Post on 31-Dec-2015
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