Among others, mathematical abilities are impaired in persons living with Williams syndrome. There were many studies revealing the impaired numerical abilities, however it was not known whether there were differences between the smaller building blocks of numerical abilities.
In our study we found that while participants with Williams syndrome solved easily the seemingly difficult single-digit multiplications and additions, they were struggling with the seemingly easier comparison tasks. This counter-intuitive result is actually in line with former models of numerical cognition and with the pattern of the impairments in Williams syndrome. (1) Comparison can be solved with the analogue magnitude system localized in the intraparietal sulcus, which area is impaired in Williams syndrome. (2) On the other hand, overlearnt addition and multiplication relies on the verbal system which is relatively intact in Williams syndrome.
Krajcsi, A., Lukács, Á., Igács, J., Racsmány, M., & Pléh, C. (2009). Numerical abilities in Williams syndrome: dissociating the analogue magnitude system and verbal retrieval. Journal of Clinical and Experimental Neuropsychology, 31(4), 439–446. https://doi.org/10.1080/13803390802244126
Krajcsi, A., Igács, J., Racsmány, M., & Pléh, C. (2005). Numerical abilities in Williams Syndrome. Cognition and its origins. Budapest.
(A short review can be found on our poster. Some other unpublished tasks and an also unpublished developmental dyscalculia data can be found. Also, selective load method (RT measurement) is introduced here.)
Description of the project in Hungarian.