Table 1.

Successive Matching Training Contingencies in Experiment 1

R → T • FI 5”	Symbolic (AB)
R → H • DRO 5”
G → T • DRO 5”
G → H • FI 5”
R → R • FI 5”	Hue identity (AA)
R → G • EXT
G → R • EXT
G → G • FI 5”
T → T • FI 5”	Form identity (BB)
T → H • EXT
H → T • EXT
H → H • FI 5”

Note. R = red, G = green, T = triangle, H = horizontal, FI = fixed interval schedule, DRO = differential-reinforcement-of-other-behavior schedule, EXT = extinction. A and B denote hue and form stimulus sets, respectively. Samples are shown to the left of the arrows; comparisons are shown to the right of the arrows. Sample-response schedules and counterbalancing of the symbolic contingencies are omitted for clarity.