Free and Bound Morpheme Errors by Children who use AAC

1
Free and Bound Morpheme Errors by Children who
use AAC

• Molly Maguire-Marshall, Undergraduate Student
• Cathy Binger, Ph.D., CCC-SLP
• Department of Speech and Hearing Sciences,
  University of New Mexico
• ASHA Convention, 2008
• Chicago, IL

2
Background

• Children who use voice output devices tend to
  have difficulties producing grammatically
  complete sentences (Binger Light, 2007)
• These children often have difficulty producing
  bound grammatical morphemes e.g.,
• plural s (shoes)
• past tense ed (walked)
• However, the types of errors that these children
  make have not been systematically documented
• We need to understand their errors to develop
  effective interventions

3
Design Participants

• Post-hoc analyses of single-subject, multiple
  probe research design (Binger, 2008)

4
Materials

• Storybooks
• Teenage Mutant Ninja Turtles, Muppet Babies, and
  Spiderman
• Targets
• Past tense ed, possessive -s, third person
  singular s, plural s, present progressive ing
• Voice Output Devices
• All students used Vantage or Vanguard (PRC)
• Probes
• Clipart characters on felt board
• Pool of 50 probes 10 used per session
• Here is grandma and here is her hamburger. This
  hamburger belongs to grandma. This hamburger is
  grandmas

5

• Independent Variable
• Use of aided AAC modeling and recasting during 15
  minute story reading sessions
• Measures
• Post-hoc analyses to determine the percentage of
  grammatical errors made by students on probe
  items

6
Results Content Words

• Fewer errors with nouns than verbs (baseline and
  post-baseline)
• All 3 children used incorrect verbs in baseline
• Some verbs were absent for all 3 children in
  baseline
• Improvements noted for all 3 children

7
Results Bound Grammatical Morphemes

• Morphemes attached to nouns absent in baseline
  for all children
• All children made errors on verb-based morphemes
  (incorrect and absent) in both conditions
• All children learned to produce bound grammatical
  morphemes
• All children made at least a few idiosyncratic
  errors
• GIRLS CLIMB (possessive s before a verb)
• HE LAUGH ED S (plural)

8
Discussion

• Students in the study exhibited both content word
  errors bound grammatical morpheme errors
• Learning/using nouns may be easier than verbs
  due to nature of symbol selection
• Learning verb morphology may be more challenging
  and/or complex than noun morphology
• Idiosyncratic errors
• Present but not predominant
• Did not necessarily follow set patterns
• Speed of acquisition indicates a level of
  grammatical competence before investigation began

9
Acknowledgements Contact Info

• Funding support
• New Century Scholars Research Grant

• For further info
• Cathy Binger
• Dept. of Speech and Hearing Sciences
• University of New Mexico
• E-mail cbinger_at_unm.edu