liina pylkk nen department of linguistics center for neuromagnetism new york university n.
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Liina Pylkkänen Department of Linguistics/ Center for Neuromagnetism New York University

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  1. LP, Aug 03, Tateshina MEG, the Mental Lexicon and Morphology Liina Pylkkänen Department of Linguistics/ Center for Neuromagnetism New York University

  2. LP, Aug 03, Tateshina MEG, the Mental Lexicon and Morphology 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

  3. LP, Aug 03, Tateshina Day 4 Morphology 2: Electrophysiological and behavioral evidence for early effects of morphology • Morphological family effects. • Early effects of superficial morphology in masked priming. • Role of semantic transparency. • Early effects of morphology in ERPs. • Grand summary of MEG results and comparison to ERP literature.

  4. LP, Aug 03, Tateshina Day 4 Morphology 2: Electrophysiological and behavioral evidence for early effects of morphology • Morphological family effects. • Early effects of superficialmorphology in masked priming. • Role of semantic transparency. • Early effects of morphology in ERPs. • Grand summary of MEG results and comparison to ERP literature.

  5. Same number of derivates High frequency derivatives Low frequency derivatives - ist –ize -ism - ic –ize –ism terror magnet Matched for surface frequency Effect of lexical frequency • High frequency words are processed faster than low frequency words. • Prediction of decompositional theories of morphology: cumulative root frequency effects.

  6. Should be faster due to high cumulative root frequency Effect of lexical frequency • High frequency words are processed faster than low frequency words. • Prediction of decompositional theories of morphology: cumulative root frequency effects. Same number of derivates High frequency derivatives Low frequency derivatives - ist –ize -ism - ic –ize –ism terror magnet Matched for surface frequency

  7. Cumulative root frequency effects for inflection • Response times to a noun depend on the cumulative frequency of the singular and plural (Schreuder & Baayen, JML, 1997) CAT CATS

  8. Family size LOW HIGH - ic –ity –ify –head –test –washed - ist acid diary But NO cumulative root frequency effects for derivation Schreuder & Baayen (1997): • Family frequency HIGH LOW Family frequency does not affect lexical decision times. - ist –ize -ism - ic –ize –ism S&B: Therefore, no decomposition in derivation. terror magnet High family size speeds up lexical decision times. S&B: this is a late post-lexical effect.

  9. Alternative explanation for lack of cumulative root frequency effects in derivation • High morphological family frequency speeds up root activation BUT this facilitation is cancelled out by subsequent competition between the highly frequent morphological family members. • Hypothesized affix-competition in priming (Marslen-Wilson, et al. 1994): In crossmodal priming, NO PRIMING FOR government – governor ALTHOUGH ROBUST PRIMING FOR government – govern (Marslen-Wilson, W. D., Tyler, L., Waksler, R., & Older, L. (1994). Morphology and meaning in the English mental lexicon. Psychological Review 101, 3-33.)

  10. Alternative explanation for lack of cumulative root frequency effects in derivation • High morphological family frequency speeds up root activation BUT this facilitation is cancelled out by subsequent competition between the highly frequent morphological family members. • How to measure timing of root activation, prior to any effect of competition? • M350, an magnetoencephalographic (MEG) response component elicited by word stimuli, peaking at ~350ms post word-onset

  11. Magnetoencephalography (MEG) • Measures magnetic fields generated by large populations of neurons firing in synchrony. • Millisecond temporal resolution. • Millimeter spatial resolution (at least for cortical sources).

  12. Magnetoencephalography (MEG)

  13. What happens in the brain when we read words? 150-200ms (M170) 200-300ms (M250) 300-400ms (M350) 400-500ms 200 [fT] 0 200 -100 0 100 200 300 400 500 600 700 [msec] Pylkkänen and Marantz, Trends in Cognitive Sciences, in press. Letter string processing (Tarkiainen et al. 1999) Lexical activation (Pylkkänenet al. 2002)

  14. What happens in the brain when we read words? Lexical activation (Pylkkänenet al. 2002) The M350 is sensitive to • Lexical frequency (a) • Repetition (b) • Phonological similarity (c) • Semantic similarity (d) • Sublexical frequency (e, f) The M350 is NOT sensitive to • Interlexical competition (e) 300-400ms (M350) • 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. • 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. (c) Pylkkänen, L., Stringfellow, A. Marantz, A. 2002. Inhibition and Competition in Word Recognition: MEG Evidence. Submitted. (d) Pylkkänen, L. Stringfellow, A., Gonnerman, L., Marantz, A. 2002. Magnetoencephalographic indices of identity and similarity in lexical access. In preparation. • 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. (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. Pylkkänen and Marantz, Trends in Cognitive Sciences, in press.

  15. What happens in the brain when we read words? Lexical activation (Pylkkänenet al. 2002) The M350 is sensitive to • Lexical frequency (a) • Repetition (b) • Phonological similarity (c) • Semantic similarity (d) • Sublexical frequency (e, f) The M350 is NOT sensitive to • Interlexical competition (e) 300-400ms (M350) • 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. • 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. (c) Pylkkänen, L., Stringfellow, A. Marantz, A. 2002. Inhibition and Competition in Word Recognition: MEG Evidence. Submitted. (d) Pylkkänen, L. Stringfellow, A., Gonnerman, L., Marantz, A. 2002. Magnetoencephalographic indices of identity and similarity in lexical access. In preparation. • 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. (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. Pylkkänen and Marantz, Trends in Cognitive Sciences, in press.

  16. Effect of probability/density (n=10) * * * * n.s. n.s. n.s. n.s. (Pylkkänen, Stringfellow, Marantz, Brain and Language, 2002)

  17. Activation Competition Selection TURN TURNIP level of activation TURF TURTLE resting level time Stimulus: TURN M350 (i) 1st component sensitive to lexical factors (such as lexical frequency) (ii) not affected by competition

  18. Effect of high morphological family frequency? M350 RT - slow-down due to competition from highly frequent family members - speed-up due to cumulative root frequency Hypothesis • Effect of high phonotactic probability/ high neighborhood density: M350 RT - slow-down due to competition - speed-up due to sublexical frequency

  19. Materials (from Baayen, R. H., Lieber, R., & Schreuder, R. (1997). Linguistics 35, 861-877) • Four categories of visual words, all nouns • Contrast 1: Family frequency HIGH • Matched for: • Length • Freq. of the sg, • Cumulative freq. of the sg. & pl. forms • Family size • Mean bigram frequency LOW - ist –ize -ism - ic –ize –ism terror (n=18) magnet (n=18) • Contrast 2: Family size LOW • Matched for: • Length • Freq. of the sg, • Cumulative freq. of the sg. & pl. forms • Family frequency (not perfectly) • Mean bigram frequency HIGH - ic –ity –ify –head –test –washed - ist acid (n=21) diary (n=21)

  20. n.s. * n.s. * Behavior (Pylkkänen, Feintuch, Hopkins & Marantz, Cognition, to appear)

  21. 100% 75% 50% 25% HBM 2003, poster 1345 M350 source analysis • Equivalent current dipole analysis • Latencies and amplitudes measured at points where the source amplitude reached 25%, 50%, 75% and 100% of the maximum source strength.

  22. MEG data, single subject (Pylkkänen, Feintuch, Hopkins & Marantz, Cognition, to appear)

  23. High family frequency HBM 2003, poster 1345 Family frequency: M350 (S1)

  24. High family frequency HBM 2003, poster 1345 Family frequency: M350 (S1)

  25. High family frequency Extra processing load at the M350 HBM 2003, poster 1345 Family frequency: M350 (S1) Low family frequency • Morphological competition at the M350

  26. HBM 2003, poster 1345 Family frequency: M350 amplitude (n=10)

  27. HBM 2003, poster 1345 Family frequency: M350 amplitude (n=10) *

  28. HBM 2003, poster 1345 Family frequency: M350 latency (n=10) all n.s.

  29. HBM 2003, poster 1345 Family size: M350 amplitude (n=10) all n.s. P = 0.09

  30. HBM 2003, poster 1345 Family : M350 latency (n=10) * **

  31. M250 M170 M350 RT (lexical decision) 1. Difference in the time course of competition. 2. High family size has an early facilitory effect. Why?

  32. fine lie - ist –ize -ism loin pine TERROR LINE lane like light lime nine fine lie loin pine LINE lane like light lime nine 1. Difference in the time course of competition High frequency morphological family High density phonological neighborhood (frequency-weighted) • Relationship between target and competitors qualitatively different: difference is due to morphology. DECOMPOSITION • Difference is due to the different phonological and/or semantic properties of the competitors. terrorism TERROR NO DECOMPOSITION terrorist terrorize

  33. fine lie loin pine LINE lane like light lime nine 1. Difference in the time course of competition • Non-decompositional account also predicts interference effects in priming for pairs such as TERRORISM – TERROR. • BUT this is completely unsupported by data – effect is robustly facilitory (e.g. a-d). • Difference is due to the different phonological and/or semantic properties of the competitors. terrorism TERROR NO DECOMPOSITION terrorist terrorize • (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. • (b) Pylkkänen, L. Stringfellow, A., Gonnerman, L., Marantz, A. 2002. Magnetoencephalographic indices of identity and similarity in lexical access. In preparation. • Gonnerman, L. 1999, Morphology and the lexicon: exploring the semantics-phonology interface, PhD thesis, University of Southern California. • 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.

  34. fine lie - ist –ize -ism loin pine TERROR LINE lane like light lime nine 1. Difference in the time course of competition High frequency morphological family High density phonological neighborhood (frequency-weighted) DECOMPOSITION • Competition between morphological family members appears to precede competition between phonological neighbors. • An account of the phenomenon needs to make a distinction between morphological and phonological competitors.

  35. Early morphological parsing/ segmentation Lexical access HBM 2003, poster 1345 Conclusion Decomposition Morphological competition effects Phonological competition effects

  36. HBM 2003, poster 1345 Conclusion Grammar happens early: • Early determination of grammatical category in ERPs (Friederici, 2002). • Early effects of morphology in masked priming (Rastle, Davis & New submitted)

  37. 2. High family size has an early facilitory effect • One possibility: • Effect is semantic in nature and is related to effects of polysemy. • Heavily polysemous words (such as belt) are processed faster than words that only have few “senses” (such as ant). • (Rodd, Gaskell & Marslen-Wilson (2002) Making Sense of Semantic Ambiguity: Semantic Competition in Lexical Access. Journal of Memory and Language 46, 245–266)

  38. 2. High family size has an early facilitory effect • 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. • Prediction: semantically opaque morphological family members should contribute to the family size effect the most, as those would involve the most “sense-switching”. • 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. • (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.)

  39. -ic -ity -ify -head -test -washed -Ø -st -ø acid diary Keeping family frequency constant but lowering family size creates more potent competitors. 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)

  40. Conclusion • Evidence for decomposition (although somewhat indirect). • Evidence for the existence of morphological competition (cf. Marslen-Wilson 1994). • Identification of a neural correlate of the morphological family size effect. Thanks to: Sophie Feintuch & Emily Hopkins (Portsmouth High School, NH)

  41. LP, Aug 03, Tateshina Day 4 Morphology 2: Electrophysiological and behavioral evidence for early effects of morphology • Morphological family effects. • Early effects of superficialmorphology in masked priming. • Role of semantic transparency. • Early effects of morphology in ERPs. • Grand summary of MEG results and comparison to ERP literature.

  42. LP, Aug 03, Tateshina Rastle, Davis & New (2003) • Masked priming – eliminates semantic effects. • 500ms forward mask, 43ms prime. TRANSPARENT: cleaner – CLEAN OPAQUE: corner – CORN ORTHOGRAPHIC: brothel - BROTH

  43. LP, Aug 03, Tateshina Rastle, Davis & New (2003) • Result: TRANSPARENT: cleaner – CLEAN OPAQUE: corner – CORN ORTHOGRAPHIC: brothel - BROTH EQUAL PRIMING NO PRIMING

  44. LP, Aug 03, Tateshina 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.  If morphological parsing occurs early, one would expect morphological competition to occur early as well, which is what the family frequency results suggest.

  45. LP, Aug 03, Tateshina Day 4 Morphology 2: Electrophysiological and behavioral evidence for early effects of morphology • Morphological family effects. • Early superficial effects of morphology in masked priming. • Role of semantic transparency. • Early effects of morphology in ERPs. • Grand summary of MEG results and comparison to ERP literature.

  46. Zweig et al.: Does morphological decomposition require semantic transparency? • If semantically opaque forms aren’t decomposed, processing a form such as UNIVERSITY would involve • access to the lexical representation UNIVERSITY (Zweig,van Rijsingen & Pylkkänen, in progress)

  47. Does morphological decomposition require semantic transparency? • If semantically opaque forms are decomposed, processing a form such as UNIVERSITY would involve • access to UNIVERSE and ITY • combining UNIVERSE and ITY • access to the special meaning that is associated with this complex structure • Processing semantically transparent morphology would not involve step (iii). (Zweig,van Rijsingen & Pylkkänen, in progress)

  48. Does morphological decomposition require semantic transparency? • Decomposition hypothesis: • Semantically opaque morphology • should be HARDER than • semantically transparent morphology. • Storage hypothesis: • Semantically opaque morphology • should be easier EASIER than • semantically transparent morphology. (Zweig,van Rijsingen & Pylkkänen, in progress)

  49. LP, Aug 03, Tateshina Does morphological decomposition require semantic transparency? • Most research on the effects of morphological transparency has used a priming paradigm. • 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. • The basic, contrasting, predictions of the Storage and Decomposition hypotheses can be tested in single-word lexical decision. (Zweig,van Rijsingen & Pylkkänen, in progress)

  50. Pseudoaffixed Opaque LP, Aug 03, Tateshina Materials • 5 bins of 16 affixed or “pseudoaffixed” forms organized according to subjective ratings of “connectivity” between the base and the affixed form • Affixes used: -ity, -ment, -er, and –en. Bin 1: CORNER Bin 2: RUBBER Bin 3: SNEAKER Bin 4: HEADER Bin 5: CONSUMER “Connectivity” to the base increases Transparent • Bins matched for length, base frequency, frequency of the affixed form and difference in frequency between the base and the affixed form. (Zweig,van Rijsingen & Pylkkänen, in progress)