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Lexical Access: Generation & Selection

Lexical Access: Generation & Selection. Main Topic. Listeners as active participants in comprehension process Model system: word recognition. Outline. Speed & Robustness of Lexical Access Active Search Evidence for Stages of Lexical Access Autonomy & Interaction. Outline.

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Lexical Access: Generation & Selection

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  1. Lexical Access:Generation & Selection

  2. Main Topic • Listeners as active participants in comprehension process • Model system: word recognition

  3. Outline • Speed & Robustness of Lexical Access • Active Search • Evidence for Stages of Lexical Access • Autonomy & Interaction

  4. Outline • Speed & Robustness of Lexical Access • Active Search • Evidence for Stages of Lexical Access • Autonomy & Interaction

  5. The mental lexicon sport figure sing door carry turf turtle gold turk turkey turn water turbo turquoise turnip turmoil

  6. How do we recognize words? • The Simplest Theory • Take a string of letters/phonemes/syllables, match to word in the mental lexicon • (That’s roughly how word processors work) • …is it plausible?

  7. Word Recognition is Fast • Intuitively immediate - words are recognized before end of word is reached • Speech shadowing at very brief time-lags, ~250ms (Marslen-Wilson 1973, 1975) • Eye-tracking studies indicate effects of access within 200-300ms

  8. Lexical Access is Robust • Succeeds in connected speech • Succeeds in fast speech • Survives masking effects of morphological affixation and phonological processes • Deleted or substituted segments • Speech embedded in noise

  9. But… • Speed and robustness depends on words in contextsentence --> word context effects • In isolation, word recognition is slower and a good deal more fragile, susceptible to error • …but still does not require perfect matching

  10. Questions • How does lexical access proceed out of context? • Why is lexical access fast and robust in context? • When does context affect lexical access? • does it affect early generation (lookup) processes? • does it affect later selection processes?

  11. Classic Experimental Paradigms

  12. Reaction Time Paradigms • Lexical Decision • Priming

  13. List 1sicklecathartic torrid gregarious oxymoron atrophy List 2parabola periodontist preternatural pariah persimmon porous Looking for Words Speed of look-up reflects organization of dictionary

  14. Looking for Words +

  15. Looking for Words DASH

  16. Looking for Words RASK

  17. Looking for Words CURLY

  18. Looking for Words PURCE

  19. Looking for Words WINDOW

  20. Looking for Words DULIP

  21. Looking for Words LURID

  22. (Embick et al., 2001)

  23. Looking for Words • Semantically Related Word Pairsdoctor nurse hand finger speak talk sound volume book volume

  24. Looking for Words • In a lexical decision task, responses are faster when a word is preceded by a semantically related word • DOCTOR primes NURSE • Implies semantic organization of dictionary

  25. Outline • Speed & Robustness of Lexical Access • Active Search • Evidence for Stages of Lexical Access • Autonomy & Interaction

  26. Active Recognition • System actively seeks matches to input - does not wait for complete matchThis allows for speed, but …

  27. Cost of Active Search… • Many inappropriate words activated • Inappropriate choices must be rejected • Two Stages of Lexical Accessactivation vs. competitionrecognition vs. selectionproposal vs. disposal

  28. Automatic activation sport figure sing door carry turf turtlegold turk turkey water turn turbo turquoise turnip turmoil TURN

  29. Lateral inhibition sport figure sing door carry turf turtle gold turk turkey water turn turbo turquoise turnip turmoil TURN

  30. What is lexical access? Activation Competition Selection/Recognition TURN TURNIP level of activation TURF TURTLE resting level time Stimulus: TURN (e.g. Luce et al. 1990, Norris 1994)

  31. S song story sparrow saunter slow secret sentry etc. Cohort

  32. SP spice spoke spare spin splendid spelling spread etc. Cohort

  33. SPI spit spigot spill spiffy spinaker spirit spin etc. Cohort

  34. SPIN spin spinach spinster spinaker spindle Cohort

  35. SPINA spinach Cohort

  36. SPINA spinach Cohort word uniqueness point

  37. SPINA spinach spinet spineret Cohort

  38. Cross-Modal Priming

  39. Evidence for Cohort Activation CAPTIVE CAPTAIN SHIP SHIP CAPT… CAPTAIN GUARD GUARD (Marslen-Wilson, Zwitserlood)

  40. Cohort Model • Partial words display priming properties of multiple completions: motivates multiple, continuous access • Marslen-Wilson’s claims • Activation of candidates is autonomous, based on cohort only • Selection is non-autonomous, can use contextual info. • How, then, to capture facilitatory effect of context?

  41. Gating Measures • Presentation of successive parts of words • S • SP • SPI • SPIN • SPINA… • Average recognition times • Out of context: 300-350ms • In context: 200ms (Grosjean 1980, etc.)

  42. Word Monitoring • Listening to sentences - monitoring for specific words • Mean RT ~240ms • Identification estimate ~200ms • Listening to same words in isolation • Identification estimate ~300ms (Brown, Marslen-Wilson, & Tyler)

  43. Cross-Modal Priming The guests drank vodka, sherry and port at the reception WINE SHIP (Swinney 1979, Seidenberg et al. 1979)

  44. Cross-Modal Priming The guests drank vodka, sherry and port at the reception WINE SHIP (Swinney 1979, Seidenberg et al. 1979)

  45. Generation and Selection • Investigating the dependence on ‘bottom-up’ information in language understanding • ‘Active’ comprehension has benefits and costs • Speed • Errors • Overgeneration entails selection • Sources of information for generating candidates • Bottom-up information (e.g., lexical cohorts) • ‘Top-down’ information (e.g., sentential context) • Questions about whether context aids generation or selection

  46. Cross-modal Priming • Early: multiple access • Late: single access …i.e., delayed effect of context

  47. CMLP - Qualifications • Multiple access observed • when both meanings have roughly even frequency • when context favors the lower frequency meaning • Selective access observed • when strongly dominant meaning is favored by context (see Simspon 1994 for review)

  48. Why multiple/selective access? • How could context prevent a non-supported meaning from being accessed at all?(Note: this is different from the question of how the unsupported meaning is suppressed once activated) • Possible answer: selective access can only occur in situations where context is so strong that it pre-activates the target word/meaning

  49. Cohort Model • Partial words display priming properties of multiple completions: motivates multiple, continuous access • Marslen-Wilson’s claims • Activation of candidates is autonomous, based on cohort only • Selection is non-autonomous, can use contextual info. • How, then, to capture facilitatory effect of context…

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