Conceptual and Nonconceptual Priming 3 Conceptual and Nonconceptual Repetition Priming in Category Exemplar Generation : Evidence from Bilinguals

One measure of conceptual implicit memory is repetition priming in the generation of exemplars from a semantic category, but does such priming transfer across languages? That is, do the overlapping conceptual representations for translation equivalents provide a sufficient basis for such priming? In Experiment 1 (N = 96), participants carried out a deep encoding task, and priming between languages was statistically reliable, but attenuated, relative to within-language priming. Experiment 2 (N = 96) replicated the findings of Experiment 1 and assessed the contributions of conceptual and non-conceptual processes using a levels-of-processing manipulation. Words that underwent shallow encoding exhibited within-language, but not between-language, priming. Priming in shallow conditions cannot, therefore, be explained by incidental activation of the concept. Instead, part of the within-language priming effect, even under deep-encoding conditions, is due to increased availability of language-specific lemmas or phonological word forms. Conceptual and Nonconceptual Priming 3 Conceptual and Nonconceptual Repetition Priming in Category Exemplar Generation: Evidence from Bilinguals The degree to which memory processes transfer between languages is an indicator of both the extent to which a memory measure relies on conceptual-level processing and the extent to which episodic representations of translation equivalents are shared across languages. The present study compares repetition priming within and between languages in an implicit memory task that has been classified as conceptually driven. Two experiments measured the extent of transfer between languages and the impact of non-conceptual processes on repetition priming in category exemplar generation. Dissociations among various implicit memory tasks have revealed that implicit memory has multiple cognitive and neural bases (see, e.g., Gabrieli, 1998). In the present investigation, instead of comparing patterns of priming for different tasks, the component processes within a single priming paradigm were isolated to reveal multiple mechanisms of priming. Implicit memory is exhibited in several behaviorally observable transfer or priming phenomena. Repetition priming can be measured as an increase in accuracy, a decrease in response time, or a response bias based on previous exposures to specific items. Several repetition priming paradigms have been developed to measure the bias to produce items presented at encoding, including category-exemplar generation, word-stem completion, word-associate generation, and homophone spelling. In the present study, category exemplar generation priming was the paradigm used. Category Exemplar Generation Priming The category-exemplar-generation priming procedure, developed by Graf, Shimamura, and Squire (1985) to measure conceptual implicit memory, involves an encoding phase and a test Conceptual and Nonconceptual Priming 4 phase. In the encoding phase, participants make judgments about words that are members of different semantic categories. In the test phase, participants are given the name of one category at a time and asked to generate the first several exemplars that come to mind. Some of the tested categories corresponded to exemplars that appeared in the encoding phase, and others to new categories for which no exemplars appeared in the encoding phase. Given appropriate counterbalancing across participants, evidence of conceptual priming consists of exemplars being produced more often when they appeared in the encoding phase then when they did not. Evidence that this effect depends on implicit rather than explicit memory comes from studies showing that category-exemplar-generation priming is preserved in both amnesic patients (Graf et al., 1985; Keane et al., 1997) and older adults (Light & Albertson, 1989; Light, Prull, & Kennison, 2000; Monti et al., 1996), whereas category-cued recall is impaired in these populations. Two main sources of evidence support a conceptual basis for the category-exemplargeneration priming effect. First, the magnitude of the priming effect depends on the degree of semantic processing during initial encoding of the category members. Priming has been shown to be sensitive to depth-of-processing manipulations, exhibiting a greater magnitude of priming with a semantic encoding task than with a non-semantic encoding task (Hamann, 1990; Keane et al., 1997; Kinoshita, 1989; Monti et al., 1996; Mulligan, Guyer, & Beland, 1999; Srinivas & Roediger, 1990; Vaidya et al., 1997; Weldon & Coyote, 1996). The priming effect is also greater for words generated at encoding rather than simply readwhen the basis for generation task is semantic (Mulligan, 2002; Srinivas & Roediger, 1990), but not if the basis is non-semantic (Kinoshita, 1989; Mulligan, 2002). Manipulations that make semantic associations among the stimuli more salient also increase priming. For example, blocking the encoding sequence by Conceptual and Nonconceptual Priming 5 category tends to increase priming (Mulligan & Stone, 1999; Mulligan et al., 1999; Rappold & Hashtroudi, 1991), as does instructing participants to use a categorical strategy with a randomly ordered sequence of exemplars (Rappold & Hashtroudi, 1991). The second source of evidence for the conceptual basis of category-exemplar-generation priming is the high degree of transfer observed between different perceptual forms of the category members. The standard implementation of the procedure is with visual encoding and spoken responses at test, meaning that the standard effect is cross-modal, and when category exemplars were presented in picture format at encoding, priming was substantial and typically did not differ reliably from priming obtained with words (McDermott & Roediger, 1996; Weldon & Coyote, 1996; but see Vaidya & Gabrieli, 2000). Considerations that Motivate the Present Research Because auditory word, visual word, and picture formats share a common concept, such transfer is often taken to indicate a conceptual contribution to priming. A problem, however, with this logic is that these forms also share non-semantic attributes. A particular word, whether presented in the auditory or the visual modality retains the same identity in terms of its syntactic, phonological, and orthographic word forms. Similarly, a picture and the word that names it are tied to common word-form information. In contrast, non-cognate translation equivalents have distinct word forms, so any transfer between these forms must be based on their common meaning rather than the word form. Both of the present experiments examine priming between translation equivalents in category exemplar generation. Although the findings reviewed above indicate a conceptual contribution to priming, they do not indicate that category-exemplar-generation priming has an exclusively conceptual basis. On the contrary, several studies have shown substantial priming following read-only or shallow Conceptual and Nonconceptual Priming 6 processing instructions at encoding (Light et al., 2000; Mulligan, 2002; Mulligan & Stone, 1999; Rappold & Hashtroudi, 1991; Srinivas & Roediger, 1990; Vaidya & Gabrieli, 2000; Vaidya et al., 1997). These effects are smaller than those obtained with semantic processing at encoding and less consistent (i.e., their reliability was not consistent across experiments within a study). The attenuated, yet substantial, priming effects observed even in non-semantic conditions suggest that there is also a substantial non-semantic component to category exemplar generation priming, perhaps based on increased availability of the word forms associated with the target exemplars. An alternative explanation is that the priming observed following read-only or shallow processing instructions is due to conceptual activation that may occur automatically when a word is read. It is premature, however, to dismiss these effects as artifacts of uninstructed semantic processing without having countervailing evidence. A bilingual design allows for a test of this explanation. To the extent that shallow encoding elicits priming between languages, the explanation based on incidental conceptual activation would be supported. In contrast, if shallow encoding did not elicit priming between languages, the idea that non-semantic factors contribute to the standard effect becomes a more plausible explanation. This issue is addressed in Experiment 2. Bilingual Representations of Translation Equivalents In Experiments 1 and 2, bilingual materials were used to facilitate the separation of different components of priming. Using bilingual materials allows using two alternative labels (translation equivalents) to refer to a single object or concept, but these labels have distinct word forms. The cognitive experimental literature on bilingual memory and language processing shows that for highly proficient bilinguals, translation equivalents of concrete nouns have shared conceptual representations (de Groot, 1992; Francis, 1999, 2005). This evidence is sufficient to Conceptual and Nonconceptual Priming 7 justify using bilingual translation equivalents as alternate paths to a single conceptual representation. One strategy used to assess whether representations are shared or separate has been to examine memory transfer between languages. This approach, based on the principle of transferappropriate processing (Morris, Bransford, & Franks, 1977; Roediger & Blaxton, 1987), assumes that the degree of transfer from encoding to test depends on the degree of processing similarity from encoding to test. Thus, if an encoding task leads to facilitation in a test task, we can conclude that the tasks have processes in common or activate common mental representations. In the bilingual case, memory transfer between languages is taken as evidence for shared (i.e., language-general) episodic representations, and this evidence is, in turn, typically interpreted as evide