Abstract

The number of responses made by pigeons in a fixed period of time is greatly increased by methamphetamine, when the birds are working under certain schedules (15' Fl and FR 900); but is only slightly increased when they are working under other schedules (1' VI and FR 50). It is suggested that, in appropriate doses, methamphetamine tends to reduce the number and length of inter-response times in excess of 5 seconds but that rather larger doses also tend to prolong inter-response times shorter than 1 second. Some similar effects were obtained with d-amphetamine and pipradrol.