PT - JOURNAL ARTICLE AU - N W Bond AU - D J Sanger AU - D E Blackman TI - Effects of d-amphetamine on the behavior of pigeons maintained by a second-order schedule of reinforcement. DP - 1975 Aug 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 327--331 VI - 194 IP - 2 4099 - http://jpet.aspetjournals.org/content/194/2/327.short 4100 - http://jpet.aspetjournals.org/content/194/2/327.full SO - J Pharmacol Exp Ther1975 Aug 01; 194 AB - The effects of various doses of d-amphetamine were studied on the responding of two pigeons exposed to a second-order schedule of reinforcement. With this schedule, food was presented following the completion of a sequence of three 2-minute fixed-interval components. A visual stimulus was presented at the completion of each fixed interval, including the one which was terminated with food. The pigeons' behavior was characterized by a pause immediately after each stimulus presentation followed by a gradual increase in response rate as the interval progressed. d-Amphetamine was found to increase the low rates of responding which occurred early in each interval and to decrease the high rates of responding at the end of each interval. These effects occurred whether responding preceded the presentation of food or the brief stimulus alone.