LAUSR

ABSTRACT The influence of visuo‐spatial skills on numerical magnitude processing is the subject of a long‐standing debate. As most of the numerical and non‐numerical magnitude abilities underpinning mathematical development are visual by nature, they are often assessed in the visual modality, thereby confusing visuo‐spatial and numerical processing. In order to assess the influence of visuo‐spatial processing on numerical magnitude representation, we examined magnitude processing in patients with 22q11.2 deletion syndrome (22q11DS), a genetic condition characterized by a cognitive profile with a relative weakness in visuo‐spatial abilities but with preserved verbal abilities. Twenty‐seven participants with 22q11DS were compared to two control groups (one matched on verbal intelligence and the other on visuo‐spatial abilities) on several magnitude comparison tasks each with different visuo‐spatial processing requirements. Our results showed that participants with 22q11DS present a consistent pattern of impairment in magnitude comparison tasks requiring the processing of visuo‐spatial dimensions: comparison of lengths and collections. In contrast, their performance did not differ from the control groups in a visual task with no spatial processing requirement (i.e. numerical comparison of flashed dot sequences) or in auditory tasks (i.e., duration comparison and numerical comparison of sound sequences). Finally, a specific deficit of enumeration processes was observed in the subitizing range. Taken together, these results show that deficits in magnitude can occur as a consequence of a visuo‐spatial deficit. This highlights the influence of the nature of the tasks selected to assess magnitude representation. HIGHLIGHTSAssessing early magnitude representation in 22q11DS.Tasks for teasing apart the influence of visuo‐spatial skills.Specific deficit in magnitude processing tasks with high visuo‐spatial demands.highlights the importance of examining magnitude representation with non‐visual tasks.