Rate-dependent effects of amphetamine resulting from behavioral competition

The rate-dependent effects, and several exceptions, of amphetamines on schedule-controlled behavior have been well documented. A hypothesis that most of the rate-dependent effects and exceptions are the result of interaction and competition with other amphetamine induced activities, e.g., locomotion and stereotypy, is reviewed and discussed. The evidence strongly suggests that such a competing-response process does occur, particularly at higher dose levels. The process is interpreted as being consistent with such anomolous results as amphetamine's lack of a reliable effect on high rate bursting in timing schedules, the differential effects of amphetamine on the low rate timing behavior of pigeons and rats, the lack of an enhancing effect of amphetamine on low rate behavior suppressed by aversive stimulation, and the apparent lack of systematic effect of amphetamine on very low rate behavior.