Verbal and nonverbal abilities in the Williams syndrome phenotype: evidence for diverging developmental trajectories.
One commonly cited feature of Williams syndrome is a characteristic dissociation between relatively spared language skills and severely impaired nonverbal abilities. However, the actual evidence for a dissociation between verbal and nonverbal abilities in Williams syndrome is equivocal. In two separate studies we examined these abilities in 16 individuals showing the Williams syndrome phenotype. When considered as a whole, the group did have significantly superior verbal abilities, but this difference was caused by a large discrepancy in abilities in only a small number of individuals. In both studies there was a clear, linear relation between individuals' verbal ability, and the magnitude of their verbal-nonverbal discrepancy. We suggest that these results are best explained in terms of verbal ability developing at a faster rate than nonverbal ability in this disorder. We discuss how this model of differential rates of development has the potential to reconcile the apparently inconsistent findings in this area.
Jarrold
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Department of Experimental Psychology, University of Bristol, U.K.
Baddeley
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AD
Hewes
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AK
D000293:Adolescent; D000328:Adult; D001076:Aptitude; D002648:Child; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000175:diagnosis / Q000235:genetics / Q000523:psychology; D007206:Individuality; D007360:Intelligence / Q000235:genetics; D007805:Language Development Disorders / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology; D007859:Learning Disabilities / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology; D008297:Male; D010641:Phenotype; D014705:Verbal Behavior; D014888:Wechsler Scales; D018980:Williams Syndrome / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology