Processing of regular and irregular past tense morphology in higly proficient L2 learners of English

Processing of regular and irregular past tense morphology in highly proficient L2 learners of English: a self-paced reading study
Background
A considerable body of research has demonstrated that adult native speakers employ two distinct mechanisms when they process morphologically complex words: 1) an associative system of full-form representations stored in lexical memory, and 2) a set of rule-like operations for decomposing inflected and derived words into their morphological constituents (Marslen-Wilson & Tyler, 1998; Pinker, 1999). For English past tense, according to this dual-route system, irregular past tense forms are stored in the mental lexicon and are memorized and retrieved by rote. On the other hand, regular past tense forms are thought to be composed each time they are accessed by the addition of the –ed suffix to the verb stem.
Research on the processing of English past tense in L2 learners of English is limited. Ullman (2001) suggested that L2 learners should rely heavily on memory rather than use rule application. According to his theory, regular past tense forms should be stored and retrieved from the mental lexicon similarly to irregular past tense forms instead of composed by the use of rules. Recently, Silva and Clahsen (2008) using a masked priming experiment with late learners of English have provided evidence that English regular past tense forms are stored in the mental lexicon. In contrast, Hahne et al. (2006) using an ERP experiment have provided evidence for a dual-route system in advanced L2 learners of English. The different findings could be due to the differences in the methodologies used (processing of single-words vs. sentences) or to differences in the populations (level of proficiency or exposure to English).
The present study addresses this issue by investigating how adult advanced L2 learners of English process regularly and irregularly inflected along with regularised and irregularised verbs embedded in sentences using the self-paced reading paradigm. To address effects of exposure to English, we recruited two groups of advanced L2 learners that had similar level of proficiency, but differed on the amount and type of exposure.
Method
Participants:
Native speakers: 30 healthy native adult speakers of English (mean age: 20 yrs, SD: 3.86).
L2 learners with exposure to English in a naturalistic setting: 30 Greek learners of English (mean age: 29 yrs, SD:3.99), who scored at the Mastery level of proficiency in the English Oxford Quick Placement Test (mean score 83.97%, SD 8.05%). These learners have lived and/or worked in the UK for 6.56 yrs (SD: 4.68) and were defined as advanced L2 learners with naturalistic exposure to English.
L2 learners with exposure to English in a classroom setting: 30 native speakers of Greek (mean age: 27 yrs, SD: 4.99), who scored at the Effective Proficiency level of proficiency in the English Oxford Quick Placement Test (mean score 76.8%, SD 7.75%). These learners were living in Greece, had not lived or worked in any English-speaking country, and their exposure to English was in a classroom setting.
Table 1 shows information about the language background of the L2 learners of English.
Table 1: Language background information
Materials
The self-paced reading task consisted of 120 experimental sentences, and 80 filler sentences. 120 different verbs were used for the experimental sentences, 60 regulars and 60 irregulars. The two verb lists were matched for mean frequency, mean length, and neighbourhood density (Frost et al,1997). The verbs were inflected and gave the following 4 verb types:
30 regularly inflected forms , e.g.: play-played
30 irregularly inflected forms , e.g.: keep-kept
30 regularised forms , e.g.: feel-feeled
30 irregularised forms , regular verbs were turned into “irregulars” according to the phonological patterns described by Pinker (1999), e.g.: reach-raught (following teach-taught)
Each sentence was divided into 6 segments, as shown below, and the verb was always in Segment 4, which is the critical segment.
Sarah / had not told us / that her father / died / from a serious illness / ten years ago.
Procedure
The sentences were presented on a CRT monitor one segment at a time using E-prime, and participants had to press a button on an E-prime button box as fast as possible to read each segment. To ensure that participants read the sentences and paid attention to their meaning, 54 of the experimental sentences and all of the filler sentences were followed by a comprehension question.
Results
Accuracy of comprehension: Table 2 below shows mean accuracy in the comprehension questions. A one-way ANOVA showed no significant between-groups differences.
Table 2: Accuracy in comprehension
Reaction Times
Non-critical segments
No significant effects were found immediately before the critical segment.
Critical Segment
Figure 1 shows RTs on the critical segment for the three groups of participants. A repeated measures ANOVA with the factor Group (L1 speakers, L2 learners with naturalistic exposure, L2 learners with classroom exposure) as a between subjects factor, and Verb Type (regular, irregular, regularised, irregularised) as a within subjects factor revealed a main effect of Verb Type (F (3,261)=66.75, p <0.001, η 2 = 0 . 43 ) , and a Verb Type x Group interaction (F(6,261)=3.34, p=0.003, η 2 =0.07).
Within group comparisons: In all groups, RTs for irregular verbs were significantly shorter than for regulars, and RTs for irregularised forms were longer than for irregulars. RTs for regulars were shorter than for regularised only in L2 the groups, and RTs for regularised forms were shorter than for irregularised in natives, and in L2 learners with classroom exposure.
Between group comparisons : RTs for irregular verbs were longer in L2 learners with naturalistic exposure than in L2 learners with classroom exposure. RTs for regularised forms were longer in L2 learners with naturalistic exposure compared to natives, and L2 learners with classroom exposure.
Summary and discussion All groups showed shorter RTs in irregularly inflected compared to regularly inflected forms matched for frequency, length, and neighbourhood density. This suggests that an additional process of morphological decomposition underlies processing of regular past tense forms in native speakers of English, and also in both groups of L2 learners. L1 speakers and L2 learners with classroom exposure showed also longer RTs for irregularised compared to regularised forms. This difference could be explained in the following way. Irregularised forms, such as raught , may have been treated as non-words, whereas regularised forms, such as feeled , may have been processed through morphological decomposition, and this is why at least in the L1 speakers there is no significant difference between regular and regularised forms. Shorter RTs for irregular compared to regular forms in both groups of L2 learners suggests that for L2 learners with Effective and Mastery Proficiency, type of exposure does not affect the way they process English past tense morphology.
References
Frost, R. Forster, KI. Deutsch, A. (1997): What can we learn from the morphology of Hebrew? A masked-priming investigation of morphological representation, Journal of Experimental Psychology: Learning, Memory, and Cognition , 23 (4) 829-856
Hahne, A. et al (2006): Morphological Processing in a Second Language: Behavioral and Event-related Brain Potential Evidence for Storage and Decomposition, Journal of Cognitive Neuroscience, 18 (1), 121-134
Marslen-Wilson, W. & Tyler, LK (1998): Rules, representations and the English past tense , Trends in Cognitive Sciences, 11(2), 428-435
Oxford Quick Placement Test , Oxford University Press, Oxford, New York, 2001
Pinker, S (1999) Words and rules , the ingredients of language, London, Weidenfeld & Nicholson .
Silva, R. & Clahsen, H. (2008): Morphologically Complex Words in L1 and L2 Processing: Evidence from Masked Priming Experiments in English , Bilingualism: Language and Cognition , 11(2), 245-260
Ullman, M. T. (2001): The neural basis of lexicon and grammar in first and second language: the declarative/procedural model. Bilingualism: Language and Cognition, 4, 105-122.
Acknowledgements This study is part of the PhD of Christos Pliatsikas, which is being funded by an ESRC studentship. We would like to thank the participants of this study, Dr Stavroula-Thaleia Kousta and Dr Gabriella Vigliocco for providing us space to test participants at UCL.Also, the “Scholars” language school (Kallithea, Greece) and Dr. Athanassios Prwtopapas (University of Athens) for providing us with space to test participants in Greece.
Contact information
Department of Clinical Language Sciences, School of Psychology, University of Reading, Whiteknights, RG6 6AL, Reading
Email: [email_address]
* * * * * * * * * * L2 with naturalistic exposure L2 with classroom exposure p value Age of onset of English lessons 8.83 (2.42) 8.11 (1.58) p = 0.18 Years of learning English 8.53 (3.32) 8.47 (2.51) p = 0.93 Daily use of Greek 0.4207 0.8257 p < .001 Daily use of English 0.5693 0.1616 p < .001 L1 speakers L2 with naturalistic exposure L2 with classroom exposure p value Accuracy of comprehension 96.7% (2.8) 97% (3.5) 96% (1.9) P = 0.633

Processing of regular and irregular past tense morphology in higly proficient L2 learners of English

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Processing of regular and irregular past tense morphology in higly proficient L2 learners of English — Presentation Transcript