Decomposition of Inflected Words in a L2 1 Published in: Studies in Second Language Acquisition 31: 403-435. Decomposition of Inflected Words in a Second Language: An Experimental Study of German Participles*

German (past) participles offer a distinction between regular forms that are suffixed with -t and do not exhibit any stem changes, and irregular forms that all have the ending -n and sometimes undergo (largely unpredictable) stem changes. This paper reports the results from a series of psycholinguistic experiments (acceptability judgments, lexical decision, and masked priming) that investigate regular and irregular participle forms in adult native speakers of German in comparison to advanced adult second language (L2) learners of German with Polish as their first language (L1). The most striking L1-L2 contrasts were found for regular participles. Although the L1 group’s performance was influenced by the combinatorial structure of past participle forms, this was not the case for the L2 group. These findings suggest that adult L2 learners are less sensitive to morphological structure than native speakers and rely more on lexical storage than on morphological parsing during processing. Decomposition of Inflected Words in a L2 3 In a recent review of neurocognitive and psycholinguistic studies of native language (L1) comprehension, Marslen-Wilson (2007) concluded that the decomposition of morphologically complex words is “one of the highest priorities” (p. 30) of the system. Morphological decomposition is an early process that attempts to identify possible stems, affixes, and other elements of morphological structure as soon as orthographic or phonological information starts to accumulate. Although irregular forms are typically represented and processed as undecomposable whole forms, decomposition applies to regular forms that, due to their morphological structure, do not “participate in language comprehension as whole forms, but rather as bearers of inflectional morphemes and of stem morphemes” (Marslen-Wilson, p. 30). This study examines the processing and representation of morphologically complex words in a nonnative language. We compare adult (so-called late) learners who acquired a language as a L2 around or after puberty with adults who acquired the same language as a L1 from birth. The background for this study is the question of how nonnative language processing differs from native language processing. Current views on this question are controversial (see Clahsen & Felser, 2006b). Some researchers have argued that in particular domains of grammar adult L2 processing is unlike L1 processing, even in L2 learners who achieve high scores in general proficiency tests. With respect to sentence processing, Clahsen and Felser (2006a) proposed that during online processing, adult L2 learners make less use of syntactic structure and abstract syntactic elements (e.g., movement traces) than native speakers and, instead, rely more on lexico-semantic information, associative patterns, and other surface cues for interpretation. A similar proposal came from Ullman (2004, 2005). For L1 processing, two brain memory systems are distinguished: a declarative system that subserves the storage of memorized words and phrases (and is rooted in a network of specific brain structures that include medial temporal and prefrontal cortical regions) and a procedural Decomposition of Inflected Words in a L2 4 system that is involved in processing combinatorial rules of language (and that depends on a network that includes inferior frontal brain areas). Ullman (2005) argued that, due to maturational changes in childhood that lead to the attenuation of the procedural and to the enhancement of the declarative brain memory system, L2 processing is largely dependent on the lexical memory system whereas reliance on the procedural system occurs to a much lesser extent than in L1 processing. Consequently, morphological computation (which engages the procedural brain system) should be underused or even absent in adult L2 processing. In contrast to these proposals, other researchers (e.g., McDonald, 2006; Perani & Abutalebi, 2005) have argued that L2 processing relies on the same mechanisms as L1 processing but that L2 processing may be slower, more effortful, and less automatized than in native speakers. Thus, from this perspective, L1-L2 performance differences should be attributable to general factors such as slower processing speed and working-memory limitations and should not be restricted to particular domains of language or grammar. There is some evidence from previous studies that suggests that L1 and L2 morphological processing differ along the lines proposed by Ullman (2005). In a speeded production task on English past-tense forms, Ullman, Babcock, and Brovetto (2008) found that frequency effects showed a different pattern between regular and irregular verb forms in L1 speakers of English and two groups of L2 speakers (with Chinese or Spanish as their L1). Whereas for the L1 speakers, the magnitude of frequency effects was significantly greater for irregular than for regular verb forms, no effect of frequency on regular or irregular verb forms was observed in the L2 data. Ullman et al. interpreted these results as evidence for a greater reliance on memorization of inflected forms (which include regular verb forms) in the L2 than in the L1. Another study (Silva & Clahsen, 2008) revealed priming effects for regular inflection and for derived word forms of English in the L1,1 but no priming effects for inflected word forms in L2 learners (with Chinese, Japanese, or German as the L1), and Decomposition of Inflected Words in a L2 5 reduced effects for derived words in Chinese and German L2 learners of English, which suggests that L2 learners rely less on combinatorial processing than native speakers. Other studies, however, did not find any such L1-L2 differences in processing inflected words, for instance in the production times (Beck, 1997; Lalleman, van Santen, & van Heuven, 1997) or in the priming patterns of regularly inflected word forms (Basnight-Brown, Chen, Hua, Kostić, & Feldman, 2007), and concluded that adult L2 learners process morphologically complex words in the same way as native speakers. The empirical picture from previous studies is fragmentary and inconclusive. More research is needed on adult L2 processing of different morphological systems and in different languages. A better understanding of L2 morphological processing may also be achieved by adopting theoretical notions from previous psycholinguistic research. An important distinction is made in models of the mental lexicon (see, e.g., Marslen-Wilson, Tyler, Waksler, & Older, 1994) between access representations, which are modality-specific (e.g., to visual or auditory recognition) and encode form-level (orthographic or phonological) information, and central lexical entries, which are modality-independent and incorporate abstract phonological as well as morphological, syntactic, and semantic information. For example, consider the results from priming studies of derivational forms in native speakers of English (see Marslen-Wilson, 2007): In crossmodal priming tasks in which primes and targets are presented in different modalities (i.e., auditory primes and visual targets), only semantically transparent pairs (e.g., calmness-calm) but not semantically opaque pairs (e.g., department-depart) produced robust priming effects. By contrast, in visual masked priming in which primes and targets are both presented visually and the prime is only shown very briefly, priming effects were found for both semantically transparent and opaque prime-target pairs. These contrasts have been taken to indicate that visual masked priming taps an early stage of lexical processing in which formal (orthographic or phonological) access Decomposition of Inflected Words in a L2 6 representations (i.e., lexemes) are activated, whereas crossmodal priming is based on abstract representations (i.e., lemmas) in the central lexicon, a level at which, for example, department and depart have separate lexical entries due to their different semantic properties (MarslenWilson). Given the distinction between access and central representations, three interdependent processes in comprehending an inflected word can be distinguished: (a) segmentation of the original form, (b) form-level access, and (c) retrieval of lexical entries; and, at each level, the morphological structure of an inflected word may or may not play a role. This study presents a detailed examination of one system of German inflection, past participle formation, in groups of L1 speakers and advanced adult L2 learners. Three different experimental techniques were employed: (a) acceptability judgments, to determine preferences for regular and irregular forms of noncanonical words; (b) unprimed visual lexical decision, to examine modality-specific access representations; and (c) masked priming, to determine whether participle forms are morphologically decomposed during early word recognition. Background Here, the linguistic properties of (past) participle formation in German are briefly outlined, some background on participle formation in Polish—the L2 participants’ L1— is provided, and previous psycholinguistic findings on German participles are summarized. Participle Formation in German Regular participles are suffixed with -t and do not exhibit any stem changes, as illustrated in (1a). Irregular or strong verbs have the ending -n and sometimes undergo (phonologically unpredictable) stem changes, as shown in (1b). Additionally, several minor Decomposition of Inflected Words in a L2 7 classes can be distinguished—for example, the so-called A-B-A subclass of strong verbs that have stem changes in the past tense but not for participles, as illustrated in (1c). Moreover, both regular and irregular participles often carry the prefix ge-, which is prosodically determined and occurs whenever the stem is stressed on the first syllable, as illustrated in (1c); the prefix is not inserted when the stress occurs on another syllable, as illustrated in (1d) (see Clahsen, 1999, for a more detailed description, including frequency information). (1) Infinitive Simple past Past participle a. kaufen kaufte gekauft “to buy” “bought” “bought” b. gehen ging gegangen “to go” “went” “gone” c. lau’fen lief gelaufen “to run” “ran” “run” d. verlau’fen verlief verlaufen “go astray” “went astray” “gone astray” Whereas both -t and -n participles have segmentable endings, the -t participle suffix is highly productive and, like the English past-tense suffix -ed, readily applies to novel verbs (Clahsen, 1997), irrespective of whether they are similar to existing verbs. By contrast, verbs that take -n participles represent a lexically restricted closed class of items, and -n participle formation only generalizes to novel words that are similar to existing strong verbs (Clahsen). Consequently, Wunderlich and Fabri (1995) proposed a linguistic analysis of German in which -t participles are formed by the affixation rule in (2a), and -n participles such as (1d) constitute subentries of a restricted set of lexical templates as illustrated in (2b).2 (2) a. /-t/; [+Verb] → [ ]+part b. [[verlauf-]en]+part “gone astray” Decomposition of Inflected Words in a L2 8 The rule in (2a) applies to any element of the syntactic category [+Verb], irrespective of its phonological or semantic properties, and computes a corresponding participle form as its output. It is thus the default process of participle formation in German. The rule is blocked by -n participle forms, which have internally structured lexical entries such as the one in (2b). Participles in Polish In Polish, the perfective passive participle endings are -n-, -on-, and -t-, which precede any person, number, or gender suffixes (Feldstein, 2001). (3) Infinitive Past 3sg masc Past participle a. czyta-ć czyta-ł czyta-n-y “read 1sg masc” b. zrobi-ć zrobi-ł zrobi-on-y “done” c. zdją-ć zdją-ł zdję-t-y “taken off” (Feldstein, p. 84) Verbs with stems ending in -a(j) or -e(j) have -nparticiples as illustrated in (3a). Verbs of the second conjugation have -onparticiple forms as in (3b). The -t suffix is selected by stems that end in a sonorant consonant or nasal vowel as in (3c). Thus, although both Polish and German have -t and -n participle forms, their distribution is clearly different. In Polish, the selection of one of these suffixes depends on conjugation class and on phonological properties of the stem. In German, -n participles are lexically restricted to a limited number of irregular verbs, and the -t suffix is an overall default, much like the past-tense suffix -ed in English. Previous Psycholinguistic Research on German Participles Much previous experimental research on adult and child native speakers of German has shown differences between -t and -n participles consistent with the idea that the former are rule-based and the latter are stored in lexical entries (see Clahsen, 1999, for review). In Decomposition of Inflected Words in a L2 9 German child language, for example, the participle -t is overapplied to irregular verbs, whereas overapplications of the participle -n to regular verbs are practically non-existent (Clahsen & Rothweiler, 1993). Online data from children’s spoken production of participles in a speeded production task also revealed contrasts between regular and irregular forms (Clahsen, Hadler, & Weyerts, 2004). High-frequency -n participles were produced faster than low-frequency ones, whereas there was no corresponding advantage for high-frequency -t participles, which indicates that both child and adult L1 speakers directly retrieve -n (but not -t) participle forms from memory. Turning to L2 processing of German participles, we are aware of just one previous study (Hahne, Mueller, & Clahsen, 2006) that examined event-related brain potentials (ERPs) to morphological violations in a group of advanced adult learners with Russian as their L1 and a control group of German native speakers. Hahne et al. found that an incorrect participle form in which the irregular -n was exchanged with the regular -t (e.g., *gelauf-t instead of gelaufen “run”) produced similar ERP effects in both participant groups—namely, a left anterior negativity in the L1 and a bilateral anterior negativity plus a later parietal positivity (P600) in the L2 group. These ERP effects are thought to be characteristic of morphosyntactic violations, such as incorrect subject-verb agreement and gender or tense marking (see Friederici, 2002). In the interpretation of their results, Hahne et al. thus argued that a form like *gelauft “run” represents a case in which an irregular verb failed to block the general -t suffixation process. Although the similarities in the L1 and the L2 group’s ERPs indicate that advanced L2 learners are sensitive to incorrect participle forms of irregular verbs, Hahne et al.’s study leaves open the question of whether L2 learners process grammatically well-formed regular and irregular participle forms in the same way as native speakers. Decomposition of Inflected Words in a L2 10