The effect ofd-amphetamine on operant behaviour maintained under variable-interval schedules of reinforcement

✍ Scribed by M. J. Morley; C. M. Bradshaw; E. Szabadi

• Publisher: Springer
• Year: 1985
• Tongue: English
• Weight: 514 KB
• Volume: 87
• Category: Article
• ISSN: 0033-3158
• DOI: 10.1007/bf00431809

✦ Synopsis

Dose-response curves were obtained for the effects of d-amphetamine sulphate (0.1-3.2 mg/kg) on the operant performance of rats in variable-interval 4-min and variableinterval 20-rain schedules of reinforcement. Response rates maintained under variable-interval 4-rain were suppressed in a dose-dependent manner. Response rates maintained under variable-interval 20-rain schedules tended to be elevated by low doses and suppressed by higher doses. The degree of response rate suppression was greater in the case of the variable-interval 4-rain schedule. The results are consistent with the previously reported effect of d-amphetamine on the values of the two constants of Herrnstein's (1970) equation: the drug reduces the reinforcement frequency needed to maintain the half-maximum response rates (Kn) and lowers the maximum response rate (Rmax) (Bradshaw et al. 1981 b). It is suggested that the effects of d-amphetamine on operant performance may involve two processes: an enhancement of motivation and a reduction of the capacity to respond.