Table 1.

Relevant dimension and positive discriminators used for each stage of the AST.

	S+	S−	Relevant dimension
SD1	Paper vs.	Aspen	Medium
SD2	Heart vs.	Square	Shape
CD	Paper/flower vs. or paper/triangle	Aspen/triangle	Medium
		Aspen/flower
CD-R	Aspen/flower vs. or Aspen/triangle	Paper/triangle	Medium
		Paper/flower
IDS	Straw/diamond vs. or straw/cross	Cardboard/cross	Medium
		Cardboard/diamond
IDS-R	Cardboard/diamond vs. or cardboard/cross	Straw/cross	Medium
		Straw/diamond
EDS	Wax paper/star vs. or cotton/star	Cottar/circle	Shape
		Wax paper/circle