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

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 1/2/2020

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? 2

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

What’s 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. 4

What’s a prefix?An instructional definition White, Sowell, and Yanagihara (1989) suggest the following definition of prefix:it is a group of letters at the beginning of a word misspellit changes the meaning of the wordmis- = incorrectlyspell incorrectlywhen you remove it, a word is left misspell 5

What’s 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-) 6

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. 7

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 word’s definition Head: NONswimmer Tail: nonSWIMMER 9

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; … 10

Semantic Cues Operationalized:Match Patterns in Definitions inanimate … denoting nonliving things rename assign a new name to overproductiontoo much production or more than expected

Initial letters: How semantically reliable are they? Numbers range from ~5-50%, shockingly low: 12

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 meaninguncle Next two slides we’ll detail best and worst case 14

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 15

Best, worst, in between Only 28.85%* – 37.39%** of words with one of the nine head strings are prefixed words! 16

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 children’s texts Children read aloud from modern and antebellum texts into a microphone – a bulbousflange, 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 17

What is the effect of prefixes on reading times? Predictions: For students who don’t read very wellwhether the word is best case or worst caseshouldn’t 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 18

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

Due to practice, length, frequency? 20

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

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

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

Summary:Not due to practice, length, frequency Reading times were still slower for best-case when looking at various subsets: 27

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

Students had different numbers of encounters. Was that it? 29

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

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

What was the effect by reading level? Prediction:effect for higher level readers, no effect for lower level readers 32

Best case slower across reading levels!(Frequency in LISTEN corpus) Sig. ? yes yes almost no no yes no 33

Best case slower across reading levels!(Frequency in SUBTLEX) Best case slower for more students, p = 0.023 34

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

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 36

Conclusions Initial letter sequences (heads) aren’t 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 37

Thank you 38

Initial letters: How good is the operationalization? Sample of 100 Project LISTEN wordsthat are also in WordNet 40

Project LISTEN’s 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

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