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Liina Pylkkänen Department of Linguistics/ Center for ...

  1. 1. Liina Pylkkänen Department of Linguistics/ Center for Neuromagnetism New York University MEG, the Mental Lexicon and Morphology LP, Aug 03, Tateshina
  2. 2. Day 1 Lexical access 1: The M350 as an MEG index of lexical activation Day 2 Lexical access 2: The M350 and mechanisms of recognition Day 3 Morphology 1: The M350 as a tool for investigating similarity and identity Day 4 Morphology 2: Electrophysiological and behavioral evidence for early effects of morphology MEG, the Mental Lexicon and Morphology LP, Aug 03, Tateshina
  3. 3. Day 4 Morphology 2: Electrophysiological and behavioral evidence for early effects of morphology LP, Aug 03, Tateshina <ul><li>Morphological family effects. </li></ul><ul><li>Early effects of superficial morphology in masked priming. </li></ul><ul><li>Role of semantic transparency. </li></ul><ul><li>Early effects of morphology in ERPs. </li></ul><ul><li>Grand summary of MEG results and comparison to ERP literature. </li></ul>
  4. 4. Day 4 Morphology 2: Electrophysiological and behavioral evidence for early effects of morphology LP, Aug 03, Tateshina <ul><li>Morphological family effects. </li></ul><ul><li>Early effects of superficial morphology in masked priming. </li></ul><ul><li>Role of semantic transparency. </li></ul><ul><li>Early effects of morphology in ERPs. </li></ul><ul><li>Grand summary of MEG results and comparison to ERP literature. </li></ul>
  5. 5. Effect of lexical frequency <ul><li>High frequency words are processed faster than low frequency words. </li></ul><ul><li>Prediction of decompositional theories of morphology: cumulative root frequency effects. </li></ul>magnet terror Matched for surface frequency - ic –ize –ism Low frequency derivatives - ist –ize -ism High frequency derivatives Same number of derivates
  6. 6. Effect of lexical frequency <ul><li>High frequency words are processed faster than low frequency words. </li></ul><ul><li>Prediction of decompositional theories of morphology: cumulative root frequency effects. </li></ul>magnet terror Matched for surface frequency - ic –ize –ism Low frequency derivatives - ist –ize -ism High frequency derivatives Same number of derivates Should be faster due to high cumulative root frequency
  7. 7. Cumulative root frequency effects for inflection <ul><li>Response times to a noun depend on the cumulative frequency of the singular and plural (Schreuder & Baayen, JML, 1997) </li></ul><ul><li>CAT </li></ul><ul><li>CATS </li></ul>
  8. 8. But NO cumulative root frequency effects for derivation <ul><li>Family frequency </li></ul>magnet terror - ic –ize –ism - ist –ize -ism HIGH LOW Family frequency does not affect lexical decision times. High family size speeds up lexical decision times. Schreuder & Baayen (1997): S&B: this is a late post-lexical effect. S&B: Therefore, no decomposition in derivation. <ul><li>Family size </li></ul>acid diary - ic –ity –ify –head –test –washed - ist HIGH LOW
  9. 9. Alternative explanation for lack of cumulative root frequency effects in derivation <ul><li>High morphological family frequency speeds up root activation </li></ul><ul><li>BUT </li></ul><ul><li>this facilitation is cancelled out by subsequent competition between the highly frequent morphological family members. </li></ul><ul><li>Hypothesized affix-competition in priming (Marslen-Wilson, et al. 1994) : </li></ul><ul><li>In crossmodal priming, </li></ul><ul><ul><li>NO PRIMING FOR </li></ul></ul><ul><ul><li>government – governor </li></ul></ul><ul><ul><li>ALTHOUGH ROBUST PRIMING FOR </li></ul></ul><ul><ul><li>government – govern </li></ul></ul><ul><ul><li>(Marslen-Wilson, W. D., Tyler, L., Waksler, R., & Older, L. (1994). Morphology and meaning in the English mental lexicon. Psychological Review 101, 3-33.) </li></ul></ul>
  10. 10. Alternative explanation for lack of cumulative root frequency effects in derivation <ul><li>High morphological family frequency speeds up root activation </li></ul><ul><li>BUT </li></ul><ul><li>this facilitation is cancelled out by subsequent competition between the highly frequent morphological family members. </li></ul><ul><li>How to measure timing of root activation, prior to any effect of competition? </li></ul><ul><ul><li>M350, an magnetoencephalographic (MEG) response component elicited by word stimuli, peaking at ~350ms post word-onset </li></ul></ul>
  11. 11. Magnetoencephalography (MEG) <ul><li>Measures magnetic fields generated by large populations of neurons firing in synchrony. </li></ul><ul><li>Millisecond temporal resolution. </li></ul><ul><li>Millimeter spatial resolution (at least for cortical sources). </li></ul>
  12. 12. Magnetoencephalography (MEG)
  13. 13. What happens in the brain when we read words? Letter string processing (Tarkiainen et al. 1999) Lexical activation (Pylkk änen et al. 2002) -100 0 100 200 300 400 500 600 700 [msec] 0 200 200 [fT] 150-200ms (M170) 200-300ms (M250) 300-400ms (M350) 400-500ms Pylkkänen and Marantz, Trends in Cognitive Sciences, in press.
  14. 14. What happens in the brain when we read words? 300-400ms (M350) Lexical activation (Pylkk änen et al. 2002) <ul><li>The M350 is sensitive to </li></ul><ul><ul><li>Lexical frequency (a) </li></ul></ul><ul><ul><li>Repetition (b) </li></ul></ul><ul><ul><li>Phonological similarity (c) </li></ul></ul><ul><ul><li>Semantic similarity (d) </li></ul></ul><ul><ul><li>Sublexical frequency (e, f) </li></ul></ul><ul><li>The M350 is NOT sensitive to </li></ul><ul><ul><li>Interlexical competition (e) </li></ul></ul><ul><li>Embick, D., Hackl, M., Schaeffer, J., Kelepir, M. & Marantz, A. (2001). A magnetoencephalographic component whose latency reflects lexical frequency. Cognitive Brain Research 10:3, 345-348. </li></ul><ul><li>Pylkkänen, L., Stringfellow, A., Flagg, E., Marantz, A. (2001). A Neural Response Sensitive to Repetition and Phonotactic Probability: MEG Investigations of Lexical Access. Proceedings of Biomag 2000. 12th International Conference on Biomagnetism. Helsinki University of Technology, Espoo, Finland. 363-367. </li></ul><ul><li>(c) Pylkkänen, L., Stringfellow, A. Marantz, A. 2002. Inhibition and Competition in Word Recognition: MEG Evidence. Submitted. </li></ul><ul><li>(d) Pylkkänen, L. Stringfellow, A., Gonnerman, L., Marantz, A. 2002. Magnetoencephalographic indices of identity and similarity in lexical access. In preparation. </li></ul><ul><li>Pylkkänen, L., Stringfellow, A. Marantz, A. 2002. Neuromagnetic evidence for the timing of lexical activation: an MEG component sensitive to phonotactic probability but not to neighborhood density. Brain and Language 81, 666-678. </li></ul><ul><li>(f) Stockall, L. Stringfellow, A. Marantz, A. 2003. The precise time course of lexical activation: MEG measurements of the effects of frequency, probability and density in lexical decision, Submitted. </li></ul>Pylkkänen and Marantz, Trends in Cognitive Sciences, in press.
  15. 15. What happens in the brain when we read words? 300-400ms (M350) Lexical activation (Pylkk änen et al. 2002) <ul><li>The M350 is sensitive to </li></ul><ul><ul><li>Lexical frequency (a) </li></ul></ul><ul><ul><li>Repetition (b) </li></ul></ul><ul><ul><li>Phonological similarity (c) </li></ul></ul><ul><ul><li>Semantic similarity (d) </li></ul></ul><ul><ul><li>Sublexical frequency (e, f) </li></ul></ul><ul><li>The M350 is NOT sensitive to </li></ul><ul><ul><li>Interlexical competition (e) </li></ul></ul><ul><li>Embick, D., Hackl, M., Schaeffer, J., Kelepir, M. & Marantz, A. (2001). A magnetoencephalographic component whose latency reflects lexical frequency. Cognitive Brain Research 10:3, 345-348. </li></ul><ul><li>Pylkkänen, L., Stringfellow, A., Flagg, E., Marantz, A. (2001). A Neural Response Sensitive to Repetition and Phonotactic Probability: MEG Investigations of Lexical Access. Proceedings of Biomag 2000. 12th International Conference on Biomagnetism. Helsinki University of Technology, Espoo, Finland. 363-367. </li></ul><ul><li>(c) Pylkkänen, L., Stringfellow, A. Marantz, A. 2002. Inhibition and Competition in Word Recognition: MEG Evidence. Submitted. </li></ul><ul><li>(d) Pylkkänen, L. Stringfellow, A., Gonnerman, L., Marantz, A. 2002. Magnetoencephalographic indices of identity and similarity in lexical access. In preparation. </li></ul><ul><li>Pylkkänen, L., Stringfellow, A. Marantz, A. 2002. Neuromagnetic evidence for the timing of lexical activation: an MEG component sensitive to phonotactic probability but not to neighborhood density. Brain and Language 81, 666-678. </li></ul><ul><li>(f) Stockall, L. Stringfellow, A. Marantz, A. 2003. The precise time course of lexical activation: MEG measurements of the effects of frequency, probability and density in lexical decision, Submitted. </li></ul>Pylkkänen and Marantz, Trends in Cognitive Sciences, in press.
  16. 16. (Pylkk änen, Stringfellow, Marantz, Brain and Language, 2002) Effect of probability/density (n=10) n.s. n.s. * * n.s. n.s. * *
  17. 17. (i) 1 st component sensitive to lexical factors (such as lexical frequency) (ii) not affected by competition M350 time level of activation resting level Stimulus: TURN TURN TURNIP TURF TURTLE Activation Selection Competition
  18. 18. <ul><li>Effect of high phonotactic probability/ high neighborhood density: </li></ul>Hypothesis M350 RT - speed-up due to sublexical frequency - slow-down due to competition <ul><li>Effect of high morphological family frequency? </li></ul>M350 RT - speed-up due to cumulative root frequency - slow-down due to competition from highly frequent family members
  19. 19. <ul><li>Contrast 1: Family frequency </li></ul><ul><li>Contrast 2: Family size </li></ul><ul><li>Four categories of visual words, all nouns </li></ul>magnet (n=18) terror (n=18) - ic –ize –ism - ist –ize -ism HIGH LOW <ul><li>Matched for: </li></ul><ul><li>Length </li></ul><ul><li>Freq. of the sg, </li></ul><ul><li>Cumulative freq. of the sg. & pl. forms </li></ul><ul><li>Family size </li></ul><ul><li>Mean bigram frequency </li></ul>acid (n=21) diary (n=21) - ic –ity –ify –head –test –washed - ist HIGH LOW <ul><li>Matched for: </li></ul><ul><li>Length </li></ul><ul><li>Freq. of the sg, </li></ul><ul><li>Cumulative freq. of the sg. & pl. forms </li></ul><ul><li>Family frequency (not perfectly) </li></ul><ul><li>Mean bigram frequency </li></ul>Materials (from Baayen, R. H., Lieber, R., & Schreuder, R. (1997). Linguistics 35, 861-877 )
  20. 20. Behavior (Pylkk änen, Feintuch, Hopkins & Marantz, Cognition , to appear ) * n.s. * n.s.
  21. 21. M350 source analysis HBM 2003, poster 1345 <ul><li>Equivalent current dipole analysis </li></ul><ul><li>Latencies and amplitudes measured at points where the source amplitude reached 25%, 50%, 75% and 100% of the maximum source strength . </li></ul>25% 50% 75% 100%
  22. 22. MEG data, single subject (Pylkk änen, Feintuch, Hopkins & Marantz, Cognition , to appear )
  23. 23. Family frequency: M350 (S1) HBM 2003, poster 1345 High family frequency
  24. 24. HBM 2003, poster 1345 Family frequency: M350 (S1) High family frequency
  25. 25. HBM 2003, poster 1345 Low family frequency <ul><li>Morphological competition at the M350 </li></ul>Family frequency: M350 (S1) High family frequency Extra processing load at the M350
  26. 26. HBM 2003, poster 1345 Family frequency: M350 amplitude (n=10)
  27. 27. HBM 2003, poster 1345 * Family frequency: M350 amplitude (n=10)
  28. 28. HBM 2003, poster 1345 Family frequency: M350 latency (n=10) all n.s.
  29. 29. HBM 2003, poster 1345 Family size: M350 amplitude (n=10) all n.s. P = 0.09
  30. 30. HBM 2003, poster 1345 Family : M350 latency (n=10) ** *
  31. 31. Why? M170 M250 M350 RT (lexical decision)    High morphological family size High morphological family frequency High sublexical frequency/ neighborhood density Shorter RT  Shorter latency    Larger amplitude  (competition)  Longer RT  (competition) Shorter latency  Smaller amplitude  1. Difference in the time course of competition. 2. High family size has an early facilitory effect.
  32. 32. 1. Difference in the time course of competition High frequency morphological family High density phonological neighborhood (frequency-weighted) TERROR terrorism terrorize terrorist DECOMPOSITION NO DECOMPOSITION <ul><li>Relationship between target and competitors qualitatively different: difference is due to morphology. </li></ul><ul><li>Difference is due to the different phonological and/or semantic properties of the competitors. </li></ul>TERROR - ist –ize -ism LINE loin fine pine nine light like lie lane lime LINE loin fine pine nine light like lie lane lime
  33. 33. 1. Difference in the time course of competition TERROR terrorism terrorize terrorist NO DECOMPOSITION <ul><li>Difference is due to the different phonological and/or semantic properties of the competitors. </li></ul><ul><li>Non-decompositional account also predicts interference effects in priming for pairs such as TERRORISM – TERROR. </li></ul><ul><li>BUT this is completely unsupported by data – effect is robustly facilitory (e.g. a-d) . </li></ul><ul><li>(a) Marslen-Wilson, W. D., Tyler, L., Waksler, R., & Older, L. (1994). Morphology and meaning in the English mental lexicon. Psychological Review 101, 3-33. </li></ul><ul><li>(b) Pylkkänen, L. Stringfellow, A., Gonnerman, L., Marantz, A. 2002. Magnetoencephalographic indices of identity and similarity in lexical access. In preparation. </li></ul><ul><li>Gonnerman, L. 1999, Morphology and the lexicon: exploring the semantics-phonology interface, PhD thesis, University of Southern California. </li></ul><ul><li>Rastle , K., Davis, M., Marslen -Wilson, W., & Tyler, L.K. (2000). Morphological and semantic effects in visual word recognition: A time course study. Language and Cognitive Processes, 15, 507-538. </li></ul>LINE loin fine pine nine light like lie lane lime
  34. 34. 1. Difference in the time course of competition High frequency morphological family High density phonological neighborhood (frequency-weighted) DECOMPOSITION <ul><li>Competition between morphological family members appears to precede competition between phonological neighbors. </li></ul><ul><li>An account of the phenomenon needs to make a distinction between morphological and phonological competitors. </li></ul>TERROR - ist –ize -ism LINE loin fine pine nine light like lie lane lime
  35. 35. Conclusion HBM 2003, poster 1345 Decomposition Morphological competition effects Phonological competition effects Early morphological parsing/ segmentation Lexical access
  36. 36. <ul><li>Early determination of grammatical category in ERPs ( Friederici, 2002) . </li></ul><ul><li>Early effects of morphology in masked priming ( Rastle, Davis & New submitted ) </li></ul>Conclusion HBM 2003, poster 1345 Grammar happens early:
  37. 37. 2. High family size has an early facilitory effect <ul><li>One possibility: </li></ul><ul><li>Effect is semantic in nature and is related to effects of polysemy. </li></ul><ul><li>Heavily polysemous words (such as belt ) are processed faster than words that only have few “senses” (such as ant) . </li></ul><ul><li>(Rodd, Gaskell & Marslen-Wilson (2002) Making Sense of Semantic Ambiguity: Semantic Competition in Lexical Access. Journal of Memory and Language 46, 245–266) </li></ul>
  38. 38. 2. High family size has an early facilitory effect <ul><li>Different morphological environments induce different senses of the root and therefore nouns with large morphological families have more senses than nouns with small morphological families. </li></ul><ul><li>Prediction: semantically opaque morphological family members should contribute to the family size effect the most, as those would involve the most “sense-switching”. </li></ul><ul><li>BUT: there is at least some evidence that the family size effect is in fact mostly carried by the semantically transparent members of the family. </li></ul><ul><li>(De Jong NH, Feldman LB, Schreuder R, Pastizzo M, Baayen RH (2002) The processing and representation of Dutch and English compounds: peripheral morphological and central orthographic effects. Brain Lang 2002 Apr-Jun;81(1-3):555-67.) </li></ul>
  39. 39. 2. High family size has an early facilitory effect Alternatively: The family size effect is not a facilitory effect of high family size, but an inhibitory effect stemming from more potent competitors in the low family size condition. (See Perea and Rosa (2000) for a review of studies indicating that the important neighborhood variable in visual word recognition is not the number of neighbors per se , but the frequency of a word's neighbors relative to its own frequency. Perea M. and E. Rosa (2000) Psicologica , 21, 327-340) acid diary -ic -ity -ify -head -test -washed -Ø -st -ø Keeping family frequency constant but lowering family size creates more potent competitors.
  40. 40. Conclusion <ul><li>Evidence for decomposition (although somewhat indirect). </li></ul><ul><li>Evidence for the existence of morphological competition (cf. Marslen-Wilson 1994). </li></ul><ul><li>Identification of a neural correlate of the morphological family size effect. </li></ul>Thanks to: Sophie Feintuch & Emily Hopkins (Portsmouth High School, NH)
  41. 41. Day 4 Morphology 2: Electrophysiological and behavioral evidence for early effects of morphology LP, Aug 03, Tateshina <ul><li>Morphological family effects. </li></ul><ul><li>Early effects of superficial morphology in masked priming. </li></ul><ul><li>Role of semantic transparency. </li></ul><ul><li>Early effects of morphology in ERPs. </li></ul><ul><li>Grand summary of MEG results and comparison to ERP literature. </li></ul>
  42. 42. Rastle, Davis & New (2003) <ul><li>Masked priming – eliminates semantic effects. </li></ul><ul><li>500ms forward mask, 43ms prime. </li></ul>TRANSPARENT: cleaner – CLEAN OPAQUE: corner – CORN ORTHOGRAPHIC: brothel - BROTH LP, Aug 03, Tateshina
  43. 43. Rastle, Davis & New (2003) <ul><li>Result: </li></ul>LP, Aug 03, Tateshina EQUAL PRIMING NO PRIMING TRANSPARENT: cleaner – CLEAN OPAQUE: corner – CORN ORTHOGRAPHIC: brothel - BROTH
  44. 44. Rastle, Davis & New (2003) Conclusion: There is an early processing stage of pre-lexical morphological segmentation which is based only on the formal properties of the input. LP, Aug 03, Tateshina  If morphological parsing occurs early, one would expect morphological competition to occur early as well, which is what the family frequency results suggest.
  45. 45. Day 4 Morphology 2: Electrophysiological and behavioral evidence for early effects of morphology LP, Aug 03, Tateshina <ul><li>Morphological family effects. </li></ul><ul><li>Early superficial effects of morphology in masked priming. </li></ul><ul><li>Role of semantic transparency. </li></ul><ul><li>Early effects of morphology in ERPs. </li></ul><ul><li>Grand summary of MEG results and comparison to ERP literature. </li></ul>
  46. 46. Zweig et al.: Does morphological decomposition require semantic transparency? <ul><li>If semantically opaque forms aren’t decomposed, processing a form such as UNIVERSITY would involve </li></ul><ul><ul><li>access to the lexical representation UNIVERSITY </li></ul></ul>(Zweig, van Rijsingen & Pylkk änen, in progress)
  47. 47. Does morphological decomposition require semantic transparency? <ul><li>If semantically opaque forms are decomposed, processing a form such as UNIVERSITY would involve </li></ul><ul><ul><li>access to UNIVERSE and ITY </li></ul></ul><ul><ul><li>combining UNIVERSE and ITY </li></ul></ul><ul><ul><li>access to the special meaning that is associated with this complex structure </li></ul></ul><ul><li>Processing semantically transparent morphology would not involve step (iii). </li></ul>(Zweig, van Rijsingen & Pylkk änen, in progress)
  48. 48. Does morphological decomposition require semantic transparency? <ul><li>Decomposition hypothesis: </li></ul><ul><li>Semantically opaque morphology </li></ul><ul><li>should be HARDER than </li></ul><ul><li>semantically transparent morphology. </li></ul><ul><li>Storage hypothesis: </li></ul><ul><li>Semantically opaque morphology </li></ul><ul><li>should be easier EASIER than </li></ul><ul><li>semantically transparent morphology. </li></ul>(Zweig, van Rijsingen & Pylkk änen, in progress)
  49. 49. Does morphological decomposition require semantic transparency? <ul><li>Most research on the effects of morphological transparency has used a priming paradigm. </li></ul><ul><li>However, it’s unclear what the decomposition account would predict the effect of step (iii) (= access to a special meaning) to be in a priming paradigm – could be a complicated combination of priming and inhibition. </li></ul><ul><li>The basic, contrasting, predictions of the Storage and Decomposition hypotheses can be tested in single-word lexical decision. </li></ul>(Zweig, van Rijsingen & Pylkk änen, in progress) LP, Aug 03, Tateshina
  50. 50. Materials <ul><li>5 bins of 16 affixed or “pseudoaffixed” forms organized according to subjective ratings of “connectivity” between the base and the affixed form </li></ul><ul><li>Affixes used: -ity, -ment, -er, and –en . </li></ul>“ Connectivity” to the base increases Transparent <ul><li>Bins matched for length, base frequency, frequency of the affixed form and difference in frequency between the base and the affixed form. </li></ul>Bin 1: CORNER Bin 2: RUBBER Bin 3: SNEAKER Bin 4: HEADER Bin 5: CONSUMER (Zweig, van Rijsingen & Pylkk änen, in progress) LP, Aug 03, Tateshina Pseudoaffixed Opaque
  51. 51. Materials <ul><li>5 bins of 16 affixed or “pseudoaffixed” forms organized according to subjective ratings of “connectivity” between the base and the affixed form </li></ul><ul><li>Affixes used: -ity, -ment, -er, and –en . </li></ul>“ Connectivity” to the base increases Transparent Bin 1: CORNER Bin 2: RUBBER Bin 3: SNEAKER Bin 4: HEADER Bin 5: CONSUMER <ul><li>+ 16 length and surface frequency matched non-affixed forms (e.g. PAINT ). </li></ul><ul><li>40 non-words formed by attaching affixes to real words ( STUPIDMENT ). </li></ul><ul><li>40 non-words formed by attaching affixed to non-words ( LIFFMENT ). </li></ul><ul><li>74 non-affixed real words (stimuli for a different experiment). </li></ul><ul><li>90 non-affixed non-words (stimuli for a different experiment). </li></ul>LP, Aug 03, Tateshina Pseudoaffixed Opaque
  52. 52. PAINT CORNER RUBBER SNEAKER HEADER CONSUMER [msec] Pseudoaffixed Opaque Transparent Non-affixed Results (n = 14) (Zweig, van Rijsingen & Pylkk änen, in progress) LP, Aug 03, Tateshina
  53. 53. Results (n = 14) PAINT CORNER RUBBER SNEAKER HEADER CONSUMER [msec] Pseudoaffixed Opaque Transparent Non-affixed (Zweig, van Rijsingen & Pylkk änen, in progress) LP, Aug 03, Tateshina
  54. 54. Results (n = 14) <ul><li>All affixation is costly. </li></ul><ul><li>Semantically opaque “real” morphology is the most costly. </li></ul><ul><li>Cannot be accounted for by the Storage hypothesis. </li></ul>(Zweig, van Rijsingen & Pylkk änen, in progress) LP, Aug 03, Tateshina PAINT CORNER RUBBER SNEAKER HEADER CONSUMER [msec] Pseudoaffixed Opaque Transparent Non-affixed
  55. 55. Day 4 Morphology 2: Electrophysiological and behavioral evidence for early effects of morphology LP, Aug 03, Tateshina <ul><li>Morphological family effects. </li></ul><ul><li>Early superficial effects of morphology in masked priming. </li></ul><ul><li>Role of semantic transparency. </li></ul><ul><li>Early effects of morphology in ERPs. </li></ul><ul><li>Grand summary of MEG results and comparison to ERP literature. </li></ul>
  56. 56. Category, first-pass parsing, ELAN <ul><li>The Rastle, Davis et al. proposal about fast semantics-free segmentation should connect to models of sentence processing where first-pass parsing occurs purely on the basis of word category information (Frazier, Friederici). </li></ul><ul><li>Earliness of morphological segmentation: </li></ul><ul><li>In ERP’s, violating a word category expectation has been reported to lead to an Early Left Anterior Negativity (ELAN). </li></ul><ul><li>NP required but participle occurs: </li></ul><ul><li>Der Freund wurde im besucht </li></ul><ul><li>‘ The friend was in-the visited.’ </li></ul>LP, Aug 03, Tateshina
  57. 57. ELAN, how early? <ul><li>Auditory: </li></ul><ul><ul><li>As early as 50ms after word uniqueness point: </li></ul></ul><ul><ul><ul><li>The holiday is being shortened/shortening. </li></ul></ul></ul><ul><li>Visual: </li></ul><ul><ul><li>Usually a LAN – around 400ms. </li></ul></ul>LP, Aug 03, Tateshina
  58. 58. Day 4 Morphology 2: Electrophysiological and behavioral evidence for early effects of morphology LP, Aug 03, Tateshina <ul><li>Morphological family effects. </li></ul><ul><li>Early superficial effects of morphology in masked priming. </li></ul><ul><li>Role of semantic transparency. </li></ul><ul><li>Early effects of morphology in ERPs. </li></ul><ul><li>Grand summary of MEG results and comparison to ERP literature. </li></ul>
  59. 59. Stimulus factors affecting the M350 <ul><li>Lexical frequency in visual and auditory modality </li></ul><ul><li>Repetition </li></ul><ul><li>Phonotactic probability (likely a secondary effect) </li></ul><ul><li>Phonological similarity in priming </li></ul><ul><li>Semantic similarity in priming </li></ul><ul><li>Regular morphological relatedness in priming </li></ul><ul><ul><li>regular AND irregular </li></ul></ul><ul><li>Constituent frequency in compounds </li></ul><ul><li>Morphological family frequency </li></ul><ul><li>Morphological family size </li></ul>LP, Aug 03, Tateshina
  60. 60. <ul><li>Representation: </li></ul><ul><ul><li>There is a modality independent lexicon. </li></ul></ul><ul><ul><li>Lexical entries connect sound and meaning – single lexicon. </li></ul></ul><ul><ul><li>All word formation is syntactic. </li></ul></ul>Revisiting: Assumptions/hypotheses that drive, and are tested by, the present research LP, Aug 03, Tateshina <ul><li>Processing: </li></ul><ul><ul><li>Timing of lexical access depends on the activation level of lexical entries at stimulus presentation. </li></ul></ul><ul><ul><li>The activation level of lexical entries depends on </li></ul></ul><ul><ul><ul><li>Frequency </li></ul></ul></ul><ul><ul><ul><li>Preceding context (priming) </li></ul></ul></ul><ul><ul><li>Phonological and semantic relatedness should affect the same neural activity. </li></ul></ul>NB: All of these assumptions are more or less controversial so we’ll continually keep evaluating how they succeed in explaining the data.
  61. 61. N400 ERP LP, Aug 03, Tateshina N =12 _ _ _ He spread the warm bread with SOCKS ____ He spread the warm bread with BUTTER (Kutas and Hillyard, 1980) <ul><li>Discovered in a semantic anomaly manipulation. </li></ul><ul><li>But today we know that every word in a sentence elicits an N400. </li></ul><ul><ul><li>Not a “violation-component” </li></ul></ul>
  62. 62. M350 = N400? LP, Aug 03, Tateshina
  63. 63. Polarity <ul><li>A typical M350 source should generate a negativity at the top of the head. </li></ul><ul><li>N400 usually largest at central/midline electrodes. </li></ul>_ +
  64. 64. Polarity <ul><li>NB: The M350 is often bilateral. </li></ul><ul><ul><li>Both the LH and RL M350 sources contribute to the midline negativity. </li></ul></ul><ul><ul><li>N400 sums over both hemispheres. </li></ul></ul>_ +
  65. 65. Localization of the N400 using MEG <ul><li>Helenius et al 1999: </li></ul><ul><ul><li>Classic N400 paradigm in MEG. </li></ul></ul><ul><ul><li>Source of the N400 localizes where the M350 localizes: in the vicinity of the left auditory cortex. </li></ul></ul>( Helenius , P, Salmelin , E, et al. 1998. Distinct time courses of word and context comprehension in the left temporal cortex. Brain, 121, 1133-1142. )
  66. 66. Timing: N400 N =12 _ _ _ He spread the warm bread with SOCKS ____ He spread the warm bread with BUTTER (Kutas and Hillyard, 1980) <ul><li>Onset: ~250ms. </li></ul><ul><li>Peak: ~400ms </li></ul><ul><li>Offset: ~550-600ms. </li></ul>
  67. 67. Timing: M350 <ul><li>Important: </li></ul><ul><ul><li>The M350 is defined as the first peak of the M350 distribution. </li></ul></ul><ul><ul><li>But the M350 field pattern often peaks twice. </li></ul></ul><ul><ul><li>Most of our M350 effects hold of the first peak, not of the second. </li></ul></ul>M350 distribution -100 0 100 200 300 400 500 600 700 [msec] 0 200 200 [fT]
  68. 68. Timing: M350 <ul><li>Important: </li></ul><ul><ul><li>The M350 is defined as the first peak of the M350 distribution. </li></ul></ul>-100 0 100 200 300 400 500 600 700 [msec] 0 200 200 [fT] <ul><ul><li>But the M350 field pattern often peaks twice. </li></ul></ul><ul><ul><li>Most of our M350 effects hold of the first peak, not of the second. </li></ul></ul>M350 NOT M350 although may have more or less the same source.
  69. 69. Timing: M350 -100 0 100 200 300 400 500 600 700 [msec] 0 200 200 [fT] M350 NOT M350 although may have more or less the same source. <ul><li>Timing of the M350 and </li></ul><ul><li>timing of the M350 source </li></ul><ul><li>are two separate questions. </li></ul>
  70. 70. Timing: M350 -100 0 100 200 300 400 500 600 700 [msec] 0 200 200 [fT] M350 NOT M350 although may have more or less the same source. <ul><li>M350: </li></ul><ul><li>From valley to valley, may as short as 50ms. </li></ul><ul><li>M350 source: </li></ul><ul><li>Onset: 300ms </li></ul><ul><li>Peak 1: ~350ms </li></ul><ul><li>(Peak 2: ~450ms) </li></ul><ul><li>Offset: ~500ms </li></ul>
  71. 71. Stimulus factors affecting the N400 (partial list) LP, Aug 03, Tateshina ? ? Position in sentence: N400 gets smaller the further into the sentence it occurs NO (latency effect for M350) YES Lexical frequency: Smaller N400 for frequent words. YES for rhyme, NO for onset-matching YES Phonological similarity: Smaller N400 for phonologically related words in priming. YES (but w/M350, also latency) YES Semantic similarity: Smaller N400 for semantically related words in priming. NO (latency effect for M350) YES Repetition: Smaller N400 for repeated words. YES YES for M350 source (Helenius et al.) Expectancy: Smaller N400 for highly expected words. Same kind of effect? Also affects M350?
  72. 72. M350 ≠ N400 but the M350 is likely a subcomponent of the N400 (the M250 might also be a subcomponent of the N400). LP, Aug 03, Tateshina
  73. 73. Possible reasons for differences in waveform morphology in MEG and ERPs LP, Aug 03, Tateshina <ul><li>EEG picks up more activity than MEG. </li></ul><ul><li>ERP data are usually grandaveraged. </li></ul><ul><ul><li>Small latency differences may be lost. </li></ul></ul><ul><li>Summation over hemispheres in ERPs. </li></ul><ul><ul><li>Differences between hemispheres may be lost. </li></ul></ul>
  74. 74. (Some) outstanding questions LP, Aug 03, Tateshina
  75. 75. Latency vs. amplitude effects LP, Aug 03, Tateshina <ul><li>Some stimulus factors affect M350 latencies (e.g. lexical frequency, morphological family size) while others affect amplitudes (e.g. morphological family frequency). </li></ul><ul><li>General assumption in cognitive neuroscience: </li></ul><ul><li>more processing load  more activity. </li></ul><ul><li>How should we understand the relationship between latency and amplitude effects? </li></ul>
  76. 76. Functional significance of the “M250” LP, Aug 03, Tateshina <ul><li>Activity at 200-300ms difficult to manipulate. </li></ul><ul><li>Lots of distributional variance across subjects. </li></ul><ul><li>Not a single source and depends on the individual’s brain physiology which part of the activity is captured by MEG? </li></ul>
  77. 77. M350 in the right hemisphere LP, Aug 03, Tateshina <ul><li>The M350 is bilateral roughly 60% of the time (impressionistic estimate). </li></ul><ul><li>There has been no systematic investigation of RH M350 sources. </li></ul><ul><ul><li>The problem being that it’s still difficult to obtain enough RH sources within a single study to obtain statistical power. </li></ul></ul>
  78. 78. What’s so special about the M350 peak (as opposed to other points on the waveform)? LP, Aug 03, Tateshina <ul><li>One might expect activation of the lexicon to be indexed as a rise in activity in a source. </li></ul><ul><li>Why do most of our effects only hold at the peak of the M350? </li></ul>
  79. 79. Post-M350 activity and neural correlates of recognition LP, Aug 03, Tateshina <ul><li>The M350 is not sensitive to (phonologically-based) interlexical competition. </li></ul><ul><li>What activity is? </li></ul><ul><ul><li>We’ve identified no MEG activity that would appear to index recognition (i.e. selection instead of activation). </li></ul></ul>
  80. 80. LP, Aug 03, Tateshina Thank you!

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