1. Early effects of morphological complexity on visual evoked fields in MEG Eytan Zweig & Liina Pylkkänen New York University 80 th Annual LSA meeting, January 7, 2006

2. Morphological decomposition - Two questions Do all affixed words decompose? Does semantic opacity play a role? What is the timing of lexical decomposition?

3. Semantic opacity Transparent words generally taken to decompose Competing hypotheses about opaque words “Farmer”Farm + -er “Folder” Fold + -er Folder ? 1. Opaque words decompose (Rastle & Davis, 2003; Davis et al., 2004) 2. Opaque words do not decompose (Marslen-Wilson et al., 1994)

4. Semantic opacity Previous experiments have produced contradictory results (as reviewed by Feldman et al., 2004).

5. Timing of decomposition Decomposition Lexical access 1.Early decomposition (Taft & Forster, 1975; Rastle & Davis, 2003; Davis et al., 2004) 3. Race (Baayen, 1992) Lexical access Decomposition 2. Late decomposition (Feldman et al., 2004) farm + -er farm, -er farmer farm + -er Decomposition Lexical access farm + -er farm, -er farmer

6. ERP evidence for early decomposition in sentence processing Word category violations elicit an early left anterior negativity (ELAN) (Friederici, 2000; Friederici et al., 2002). Category is determined through morphological cues. Indirectly supports an early effect of morphology.

7. This study Takes advantage of the millisecond temporal resolution of MEG. Simple lexical decision task without priming.

8. Magnetoencephalography (MEG) http://www.ctf.com/Pages/page33.html EEG MEG

9. MEG analysis

13. Typical MEG response to visual words

14. Experiment 1 Suffixed words

15. Experiment 1 Stimuli No Suffix No Suffix Orth. -er Opaque Suffix Transparent Suffix SWITCHWINTERFOLDERFARMER 34 words per condition Conditions were controlled for matched for length, surface frequency, orthographic neighborhood density and frequency, and syntactic category. Suffixed conditions were further controlled for stem frequency and orthographic regularity.

16. Testing for pre-lexical effects M350 is the first component to show effects of lexical factors (Embick et al., 2001; Pylkkänen & Marantz, 2003). Fiorentino & Poeppel (2003) found that the M350 is sensitive to constituent frequency in compounds. –Decomposition likely to happen before M350.

17. Prediction - Timing If decomposition is pre-lexical, we should find effects before the M350.

18. M170 The first component that has been found to be sensitive to the presence of letter strings (Tarkiainen et al., 1999). Most research has found that the M170 is not sensitive to lexical factors such as frequency.

19. M170 Fusiform gyri have been found to be the primary generators of M170 activity.

20. Fusiform Gyri Functional asymmetry between hemispheres (Tarkiainen et al., 2002) : –The left fusiform gyrus sensitive to letter strings (Cohen et al., 2000; Dehaene et al., 2002). “Visual Word Form Area” –The right fusiform gyrus primarily sensitive to faces.

21. Prediction – Semantic opacity If opaque words decompose, they will pattern with transparent words. If they do not, they will pattern with orthographic controls.

22. M170 - Left Hemisphere Grandaveraged waveform n=16 no effect Time nAm

23. M170 - Left Hemisphere Amplitudes SWITCHWINTERFOLDERFARMER nAm

24. M170 - Right Hemisphere Grandaveraged waveform n=16 p < 0.001 Time nAm

25. M170 - Right Hemisphere Amplitudes SWITCHWINTERFOLDERFARMER nAm

26. Other measures No M100 effects. No M350 effects. No response time effect.

27. Conclusions M170 activity is influenced by the presence of derivational suffixes. Early lexical decompositon. No effect of opacity All affixed words decompose.

28. Conclusions The right lateralization of the effect is surprising. Early visual word processing may be bilateral, with distinct functional roles for the left and the right hemispheres. However, there is a second hypothesis.

29. Why the right hemisphere? FARMER

30. Experiment 2 Prefixed words

31. Experiment 2 Stimuli No PrefixNo Prefix Orth. re- Prefix ROTATERESUMEREFILL 32 words per condition Conditions were controlled for matched for length, surface frequency, orthographic neighborhood density and frequency, and syntactic category. Prefixed condition was further controlled for stem frequency and orthographic regularity.

32. M170 - Right Hemisphere Grandaveraged Waveform Time nAm n=10 p < 0.02

33. M170 - Left Hemisphere Grandaveraged Waveform n=10 p < 0.02 Time nAm

34. Other measures No M100 effects. No M350 effects. No response time effect.

35. Conclusions Experiment 1 replicated. Stem lexicality cannot be the sole reason for the RH effect in Experiment 1. Possibly a combined effect of morphological complexity and stem lexicality.

36. /ta-ba-ko/ Kana Kanji smoke-weed

37. Nakamura et. al (2005) FMRI activity in fusiform gyri

38. Conclusions Morphological decomposition is a pre- lexical effect, and is not sensitive to semantic opacity. The RH M170 source is sensitive to morphological complexity irrespective of the linear ordering between a stem and an affix. A crucial role for the right hemisphere in early word processing.