Holger Hopp
email: hopp@let.rug.nl

Syntactic features and reanalysis in near-native processing

In order to investigate second language (L2) processing at ultimate attainment, 20 first language (L1) English and 20 L1 Dutch advanced to near-native speakers of German as well as 20 native Germans were tested in two experiments on subject-object ambiguities in German. The results from a self-paced reading task and a speeded acceptability judgement task show that the lowerproficient advanced learners in this study display the same processing preferences as natives in reading accuracy yet fail to demonstrate differential response latencies associated with native syntactic reanalysis. By contrast, near-native speakers of either L1 converge on incremental native reanalysis patterns. Together, the findings highlight the role of proficiency for processing the target language since it is only at near-native levels of proficiency that non-natives converge on native-like parsing. The results support the view that endstate non-native processing and native processing are qualitatively identical.

I Introduction

Research on ultimate attainment in the L2 has hitherto investigated whether endstate L2 speakers attain levels of grammatical knowledge comparable to that of native speakers (e.g. [START_REF] Hyltenstam | Maturational constraints in SLA[END_REF][START_REF] Sorace | Near-nativeness[END_REF]. By contrast, little or no research on endstate L2 learners has addressed the real-time processing of the target language, in spite of the potentially far-reaching implications. After all, the psycholinguistic mechanisms and processes involved in L2 comprehension could be a barrier to attaining native-like proficiency and competence in a second language.

A large body of psycholinguistic research on native-language sentence comprehension attests that parsing involves, amongst other things, the incremental computation of phrase structure according to grammatical rules and parsing preferences (e.g. [START_REF] Frazier | Sentence processing: a tutorial review[END_REF]. Not least, sentence comprehension implicates the rapid coordination of syntactic, morphological, lexical, semantic and pragmatic information. Faced with this task, non-native processing might be subject to delays, inefficiencies or qualitative differences compared to native processing that potentially persist up to and including ultimate attainment. Some psycholinguistic studies on intermediate to advanced L2 learners indeed claim that L2 learners in general show a reduced sensitivity to syntactic information in non-native parsing (e.g. Felser and Roberts, to appear) compared to native speakers, while several off-line studies on fossilized endstate learners suggest that the computational demands of coordinating different types of morphological and syntactic information in real time leads to non-convergence at the L2 endstate (Lardiere, 2000;[START_REF] White | Fossilization in steady state L2 grammars: persistent problems with inflectional morphology[END_REF]; see also Sorace, 2005).

This study explores the on-line use of parsing principles and syntactic features in the L2 processing by English and Dutch advanced to near-native speakers of German. Two psycholinguistic experiments on local subject-object ambiguities in German were run to investigate, first, the extent to which non-natives employ syntactic information in parsing similar to native speakers and, second, the extent to which such sensitivity varies as a function of proficiency or L1. The article is structured as follows: Section II reviews previous research on non-native processing of syntactic ambiguities. Section III outlines the native processing of subject-object ambiguities in German. The two experiments are reported in Section IV, and Section V offers a general discussion of the findings.

II L2 Processing of syntactic ambiguities

Psycholinguistic research often studies the processing of sentences that are (temporarily) syntactically ambiguous in order to explore preferences and strategies in parsing. Research on syntactic ambiguity resolution in L2 processing has focused on relative clause attachment and filler-gap ambiguities in wh-movement. Considering first relative clauses such as 'He thanked the secretary of the professor who never drank wine', cross-linguistic studies find that relative clauses preferentially attach to the second NP in English (i.e. low attachment), yet to the first NP in Greek, Spanish, German and French (i.e. high attachment). Attachment preferences have been argued to reflect parameterized syntactic processing principles [START_REF] Gibson | Recency preferences in the human sentence processing mechanism[END_REF]. Testing advanced learners of English and Greek of various L1 backgrounds on self-paced reading, [START_REF] Felser | The processing of ambiguous sentences by first and second language learners of English[END_REF] and [START_REF] Papadopoulou | Parsing strategies in L1 and L2 sentence processing: a study of relative clause attachment in Greek[END_REF], respectively, conclude that non-natives do not show any attachment preference in on-line reading in the L2, irrespective of L1 background. These authors suggest that the lack of attachment preferences is owing to the learners' failure to apply native-like syntactic parsing principles in the L2 (see also [START_REF] Papadopoulou | Reading-time studies of second language ambiguity resolution[END_REF]. Other studies, however, find robust preferences in on-line reading. [START_REF] Dussias | Syntactic ambiguity resolution in second language learners: some effects of bilinguality on L1 and L2 processing strategies[END_REF] reports that Spanish learners of English show native-like preferences in reading the L2; however, these learners, unlike Spanish monolinguals, also show a low attachment preference in their native Spanish (see also [START_REF] Fernandez | Bilingual sentence processing[END_REF]. Using eye-tracking, [START_REF] Frenck-Mestre | An on-line look at sentence processing in the second language[END_REF]2005) finds that highly proficient English speakers of French show a native-like high attachment preference in the L2, while a less proficient group demonstrates a low attachment preference as in the L1 (see also [START_REF] Frenck-Mestre | Syntactic ambiguity resolution while reading in second and native languages[END_REF].

Reading-time studies on gap-filling effects in wh-movement by [START_REF] Juffs | Garden-path sentences and error data in second language sentence processing[END_REF], [START_REF] Williams | Native and non-native processing of English wh-questions: parsing strategies and plausibility constraints[END_REF] and Juffs (2005) demonstrate that, like natives, non-natives attempt to integrate a displaced constituent as early as possible with a potential subcategorizer, thus showing evidence of the application of economy-based parsing principles like the Active Filler Strategy [START_REF] Clifton | Comprehending sentences with longdistance dependencies[END_REF]. These results suggest native-like processing in the L2. However, using cross-modal priming, [START_REF] Marinis | Gaps in second language sentence processing[END_REF] and Felser and Roberts (to appear) find no evidence of native-like reactivation of the filler at intermediate trace positions in wh-chains. They suggest that the non-natives relate the filler directly to the verb by means of its thematic structure. In a similar vein to [START_REF] Felser | The processing of ambiguous sentences by first and second language learners of English[END_REF] and [START_REF] Papadopoulou | Parsing strategies in L1 and L2 sentence processing: a study of relative clause attachment in Greek[END_REF], they argue that non-natives underuse syntactic information in parsing and over-rely on lexical-semantic and pragmatic information to compensate for their relatively 'shallower' syntactic processing. [START_REF] Clahsen | Grammatical processing in first and second language learners[END_REF] dub this approach, which postulates a qualitative difference between native and non-native parsing, the 'Shallow Structure Hypothesis'.

All of the studies reported above were conducted with intermediate to advanced L2 learner groups and did not include proficiency as a potential variable for parsing behaviour in the L2. Even though the findings by [START_REF] Frenck-Mestre | An on-line look at sentence processing in the second language[END_REF] suggest that degree of proficiency affects the degree to which syntactic processing in the L2 proceeds in nativelike fashion, there have been no studies to date on processing syntactic ambiguities at ultimate attainment in the L2.

III Word order, syntactic features and native processing in German

In German, which has base SOV order, the object can optionally precede the subject in embedded clauses, such as in (1b Syntactic reordering as in (1b), so-called scrambling, is usually analysed as movement of the dislocated object targeting an adjoined position higher than the subject (e.g. [START_REF] Haider | Scrambling[END_REF]. The syntactic function of NPs in German is overtly expressed by case marking as in (1) where the definite determiners disambiguate the sentence. Due to syncretistic case morphology, however, the syntactic status of NPs can also remain locally ambiguous up to the clause-final verb as in (2), in which the order of NPs is disambiguated by virtue of number agreement between the verb and the subject.

2) a. Er sagt, dass die Kellnerin SG die Kollegen PL gesehen hat SG . He says that the NOM/ACC waitress the NOM/ACC colleagues seen has 'He says that the waitress saw the colleagues.' b. Er sagt, dass die Kellnerin SG die Kollegen PL gesehen haben PL . He says that the NOM/ACC waitress the NOM/ACC colleagues seen have 'He says that the colleagues saw the waitress.' A large set of processing studies has exploited the different syntactic ordering options in German. Native speakers of German show a robust subject-initial preference when reading clauses with multiple animate arguments (e.g. [START_REF] Bader | Subject-object ambiguities in German embedded clauses: an across-the-board comparison[END_REF][START_REF] Hemforth | German sentence processing[END_REF]. Such a preference has been viewed as the result of universal parsing principles dictating the serial parser to construct as economical a well-formed grammatical structure as possible (3).

3) Minimal Chain Principle (de Vincenzi, 1991: 13; see also [START_REF] Frazier | Sentence processing: a tutorial review[END_REF][START_REF] Gorrell | Syntax and parsing[END_REF]; 'Avoid postulating unnecessary chain members at S-structure, but do not delay required chain members.'

In accordance with (3), the parser incrementally constructs the default subject-initial phrase structure in (4a) upon encountering the first NP. However, when morphosyntactic information disabuses the parser of its subject-initial preference (e.g. case marking on determiners in (1b)), phrase-structural revision (reanalysis) to the less economical OS order in (4b) becomes necessary.

4)

Reanalysis to the OS order is computationally costly in that native speakers evince measurable garden-path effects with OS orders in parsing. These garden-path effects are expressed in reading slowdowns on the regions of disambiguation towards the OS order and in lower comprehension accuracy of OS orders. The strength of garden-path effects has been shown to be relative to the type of syntactic disambiguation (among other things). Disambiguation of order via case on NPs as in (1) elicits fairly weak reanalysis effects, while disambiguation via verbal agreement as in (2) gives rise to strong garden-path effects [START_REF] Meng | Ungrammaticality detection and garden path strength: evidence for serial parsing[END_REF]. This difference is not simply due to the delay of disambiguation in (2) compared to (1), since studies on ambiguous wh-questions in German matrix clauses (e.g. the equivalent of 'Which waitress have/has the colleague seen?'), where the region of disambiguation by verbal agreement precedes the region of disambiguation by case on the second NP, yield the same result [START_REF] Meng | Ungrammaticality detection and garden path strength: evidence for serial parsing[END_REF][START_REF] Schlesewsky | Case as a trigger for reanalysis: some arguments from the processing of double case ungrammaticalities in German[END_REF].

Instead, the difference between case and number features for disambiguation has been linked to the degree of informativity of syntactic features for reanalysis (Fodor and Inoue, 2000). According to the Diagnosis Model of reanalysis of [START_REF] Fodor | The diagnosis and cure of garden paths[END_REF]1998), reanalysis is facilitated if the syntactic feature identifying a misparse redirects the parser to the original parsing error by means of grammatical relations and then also leads to the automatic correction of the erroneous parse.

To illustrate, overt accusative case marking on the first incoming NP in (1b) signals to the parser, first, that this NP is an object rather than the grammatical subject of the clause and, second, that the parser needs to create an additional slot for this NP to keep the subject position available. Hence, a case cue signals a misparse (diagnosis) in parsing and automatically leads to the correct parse (repair). By contrast, consider (2) in this respect: Having filled the subject position with the singular NP die Kellnerin ('the waitress'), the parser encounters the plural verb haben ('have') and tries to coindex the two by means of an agreement relation. This, however, leads to a number mismatch that signals an erroneous parse (diagnosis). Although the number mismatch engenders a severing of the agreement relation between the first NP and the verb, it does not entail the correct parse, since it specifies neither the syntactic function of the first NP nor the correct agreement relation of the verb. In short, verbal agreement is a negative symptom in that it diagnoses the misparse, yet does not automatically lead to repair, whereas case is a positive symptom in reanalysis that elicits automatic repair (Fodor and Inoue, 2000). The differential characteristics of syntactic features in parsing lead to more depressed processing accuracy for OS orders disambiguated by verbal agreement than by case.

The Diagnosis Model also correctly predicts that the inverse pattern, i.e. more depressed accuracy for case than for verbal agreement, obtains in the processing of ungrammatical sentences under time pressure [START_REF] Meng | Ungrammaticality detection and garden path strength: evidence for serial parsing[END_REF][START_REF] Schlesewsky | Case as a trigger for reanalysis: some arguments from the processing of double case ungrammaticalities in German[END_REF]. Judging a sentence to be ungrammatical presupposes that no grammatical parse could have been constructed. Crucially, this means that the reanalysis process sketched above applies for ungrammatical sentences, too, since the parser must attempt reanalysis before concluding that a sentence is ungrammatical. Detecting a case mismatch on the second NP in an ungrammatical sentence as in (5) thus leads the parser to attempt automatic repair of the mismatch by (erroneously) reanalysing the parse towards an OS structure and -under time pressure -engenders false positive responses.

5) Maria glaubt, dass der

Vater der Onkel schlägt. Maria thinks that the NOM father the NOM uncle beats 'Maria thinks that the father beats the uncle.' By contrast, the characteristics of agreement mismatches ensure more reliable ungrammaticality detection even under time pressure since they do not initiate an automatic repair process. Table 1 shows how the processes of diagnosis and repair lead to different parsing accuracy for case and verbal agreement in grammatical and ungrammatical sentences.

In sum, processing preferences and the strength of reanalysis effects are determined by the interaction of universal phrase-structural parsing principles and the type of syntactic features that disambiguates order (case vs. verbal agreement). Since German scrambling thus gives rise to a varied pattern of reanalysis effects, comparing SO to OS orders constitutes a good test case for identifying qualitative similarities and dissimilarities between non-native and native processing.

Holger Hopp 375

IV The experiments

The present study tests how L1 English and L1 Dutch speakers process subject-object ambiguities in German. Neither English nor Dutch instantiates pre-subject scrambling of objects or case marking on full NPs. Dutch does, however, show scrambling as movement of the object across adverbs or negation [START_REF] Zwart | Morphosyntax of verb movement: a minimalist approach[END_REF]), yet, importantly, Dutch does not allow object-subject reordering. Hence, neither non-native group can make recourse to analogous processing routines or syntactic features of their L1 when parsing their L2. Two on-line experiments were designed to probe:

• whether -in the absence of lexical-semantic and pragmatic cuesnon-natives can effect incremental revisions of phrase structure; • whether, like natives, non-natives show a difference in strength of garden-path effects depending on type of syntactic disambiguation (case vs. verbal agreement); and • whether, like natives, non-natives show an interaction of syntactic feature type and accuracy in the processing of grammatical and ungrammatical sentences.

Finally, the experiments investigate if level of proficiency affects the time course and the accuracy of non-native parsing.

Participants

Twenty advanced to near-native L1 English speakers (13 female; 7 male) and 20 L1 Dutch speakers (15 female; 5 male) and 20 native German controls (9 female; 11 male) took part in the experiments. All non-native speakers of German started learning German after age 11 and were residents in Germany at the time of testing. They had each been exposed to German for more than 12 years. All non-natives completed a timed web-based C-test to gauge their proficiency in German. Similar to the cloze test, the C-test is a general proficiency test based on multiple deletions of parts of words in continuous texts (for details, see for example [START_REF] Grotjahn | Der C-Test: Theoretische Grundlagen und praktische Anwendungen[END_REF]. The non-natives scored between 43% and 89%, and the natives scored between 76% and 93%. In order to be able to consider potential effects of proficiency level, the non-natives were allocated to two proficiency groups according to the median score in the cloze test for each group, namely, advanced (Ͻ67%) and near-native (Ն67%). 2 Detailed participant information is listed in Table 2. All participants took part in two experiments: a self-paced reading task and a speeded grammaticality judgement task.

Experiment 1: self-paced reading

In a self-paced reading task, participants read sentences segment by segment. The rationale of this paradigm is that increased processing effort, i.e. reanalysis effects, can be detected locally in higher reading times on a given segment compared to the same segment in a control condition.

a Materials: Twenty-four quadruplets of experimental sentences were constructed. Half of the quadruplets were disambiguated by case Holger Hopp 377

2 An anonymous reviewer wonders whether the classification according to proficiency is legitimate noting that the difference between the highest-scoring participant in the advanced group is just 6% below the score of the lowest-scoring participant in the near-native group. However, the difference between group means is 20%; a t-test for independent samples on the C-test scores shows a significant difference between advanced and near-natives (F(1,38) -9.370, p Ͻ 0.001), yet no difference between the L1 English and L1 Dutch advanced or near-natives (p Ͻ 0.05). The allocation of participants into proficiency groups was, thus retained in order to render potential effects of proficiency statistically interpretable. Sentences were in SO or OS order (Factor Order). Two additional versions within each quadruple set were constructed by reversing the position of the nouns (i.e. N1-N2 and N2-N1), so that any potential effect of lexical semantics or pragmatics of the SO and OS manipulation would be completely matched. Further, all N1-N2 and N2-N1 SO combinations were matched on plausibility, i.e. they had been judged to be semantically reversible in an off-line plausibility judgement pretest by a separate group of German natives. Sentences disambiguated by verbal agreement contained two NPs -one plural and one singularwith ambiguous case inflection, and the finite verb was plural in half of the sentences and singular in the other. Sentences disambiguated by case contained two NPs: one unambiguously marked for nominative, the other unambiguously marked for accusative. The quadruplets were matched in length of NPs and verbs (number of characters), gender, number, animacy, and in corpus frequency (CELEX database; [START_REF] Baayen | The CELEX lexical database[END_REF]. In this way, the stimulus design ensured that case or number, respectively, was the only cue for the syntactic function of the NPs in the respective conditions. The quadruple sets were distributed across four lists in such a way that a list contained only one member of each set and an equal number of sentences in each condition. For each participant, the self-paced reading task comprised 24 items (plus 72 fillers), with six items per experimental condition. During list creation it was ensured that length and frequency were matched across conditions per list.

The paradigm was a non-cumulative Moving Windows task [START_REF] Just | Paradigms and processes in reading comprehension[END_REF] and was run using E-Prime software [START_REF] Schneider | E-Prime reference guide[END_REF]. The experimental sentences were divided into 7 segments (8), which were presented consecutively at the push of a button. The end of a sentence was signalled by a full stop following the last word in the final segment. Each item was followed by a comprehension sentence to check if participants accurately understood the items. The participants had to judge whether the comprehension sentence expressed the same meaning as the experimental item by pressing a green button ('yes') or a red button ('no'). For half of the experimental stimuli and the fillers, the comprehension sentence expressed the same meaning as the experimental item. Instructions and practice items preceded the task. All stimuli were presented in Courier New Font, font size 14, in white letters against a black background on a 15-inch TFT screen. Reading times for each segment, type of response and response time were recorded.

In the discussion, I focus on the analyses of all items regardless of comprehension accuracy, since at issue is how (non-native) participants typically read and process sentences, rather than how they read and process the proportion of sentences about which they correctly answer questions. Considering only this subset of sentences might give a picture of L2 performance that is in fact characteristic only of a small percentage of items. Moreover, for the question as to whether non-natives use syntactic information in on-line reading of the target language, it is irrelevant if participants correctly respond to a comprehension question that they read and answer subsequent to reading the item sentence. Answering questions about linguistic stimuli involves additional processes, preferences and strategies compared to the process of reading sentences. Hence, errors in the comprehension questions may be caused by many factors and, for this reason, the participants' accuracy scores for answering the comprehension questions is be analysed and discussed separately.

Two mixed three-way Repeated Measures ANOVAs both with Order and Ambiguity as within-participants factors and with, respectively, Language (German, English, Dutch) and Proficiency (native, advanced L2 and near-native L2) as between-participants factors were performed on accuracy scores and on reading times of all items by segment. Finding interactions with the factor Language would indicate that non-native processing is different from native processing; finding interactions with the factor Proficiency would indicate that processing differs according to proficiency level. Post-hoc two-way analyses were computed to investigate the cause of interactions of the within-participants factors and Language or Proficiency. The segments of interest were, for disambiguation by case, segment 3 (first NP), which was collapsed with the following segment 4 (adverbial) to catch potential spillover effects, and, for disambiguation by verbal agreement, segment 7 (finite verb).

b Data trimming: If a participant did not make a judgement within 4000 ms, the trial was aborted and the response recorded as incorrect. In total, this affected less than 1% of the trials. In addition, the participants' reading times were screened for outliers; reading times above 5000 ms on a segment were treated as missing values, and reading times of a segment below or above two standard deviations of the group mean for that segment were trimmed to the group mean Ϯ2sd. This affected less than 2% of the trials in each group. Finally, one participant in the near-native English group was removed from analyses because the data set was incomplete.

c Accuracy: Table 3 gives the results (accuracy and reading times by segments) of the self-paced reading task. The high comprehension accuracy scores for the SO sentences in (6a) and (7a) for all groups (85%-96%) bear out that the participants paid attention to the task and read the sentences properly. The between-participants analysis yields a significant effect of Order (F 1 (1,54) 224.067, p Ͻ 0.001; F 2 (1,117) 219.639, p Ͻ 0.001), Ambiguity (F(1,54) 14.614, p Ͻ 0.001) and an interaction of Order and Ambiguity (F(1,54) 34.573, p Ͻ 0.001). There are no significant interactions with the factor Language, but the interaction between Order and Proficiency reaches significance (F 1 (2,54) 14.297, p Ͻ 0.001; F 2 (2,115) 54.487, p Ͻ 0.001), largely due to the better performance of the near-natives on the OS sentences in general compared to the natives and to the advanced L2 group. In addition, there are three-way interactions between Order, Ambiguity and Language (F(2,54) 6.251, p ϭ 0.015) as well as a marginal interaction between Order, Ambiguity and Proficiency (F(2,54) 3.189, p ϭ 0.080), which appears to be due to the fact that the advanced Dutch group does not differ in comprehension accuracy between OS sentences disambiguated by For natives, the self-paced reading task bears out the structural subjectinitial preference of the parser in terms of depressed comprehension accuracy and locally elevated reading times for OS sentences. OS orders disambiguated by case and by verbal agreement elicit garden-path effects of differing strengths in that OS orders signalled by verbal agreement are associated with greater difficulty than OS orders signalled by case.

In terms of comprehension accuracy, the L2 groups demonstrate analogous garden-path effects for OS sentences in both conditions. Except for the advanced Dutch group, the differentially depressed accuracy scores for OS orders depend on the type of disambiguation. More specifically, this demonstrates that the non-native groups are garden-pathed more strongly when syntactic disambiguation is by verbal agreement than by case. Since all lexical-semantic, pragmatic and frequency cues were controlled for in Experiment 1, this finding demonstrates that the second language speakers were able to use case information more robustly than verbal agreement information to reach appropriate interpretations.

In the analysis of reading times, however, the non-native groups differ in their behaviour according to proficiency. Despite showing relative contrasts in comprehension accuracy similar to the natives, the advanced learners fail to show a native-like pattern in on-line reading in that they evince no locally specific slowdowns for OS sentences. By contrast, the near-natives demonstrate a native-like pattern of slowdowns for sentences disambiguated by case (6) on segments 3 and 4 and for sentences disambiguated by verbal agreement (7) on segment 7. This finding attests to incremental sensitivity to syntactic features in phrase-structural reanalysis by the near-native group.

Experiment 2: speeded grammaticality judgements

Experiment 2 asks whether the non-native groups can effect reanalysis under speeded presentation. In addition, Experiment 2 probes whether the processing differences between syntactic features show up in inverse direction in the processing of ungrammatical sentences. The rationale underlying the speeded judgement paradigm of Experiment 2 is that, under time pressure, dispreferred sentences elicit lower accuracy scores and higher reaction times than comparable control sentences.

a Materials: In a partially factorial design, four lists were created: (9) and ( 10) according to the factor Order (SO and OS) and reversed noun position (i.e. N1-N2 and N2-N1); ( 11) and ( 12), and ( 13) and ( 14) according to the factor Condition (type: case violation, type: agreement violation) and reversed NP position. For case violations, the double nominative in (11) was the ungrammatical counterpart of the SO order, and the double accusative in (12) was the ungrammatical equivalent of the OS order. The speeded-grammaticality judgement task thus included the six following conditions: SO (9) and OS (10) sentences disambiguated by case marking vs. case violations, i.e. 'doubly-nominative marked' sentences (der-der) (11) and 'doubly-accusative marked' sentences (den-den) (12), and violations of verbal agreement (number) in SO order (13) and in OS order (14). The task comprised 36 experimental items, i.e. 6 items per condition, and 66 fillers of various other structures. As in Experiment 1, reversed orders were used to control for potential lexical and plausibility differences. All items were matched in and across conditions as in Experiment 1. In this way, the stimulus design ensured that case was the only cue for the syntactic function of the NPs in the respective conditions.

In the task, the sentences were presented word-by-word in the centre of a 15-inch TFT screen in white font (Courier New, 18) against a black background. The rate of presentation was 250 ms per word plus 17 ms per letter. After the final word of each sentence the screen changed colour and the participants made an immediate binary grammaticality judgement by pressing a green ('grammatical') or red ('ungrammatical') button. Participants' responses and response times following the off-set of the final word in the sentence were recorded.

Three Repeated Measures ANOVAs with the factors Order (SO, OS) or Condition (grammatical, case violation, agreement violation) as within-particpants factors and Language (German, English, Dutch) and Proficiency (native, advanced L2 and near-native L2) as between-participants factors were performed on accuracy scores and on the reaction times. Analyses of the reaction times were run separately on all items and on items that had been judged correctly. Data trimming was as in Experiment 1. The data from all 20 native and 40 non-native participants were analysed. Table 4 displays the number (as a percentage) of accurate responses per condition. Mean reaction times (RT) for all responses are also given.

b Accuracy: A between-groups comparison for sentences (9) and (10) shows a significant main effect of Order (F 1 (1,55) 21.228, p Ͻ 0.001; F 2 (1,54) 34.232, p Ͻ 0.001). There are no significant interactions with the factors Language or Proficiency, bearing out that all groups demonstrate an SO preference compared to the OS order. To determine whether participants make a difference between grammatical and ungrammatical case marking, comparisons of accurate judgements on ( 9) and (10) (Condition: grammatical), on the one hand, with the false positive judgements of ( 11) and (12) (Condition: case violation), on the other hand, were run. They reveal a main effect of Condition (F(1,55) 83.888, p Ͻ 0.001) and a significant interaction of Condition with the factor Proficiency (F(2,55) 10.004, p ϭ 0.003), yet not with the factor Language (F(2,55) 0.545, p ϭ 0.464). Subsequent analyses by proficiency group reveal significant differences between grammatical (10) and ungrammatical (12) OS orders show significant effects for the natives (F(1,19) 25.126, p Ͻ 0.001) and the near-natives (F(1,19) 14.052, p ϭ 0.001), yet not for the advanced group (F(1,19) 1.430, p ϭ 0.246). These results demonstrate that the natives and the nearnative group distinguish between grammatical and ungrammatical case marking in OS orders, while the advanced group does not distinguish significantly between case violations and grammatical case marking. Finally, the comparison of case and number violations yields a main effect of Condition (F 1 (1,55) 110.924, p Ͻ 0.001; F 2 (1,115) 133.410, p Ͻ 0.001) and an interaction of Condition with the factor Proficiency (F 1 (2,55) 7.172, p ϭ 0.010; F 2 (2,115) 18.426, p Ͻ 0.001), yet only marginally with the factor Language in the analysis by item (F 1 (2,55) 0.672, p ϭ 0.416; F 2 (2,115) 3.076, p ϭ 0.082). This interaction reflects the much lower accuracy in detecting the ungrammaticality of case violations by the advanced group. Analyses by proficiency group yield highly significant effects of condition for each group (p Ͻ 0.001), bearing out that, for each group, the judgement accuracy on detecting case violations is lower than on detecting verbal agreement violations. In sum, the slowdowns for OS orders compared to SO order for the natives and the near-natives provide evidence of reanalysis according to syntactic case features under time pressure; by contrast, the advanced groups do not show robust reanalysis effects under pressure.

5 Discussion: Experiment 2

The speeded acceptability judgement task replicates the finding of Experiment 1 that differences in reanalysis are due to proficiency, not language. The phrase-structural SO preference is operative in the processing by native and near-native speakers as borne out in depressed accuracy and elevated response time for the OS orders. By contrast, the advanced group shows decreased judgement accuracy for OS orders, yet no increased reaction times. In addition to effecting reanalysis under time pressure, the near-natives robustly differentiate between grammatical and ungrammatical case marking, which shows that the target-like processing of case persists under time pressure. The advanced learners, however, accept OS orders (10) disambiguated by case (at 67.5%) as readily as OS orders with case violations (12) (at 62.5%), which suggests that -under speeded presentation -they do not make a distinction between sentences with dispreferred grammatical orders and sentences rendered ungrammatical by case marking.

As for case and number violations, for all groups, sentences ungrammatical by case lead to significantly more false positive responses than sentences ungrammatical by verbal agreement. This disjunction in ungrammaticality detection indicates two things: first, the difference in garden-path strength between the disambiguation of sentences by case vs. by verbal agreement in Experiment 1 is not due to a difference in the linear position of the regions of disambiguation (see also [START_REF] Meng | Ungrammaticality detection and garden path strength: evidence for serial parsing[END_REF]. Otherwise case violations, for which information identifying the violation occurs earlier than for verbal agreement violations in Experiment 2, should receive higher accuracy scores than verbal agreement violations. Second, for all groups, case disambiguation was judged more accurately than verbal agreement disambiguation (Experiment 1), while case violations in Experiment 2 are judged less accurately than verbal agreement violations. This interaction between syntactic feature type and sentence type (Table 1) points to differential properties of the syntactic features for phrase-structural reanalysis in both native and near-native parsing.

V General discussion

Two experiments probed syntactic reanalysis effects in the processing of locally ambiguous OS clauses by advanced and near-native English and Dutch speakers of German. In line with previous studies on native German processing (e.g. [START_REF] Meng | Ungrammaticality detection and garden path strength: evidence for serial parsing[END_REF], the present experiments find that native parsing preferences of word order are effected by the interaction of phrase-structural parsing principles and syntactic feature types marking ordering variants. In grammatical sentences, OS orders were found to induce weaker garden-path effects when disambiguation was by case compared to verbal agreement (Experiment 1); in ungrammatical sentences, however, case violations elicited a higher number of misparses in comparison to verbal agreement violations (Experiment 2).

In both experiments, the non-native groups did not mainly manifest different behaviour according to L1 (English vs. Dutch); rather, they predominantly demonstrated different performance according to proficiency level:

• The advanced speakers manifest a general SO-preference in reading and judgement accuracy, yet they do not reliably show local reading delays (Experiment 1) or response latencies and judgement accuracies associated with native reanalysis patterns (Experiment 2). • The near-native speakers demonstrate an SO-preference and incremental reanalysis effects (Experiment 1) whose strength is differentially modulated by the type of syntactic features in grammatical and ungrammatical sentences (Experiment 2).

In these respects, the near-native behaviour proves isomorphic to the performance by native speakers. One of the clearest findings in the experiments is an effect of proficiency level on parsing routines in the L2. Despite the fact that all second language learners have had long exposure to German and have reached a high command in the language, proficiency differences at advanced stages of L2 acquisition account for major differences in non-native processing. Compared to the advanced speakers, who show lower accuracy and flatter processing patterns in comprehending the L2, speakers at nearnative proficiency levels show evidence of more nuanced processes in parsing the L2. In fact, in this study, it is only at the near-native level that L2 speakers of German converge on the parsing accuracy and functional reanalysis patterns in native German processing.

Proficiency effects in non-native processing have been reported in an eye-tracking study by [START_REF] Frenck-Mestre | An on-line look at sentence processing in the second language[END_REF] and in event-related potential (ERP) studies [START_REF] Hahne | What's different in second-language processing? Evidence from event-related brain potentials[END_REF][START_REF] Hahne | Processing a second language: late learners' comprehension mechanisms as revealed by event-related brain potentials[END_REF][START_REF] Sabourin | Grammatical gender and second language processing[END_REF], in which more advanced learners demonstrate evidence of automatic neurophysiological responses to morphosyntactic ungrammaticalities in the L2 that are absent in less proficient participants. However, L1 effects are a potential confound of proficiency in these studies, since comparisons are made across different L1 groups of different proficiency levels. Also using ERPs, [START_REF] Friederici | Brain signatures of artificial language processing: evidence challenging the critical period hypothesis[END_REF] and [START_REF] Mueller | Electrophysiological correlates of second language processing[END_REF] report similar proficiency effects in the acquisition of 'miniature' L2 systems, where comparatively fast advances in proficiency correlate with massive changes in ERP responses. In neuroimaging studies on sentence comprehension in the L2, [START_REF] Perani | The bilingual brain: proficiency and age of acquisition of the second language[END_REF]2003) and [START_REF] Abutalebi | The bilingual brain as revealed by functional neuroimaging[END_REF] equally find that the areas and extent of neural activation in processing the L2 converge on native activation patterns as a function of proficiency. The findings of the present study on syntactic ambiguities underline the importance of proficiency level in the development of the architecture and mechanisms in L2 processing. Seeing distinct performance in the two proficiency groups in the present study suggests that even at very advanced proficiency levels and after long L2 exposure and immersion, further acquisition and practice in the L2 leads to more native-like parsing routines. Not least, this finding highlights the importance of studies on ultimate attainment in the L2 and cautions that arguments about the qualitative status of interlanguage systems in comparison with those of mature native speakers necessitate careful consideration of variables such as degree of proficiency.

The present findings do not support the hypothesis that L2 processing is 'shallower' than native-language processing such that L2 speakers are sensitive to lexical-semantic and pragmatic information, yet make only very restricted or no use of syntactic or phrase-structural information in parsing (compare Felser et al., 2003;[START_REF] Clahsen | Grammatical processing in first and second language learners[END_REF]Felser and Roberts, to appear). The Shallow Structure Hypothesis might explain the relatively poor performance by the advanced group on incremental processing (Experiment 1) and the use of syntactic cues under time pressure in this study (Experiment 2). However, the Shallow Structure Hypothesis fails to account for the behaviour of the nearnatives. The near-native group shows reliable use of syntactic features in phrase-structural reanalysis. They also show evidence of incremental processing by syntactic features. Moreover, the near-natives show an interaction of syntactic feature type and phrase-structural parsing principles in parsing ambiguous grammatical sentences as well as ungrammatical sentences. Given that all lexical, semantic, pragmatic and frequency-based cues to sentence interpretation were absent in Experiments 1 and 2, the observed behaviour cannot possibly derive from the use of non-syntactic information in processing. Moreover, the near-native behaviour cannot be accounted for by means of surface strategies, e.g. a linear 'subject-first' preference. As shown by the interactions of the factors Order and Ambiguity in the reading delays (Experiment 1), the subject-initial preference varies in native and near-native speakers according to the syntactic type of disambiguation. The reading delays reflecting reanalysis in the near-natives are locally specific to the regions of syntactic disambiguation, i.e. segments 3 and 4 for case and segment 7 for verbal agreement. In addition, the interaction (Table 1) between syntactic feature type (case vs. verbal agreement) and sentence type (grammatical vs. ungrammatical) in native and near-native processing (Experiments 1 and 2) implies that syntactic features are used differentially in sentence comprehension. A general linearization principle could not capture any of these effects. Any satisfactory explanation thus needs to include a syntactic analysis that makes use of a distinction of syntactic features and that accounts for their differential status in reanalysis.

The observed reanalysis pattern by the near-natives in both experiments can easily be explained by parsing models that posit that native speakers:

• employ a phrase-structural preference like the Minimal Chain Principle (3) (de Vincenzi, 1991); • establish syntactic relations incrementally in parsing; and • attempt reanalysis by means of syntactic relations in parsing.

As argued by [START_REF] Fodor | The diagnosis and cure of garden paths[END_REF]1998;2000), the serial parser is redirected to the source of a misparse by the syntactic relations expressed by the mismatching feature (Det-Noun or Subject-Verb agreement) and attempts reanalysis. Reanalysis is attempted irrespective of whether the structure turns out to be dispreferred or ungrammatical. The different degrees of informativity of case and verbal agreement features for reanalysis lead to a disjunction in parsing accuracy between dispreferred OS sentences and ungrammatical sentences (Table 1). Since near-natives show evidence of exactly this performance, syntactic parsing principles and syntactic features are implicated in processing the L2.

In spite of the convergence of near-native and native processing patterns, all L2 groups suffer a much larger proportional decrease than the natives in judgement accuracy on case violations than on violations of verbal agreement in Experiment 2. At first glance, it seems that this specific difference between natives and non-natives could follow from two factors: first, L1 transfer and, second, greater computational difficulty in coordinating different types of grammatical information in the L2. We consider each in turn.

The role of L1 transfer in non-native processing is a matter of contention. Some studies find evidence of L1 properties in L2 parsing (e.g. [START_REF] Juffs | Main verb versus reduced relative clause ambiguity resolution in second language sentence processing[END_REF][START_REF] Frenck-Mestre | An on-line look at sentence processing in the second language[END_REF][START_REF] Fernandez | Bilingual sentence processing[END_REF][START_REF] Sabourin | Grammatical gender and second language processing[END_REF] and others report no L2 processing differences between L1 groups [START_REF] Papadopoulou | Parsing strategies in L1 and L2 sentence processing: a study of relative clause attachment in Greek[END_REF][START_REF] Marinis | Gaps in second language sentence processing[END_REF]. Since neither English nor Dutch uses case marking to signal the syntactic function of non-pronominal NPs, the L2 German finding that integrating such case-marked NPs into syntactic structure causes additional processing effort for the non-natives might derive from the lack of such automatic processes in parsing the L1 (e.g. [START_REF] Macwhinney | Cue validity and sentence interpretation in English, German, and Italian[END_REF]. With no L2 group from a case-marking L1 background for comparison in the present experiments, it is unfortunately not possible to ascertain whether the specific demands of these NPs reflect L1 effects. In another study, this issue has been explored with L1 Russian speakers of German (see [START_REF] Hopp | Subject-object ambiguities in L2 parsing[END_REF].

Other research argues for increased integration difficulty of morphological and syntactic knowledge. [START_REF] Hahne | What's different in second-language processing? Evidence from event-related brain potentials[END_REF] argues on the basis of ERP studies on phrase-structure violations that the degree of automaticity in integrating syntactic category information into phrase structure is reduced in non-native processing. In case studies on fossilized endstate learners, Lardiere (1998a;1998b;2000) and [START_REF] White | Fossilization in steady state L2 grammars: persistent problems with inflectional morphology[END_REF] suggest that dissociations between impaired suppliance of morphology and targetlike production of associated syntactic properties stem from increased computational demands in accessing morphological forms and matching them with syntactic features. According to these claims, processing delays and failures in coordinating morphosyntactic information in comprehension and production obtain generally in non-native processing and can persist to near-native proficiency levels, possibly irrespective of L1 properties. The findings of the current study are compatible with this proposal, although the difficulties found here seem specific to case marking and do not seem to extend to other morphosyntactic phenomena, specifically verbal (number) agreement. Further research is needed to give substance to the nature and extent of computational difficulties in form-function mapping at the endstate of L2 acquisition.

VI Conclusions

This study shows that level of proficiency arbitrates the degree of native-like processing of subject-object ambiguities in the L2. The near-native group, yet not the advanced group, of L1 English and Dutch speakers of German was found to employ syntactic principles and syntactic features in parsing to native-like degrees, even though the L1s instantiate neither analogous options for syntactic reordering nor the same morphosyntactic cues. These results suggest that sensitivity to syntactic information is not in principle restricted in non-native processing. It of course remains to be seen in future research whether the finding that highly proficient L2 speakers at ultimate attainment invoke native-like syntactic processing routines in the L2 generalizes to other phenomena and other language groups.

  Er denkt | dass | der Physiker | am Freitag | den Chemiker | gegrüsst | hat.

  Maria thinks that the NOM father the ACC uncle beats 'Maria thinks that the father beats the uncle.' b. Maria glaubt, dass [den Onkel] 1 der Vater t 1 schlägt.

			). 1
	1) a. Maria glaubt, dass der	Vater den	Onkel schlägt.

Table 1

 1

	Interaction of feature of disambiguation and sentence
	type in first-pass parsing: accurate responses
		Case	Verbal agreement
	Grammatical OS sentences	high	low
	Ungrammatical sentences	low	high

Table 2

 2 Participant information by group Physiker am Freitag den Chemiker gegrüsst hat. He thinks that the NOM physicist on Friday the ACC chemist greeted has b. Er denkt, dass den Physiker am Freitag der Chemiker gegrüsst hat. 7) a. Sie sagt, dass die Baronin am Freitag die Bankiers eingeladen hat. She says that the baroness SG on Friday the bankers PL invited has b. Sie sagt, dass die Baronin am Freitag die Bankiers eingeladen haben. She says that the baroness SG on Friday the bankers PL invited have

		English:	English:	Dutch:	Dutch:	German:
		advanced	near-natives advanced	near-native	native
		(n ϭ 10)	(n ϭ 10)	(n ϭ 10)	(n ϭ 10)	speakers
						(n ϭ 10)
	C-test	43-61 (53)	67-81 (71)	46-62 (54)	67-89 (76)	76-93 (83)
	(timed) (%)
	Length of	17-35 (24.2) 12-41 (22.2) 14-43 (27.0) 12-32 (23.0)
	exposure
	(years)
	Length of	3-31 (19.5)	3-32 (14.5)	3-15 (7.7)	5-30 (14.2)
	residence
	(years)
	Age of onset 12-30 (19.3) 11-22 (15.3) 11-26 (13.9) 12-20 (13.7)
	(years)
	Age (years)	31-62 (50.6) 27-55 (37.6) 28-58 (38.8) 24-48 (36.8) 25-69
						(51.4)

Note: Figures given are ranges, with averages in parentheses on determiners -e.g. (

6

) -and half by number marking on the verb: e.g. (

7

) (Factor Ambiguity). All sentences were initiated by a matrix clause. 6) a. Er denkt, dass der

Table 3

 3 Accuracy scores and reading times (standard deviations) for relevant segments by group and condition: (6a) SO order disambiguated by case; (6b) OS order disambiguated by case; (7a) SO order disambiguated by verbal agreement; (7b) OS order disambiguated by verbal agreement case or by verbal agreement. In total, though, all groups prefer SO sentences to OS sentences, with the preference being considerably stronger for the native and the near-native group when disambiguation occurs via verbal agreement. Pairwise comparisons by proficiency group between

	Type	Correct	S1/	S2/	S3/	S4/	S5/	S6/	S7/
		answers	matrix COMP	NP1	adv.	NP2	V-part V-fin
			(ms)
	6a) SO order disambiguated by case:
	German:	103/120	920	668	927	821	1115 1020	875
	native	(86%)	(386)	(232)	(342) (277) (505) (399) (383)
	speakers
	English:	53/60	1181	752	1227 932	1486 1095	961
	advanced	(88%)	(401)	(270)	(405) (276) (594) (469) (453)
	Dutch:	57/60	823	605	1080 896	1500 957	966
	advanced	(95%)	(314)	(199)	(397) (316) (682) (363) (448)
	English:	47/54	870	644	1159 820	1357 1105	959
	near-native (87%)	(409)	(275)	(525) (286) (603) (474) (437)
	Dutch:	54/60	784	568	864	789	1101 907	840
	near-native 90%	(314)	(167)	(298) (242) (441) (323) (432)
	6b) OS order disambiguated by case:
	German:	67/120	838	648	1087 862	1149 1193	1043
	native	(56%)	(278)	(191)	(465) (277) (477) (570) (653)
	speakers
	English:	25/60	1039	767	1373 959	1532 1307	1019
	advanced	(42%)	(394)	(314)	(585) (337) (775) (661) (568)
	Dutch:	13/60	974	671	1151 878	1353 1130	1179
	advanced	(22%)	(381)	(244)	(438) (256) (546) (461) (750)
	English:	40/54	811	629	1378 979	1379 1176	1043
	near-native (74%)	(351)	(272)	(579) (423) (649) (548) (558)
	Dutch:	36/60	771	591	997	849	1163 937	977
	near-native (60%)	(325)	(221)	(387) (257) (435) (421) (678)
	7a) SO order disambiguated by verbal agreement:
	German:	111/120	890	684	945	777	1095 1003	964
	native	(93%)	(354)	(242)	(375) (250) (469) (387) (460)
	speakers
	English:	57/60	1105	765	1407 1073 1486 1173	1105
	advanced	(95%)	(409)	(270)	(586) (348) (613) (494) (535)
	Dutch:	57/60	833	614	1039 878	1357 1033	1209
	advanced	(95%)	(318)	(186)	(324) (355) (546) (438) (658)
	English:	49/54	724	627	1289 936	1492 1090	1123
	near-native (91%)	(256)	(238)	(588) (336) (610) (456) (523)
	Dutch:	56/60	774	615	913	770	1055 924	1003
	near-native (93%)	(325)	(204)	(374) (190) (399) (415) (613)
	7b) OS order disambiguated by verbal agreement:
	German:	34/120	844	657	1003 839	1139 1038	1496
	native	(28%)	(333)	(197)	(381) (279) (527) (413) (1107)
	speakers
	English:	14/60	975	687	1258 974	1421 1104	1269
	advanced	(23%)	(328)	(197)	(499) (345) (643) (478) (917)
	Dutch:	17/60	832	622	1107 865	1279 1036	1442
	advanced	(28%)	(318)	(193)	(437) (312) (613) (373) (1012)
	English:	24/54	738	623	1342 938	1426 1195	1753
	near-native (44%)	(230)	(232)	(665) (363) (632) (531) (1410)
	Dutch:	27/60	728	627	893	770	1051 950	1333
	near-native (45%)	(238)	(189)	(373) (208) (475) (371) (807)

2 (1,115) 9.238, p ϭ 0.003) and an interaction between Order and Ambiguity (F(1,54) 19.567, p Ͻ 0.001). This interaction signals that the slowdowns are specific to the OS order in (6b), where disambiguation by case occurs. Furthermore, there is an interaction between Order and Proficiency in the analysis by participants and marginally in the analysis by items (F 1 (2,54) 4.365, p ϭ 0.041; F 2 (2,115) 2.683, p ϭ 0.104). There is no interaction with the factor Language (F 1 (2,54) 0.2, p ϭ 0.889; F 2 (2,115) 0.356, p ϭ 0.552). On segment 7 (V-fin), i.e. where reanalysis to the OS order for disambiguation by verbal agreement is expected to occur, the between-groups analysis unearths a main effect of Order (F 1 (1,54) 27.967, p Ͻ 0.001; F e Reading times: native speakers: On segments 3 and 4, natives show a main effect of Order (F 1 (1,19) 19.751, p Ͻ 0.001; F 2

(1,23)

f Reading times: non-native speakers: near-native second language speakers: On segments 3 and 4, the near-natives show a main effect of Order (F 1 (1,18) 12.512, p ϭ 0.002; F 2 (1,23) 5.454, p ϭ 0.1 (1,19) 7.019, p ϭ 0.016; F 2 (1,23) 2.698, p ϭ 0.114); furthermore there is a main effect of Ambiguity (F(1,19) 14.452, p Ͻ 0.001),

  9) Er glaubt, dass derVater am Freitag den Onkel gegrüsst hat. He thinks that the NOM father on Friday the ACC uncle greeted has 10) Er glaubt, dass den Onkel am Freitag der Vater gegrüsst hat. He believes that the NOM baker for long time the ACC butcher supplied have 14) * Er glaubt, dass den Bäcker seit langer Zeit der Metzger beliefert haben.

	11) * Er glaubt, dass der	Bäcker seit langer Zeit der	Metzger beliefert hat.
	He believes that the NOM baker for long time the NOM butcher supplied has
	12) * Er glaubt, dass den	Bäcker seit langer Zeit den	Metzger beliefert hat.
	He believes that the ACC baker for long time the ACC butcher supplied has
	13) * Er glaubt, dass der	Bäcker seit langer Zeit den Metzger beliefert haben.

Table 4

 4 Accuracy scores (with mean reaction times in parentheses) per group and condition Reaction times: A between-groups analysis of the SO (9) and the OS (10) orders yields a significant main effect of order in the analysis of all items (F 1(1,55) 20.406, p Ͻ 0.001; F 2 (1,55) 11.766, p ϭ 0.001) and in the analysis of correct trials (F 1 (1,53) 18.221, p Ͻ 0.001; F 2 (1,55) 6.668, p ϭ 0.013), yet no interactions with the factors Language or Proficiency. Subsequent analyses by proficiency group replicate the main effect of order for the natives (all items: F 1 (1,19) 8.777, p ϭ 0.008;

		English:	English:	Dutch:	Dutch:	German:
		advanced	near-native	advanced	near-native	native
		(n ϭ 10)	(n ϭ 10)	(n ϭ 10)	(n ϭ 10)	speaker
						(n ϭ 20)
	9) SOV	93%	92%	85%	82%	94%
		(1035 ms)	(1008 ms)	(1192 ms)	(839 ms)	(770 ms)
	10) OSV	65%	83%	70%	65%	75%
		(1204 ms)	(1194 ms)	(1321 ms)	(1121 ms)	(941 ms)
	11) *NP NOM NP NOM V 12) *NP ACC NP ACC V 13) *SOV *NUM	28% (1083 ms) 35% (966 ms) 72% (1377 ms)	50% (1166 ms) 48% (1051 ms) 72% (1078 ms)	15% (1215 ms) 42% (1149 ms) 82% (1269 ms)	48% (930 ms) 65% (984 ms) 85% (1003 ms)	71% (858 ms) 62% (989 ms) 88% (975 ms)
	14) *OSV *NUM	75% (1437 ms)	78% (1295 ms)	80% (1296 ms)	83% (1080 ms)	92% (1029 ms)

c

I use embedded clauses in order to avoid the interference of additional reordering to verb-second in German main clauses.

Acknowledgements

For helpful comments and discussion, I would like to thank Kees de Bot, Harald Clahsen, Bonnie Schwartz, Laurie Stowe and two anonymous reviewers for Second Language Research. All remaining errors are my responsibility.


Ashley Fidler

Reconceptualizing fossilization in second language acquisition: a review

) describes a conceptual framework within which to understand existing work on fossilization, and Han and Odlin (2005) present a collection of empirical and analytical studies that help to ameliorate both the definitional and empirical shortcomings of contemporary fossilization research. Taken together, these volumes provide an admirable synthesis of existing research and problems, as well as noteworthy analyses of how to move forward empirically. For the moment, however, idiosyncratic perspectives on fossilization still prevail.

I Introduction

The term 'fossilization', introduced by [START_REF] Selinker | Interlanguage[END_REF], captures the observation that most adult second language learners never reach native-like proficiency in their target languages. This general lack of success contrasts starkly with child first language acquisition where native competence is the norm. The drive to understand this apparent discrepancy has sustained fossilization research, but has, thus far, produced relatively little empirical description and no universally acknowledged definition or explanation (e.g. [START_REF] Long | Stabilization and fossilization in interlanguage development[END_REF][START_REF] Birdsong | Second language acquisition and ultimate attainment[END_REF]. The two works reviewed here undertake to remedy these problems. Han (2004) introduces a conceptual framework for fossilization research, while [START_REF] Han | Studies of fossilization in second language acquisition[END_REF] collect empirical and analytical studies that enhance current knowledge of the second language (L2) end state (e.g. the chapters by Han and Lardiere), and suggest alternative empirical approaches to non-native-like ultimate attainment (e.g. the chapters by Birdsong and Lakshmanan). The present review begins with an introduction to relevant conceptual and empirical problems in fossilization research. An examination of each work individually follows. Finally, it is shown that, despite the notable contribution of these volumes to clarifying the aims of fossilization research, the essential problems of defining and empirically describing the concept remain.

Recent analyses of contemporary fossilization research (e.g. [START_REF] Han | Fossilization: from simplicity to complexity[END_REF][START_REF] Long | Stabilization and fossilization in interlanguage development[END_REF][START_REF] Birdsong | Second language acquisition and ultimate attainment[END_REF] have pointed out a great deal of variability in current definitions and descriptions of fossilization. Three significant areas of divergence are raised here. First, Han distinguishes between global and local fossilization. Globally, fossilization affects the entire interlanguage (IL), making it unlikely that any further L2 learning will occur. This impression arises from general portrayals of the cessation of development, where no attempt is made to distinguish particular subdomains or features of fossilized grammatical knowledge (e.g. [START_REF] Selinker | Interlanguage[END_REF][START_REF] Tarone | Systematicity/variability and stability/instability in interlanguage systems[END_REF]. On the other hand, fossilization can also be seen in local terms, such that one particular subsystem (e.g. syntax) or even a particular feature (e.g. past-tense marking) can fossilize while development in other areas proceeds unabated. For example, such a combination of progress and stagnation for one Japanese learner of English is described by [START_REF] Schmidt | Interaction, acculturation, and the acquisition of communicative competence: a case study of an adult[END_REF].

Second, fossilization is alternately understood as a product or a process.1 From the product perspective, fossilization is the state of permanently frozen development, either globally or locally. Historically, this view originates from definitions such as the following (from Selinker and Lakshmanan, 1992: 197): '[fossilization is] the long term persistence of plateaus of non-target-like structures in the interlanguage of non-native speakers. . .'. Statements such as this imply that it should be possible to locate and document fossilized (i.e. completely non-developing) structures through empirical investigation. Frequent attempts to this effect have been made by fossilization researchers, as is shown below. From a process perspective, on the other hand, fossilization does not necessarily require the absence of development in a particular area; rather, the term can also refer to a tendency towards the cessation of development. Originally, the idea of fossilization-as-process came from [START_REF] Selinker | Interlanguage[END_REF] notion of a fossilization mechanism, part of the latent psychological structure for language [START_REF] Lenneberg | Biological foundations of language[END_REF]. The operation of this mechanism over time was thought to prematurely interrupt L2 development in the vast majority of learners (perhaps up to 95%). Thus, the term 'fossilization' referred to the explanation for slowing/stopped development, and could be observed empirically only through its symptoms, such as 'backsliding'. The process-product distinction, then, boils down to whether the term 'fossilization' refers to a state that can be examined directly, or a cognitive process, observable only indirectly.

In recent years, however, this distinction has blurred to a degree. [START_REF] Han | Fossilization: from simplicity to complexity[END_REF]Han ( , 2004)), for example, redefines the process view in terms of the empirical predictions it makes. She emphasizes that evidence of fossilization can exist without proof that learning has stopped completely; importantly, though, fossilization-as-process need not be understood as an explanation or mechanism for this to be the case. On the other hand, from a product perspective there is no consensus that fossilization must indicate a total lack of change or variability in the IL. [START_REF] Sorace | Permanent optionality as divergence in non-native grammars[END_REF], for example, develops the notion of 'permanent optionality', which proposes that the L2 end state can encompass variation and indeterminate linguistic competence. By contrast, Long (2003: 508-12) discusses his study of Ayako, a Japanese immigrant to Hawaii in 1948, who still exhibits 'volatile' inflectional marking on both nouns and verbs. From Long's point of view this instability (presumably an instance of stabilized optionality) indicates a lack of fossilization.

Finally, directly related to this product-process distinction is the problem of what constitutes suitable empirical demonstration of fossilization. Many researchers have sought to document fossilized structures in adult IL. To take one example, [START_REF] Thep-Ackrapong | Fossilization: a case study of practical and theoretical parameters[END_REF]discussed in Long, 2003;Han, 2004) conducted a semester-long pedagogical intervention on a presumably fossilized learner, Lin, who had resided in the USA for 6 years at the time of the study. The investigation focused on infinitival complements. Lin was given explicit instruction, feedback and opportunity to practise these constructions, but, in a follow-up session one year later, there was no evidence that the intervention had had an effect. This result was taken as evidence that these structures had fossilized. Under some views (e.g. [START_REF] Long | Stabilization and fossilization in interlanguage development[END_REF], however, this result cannot be seen as conclusive due to insufficient length of the study and data collection. Only multi-year longitudinal production data from learners immersed in the target language can shed light on the slowing and ultimate cessation of L2 learning (for an example of a relevant study, see Lardiere, to appear).

In sum, in order for the study of fossilization to proceed effectively, some conceptual unity is required. Without agreement as to whether fossilization can operate on a global or local level, whether it is a product that can be measured or a tendency to be observed, or whether it must exhibit stability or simply stable optionality, it is impossible to design acceptable empirical studies and to interpret their results. These central issues have motivated the works presented here.

II Han (2004)

Han's overall goal in Fossilization in adult second language acquisition, then, is to construct a preliminary account of failure in second language acquisition (SLA; Han, 2004: 4). Here, failure is defined as the permanent lack of mastery of a target language despite continuous exposure to adequate input; thus, for the purposes of this book, the term 'fossilization' can be equated with such failure in SLA. The impetus behind Han's effort is the need, discussed above, for a unified and systematic approach to fossilization research, and the hope that a coherent understanding of fossilization will lead to a more complete theory of SLA. Clearly, the development of an account of fossilization, even if only preliminary, is an ambitious goal for a work of 175 pages, and it cannot be said to have been completely successful. However, taken as a whole, Han's volume provides a useful synthesis of current problems in the field and a comprehensive framework within which to consider research on fossilization up to this point.

The body of this work consists of 7 chapters. Chapters 1-3 outline Han's conceptual framework for fossilization research, and explore definitions and explanations of the term. Chapters 4-6 apply Han's conceptual framework to empirical and analytical studies of fossilization. Chapter 4 examines critical period effects in SLA. Chapter 5 looks at native language transfer, and Chapter 6 reviews empirical investigations of fossilization accompanied by a critique of existing research designs. Finally, Chapter 7 addresses the relationship of second language instruction to fossilization. Although not explicitly stated, the intended audience for this book appears to be researchers in the field of SLA and fossilization. Nevertheless, the material should be also be accessible to students at both the graduate and advanced undergraduate levels, and will likely be especially informative to those just beginning research into fossilization.

Han's conceptual framework (outlined on pp. 8-9) is the foundation of this work. Motivated by the goal of unity in fossilization research, Han argues for the need to understand the concept on two levels: macroscopic and microscopic. Fossilization research on a macroscopic level seeks to explain why children learn languages more effectively than adults overall. Specifically, maturational constraints (i.e. critical period effects) and native language transfer are presented as macro-level factors. On a microscopic level, by contrast, fossilization research examines the linguistic features/domains that often fossilize differentially within learners (e.g. morphology is more likely to fossilize than vocabulary), as well as the factors (socio-affective, psychological, etc.) that cause learners to differ in their overall proficiency. The terms intralearner, to refer to differential success within the IL of an individual learner, and inter-learner, to indicate overall differences in ultimate attainment across learners, are introduced (p. 7). Han's central message, then, is that the biological and cognitive constraints that exist on a macro-level cannot fully account for the variation in acquisition outcomes that has been attested in the ultimate attainment literature. A microscopic level of analysis is also necessary.

Han's framework includes several contentious positions vis-à-vis the fossilization literature. First, take the definition of fossilization with respect to ultimate attainment:

L2 ultimate attainment has at least three facets: (1) cross-learner general failure; (2) inter-learner differential success/failure; and (3) intra-learner differential success/failure . . . clearly, within the ultimate attainment, success and failure co-exist. Nevertheless, the three facets of ultimate attainment do exhibit fossilization in that they involve permanently arrested development of some sort (pp. 7-8; italics in original).

This description seems to rule out the possibility of complete success (e.g. native-likeness) as an SLA outcome. However, [START_REF] Birdsong | Second language acquisition and ultimate attainment[END_REF]2005) and [START_REF] Moyer | Age, accent, and experience in second language acquisition: an integrated approach to critical period inquiry[END_REF], for example, take issue with this position. Birdsong (2005) cites a study by [START_REF] Marinova-Todd | Comprehensive analysis of ultimate attainment in adult second language acquisition[END_REF] in which 30 advanced L2 learners of English performed 9 tasks (2 pronunciation, 2 lexical knowledge, 3 morphosyntax, 2 language use) designed to assess their English proficiency. She found that 3 informants performed at or above native levels on all 9 tasks. Thus, it is not obvious that fossilization is an inherent part of ultimate attainment. Further empirical study is required to evaluate this conclusion.

Additionally, Han's framework encompasses the claims that fossilization is local as opposed to global, and that it is a process, not a product. The latter of these points is the more controversial. Recall that conceptualizing fossilization-as-process requires researchers to seek evidence of a tendency towards permanent stabilization as opposed to an invariant endstate. Han writes that, because of the methodological problems associated with demonstrating fossilization-as-product, 'it would seem necessary (and plausible) to conceptualize fossilization as a process, a process whereby learning manifests a strong tendency towards cessation.' (p. 23). However, empirically determining that a tendency towards the cessation of learning exists is not without its own problems (for a relevant discussion, see [START_REF] Long | Stabilization and fossilization in interlanguage development[END_REF]. Han offers no suggestions, neither here nor as part of her critique of research methodologies (Chapter 6), regarding how fossilization-as-process can be operationalized for empirical study.

The elaboration of Han's conceptual framework is followed by a review of macroscopic and microscopic research in fossilization. In order to demonstrate that 'L2 learners are universally preconditioned to fossilization' (p. 44; italics in original), both biological (i.e. critical period effects) and cognitive (i.e. native language transfer) constraints on SLA are raised. Han's discussion of the critical period literature will be our focus. Here, age of arrival into the target language environment is highlighted as the strongest predictor of ultimate attainment. Studies by [START_REF] Johnson | Critical period effects in second language learning: the influence of maturational state on the acquisition of English as a second language[END_REF], which provides evidence for an age-related decline in syntactic competence starting around age 7, and [START_REF] Oyama | A sensitive period for the acquisition of nonnative phonological system[END_REF], which focuses on the effect of age of arrival on phonological attainment, are described in some detail. In addition to this evidence for age effects on a macro-level, however, Han also emphasizes the modular nature of the critical period (e.g. following [START_REF] Patkowski | The sensitive period for the acquisition of syntax in a second language[END_REF] and the interaction between biological constraints and environmental/affective factors (e.g. [START_REF] Bialystok | The problem of age in second language acquisition: influences from language, structure, and task[END_REF]. The modularity of the critical period is argued to provide support for fossilization on a local level (p. 62), and the ability of affective variables to modulate ultimate levels of proficiency suggests that individual differences abound in SLA. Thus, Han argues, there is a basis for the belief that differential linguistic proficiency exists on both the intra-learner and inter-learner levels, as described within her framework.

The goal of Han's microscopic analysis of fossilization follows directly from this conclusion; Chapter 6 is intended to show that a variety of additional factors (four broad classes are mentioned: environmental, social, cognitive and psychological) are required to account for the wide range of possible L2 acquisition outcomes. Han does not actually elaborate on the details of inter-and intra-learner variation here. Instead, the chapter has three foci: presenting and critiquing existing research methodology, arguing for the modular nature of fossilization, and describing the Multiple Effects Principle [START_REF] Selinker | Language transfer and fossilization: the multiple effects principle[END_REF] as a way to understand the combination of microlevel factors in fossilization.

Han's exposition of what she considers to be the five main approaches to fossilization research (longitudinal, typical-error, advanced-learner, corrective-feedback and length-of-residence) is generally clear, if not optimally arranged. The discussion is divided into two sections, one presenting the methodologies and one critiquing them; however, no comment is made regarding the relative utility of the approaches or of the individual studies she describes in demonstrating fossilization. For example, in order to present longitudinal methodology, studies by Lardiere (1998a) and [START_REF] Schumann | The pidginization process: a model for second language acquisition[END_REF] are described (pp. 88-90). The latter of these studies was based on 10 months of data collection from a learner who had been in the USA for 4 months at the time research began, while the former study described recordings made over 8 years apart from a learner who had immigrated to the USA approximately 10 years before the first recording session took place.

From the fossilization-as-process perspective that Han explicitly adopts, it is not clear that Schumann's study, unlike Lardiere's, is at all informative with respect to demonstrating fossilization. Schumann's informant, Alberto, showed very little development in terms of negation across the 20 recordings collected; however, at the end of the study Alberto had only been in an English-speaking environment for 14 months. There is no reason to believe that his development in this area had not reached a temporary plateau. Han never raises this point, neither in the presentation nor in the critique of methodologies. She simply argues that the use of multiple research methodologies is important for characterizing the L2 end state, and that longitudinal studies are necessary to establish long-term stabilization (p. 99). The line between adequate and inadequate methodologies for studying fossilization is never made sufficiently clear.

Taken as a whole, Han's work convincingly argues that there are a number of factors -biological, cognitive, psychological and social -which give rise to differences in ultimate attainment (and fossilization) on both an inter-and an intra-learner level. At the same time, however, the presentation can be unclear and superficial in places, as in Chapter 6 (on micro-level factors) discussed above. Despite any issues that might linger, many of which simply await more conclusive research, this book has several notable strengths. The summary of existing problems is concise and thorough. The review of the literature provides a useful starting point for research in this area, and the chapter on teaching and fossilization will certainly be of interest to second language educators. Han's framework as well, though still preliminary, holds some promise as a means of situating fossilization research within the study of ultimate attainment.

III Han and Odlin (2005)

In the introduction to their edited volume, Studies of fossilization in second language acquisition, Han and Odlin (p. 7) return to the major weaknesses of current fossilization research. First, there is no consensus as to how the term 'fossilization' should be understood. In order to address this problem, Han and Odlin argue, following Han (2004), that every interlanguage encompasses both success and failure. There will inevitably be aspects of the L2 that have fossilized as well as those which are native-like or still developing (pp. 9, 12). It follows from this claim that L2 learners can never attain truly native proficiency and, also, that fossilization must only apply locally as opposed to globally (pp. 8-9). The second problem, it is argued (p. 7), is that explanation and description in fossilization have been 'flip-flopped'. That is, 'what we have here is not the logically prior description before explanation, but worse: explanation without description' (quoted from Selinker and Han, 2001: 276). A central goal of this work, then, is to collect recent empirical and analytical studies with a view to addressing these deficiencies.

Following the introduction, the volume contains 8 papers (4 analytical and 4 empirical), a commentary by Larsen-Freeman (Chapter 10) and an afterword by Selinker. Analytical papers by Nakuma (Chapter 2), MacWhinney (Chapter 7), Tarone (Chapter 8) and Birdsong (Chapter 9) address each of the central problems of fossilization research: definitions, description and explanation. Nakuma and Birdsong focus on the concept of fossilization, Nakuma arguing for increased research into the empirically investigable components of fossilization, and Birdsong for a shift of attention towards success in ultimate attainment as opposed to failure. MacWhinney and Tarone concentrate on explaining fossilization: MacWhinney through an assessment of existing explanations, and Tarone by highlighting the role social factors have to play in determining levels of L2 ultimate attainment. The empirical studies by Lardiere (Chapter 3), Han (Chapter 4), Odlin, Alonso Alonso and Alonso-Vázquez (Chapter 5) and Lakshmanan (Chapter 6) consider a wide range of data from children and adults, both longitudinal and experimental. Lardiere and Han investigate the contribution of grammaticality judgements to ongoing longitudinal studies of adult end-state learners. Odlin et al. look at the acquisition of the English present perfect by monolingual Spanish and bilingual Spanish-Galician speakers, and Lakshmanan examines child attrition-reacquisition data (of Hindi-Urdu) as a means to advancing understanding of fossilization. Taken as a whole, the studies included in this volume represent multiple theoretical viewpoints (e.g. sociolinguistic, generative, emergentist), which is beneficial from the perspective of developing a more comprehensive conceptualization of fossilization and advancing empirical work in this area.

Let us turn to some perspectives on how fossilization can be effectively researched empirically. This issue is a primary concern of many of the authors represented here and, clearly, is of central importance to work on both fossilization and ultimate attainment in SLA. From an analytical perspective, Nakuma argues against the view that fossilization is a 'phenomenon' that can be safely assumed to exist. Instead, he proposes that empirical research in fossilization should concentrate on deconstructing and testing the underlying hypotheses that make up the construct 'fossilization', such as how the product of fossilization can be successfully identified and measured (Nakuma argues that it cannot be; for a related discussion, see [START_REF] Long | Stabilization and fossilization in interlanguage development[END_REF]. However, Nakuma's argument is weakened in that he does not discuss any specific hypotheses that should be tested, nor how this line of research would differ from, say, conducting longitudinal studies to discover the extent and nature of fossilization as a phenomenon.

From an experimental angle, Lardiere and Han each look at how grammaticality judgement data can confirm prior findings based on naturalistic production data within ongoing longitudinal investigations of fossilization. Lardiere administered two grammaticality judgement tasks on English adverb placement 18 months apart to an adult native speaker of Chinese and Hokkien (named Patty) who has lived in the USA for more than 20 years. The findings of this study were consistent across both tasks and confirm the results of a previous study (Lardiere, 1998b) arguing that Patty's underlying knowledge of verb raising is native-like, despite her low level of suppliance of verbal morphology. Han similarly compared the results of two grammaticality judgement tasks with naturalistic data over a 7-year period. Her informants, two adult Chinese learners of English and one native English control, exhibited reliable judgements across the two tests. A comparison of these results with the naturalistic production of the Chinese learners from the same period confirmed this finding. These results are important both in terms of showing how multiple approaches to empirical research can be used in concert to good effect, as well as demonstrating the reliability of grammaticality judgement data over time.

Finally, arguments for a more dynamic conception of language and L2 learning can be found in several chapters of this volume, both experimental and analytical. Larsen-Freeman, for example, takes the following (comparatively strong) view:

What if we acknowledge, instead, that there is no end state because, first of all, there is no end? There is no finite uniformity to conform to. When we entertain a view of language as a dynamic complex adaptive system . . . we recognize that every use of language changes its resources, and the changed resources are then available for use in the next speech event. (p. 194) From this perspective, it is argued, fossilization research would benefit from acknowledging the inherent variability of the linguistic system being acquired, as well as of the acquisition process itself. Conclusive evidence of non-development may never be found because the target itself is not stable.

This idea of dynamic interlanguage is applied by Tarone, who argues for the investigation of language play as a manifestation of the force of creativity that is essential to the process of language acquisition and change, thereby weakening the tendency towards stabilization (p. 163). Tarone cites examples of SLA language play among children from [START_REF] Broner | Is it fun? Language play in a fifth grade Spanish immersion classroom[END_REF], among others. This study found a number of cases where children -in this case fifth grade Spanish immersion students (10-11 year olds) -appeared to introduce new variability into the IL syntax and phonological systems through language play. In one example (p. 169), a boy, Leonard, introduces the word celebro as a variant for cerebro (meaning 'head') in order to amuse his classmates. After playing with the alternation for a time, both versions seem to remain in Leonard's IL, as evidenced by his use of the novel form in a presentation later that week. According to Tarone, this occurrence suggests that language play may serve to destabilize rules or lexical items that might otherwise fossilize (even if these were correct to begin with).

The examples included here, albeit limited, demonstrate a great variety of perspectives, combined with a modicum of essential unity. In terms of the problems for fossilization raised in the introduction, for example, at least one unified position emerges: the preference for a local approach to fossilization. Lardiere (p. 48), for instance, explicitly states that her results are not consistent with a global view of fossilization. MacWhinney (p. 135) also supports the application of the term 'local fossilization' to characterize the specific areas of a learner's idiolect that show little change. Within the process-product distinction, as well, there appears to be agreement that the notion of 'fossilization' does not entail an invariable frozen product nor a causal mechanism. This position is inherent, for example, in a dynamic systems approach to SLA, and also seems to be favoured by Nakuma and by Birdsong.

Thus, points of agreement can be found despite theoretical and methodological diversity.

IV Conclusions

Taken together, these volumes make an important contribution to the study of fossilization in that they combine a substantial body of empirical findings with a complete exploration of possible definitions, descriptions and explanations of this central concept in SLA research. The ultimate goal, however, is to arrive at a consensus regarding what fossilization is and how it can be described empirically. Here, less progress has been made. We have seen that theoretical unity in some areas has been reached by the authors represented here. Nevertheless, perspectives on fossilization remain diverse and idiosyncratic. Empirically, as well, there is little consensus as to what methodologies for investigating fossilization -apart from conducting multi-year longitudinal studies of learners immersed in the target language -will yield reliable results. Moving forward from this point, new methodological perspectives and additional empirical research will hopefully pave the way for increasing clarification of the issues that have been raised within these works.

Or sometimes both (e.g.[START_REF] Kellerman | The imperfect conditional: fossilization, cross-linguistic influence and natural tendencies in a foreign language setting[END_REF].

Acknowledgements

Thanks are due to Donna Lardiere for helpful comments on earlier drafts of this review.