Table 1. Schematic representation of the levels of congruity for each control condition (reported in the table rows) applied in the study; the columns represent the different variables that could covary with numerosity (C: congruent with number, IC: incongruent with number).

Control condition	Overall area	Overall perimeter	Convex-hull (CH)	Inter-distance (ID)	Congruency level
Perimeter – CH	IC	=	=	C	1a
Perimeter – ID	IC	=	C	=	1b
Area – CH	=	C	=	C	2a
Area – ID	=	C	C	=	2b
Radius fixed – CH	C	C	=	C	3a
Radius fixed – ID	C	C	C	=	3b