Kelleher R T, Goldberg S R
J Exp Anal Behav. 1977 Nov;28(3):221-31. doi: 10.1901/jeab.1977.28-221.
Squirrel monkeys operated a key under second-order schedules in which every tenth completion of a 5-minute fixed interval resulted in either presentation of food or intravenous injection of cocaine. When a 2-second light was presented at the completion of the component fixed-interval schedules, positively accelerated responding developed and was maintained in each component. Over a tenfold range of doses of cocaine(30 to 300 microgram/kg/injection) and amounts of food (0.75 to 7.5 g/presentation); the second-order schedule of cocaine injection maintained higher average rates of responding than the second-order schedule of food presentation. Substituting saline for cocaine or eliminating food presentation decreased average rates of responding. When no stimulus change occurred at the completion of the first nine component fixed-interval schedules, but the 2-second light and food presentation or cocaine injection still occurred after the tenth component, only low and relatively constant rates of responding were maintained in each component. Patterns of responding characteristic of 5-minute fixed-interval schedules were maintained by the 2-second light paired with either cocaine injection or food presentation, though the maximum frequency of cocaine injection or food presentation was less than once per 50 minutes.
松鼠猴在二阶程序下操作一个按键，在该程序中，每完成十次5分钟的固定间隔就会导致食物呈现或静脉注射可卡因。当在每个成分固定间隔程序结束时呈现一个2秒的灯光时，就会出现正加速反应，并在每个成分中保持。在十倍剂量范围的可卡因（30至300微克/千克/注射）和食物量（0.75至7.5克/次呈现）下；注射可卡因的二阶程序比呈现食物的二阶程序保持更高的平均反应率。用生理盐水替代可卡因或取消食物呈现会降低平均反应率。当在前九个成分固定间隔程序结束时没有刺激变化，但在第十个成分后仍出现2秒灯光和食物呈现或可卡因注射时，每个成分中仅保持低且相对恒定的反应率。与可卡因注射或食物呈现配对的2秒灯光维持了5分钟固定间隔程序特有的反应模式，尽管可卡因注射或食物呈现的最大频率低于每50分钟一次。
