Table 2.

The change in log ratio (standard/variable) produced by each dose, expressed as a proportion of the log ratio during saline sessions, for sessions in which the variable-delay schedule was FI 16 s and sessions in which the variable-delay schedule was FI 4 s.

Pigeon	0.3 mg/kg		1.0 mg/kg		1.7 mg/kg		3.0 mg/kg
	FI 16 s	FI 4 s	FI 16 s	FI 4 s	FI 16 s	FI 4 s	FI 16 s	FI 4 s
105	0.19	−0.86	−0.25	−0.85	−0.34	−1.31	−1.04	−1.00
106	−0.52	−0.01	−1.49	0.08	−1.06	−0.53	—	−0.43
107	−0.71	−1.16	−0.47	−0.71	−0.46	−0.02	—	−0.90
108	−0.07	−0.42	−0.58	−0.77	−0.64	−1.55	−0.96	−1.62
225	−0.11	−0.81	−0.03	−0.47	−1.66	−0.51	−2.11	−0.25
226	0.05	−0.01	0.23	−0.72	−0.50	−0.72	−0.74	−1.10
227	0.28	−0.39	−0.44	−0.23	−1.19	−0.43	−1.88	1.11
228	−1.65	0.12	1.17	−0.60	0.11	−0.66	—	−0.65
Mean	−0.32	−0.44	−0.23	−0.53	−0.72	−0.72	−1.35	−0.61
SD	0.64	0.47	0.76	0.32	0.56	0.49	0.61	0.81
t-test	t(7)  =  .39, p  =  .71		t(7)  =  .89, p  =  .40		t(7)  =  .00, p  =  1.0

Note. See Data Analysis for an explanation of the method used to calculate these values. Results of t-tests comparing values across the two schedules are presented in the bottom row (no test was conducted for the data at 3.0 mg/kg because of missing values for 3 of the pigeons).