Figure 2:

Mean (±SEM) infusions obtained (A, B) and the percent of responses directed to the drug-associated lever (C, D) by female (XX) α-PVP (N=6), male (XY) α-PVP (N=7), female MA (N=5–6; one animal failed to complete 0.1, 0.3 conditions) and male MA (N=8) groups responding under a Fixed Ratio 1 contingency in 2 hour sessions. The dotted line is included to emphasize when mean discrimination ratios exceed 80%. Data are depicted by original training drug (A, C) and when the alternate drug (B, D) was available. Bars indicate the SEM. Open symbols depict a significant difference from the Vehicle, within group. A significant difference from all other groups is indicated with #, a sex difference, within drug identity, with *, and a difference between drugs, within sex, with &.