[en] Recent studies suggest that people with Williams syndrome (WS) present specific deficit in processing numerical magnitudes (Krajcsi et al., 2009; O’Hearn et al., 2007; Paterson et al., 2006).As patients with WS were always tested in the visual modality, their deficit could either be specific to the processing of numerical magnitude or result from their basic visuo-spatial impairment (main characteristic of their cognitive phenotype). Supporting the second hypothesis, a first study showed that people with WS have lower numerical acuity only in numerical tasks with high visuo-spatial processing requirements (i.e. comparing two lengths or two arrays of elements but not when comparing two durations or two sequences of flash in a single location; Rousselle et al., 2013). Recently, we tested whether a similar dissociation would be observed in processing the meaning of numerical symbols. Patients with WS were asked to compare the numerical magnitude of two Arabic d vs two spoken verbal numerals. Their subitizing abilities were also assessed through the enumeration of 1 to 7 dots shown for 250 ms. Participants with WS were compared to children matched on verbal or nonverbal mental abilities. Results show that they have difficulties in accessing the meaning of numerical symbols whatever the format and present smaller subitizing
