Table 1.

Performance of monkeys responding under a fixed-interval 3 min schedule

FoodCocaine 0.03 mg/kg per injectionCocaine 0.3 mg/kg per injection
Pre-extinction food rate (responses/min)7.93  ± 1.66.83  ± 1.78.03  ± 2.6
Total pre-extinction sessions27.0  ± 4.933.5  ± 8.425.5  ± 4.0
Food extinction rate (responses/min)3.3  ± 3.00.13  ± .051.25  ± 0.7
Mean cocaine rate (responses/min)3.28  ± 1.320.53  ± 0.13
Post-extinction session length (min)143.4  ± 23.7150.0  ± 38.2235.5  ± 19.1*
Total cocaine intake (mg/kg)4.5  ± 0.045.0  ± 0.0
  • * One-way ANOVA, F(2,9) = 7.43; p <0.05. Least significant difference, cocaine 0.03 mg/kg per injection versus 0.3 mg/kg per injection; p<0.05; food control versus 0.3 mg/kg.