Table 3.

A mixed factorial ANOVA with repeated measures was used to analyze the effects of psychostimulant conditioning

Effect	d.f.	SS	F	P-value
Drug	2	0.938	15.40	<0.0001*
Psychostimulant vs. vehicle	1	0.747	24.52	<0.0001*
Amphetamine vs. cocaine	1	0.186	6.10	<0.01*
Time	3	0.248	2.72	<0.05*
Time bin 1 vs. time bins 2, 3, and 4	1	0.087	2.86	<0.05*
Time bin 2 vs. time bins 3 and 4	1	0.073	2.41	=0.062
Time bin 3 vs. time bin 4	1	0.091	2.98	<0.05*
Drug × time interaction	6	0.178	0.97	=0.445
Time bin 1—psychostimulant vs. vehicle	1	0.100	3.29	=0.036
Time bin 2—psychostimulant vs. vehicle	1	0.055	1.80	=0.091
Time bin 3—psychostimulant vs. vehicle	1	0.315	10.35	<0.001*
Time bin 3—amphetamine vs. cocaine	1	0.053	1.74	=0.094
Time bin 4—psychostimulant vs. vehicle	1	0.378	12.42	<0.001*
Time bin 4—amphetamine vs. cocaine	1	0.174	5.73	<0.01*

A series of orthogonal contrasts were carried out as planned comparisons for each factor. Such tests do not inflate type I error, as the variance components (sums of squares, SS) and degrees of freedom (d.f.) are independent and additive. The SS for the interaction factor did not meet the requirement of additivity and thus the Bonferroni step-down procedure was used to maintain type I error at a constant rate. Asterisks indicate P-values that were statistically significant at an experiment-wise α of P = 0.05.