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Mental Lexicon

Mental Lexicon. All of your knowledge about words and you know a lot of words! Average college-educated adult Speaking vocabulary = 75,000 - 100,000 words Recognition vocabulary is substantially larger You're not equally likely to use all of those words

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Mental Lexicon

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  1. Mental Lexicon • All of your knowledge about words • and you know a lot of words! • Average college-educated adult • Speaking vocabulary = 75,000 - 100,000 words • Recognition vocabulary is substantially larger • You're not equally likely to use all of those words • The 50 most common words make up • ~60% of the words we speak • ~45% of the words we write • On average, you only say 10-15 words before repeating one Psyc / Ling / Comm 525 Fall 10

  2. 10 Most Frequent English Words(counts out of ~1,000,000 words) Notice that most are function words rather than content words Psyc / Ling / Comm 525 Fall 10

  3. Bottom-up & Top-down Processing in Visual Word Recognition Psyc / Ling / Comm 525 Fall 10

  4. Writing Systems • Two basic types of writing systems • Ones that indicate pronunciation • Ones that do so less • Systems that do represent pronunciation: • Alphabets- One character supposed to represent one “sound” • ALL modern alphabets are derived from Phoenician • Syllabaries- One character represents a whole syllable • In most, 2 syllables that share a sound don’t look anything alike • Japanese hiragana:か= /ka/ vs き=/ki/ vs く=/ku/ • But, Korean hangul has C & V characters within syllable: 수잔 = /suzn/? • Systems that represent pronunciation less directly: • Ideograms (pictograms) - One character represents a meaning • Words with similar meanings usually share characters, even if pronunciation is completely different • But often words that share a syllable that has different meanings in each word also share a character Psyc / Ling / Comm 525 Fall 10

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  6. Word Boundaries • Most (all?) languages using Roman alphabet put spaces between words • But some other writing systems do not (e.g. Chinese, Japanese) • - Sometimes ambiguous where word boundaries are (just as in speech) Psyc / Ling / Comm 525 Fall 10

  7. Bottom-up and Top-down Processingin Reading • Some examples: • Detecting particular letters is less accurate in highly familiar words • Proofreading is harder the more familiar the text Psyc / Ling / Comm 525 Fall 10

  8. Does this remind you of anything about auditory word recognition ? Psyc / Ling / Comm 525 Fall 10

  9. Bottom-up and Top-down Processingin Reading • Some examples: • Detecting particular letters is less accurate in highly familiar words • Proofreading is harder the more familiar the text • - ... • Race Models of word recognition • Top-down and bottom-up processes go on in parallel • Racing with each other • Whichever "finishes" first wins the race • i.e. determines how you identify the word • If bottom-up processing is hard because input is noisy, top-down wins • If little help from context, bottom-up wins • Decision Criterion = Finish line in race • How sure must you be that the input is a word before saying so? Psyc / Ling / Comm 525 Fall 10

  10. Disorders of Reading • Patterns of Acquired Dyslexia have influenced theories and models of normal reading • More than observations of any other kind of language deficit have influenced models of other aspects of normal language processing Psyc / Ling / Comm 525 Fall 10

  11. Surface Dyslexia(tends to occur in fluent aphasics with posterior brain damage) • Read regularly spelled words aloud ok • Read nonwords aloud ok • Tend to mispronounce irregularly spelled words • They regularize them • island > /Izlǽnd/ • pint > /pInt/ • So, they seem to • construct pronunciations via direct letter-to-sound mappings • without retrieving knowledge about particular words' pronunciations Psyc / Ling / Comm 525 Fall 10

  12. Phonological Dyslexia(often no other aphasia)(most similar of the acquired dyslexias to developmental dyslexias) • Read highly familiar words aloud ok, regardless of spelling regularity • Trouble reading both less familiar words and non-words aloud • Tend to pronounce them as similar-looking familiar words • i.e., they lexicalize them • forb > fork • moth > mother • border > bread • If the word they come up with happens to have an irregular spelling for its pronunciation, they pronounce it in the correct irregular way • So, they seem to • get into the neighborhood of words that look like what they see • & retrieve the pronunciation of one of the more familiar words in that neighborhood Psyc / Ling / Comm 525 Fall 10

  13. Deep Dyslexia(tends to occur in non-fluent aphasics with anterior brain damage) • Read content words aloud a lot better than function words • Within content words, better on concrete, imageable ones • Often can't read non-words at all, or may lexicalize them • Errors sometimes semantically related, with no sound or spelling similarity • ape > monkey • forest > trees • Errors sometimes visually related instead, or mixed visual and semantic • scandal > sandals • orchestra > sympathy • So, they seem to (sometimes) • get into the neighborhood of words with meanings like what they see • & then retrieve the pronunciation of another word in that neighborhood Psyc / Ling / Comm 525 Fall 10

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  19. ModularvsInteractive Processing Systems • It’s obvious that bothbottom-up and top-down processes contribute to the recognition of letters & sounds & words • But how does top-down processing work? • Interactive account: • Context & knowledge guide actual perception of input vs • Modular account (= post-perceptual, autonomous): • Context & knowledge influence choices among alternative candidates proposed by perceptual processes Psyc / Ling / Comm 525 Fall 10

  20. Localist Psyc / Ling / Comm 525 Fall 10

  21. Localist Psyc / Ling / Comm 525 Fall 10

  22. Localist Psyc / Ling / Comm 525 Fall 10

  23. Modular Account of Phoneme Restoration • The connectionist account is interactive • In contrast, a modular account says: • No top-down feedback from words to sounds • Instead, system guesses there must have beens because that's what would make sense • An unconscious decision process Psyc / Ling / Comm 525 Fall 10

  24. Each of the next 3 slides has a list of letter strings • Your task is to read through them as quickly as you can and count how many of them are words • Raise your hand as soon as you’re done Psyc / Ling / Comm 525 Fall 10

  25. zyndc cnccl apple frgtd wrpts brat nxprd must lbdry other nrgln sfbdl war cloth dtrnp library stwsn mplfs Psyc / Ling / Comm 525 Fall 10

  26. bant anger fold bagin pretser mash kalt magic lomp sinos arid hink radle track rean supper weth amol Psyc / Ling / Comm 525 Fall 10

  27. brane leev want damp stane mair quick lowd heeter power wim pryse muther prefer koller heaven much prufe Psyc / Ling / Comm 525 Fall 10

  28. Why were you slower on the second list than on the first, and even slower on the third list, even though there were 7 words in each list? • Because the nonwords (NWs) grew progressively more word-like across the lists • In list 1, the NWs were not even pronounceable and had illegal sequences of letters • In list 2, the NWs were pronounceable and followed legal English spelling patterns • In list 3, NWs all had the same pronunciation as a real word = pseudohomophones Psyc / Ling / Comm 525 Fall 10

  29. Tasks & Strategies • You adopted different decision criteria in the 3 different lists • about how fully to process the letter strings before moving on to the next one • So, sometimes the "distractors/fillers" in an experiment can matter a lot! • Influence task-specific response strategies people can adopt • Crucial to think very carefully about how participants could be doing the tasks we give them • But also important to realize people’s intuitions about how they’re doing something are often not reliable Psyc / Ling / Comm 525 Fall 10

  30. The rest of the slides here are ones I didn’t get to in class Psyc / Ling / Comm 525 Fall 10

  31. When you encounter a new word you don’t know, you can tell a lot about it from: • its position in the sentence relative to other words you do know = Syntax • its prefixes and suffixes = Morphology Psyc / Ling / Comm 525 Fall 10

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  33. The JabberwockyLewis Carroll One two! One two! And through and through The vorpalbladewent snicker-snack! He left it dead, and with its head He wentgalumphing back. "And hast thou slain the Jabberwock? Come to my arms, my beamishboy! Oh frabjousday! Callooh! Callay!" He chortled in his joy. 'Twas brillig, and the slithytoves Did gyre and gimble in the wabe: All mimsywere the borogoves, And the momerathsoutgrabe. Adjectives, Nouns, Verbs = Parts of speech = Syntactic categories 'Twas brillig, and the slithytoves Did gyre and gimble in the wabe: All mimsywere the borogoves, And the momerathsoutgrabe. "Beware the Jabberwock, my son! The jaws that bite, the claws that catch! Beware the Jubjub bird, and shun The frumiousBandersnatch!“ He took his vorpalsword in hand: Longtime the manxomefoe he sought -- So rested he by the Tumtum tree, And stood a while in thought. And, as in uffishthought he stood, The Jabberwock, with eyes of flame, Came whiffling through the tulgeywood, And burbled as it came! Psyc / Ling / Comm 525 Fall 10

  34. Morphology • Many words have internal structure • friend > friendly > unfriendly > unfriendliest • Morpheme = smallest meaningful unit in language • friend = 1 morpheme • unfriendliest = 4 morphemes (end is not a morpheme in friend) • Affixes = prefixes, suffixes, & infixes • Free morphemes (friend, the) vs Bound morphemes (un-, -ly, -est) • Lexical (= Content)morphemes(friend) vs Grammatical (= Function) morphemes (the, un-, -ly, -est) • Allomorphs = different versions of same morpheme • (Remember allophones?) • English plural = /s/, /z/, /Iz/, /In/, ... • English indefinite article = a, an Psyc / Ling / Comm 525 Fall 10

  35. Languages vary from having: • Many short simple words and using more of them • (e.g. Chinese = isolating) • To having mostly long complex words and using few of them • (e.g. Turkish, Hungarian = agglutinative) • English is somewhere in between • Term Morphosyntax reflects the fact that the same kinds of relationships are coded morphologically in some languages & syntactically in others Psyc / Ling / Comm 525 Fall 10

  36. Does Morphological StructureAffect Reading? • People do seem to decompose complex words during reading • Priming from regularly inflected morphological relatives can be equivalent to repetition priming • e.g., believes primes believe just as much as believe primes itself • But priming from irregularly inflected or derivational relatives is smaller • e.g., believer doesn’t prime believe as much as believe primes itself, nor does went prime go as much as go primes itself or as much as repeated primes repeat • Even when what looks like a morpheme really isn’t • e.g., beak- and -er in beaker • Get effects of frequencies of apparent subcomponents • The frequency of the word beak (meaning a bird’s beak) influences response time to beaker even though its meaning is not a component of the meaning of beaker Psyc / Ling / Comm 525 Fall 10

  37. Eye Movements • Two types of eye movements • Smooth pursuit • Long smooth movements • Can only do this if eyes are following something • Saccades • Short jumps • Most eye movements • When eye is not moving = fixations • Reading consists of saccades and fixations • Backward saccades = regressions Psyc / Ling / Comm 525 Fall 10

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  40. Eyetracking (Dual Purkinje Tracker) • - Dim infrared light shines on eye • - Reflections bounce back from different layers in eye • Relative positions of different reflections show where eye is pointing • Some other kinds of eyetrackers work in different ways Psyc / Ling / Comm 525 Fall 10

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  42. Span of Fixation • How much can you see during a single fixation? • - • It depends on: • your visual acuity • your reading skill level • how hard what you’re reading is, overall • how familiar the current and preceding and next words are • how predictable the current and preceding and next words are • ... • how much of current word you could see on previous fixation Psyc / Ling / Comm 525 Fall 10

  43. What techniques could be used to answer this question? • Eyetracking • Contingent display changes (McConkie & Rayner) • Moving window = 1 special type • Works because you’re functionally blind during saccades • so you don’t see the change itself happen • Need eyetracker & computer fast enough to complete display changes before saccade ends • Average saccade only lasts 10-20 msec Psyc / Ling / Comm 525 Fall 10

  44. The person who is fixating where the * is does not see the xxx’s Psyc / Ling / Comm 525 Fall 10

  45. So, how far ahead does the eye see? • Get different answers when • Ask people what they consciously notice vs • See what affects their eye movement patterns Psyc / Ling / Comm 525 Fall 10

  46. Contingent Display Change • Idea: • If something peripheral changes just before the eye reaches it • during a saccade, so don’t see change itself happening • If the eye stays on the changed thing longer than when that’s what was there all along • what was originally there must have been "seen" peripherally • Answer to the question: • You can sometimes get wordshape and initial letter info as far ahead as 10-14 characters • But you have to get as close as 6 characters before you detect the "wordness" of the next unit Psyc / Ling / Comm 525 Fall 10

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  50. Semantic Priming(Phenomenon & Tool) ... ... arm arm kitchen kitchen tree tree Related prime >doctoractor < Unrelated prime nurse<Target> nurse floor floor ... ... • In a priming experiment: • Some people see nurse immediately after doctor in a list of words = Related condition • Others see nurse after an unrelated word like actor = Unrelated condition - Notice that target word is identical across conditions, so important word properties like frequency & length are perfectly controlled • People respond faster, on average, in Related condition = Priming (= facilitation) Psyc / Ling / Comm 525 Fall 10

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