Presented by: Qinghua Tang Oct 25, 2006

1. Neural Correlates of second-language word learning: minimal instruction produces rapid change Judith McLaughlin, Lee Osterhout & Albert Kim (2004) Presented by: Qinghua Tang Oct 25, 2006

2. Background • Adult second-language (L2) learning is often considered slow and laborious compared to how fast children acquire their first language. • But, is it the case that all aspects of L2 learning are uniformly slow? What about the rate of L2 word learning, for example? • Besides, the claim is often based on behavioral performances of L2 learners • What about the neurophysiological status of the learners? Is there a gap between the behavioral performance of L2 learners and their neurophysiological status?

3. The goal of the study • Decide how much L2 exposure is needed before an adult L2 learner’s brain activity reflects the lexical status(i.e. whether the letter string is a legitimate word or not) and meaning of L2 words?

4. Experimental design:technique • ERP recording provides a nearly continuous sampling of the brain’s electrical activity. • N400 reflects word status and word meaning • native speakers of a language are supposed to show the largest N400 amplitude for pronounceable pseudowords, second largest for words preceded by semantically unrelated words, smallest for words preceded by semantically related words • That is, for N400 amplitude pseudowords > unprimed words > primed words

5. Experimental design:process (1) • Three sessions all together: • Session 1: Mean 14 hours of instruction(range 5-28 hours) • Session 2: mean 63 hours of instruction(range 59-67 hours) • session 3: mean 138 hours of instruction(range 126-150 hours)

6. Experiment design:process (2) • In each session: • Participants made a lexical decision for each of the prime-target pair. • Each trial started with fixation cross (500ms), followed by blank screen (500ms), prime (400ms), target (400ms), response prompt • ERP was recorded at the same time at 200Hz from 13 scalp sites (three midline, five lateral pairs)

7. Subjects • A group (n = 18, 16,13 for each session respectively) of university students taking a 9-month long introductory French course (mean age: 21.3 years) • A control group (n = 8) who had never had significant exposure to French (mean age 27.6 years) • All the participants had received at least 1 year of instruction in another foreign language • 5 learners dropped the course • All the participants were included in single session analyses, but only those who participated fully were included in multi-session comparisons.

8. stimuli • 2 lists of 112 ‘prime- target’ pairs of letter strings, including: • 40 semantically related pairs. E.g. chien - chat • 40 semantically unrelated pairs. E.g. maison – soif • 32 pairs in the pattern of word-pseudoword E.g. mot - nasier • Target words were identical across lists but counterbalanced across prime type • Each participant saw one list per session • The list in session 1 was repeated in session 3

9. Results:behavioral • Non-learners showed no sensitivity in lexical decision task in all three sessions • Sensitivity is measured using a d’ representing the likelihood of a real target being recognized (d’=0 indicates no sensitivity, d’ = 4 indicates near perfect sensitivity.) • Learners showed no sensitivity in session 1, but with moderate increase in sensitivity in session 2 and 3

11. Results:N400 • No change observed in N400 amplitude for non-learners across all three sessions • Learners showed larger N400 amplitude for pseudowords than for unprimed and primed words. The word-pseudoword difference started in session 1 and increased across all three sessions. By session 3, learners’ ERP responses were qualitatively similar to analogous native language responses. • There was no significant difference between unrelated words and related words for learners in session 1 • N400 effects were evenly distributed over midline sites and posteriorly distributed over lateral sites

13. Discussion (1) • Learners showed a word - pseudoword N400 effect after approximately 14 hours of instruction. • Did the presence of this N400 effect result from L2 exposure? • Both N400 amplitude and d’ score of session 1 were regressed onto the number of instructional hours for each learner • N400 amplitude difference was correlated with hours of instruction. • d’ score was not correlated with hours of instruction • N400 differences in session 1 were also correlated with the proportion and frequency of target words in the text material assigned to each learner before session 1 • Therefore, the N400 effect was a result of L2 exposure

15. Discussion (2) • According to Saffran, Alison & newport (1996), people rapidly extract co-occurrence statistics for letter and sound combintaions within a language. • Was the N400 difference between pseudowords and words due to the smaller mean grapheme co-occurrence values for the pseudowords than for words? • In other words, did the graphemes of words co-occur more often than pseudowords and therefore caused the N400 difference?

16. Discussion (2) continued • The digram, trigram and quadragram frequencies of all the French words from the first four chapters of the textbook were computed. • The words and pseudowords did not differ in bigram and trigram frequency(P>0.3), but there was a difference in quadragram frequency (t128=1.76, P<0.04), however, the quadragram frequency was highly correlated with target word frequency(r=0.99). • Therefore, the results of the study probably reflected whole-word rather than grapheme co-occurrence frequency.

17. Conclusion • Adult language learners quickly grasp information such as word form and word meaning (initially word form, and then word meaning) • L2 learning is not as slow as it is often thought to be • Some behavioral experiments might underestimate what has been learned.

18. Implications of the study • The method used in the study can be extended to test the influence of L1-L2 similarity, instructional methods and learners’ age on L2 learning.

19. Thank you!