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Abstract:
Abstract: Johnson and Carey (1998) documented a selective
deficit in the conceptual development of people with the
neurodevelopmental disorder of Williams syndrome (WS). Examination
of their intuitive reasoning about living things suggests that they
are developmentally unable to resolve incommensurabilities with the
adult folkbiology that normal children resolve unaided around the
age of seven. The current work on number concepts examines the
extent to which their impairment is specific to either causal
reasoning or folkbiology. Five individuals with WS (CA = 228
months; Verbal MA = 106 months; SS = 65) and five typically
developing children (CA = 116 months; Verbal MA = 111 months; SS =
97) were compared on their successful acquisition of the numerical
concepts 'cardinality', 'zero', and 'infinity', as well as number
conservation. The acquisition of these concepts are all thought to
involve incommensurabilities and therefore require conceptual
change. All five typically developing children possessed the
concepts 'cardinality', 'zero', and 'infinity', and understood
number conservation. Among the WS participants, all five understood
cardinality, two understood the concept 'zero', and none understood
that there is no highest number ('infinity'). Three of the five
passed a number conservation task. Interestingly, all five
individuals with WS could count fluently by ones, fives, and tens.
These results suggest that the impairment in conceptual change
abilities in people with Williams syndrome is not limited to either
causal reasoning or the domain of biology.
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