Time course of the discriminative stimulus effects of (±)-methcathinone (A; 0.032 – 0.32 mg/kg, IM), (±)-3,4-methylenedioxymethcathinone (MDMC) (B; 0.1 – 3.2 mg/kg, IM), and (±)-4-methylmethcathione (4MMC) (C; 0.32 – 201 mg/kg, IM) in male rhesus monkeys (n=4). Ordinates: percent cocaine-appropriate responding. Symbols above “S” and “C” represent the group averages for all saline- and cocaine-training sessions preceding test sessions, respectively. Filled symbols indicate statistical significance compared to saline at a given time point (p < 0.05). Number in parentheses indicate the number of subjects contributing to that data point if fewer than the total number (4) of subjects tested (i.e. indicative of a time point where one or more monkeys failed to complete at least one ratio requirement).