Development of CDIs for rural Africa

K. Alcock

K. Rimba

A. Abubakar

P. Holding

Assessing vocabulary and grammatical development

• “Clinical” testing– e.g. Picture vocabulary tests, TROG, elicited speech– Carter et al.

• Laboratory testing (HA!)• Spontaneous speech samples• Checklists

– Fenson et al.– Bornstein et al. crosslinguistic

Bornstein et. al 2004

• Data from 7 languages • Checklist similar to MacArthur/Bates but

shorter• All have higher noun proportion. in 20mo

vocabulary– Even Korean – unlike previous data – Suggest child constraints lead to this– But modified by language features

Two East African languages

• Kiswahili and Kigiriama– Both spoken in coastal Kenya– Town and. village families

Overall study

• Impact of HIV exposure on child development

• Age 6 months to 3 years

• Language, motor and cognitive development

• 200 families so far

Relevant sentence features

• Very variable word orderThe child likes potatoesMtoto anapenda viazi – basic word order SVOAnapenda viazi mtoto – common, VOSMtoto viazi anapenda – less common but possible, SOV

• Sentences can miss out subjectHe likes potatoesAnapenda viazi

• Rather like Italian in that respect

• Sentences can miss out subjectHe likes (them)Anapenda/Anavipenda

Data collection

• Adaptation of MacArthur CDI

• 175 families of children aged 8-15 mo

• Interview technique - not literate

Construction 1

• Macarthur-Bates CDI - younger (words & gestures)

• Elimination of inappropriate words (snow, penguin)

• Translation in parallel to both languages

Construction 2

• Adding words:– RAs experienced w. children – Mothers on staff & in community – Speech samples – Situational vocabulary (goat, maize porridge)– Function words

• Back translation & checking

Construction 3

• MacArthur-Bates CDI Older (Words and Sentences)

• Same method with vocabulary• Grammatical development:

– Spontaneous samples– Examination of errors actually made– Enumeration of parts of speech children need to learn– Not possible to produce an order of learning in the time– But we will be able to tell what is learnt between 16-30

months

Validation

• Internal validity

• External validity– Vocabulary and gestures – 9-15 months– Vocabulary and grammar – 16-30 months

Production 8-15 mo

-5

0

5

10

15

20

25

30

35

40

8 mo 9 mo 10 mo 11 mo 12 mo 13 mo 14 mo 15 mo

Lower conf intervalMeanHigher conf interval

Comprehension 8 - 15 mo

-10

10

30

50

70

90

110

130

150

8 mo 9 mo 10 mo 11 mo 12 mo 13 mo 14 mo 15 mo

Lower conf interval

Mean

Higher conf interval

Production 16-30 mo

-5

95

195

295

395

495

595

695

795

895

16 mo17 mo18 mo19 mo20 mo21 mo22 mo23 mo24 mo25 mo26 mo27 mo28 mo29 mo30 mo

Lower conf intervalMeanHigher conf interval

Word combining 16-30 mo

00.10.20.30.40.50.60.70.80.9

1

16mo

17mo

18mo

19mo

20mo

21mo

22mo

23mo

24mo

25mo

26mo

27mo

28mo

29mo

30mo

Ever

Reliability and validity

• Internal reliability– Alphas over .9 for most sections– Alphas much over .9 for half of test

• Correlation with age– Total vocabulary (younger) .505– Gestures .679– Total vocabulary (older) .620– Grammatical affixes .469

• Effect of HIV– When covary age, vocabulary approximately half that of

community children

Validity testing

• 9-15 months

• Challenge items– Production, comprehension and gesture– Low, medium, and high frequency

• Mother list of words

Challenge items

• No child produced any words in production– Some incomprehensible sounds

• Comprehension and gesture more useful– Significant correlations:

Gesture without prompt and gesture on CDIGesture without prompt and comprehension on CDI

Specific items tested in comprehension challenge did not correlate with challenge comprehension items

Mother lists of words

– Neither prompted nor spontaneous lists correlate with:

• Age

• Gesture total

• Language total

• Challenge task

– Asked for words for actions/toys/things child likes tends to give names of actions child can do etc.

Conclusions for validity

• Test hugely internally valid• Mothers better at observing gesture than

language?• 10 challenge words very poor test?• Mother spontaneous list paradigm poorly

understood – CDI paradigm involves clearer explanation– Reminder “can he say the word or does he just

understand the word”

Summary

• Reliability of test• Validity• Further work

– Spontaneous speech during cognitive testing session• But no speech produced

– Spontaneous speech at home

– Written versus interview method for literate local mothers