Table 1.

Cue reactivity tests of lever B rewards after forced abstinence. Calculated least squares mean for both experiment 1 (cocaine lever A) and experiment 2 (heroin lever A), and two-way ANOVA of drug cued on lever B × experiment 1 vs. 2 for each cue test. Data are presented as mean ± standard error of the mean (SEM).

	Least squares mean of experiment 1: cocaine (lever A)	Least squares mean of experiment 2: heroin (lever A)	Mean difference (SEM of difference)	Two-way ANOVA: experiment	Two-way ANOVA: reward cued (lever B)	Two-way ANOVA: interaction (experiment × reward cued)
Cue test 1 (day 1)	80.28	90.70	− 10.42 (14.77)	F (1,26) = 0.4979	F (2, 26) = 0.7171	F (2, 26) = 0.6866
Cue test 2 (day 13)	21.65	51.02	− 29.37 (5.177)	F(1, 29) = 32.19****	F (2, 29) = 3.525*	F (2, 29) = 1.531
Cue test 3 (day 29)	44.35	63.79	− 19.44 (5.982)	F (1,28) = 10.56**	F (2, 28) = 1.774	F (2, 28) = 2.549

^*p < 0.05,

^**p < 0.01,

^****p <0.0001 with respect to differences in responding between experiments or the reward corresponding to the lever B cue (i.e., responding for lever B rewards for SDL, SDH, and PD groups)