Table 2.

Baseline successive matching contingencies (first three columns) and nonreinforced probe-test trials (last column) for the two groups in Experiment 1.

Dual Oddity Group
Hue–form Arbitrary	Hue Oddity	Form Oddity	Probe-test Trials
R → T - FI 5 s +	R → R - EXT	T → T - EXT	T → R (√)
R → H - EXT	R → G - FI 5 s +	T → H - FI 5 s +	H → R
G → T - EXT	G → R - FI 5 s +	H → T - FI 5 s +	T → G
G → H - FI 5 s +	G → G - EXT	H → H - EXT	H → G (√)
Control Group
Hue–form Arbitrary	Hue Oddity	Form–hue Arbitrary	Probe-test Trials
R → T - FI 5 s +	R → R - EXT	T → W - EXT	T → R (*)
R → H - EXT	R → G - FI 5 s +	T → B - FI 5 s +	H → R (*)
G → T - EXT	G → R - FI 5 s +	H → W - FI 5 s +	T → G (*)
G → H - FI 5 s +	G → G - EXT	H → B - EXT	H → G (*)

Note. R = red, G = green, W = white, B = blue, T = triangle, H = horizontal, FI = fixed interval schedule, EXT = nonreinforced, + = reinforced. The first and second center-key stimuli in a trial sequence (sample and comparison, respectively) are shown to the left and to the right of the arrows, respectively.

^(√)indicates the probe trials for which higher comparison-response rates are predicted (i.e., associative symmetry).

^(*)indicates that comparison-response rates should be nondifferential across probe-test trials.