RECEPTIVE VOCABULARY DEVELOPMENT IN CHILDREN WITH COCHLEAR IMPLANTS: Achievement in an intensive, auditory-oral educational setting

Heather Hayes, Ann E. Geers, Rebecca Treiman, & Jean S. Moog

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Outline

What do we know about vocabulary development in deaf children?

Our study

Implications for parents and professionals

Future directions

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General findings

Cochlear implants vs. hearing aids CI kids have better performance in...

speech perception (e.g., Blamey et al., 2001; Osberger et al., 1991)

receptive language (e.g., Geers & Moog, 1994; Tomblin et al., 1999; Truy et al.,1998)

Yet, is this the most appropriate comparison?

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Findings: Receptive vocabulary (PPVT) CI kids have poorer receptive vocab than

hearing peers(Blamey et al., 2001; Connor et al., 2000; Eisenberg et al., 2004; El-Hakim et al., 2001; Geers & Moog, 1994; Kirk et al., 2000; Miyamoto et al., 1999; Spencer, 2004)

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Findings: Receptive vocabulary (PPVT) CI kids improve receptive vocab skills over

time, but below rate of hearing peers growth rates range from .45 to .72 year’s growth per year

(Blamey et al., 2001; Connor et al., 2000; El-Hakim et al., 2001; Geers & Moog, 1994; Kirk et al., 2000)

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Individual differences

Does age at implant make a difference in outcome? Theoretical implications

critical period? Practical implications

surgery at 12 mos or surgery at 3 yrs?

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Findings: Receptive vocabulary (PPVT) Some found (-) age at implant effect on

overall receptive vocab level, (Connor et al., 2000)

...some have found (+) age at implant effect, (El-Hakim et al., 2001; Kirk et al., 2002)

...and others have found no effect. (Miyamoto et al., 1999)

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Findings: Receptive vocabulary (PPVT) Some found age at implant effect on growth

rates... < 5 better than > 5 (Connor et al., 2000) < 2 better than 2-4 (Kirk et al., 2000)

...but others didn’t. (El-Hakim et al., 2001; Miyamoto et al., 1999)

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Problems with previous research Sample populations

Small numbers of CI kids Mixed communication methods

Signed English, speech, ASL Tests given in preferred communication mode

Kids older at implantation (mean 3-5 years – not current) Differing definitions of prelingual onset Educational environment often overlooked Advances in technology often overlooked

Inadequate methods for investigating growth over time

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Current study

Moog Center for Deaf Education testing database Receptive vocabulary test (PPVT) NVIQ Age at CI Year of CI

Controls for communication method, educational environment, access to audiologists, parental involvement

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Study questions:

How do implanted kids in an oral educational setting compare to hearing peers on a receptive language measure (PPVT)? vocab level growth rate

Does age at implant affect... vocab level? growth rate?

ParticipantsN kids 65

N vocabulary scores 231

Mean # vocab tests taken per child 3.5

Mean age at implant 2.69 yrs

Range when children received implants 1991-2004

Mean interval between tests 1.01 yrs

Mean age at 1st test 5.12 yrs

Mean duration of implant experience at 1st test

2.39 yrs

Mean NVIQ 108

Age at onset < 3 yrs

Mean highest level of parent education 16.36 yrs30 June 08

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Growth curve analysis

More flexible than traditional approach different numbers of tests per kid unequal spacing between tests takes autocorrelation into account allows both intercepts and slopes to vary

randomly between participants

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Multilevel model

Level 1: How do individuals change over time?

Yij = π0i + π1i TIME + π2i TIME2 + ɛij

Level 2: How do these changes vary across individuals?

π0i = ɣ00 + ɣ01PREDICTOR + ζ0i

π1i = ɣ10 + ɣ11PREDICTOR + ζ1i

π2i = ɣ20 + ɣ21PREDICTOR + ζ2i

Results

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Significant effects (in Standardized

Scores)

Initial vocabulary level 57

Growth rate 9 pts per yr

Year of implant 4

Age at implant (-) 4 pts per yr

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Expected growth curves: Average child from our sample

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Expected curves: Age at implant effect

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Language study summary CI kids are at disadvantage compared to hearing

peers.

However, CI kids make more than a year’s worth of progress in one year.

Age at implant effect: Younger is better for greater yearly progress and for

achieving normal levels earlier.

Future directions

Investigate whether these results generalize to other areas of language

Investigate whether children maintain a normal level of language growth when they leave this very special environment and go into mainstream

Encourage schools to conduct and maintain repeated assessment results over time to be used for practical research projects.

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