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poster
The Second Cambridge Infant Refractive Screening Programme usednon-cycloplegic videorefraction to detect children, in a population of over5000 nine-month-olds, who showed inaccurate hyperopic focussing. Fromcycloplegic refraction, these were divided into 'confirmed hyperopes' (>3.5dioptres) and 'poor accommodators' whose errors of focus were not due tothis level of hyperopia. A control group of children without refractiveanomalies was also selected. These groups are being followed up to age 6years, making it possible to examine hypotheses that hyperopic refractionand/or poor focussing behaviour in infancy are associated with subsequentmild deficits in visual and cognitive development. A specific hypothesis,given reports that childhood reading disability can be associated withvisual and orthoptic factors, is that these refractive indicators maypredict later linguistic measures that are associated with readingdevelopment.At 13-15 months children were tested with the ABCDEFV battery ofvisually-based performances. A significantly greater number of hyperopesthan controls failed one or more of the subtests. At 42-48 monthshyperopes showed significantly poorer performance than controls onperceptual tests (shape matching, embedded figures), and overall score onthe ABC battery of motor skills.At 5-6 years, tests included Hulme's Phonological Awareness Test (PAT) andGathercole's Test of Nonword Repetition (which have been found predictiveof subsequent reading performance) and the British Picture VocabularyScale. The groups defined by refractive status in infancy showsignificant differences in scores on the Phonological Awareness Test, butnot in vocabulary. These results suggest the existence of a cluster of mild developmentaldeficits, including but not limited to skills underlying reading, that areassociated with infant refractive status. Several possibilities will beconsidered, including (a) that refractive development reflects more generaldevelopment of cerebral function in infancy; and (b) that the visual orvisuo-motor consequences of refractive status can have an impact on widerdevelopment.Supported by MRC programme grant G7908507
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Infant visual processing measures, such as habituation rate andrecognition memory, are predictive of later cognitive and language outcome,particularly in high-risk populations (McCall & Carriger, 1993). Two lines ofevidence suggest a more specific relationship between the early ability toprocess rapidly presented auditory information and later language skills.First, infants with a family history of language impairment or dyslexiadiffer from controls both in their ability to discriminate two-tone sequenceswith short but not long intervals between the tones (Benasich & Tallal,1996) and in their brain event-related potentials (ERPs) to consonant-vowelpairs (LeppE4nen et al., 1999; Pihko et al., 1999). Second, languageperformance in normal populations has been related to infant performance on agap detection task (Trehub & Henderson, 1996) and to infant ERPs toconsonant-vowel pairs (Molfese & Molfese, 1997).We investigated the potential of infant auditory-visual (AV) processingmeasures to predict language outcome in healthy fullterm infants and ininfants at risk of language problems from preterm VLBW birth. Infants weregiven an AV task, in which they were habituated to an unchanging visualpattern combined with a computer generated speech stimulus (/ba/). Measures ofhabituation rate were interpreted to reflect attention towards andencoding of AV stimuli. After habituation, infants were tested with the samevisual pattern and a new speech stimulus (/da/). Infants must detect thedifferent transient auditory signals (formants of stop consonants) immediatelyfollowed by the same vowel sound to discriminate between the novel andfamiliar auditory stimuli; this discrimination is difficult for somechildren with language impairment (Tallal & Piercy, 1973). Contrasting thepredictive value of habituation and discrimination measures, should revealwhether the high rates of language problems seen in children born VLBW arerelated to difficulties in processing rapidly presented brief acoustic cues orwhether they reflect more general social, cognitive, or attentionproblems. In addition, the predictive value of the infant measures in the VLBWsample was contrasted with measures of perinatal risk (medical checklistsand presence of ultrasound abnormalities indicating brain injury).A group of 37 VLBW infants and 38 fullterm control infants participatedin two infant visits at approximately 6 and 9 months and a cognitive andlanguage assessment at around 24 months corrected age. In the infant visits,visual and AV habituation and recognition memory tasks were presented.Preliminary correlation and regression analyses reveal group differences inthe relations between infant and outcome measures (27 VLBW and 29 controlchildren). As expected, language outcome in the control group wasmoderately related to visual novelty preference. In contrast, in the VLBW group,language outcome was related to measures of attention to AV stimuli; inaddition, cognitive outcome related to measures of perinatal medical risk.Based on our analyses to date, we can conclude that language problems inthis VLBW sample are related to general processing problems, includingattending to and encoding of AV stimuli, rather than specific difficulties withrapidly presented auditory stimuli. In addition, perinatal events areimportant in determining general cognitive outcome.
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The term 'language development' as applied to hearing children typically refers to communication in the verbal modality. However, focusing only on verbal communication ignores another avenue available to hearing infants, the use of simple gestures to represent objects (e.g., sniffing for 'flower'), conditions (e.g., blowing for 'hot'), and desires (e.g., finger tips tapping for 'more'). Results of a case study (Acredolo & Goodwyn, 1985) and cross-sectional and longitudinal studies (Acredolo & Goodwyn, 1988) have shown that infants between 10 and 20 mos are so highly motivated to communicate that they often spontaneously recruit such 'symbolic gestures' as a way around the obstacle posed by the articulatory demands of verbal words. In 1989 a longitudinal study was undertaken to determine whether actively encouraging babies to use this type of preverbal communication would have an effect on subsequent language and cognitive development. To this end, three groups of infants were assessed in laboratory sessions at 11, 15, 19, 24, 30, and 36 months. Relevant to the current study are the Sign Training Group (ST Group: N 32), whose parents were instructed to promote the use of symbolic gestures by consciously modeling them along with their verbal equivalents, and the Non-Intervention Control Group (NI Group: N 37) whose parents were told nothing about gesturing. Three main results of this training study are particularly important to the current report. First, the study indicated that infants would, in fact, use symbolic gestures if encouraged to do so by their parents (M 20.3, Range: 9-61). (See Table 1 for examples). Second, the results of the various verbal language assessments indicated an advantage for the ST over the NI children in both receptive and expressive development (Goodwyn & Acredolo, 1998). Third, the ST children scored significantly higher than the NI children on the Bayley MDI at 24 mos. The purpose of the present study was to extend these group comparisons into the elementary school years. Specifically, all of the original ST and NI children who could be re-located (19 of 32 ST children and 24 of 37 NI children) were assessed using the WISC-III during the summer following their second grade year. The results indicated that the ST children were indeed continuing to outperform the control children, even 6 years after the original intervention. As indicated in Table 1, an ST advantage was found for the Verbal Sub-Scale (F [1, 41] 9.45, p.0038) and the Performance Sub-Scale (F[1, 41] 6.19, p.017), in addition to the Full IQ (F [1, 41] 12.06, p.0012). Analyses to rule out attrition effects as contributors indicated (a) no differences for either the ST or NC groups between the returnees and non-returnees in Bayley MDI scores at 24 months, (b) no difference between the ST returnees and non-returnees in the number of symbolic gestures used during infancy, and (c) no differences between the returnee groups in maternal education or age. The results outlined above are exciting, surprising, and have both important theoretical and practical implications. [L.P. Acredolo, Psych. Dept., UC Davis, Davis, CA 95616 -- lpacredolo@ucdavis.edu]Table 1.Examples of Symbolic Gestures in Sign Training Subjects' RepertoiresReferent Gesture Example Usage Drink Thumb to mouth DS: To ask for bottle More Index fingers tapping BH: To ask to have picture taken againMonkey Scratching arm pits KA: To alert dad to very hairy stranger approaching Hat Patting top of head BH: To Grandma with towel around her headCheerios Index fingers to thumbs MR: To request more CheeriosFish Smacking lips together KA: To fish toy in tub and goldfish crackersWater Rubbing palms together CH: With FISH gesture to fish in pond Book Open/Close with palms AT: With MORE gesture to ask for another book Pig Tap nose with finger TA: To potbelly pigs at county fairCamera Hooked hand to eye BH: With MORE to ask for photo to be taken againFan One finger up & circling ZB: To helicopter Gentle Petting back of one hand MB: When legs held too tight during diaperingSmelly Finger to wrinkled nose AZ: To comment on Grandma's bad breathAfraid Pat chest repeatedly ZW: In response to barking dog approachingOut Knob-turning action PB: With DOG gesture for 'Dog wants out'Giraffe Hand around neck MR: To giraffes in books and at the zooTractor Steering wheel action NP: When his farmer Dad drives up in his tractorWhere? Palms up KA: When airplane disappeared into the cloudsTable 2.Mean IQ Scores (and Percentile Ranks) for ST and NI Children At Post-Second Grade Testing________________________________________________________________________GROUP FULL IQ VERBAL IQ PERFORMANCE IQ________________________________________________________________________ST (N 19) 114 (75%) 116 (75%) 109 (70%)NI (N 24) 102 (53%) 103 (55%) 101 (52 %) Note. All scores based on the WISC-III Intelligence Test
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Although researchers have linked information processing at 5 monthsto 'representational competence' at 13 months (Tamis-LeMonda & Bornstein,1989), and to IQ at 4 years (cf. Colombo & Mitchell, 1990), to ourknowledge there have been no published studies linking early informationprocessing to linguistic productivity in the second year. We wonderedwhether such a relationship could be found. We also wondered whetherinformation processing might differentially predict language comprehensionversus production during the second year, given the apparent dissociationbetween the two taking place at this time (Bates, Bretherton, & Snyder,1988). The subjects consisted of 43 children, primarily European-Americanand middle-class, who visited the laboratory at 5 months and who werevisited in the home at 13 months. Thirty-eight of these infants returnedto the laboratory at 20 months. Habituation rate was assessed during the5-month visit. Children were habituated to one of four visual stimuliusing a criterion of 50% decrement from first look. Trials to criterion,number of peak fixations, and total fixation time served as dependentmeasures. No dependent measure differed as a function of stimulus type, sodata from all 4 habituation stimuli were pooled. The MacArthurCommunicative Development Inventory: Words and Gestures was used to assesslanguage comprehension and production at 13 months. The Sentences versionwas used to assess production at 20 months. Five-month habituation rate was significantly predictive of13-month linguistic comprehension. Specifically, rapid habituation wasassociated with advanced language comprehension. Paradoxically, five-monthhabituation was not associated with language productivity at either 13 or20 months, despite considerable covariation between the comprehension andproduction measures. Because of this inconsistency, we next tested forstatistical suppression using regression analysis. Twenty-month languageproduction measures were regressed first on 13-month comprehension measuresand second on the first principal component of the 5-month habituationmeasures. Intriguingly, production of predicates and function words at 20months was significantly predicted by 5-month habituation measures onlywhen first controlling for 13 month comprehension (Table 1). In otherwords, habituation by itself was a poor predictor of 20-month production,but when habituation was entered after 13-month comprehension, it increasedthe explained variance in production by about 10%. Removal of thesuppression revealed that faster habituation was associated with lesswell-developed (residualized) production. Although there appears to be some underlying continuity across the5-month to 20-month period, the nature of this continuity is evidentlycomplex. An understanding of this relationship might be better informed byfirst addressing what is left over in linguistic production when varianceassociated with comprehension is partialled out; because it is thisresidualized linguistic productivity which covaries with habituation. Tospeculate, it could be that partialling out linguistic comprehension leavesbehind social-emotional-motivational characteristics which might make achild more or less talkative. If accurate, such an interpretation wouldsuggest that faster habituating children would tend to be interpersonallyless sociable. In fact, recent research by Smith et al. (1997) supportsexactly such an interpretation.Table 10Summary of Regression Analyses Predicting 20-Month Production Measures from13-Month Comprehension and 5-Month HabituationDV #IVs IV B SE B D R2 DR2Predicates 1 13M Comp .21 .06 .49** .22 1 Habituation 4.26 3.96 .17 .00 2 13M Comp .25 .06 .59** Habituation 8.34 3.43 .34* .31 .08Function Words 1 13M Comp .08 .02 .52** .25 1 Habituation 1.65 1.44 .18 .01 2 13M Comp .10 .02 .62** Habituation 3.21 1.21 .36* .36 .11*p < .05, **p < .01. Notes: R2 in this table represents the 'shrunken'version of obtained R2. DR2 represents the increase in variance accountedfor when both measures are entered into the equation over the largest R2 inthe single variable equations.References Bates, E., Bretherton, I., & Snyder, L. (1988). From first words togrammar: Individual differences and dissociable mechanisms. Cambridge, MA:Cambridge University Press. Colombo, J., & Mitchell, D. W. (1990). Individual differences inearly visual attention: Fixation time and information processing. In J.Colombo & J. W. Fagen (Eds.), Individual differences in infancy:Reliability, stability, and prediction. Hillsdale, NJ: Erlbaum. Dixon, W.E., Jr., & Smith, P.H. (1999, April). Easy-Going BabiesMake Better-Talking Toddlers. Poster submitted for presentation at theBiennial Meetings of the Society for Research in Child Development,Albuquerque, NM. Smith, P.H., Dixon, W.E., Jr., Jankowski, J.J., Sanscrainte, M.M.,Davidson, B., & Loboschefski, T. (1997). Longitudinal relationships betweenhabituation and temperament in infancy. Merrill-Palmer Quarterly, 43,291-304. Tamis-LeMonda, C. S., & Bornstein, M. H. (1989). Habituation andmaternal encouragement of attention in infancy as predictors of toddlerlanguage, play, and representational competence. Child Development, 60,738-751.