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How often are prefixes useful cues to word meaning? Less than you might think!

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How often are prefixes useful cues to word meaning? Less than you might think! Jack Mostow *, Donna Gates *, Gregory Aist *, and Margaret McKeown + – PowerPoint PPT presentation

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Title: How often are prefixes useful cues to word meaning? Less than you might think!


1
How often are prefixes useful cues to word
meaning? Less than you might think!
  • Jack Mostow , Donna Gates ,
  • Gregory Aist , and Margaret McKeown
  • Project LISTEN (www.cs.cmu.edu/listen)
  • Carnegie Mellon University
  • LRDC, University of Pittsburgh
  • Funding IES
  • 15th Annual Meeting of the Society for the
    Scientific Study of Reading, June, 2009

1
3/15/2013
2
Research question
  • Conventional wisdom is to not give instruction on
    morphology until perhaps grade four
  • However, kids do encounter words with prefixes
  • As part of the IES-funded vocabulary grant, we
    wanted to take opportunistic advantage of
    prefixes when prefixes occur, explain them to
    help vocabulary
  • How often do such opportunities occur?That is,
    how often are prefixes good cues to meaning?
  • What happens when they do? That is, what is the
    effect of reliable prefixes on reading times?

3
Outline
  • Whats a prefix?
  • Linguistically
  • Instructionally
  • For this talk
  • How reliable are prefixes as cues to meaning?
  • What is the effect of prefixes on reading times?

4
Whats a prefix?A linguistic definition
  • affix Any element in the morphological structure
    of a word other than a root(1). E.g. unkinder
    consists of the root kind plus the affixes un-
    and er. Affixes are traditionally divided into
    prefixes, which come before the form to which
    they are joined suffixes, which come after and
    infixes, which are inserted within it. Others
    commonly distinguished are circumfixes and
    superfixes.
  • P.H. Matthews, The Concise Oxford Dictionary of
    Linguistics, Oxford UP, 2007. p. 11.

5
Whats a prefix?An instructional definition
  • White, Sowell, and Yanagihara (1989) suggest the
    following definition of prefixit is a group of
    letters at the beginning of a word
  • misspellit changes the meaning
    of the wordmis- incorrectly
    spell incorrectlywhen you remove it, a word is
    left misspell

6
Whats a prefix?For this talk The ones to teach
  • White et al. (1989) analyzed English words in
    printed school materials.
  • They found that the 20 most common prefixes make
    up 97 of prefixed words in English school texts.
  • The 9 most frequent prefixes make up 76 of these
    words.
  • Stahl and Nagy (2006) advise teaching the 9 most
    common prefixes
  • 1. un- 6. non-
  • 2. re- 7. in- (im-) into
  • 3. in- (im- il- ir-) not 8. over- too much
  • 4. dis- 9. mis-
  • 5. en- (em-)

7
A note on terminology
  • In some places in this talk we will use these
    terms to avoid undesired implications of prefix
    and stem / root
  • Head letters at the beginning of a word
  • Tail rest of letters in the word.
  • Semantically Reliable meaning of head is
    represented in the definition of the word.

8
Outline
  • Whats a prefix?
  • Linguistically
  • Instructionally
  • For this talk
  • How reliable are prefixes as cues to meaning?
  • What is the effect of prefixes on reading times?

9
How reliable are those nine prefixes as cues to
word meaning?
  • Materials WordNet definitions and
    relationsProject LISTEN story vocabularyAmerican
    National Corpus vocabulary
  • Methods Calculate percentage of word typesfor
    which one of the nine most frequent prefixes is
    semantically reliable in a words definition
  • Head NONswimmer
  • Tail nonSWIMMER

10
Head that looks like prefix may not be
  • displeased not pleased experiencing or
    manifesting displeasure
  • dismay fear resulting from the awareness of
    danger the feeling of despair in the face of
    obstacles fill with apprehension or alarm

11
Semantic Cues OperationalizedMatch Patterns in
Definitions
inanimate denoting nonliving things
rename assign a new name to
overproduction too much production or more
than expected
12
Initial letters How semantically reliable are
they?
  • Numbers range from 5-50, shockingly low

13
Outline
  • Whats a prefix?
  • Linguistically
  • Instructionally
  • For this talk
  • How reliable are prefixes as cues to meaning?
  • What is the effect of prefixes on reading times?

14
What is the effect of prefixes on reading time?
  • Compare reading time (letters per second)on
    reliable vs. not reliable words
  • MaterialsBest case head and tail both cues to
    meaning unnaturalWorst case neither head nor
    tail cues to meaning uncle
  • Next two slides well detail best and worst case

15
Head is cue? Already discussedTail is cue? Two
questions enough
  • Is the remainder a word? Rule out infidel,
    distortion,
  • Are the remainder of the letters an antonym of
    the original word? (only relevant for negative
    prefixes)Rule in unjustly (defined as unjust
    manner) since justly is antonym of
    unjustly

16
Best, worst, in between
Only 28.85 37.39 of words with one of the
nine head strings are prefixed words!
17
Measures
  • Reading times (milliseconds / letter)
  • Data was logged by the Reading Tutor, an
    automated tutor that uses automatic speech
    recognition to listen to children read aloud
  • Words were displayed in authentic contexts
    complete sentences in childrens texts
  • Children read aloud from modern and antebellum
    texts into a microphone a bulbous flange, sold
    in a blister pack, whose noise cancellation
    serves as a talisman against speech recognition
    errors
  • Compare best case vs. worst case unnatural vs.
    uncle

18
What is the effect of prefixes on reading times?
Predictions
  • For students who dont read very wellwhether the
    word is best case or worst caseshouldnt matter
  • Prefixes should help better readers
  • That is, for students at higher reading
    levels,reading times should be faster for best
    case words than for worst case words

19
Results
  • Reading times were slower for best-case
    wordsthan for worst-case words by 18.6 msec
    (19)

20
Due to practice, length, frequency?
21
Due to practice, length, frequency?
22
Due to practice, length, frequency?
  • No. Reading times were slower for best-case for
    first encounters by 17.4 msec (17)

23
Due to practice, length, frequency?
24
Due to practice, length, frequency?
  • No. Reading times were still slower for best-case
    for matched length range by 27.0 msec (27)

25
Due to practice, length, frequency?
26
Due to practice, length, frequency?
  • No. Reading times were still slower for best-case
    for matched freq. range by 28.4 msec (30)

27
SummaryNot due to practice, length, frequency
  • Reading times were still slower for best-case
    when looking at various subsets

28
Not due to practice, length, frequency when
looking at all 3 combined
  • Reading times were still slower for
    best-casethan for worst-case words by 48.8 msec
    (51)

29
Students had different numbers of encounters. Was
that it?
30
Students had different numbers of encounters. Was
that it? No.
  • Per-student average differs by 19.8 msec (18)
  • p lt 0.001

31
Filtering by frequency (LISTEN)yields similar
results
  • Per-student average differs by 21.1 msec (19)
  • p lt 0.001

32
What was the effect by reading level?
  • Predictioneffect for higher level readers, no
    effect for lower level readers

33
Best case slower across reading
levels!(Frequency in LISTEN corpus)
Sig. ? yes yes almost no no yes
no
34
Best case slower across reading
levels!(Frequency in SUBTLEX)
  • Best case slower for more students, p 0.023

35
Potential explanation(s)
  • Neighborhood effects? encourage --- entourage
  • Context?
  • Competition with tail disagree vs. agree?
  • Competition with head disagree vs. dis-?
  • Processing disagree takes more steps than
    distance
  • At least some of these explanations rely
    onreading time being affected by sublexical
    structure.

36
What about neighborhood effects?
  • Currently investigating. Sample

Medler, D.A. Binder, J.R. (2005) MCWord An
On-Line Orthographic Database of the English
Language. http//neuro.mcw.edu/mcword
37
Conclusions
  • Initial letter sequences (heads) arent all that
    reliable as cues to meaning
  • Yet reading times appear to be sensitive to real
    vs. fake prefix, even for low reading levels
  • Cliffhanger Does this sensitivity provide a hint
    that we could teach prefixes earlier?
  • Announcements
  • Gregory Aist joins Iowa State faculty in fall
    2009and co-founds journal, Dialogue and
    Discourse ,on language beyond the single
    sentence launching summer 2009
    www.dialogue-and-discourse.org

38
Thank you
39
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40
Initial letters How good is the
operationalization?
  • Sample of 100 Project LISTEN wordsthat are also
    in WordNet

41
Project LISTENs Reading Tutor
  • An automated tutor that helps children learn to
    read
  • See www.cs.cmu.edu/listen
  • Displays stories and listens to children read
    them aloud
  • Provides help when necessary
  • Uses automatic speech recognition to analyze
    oral reading
  • Logs sessions in detail, including speech
    recognizer output
  • Millions of read words in the aggregated
    database

41
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