEGORIES (NOT AUTOMATED MOTOR RESPONSES)

Semantic priming by visually masked, unidentifiable ("subliminal") words occurs robustly when the words appearing as masked primes have been classified earlier in practice as visible targets. It has been argued (Damian, 2001) that practice enables robust subliminal priming by automatizing learned associations between words and the specific motor responses used to classify them. Two experiments demonstrated that, instead, the associations formed in practice that underlie subliminal priming are between words and semantic categories. Visible words classified as "pleasant" or "unpleasant" in practice with one set of response key assignments functioned later as subliminal primes with appropriate valence, even when associations of keys with valences were reversed before the test. This result shows that subliminal priming involves unconscious categorization of the prime, rather than just the automatic activation of a practiced stimulus-response mapping. 2 Subliminal Words Activate Categories Subliminal Words Activate Semantic Categories (Not Automated Motor Responses) It is well established that recent experience with a word facilitates its processing on next occurence. This repetition priming effect has lately become germane in the interpretation of unconscious, or subliminal, semantic priming, in which classification of a visible target word is affected by the category (congruent or incongruent) of an immediately preceding, visually masked, unidentifiable ("subliminal") prime word. Evidence accumulated over the last several years indicates that the effectiveness of subliminal words as primes is highly dependent upon recent practice classifying those words in visible form. From this evidence, four conclusions are warranted: First, in studies that used subliminal primes that participants had previously classified in visible form (‘practiced words’, hereafter), priming effects have been robust and easily replicable (e.g., Dehaene et al., 1998; Draine & Greenwald, 1998; Greenwald, Draine, & Abrams, 1996). The robustness of these effects contrasts markedly with findings from procedures that have used nonpracticed subliminal primes (i.e., words that never appeared in visible form in the experiment). Semantic priming effects produced by nonpracticed masked words are widely acknowledged to be small in magnitude and difficult to replicate (for reviews, see Draine & Greenwald, 1998; Forster, 1998). Second, the just-described pattern of contrasting results from experiments using different procedures has been directly confirmed in recent experiments that compared subliminal priming by practiced and nonpracticed words (Abrams & Greenwald, 2000; Damian, 2001; Drury & Klinger, 2000). In these studies, practiced primes produced consistently large subliminal priming effects, whereas nonpracticed primes produced effects that were either nonsignificantly positive or statistically significant but small in magnitude. Third, practice has been shown not only to enable robust subliminal priming as just described, but also to override effects expected on the basis of existing, well established semantic knowledge. For example, in a lexical decision experiment in which participants have practiced classifying doctor as a visible word, the subliminal word doctor primes both semantically related (nurse) and unrelated (truck) word targets (relative to a baseline condition in which primes are nonwords; Klinger, Burton, & Pitts, 2000). Fourth, this practice effect depends on more than just perceptual encounter with the visible words at time of practice. Practice benefits subliminal priming only when it involves classification into the same categories that will later be used to classify target words in the priming task. When words are repeatedly named but not classified in practice, those words remain ineffective as subliminal primes in a semantic classification task (e.g., animate vs. inanimate object; Damian, 2001). In sum, practice enables effective priming by words that, without practice, apparently receive little analysis. How might practice produce this benefit? Several theories of repetition effects potentially bear on this question (e.g., Morton, 1969; 3 Subliminal Words Activate Categories Treisman, 1960). We focus here, however, on a recent suggestion that links subliminal priming by practiced words to the phenomenon of automaticity. Specifically, it has been suggested that subliminal priming is driven by automation of motor responses (Damian, 2001). According to this view, the critical associations established in practice are between individual words and the responses that are made in categorizing them (word-response mappings). Repeated association of a word with its motor response makes the mapping automatic. When the same word later appears as a subliminal prime, it elicits automatically—outside of attention and awareness—the practiced motoric response. The chief alternative view is that practice establishes word-to-category mappings, rather than word-to-response mappings (cf. Logan, 1990). Word-category mappings are the associations of words to the categories that are used to classify them in the experimental task. These categories may be long-established ones, such as pleasant versus unpleasant meaning, or they may be more ad hoc, such as the word-nonword categories that are used in lexical decision tasks. The word-category interpretation is not necessarily incompatible with automaticity, but it is in contrast with the view that automaticity develops principally for specific motor responses. The present experiments sought to distinguish between the word-to-response and word-to-category interpretations of the effect of classification practice on subliminal priming. The method was straightforward – we arranged conditions such that the response called for by the practiced word-to-category mapping was opposite from that called for by the practiced word-to-response mapping. Words practiced using one set of response assignments (for example, left-hand keypress for pleasant words, right-hand for unpleasant) appeared as subliminal primes in a later task in which classification instructions were reversed from the earlier practice (left hand for unpleasant, right hand for pleasant). If word-to-response mappings underlie subliminal priming, then words practiced with one hand should prime targets classified with the same hand (even though those targets belong to the opposite category). Alternatively, the word-to-category view predicts that practiced words should act with their appropriate valence even though the response assignments have been reversed. Experiment 1 Experiments 1 and 2 were designed to test between the predictions of the word-response interpretation (that priming should be determined by practiced response assignment) and the word-category interpretation (that priming should be determined by practiced category). They were carried out in parallel, Experiment 1 at University of Alabama and Experiment 2 at University of Washington. Both used similar designs and procedures, the main difference being that Experiment 1 presented masked primes for a slightly longer duration (50 ms) than in Experiment 2 (33 ms). 4 Subliminal Words Activate Categories