Foltin R W
New York State Psychiatric Institute, New York 10032, USA.
J Exp Anal Behav. 1999 Sep;72(2):215-34. doi: 10.1901/jeab.1999.72-215.
The effects of the availability of an alternative reinforcer on responding maintained by food pellets or drug solutions were examined in 8 adult male baboons (Papio hamadrayas anubis). During daily 23-hr experimental sessions, baboons had access to both food pellets and fluid under a two-choice procedure, in which the response requirement, under a fixed-ratio schedule, differed for the two commodities. There were no restrictions on access to water, which was continuously available from a spout at the rear of each cage. In Experiment 1, the fixed-ratio requirement, or cost, for fluid delivery remained constant while the fixed-ratio requirement for pellets was changed every 2 or 3 days when (a) no fluid, (b) a dilute dextrose vehicle, (c) 0.008 mg/kg per delivery cocaine, (d) 0.016 mg/kg per delivery cocaine, or (e) 0.032 mg/kg per delivery cocaine was available concurrently. In Experiment 1, progressively increasing the response requirement for pellets decreased pellet intake, but for 4 baboons pellet intake at maximum pellet cost was lower when cocaine, compared to the vehicle, was available. Increasing the response requirement for pellets had variable effects on vehicle intake. However, increasing the response requirement for pellets increased intake of at least one dose of cocaine to a greater extent than vehicle in all 8 baboons. Thus, cocaine could be considered a more effective economic substitute than vehicle for pellets. Experiment 2 systematically varied the order in which the response requirements for a pellet delivery were presented and added a control condition in which cocaine doses, yoked to the amount self-administered, were given three times during the session by the experimenter. Again, pellet intake at maximal pellet cost was lower when cocaine, compared to the vehicle, was available. In contrast, experimenter-given cocaine doses did not alter responding maintained by pellets. Thus, the effects of self-administered cocaine on responding maintained by food pellets differed from the effects of experimenter-given cocaine on responding maintained by food pellets.
在8只成年雄性狒狒（阿拉伯狒狒指名亚种）身上研究了替代强化物的可得性对由食物颗粒或药物溶液维持的反应的影响。在每天23小时的实验时段内，狒狒通过二选一程序可以获取食物颗粒和液体，在该程序中，两种物品在固定比率时间表下的反应要求不同。对水的获取没有限制，每只笼子后部的喷嘴持续提供水。在实验1中，液体递送的固定比率要求或成本保持不变，而当（a）无液体、（b）稀释的葡萄糖载体、（c）每次递送0.008毫克/千克可卡因、（d）每次递送0.016毫克/千克可卡因或（e）每次递送0.032毫克/千克可卡因同时可得时，食物颗粒的固定比率要求每2或3天改变一次。在实验1中，逐步增加食物颗粒的反应要求会减少食物颗粒摄入量，但对于4只狒狒来说，与载体相比，当有可卡因时，在最大食物颗粒成本下的食物颗粒摄入量更低。增加食物颗粒的反应要求对载体摄入量有不同影响。然而，在所有8只狒狒中，增加食物颗粒的反应要求使至少一剂可卡因的摄入量比载体增加的幅度更大。因此，与载体相比，可卡因可被认为是食物颗粒更有效的经济替代品。实验2系统地改变了食物颗粒递送的反应要求呈现的顺序，并增加了一个对照条件，即实验者在时段内三次给予与自我给药量匹配的可卡因剂量。同样，与载体相比，当有可卡因时，在最大食物颗粒成本下的食物颗粒摄入量更低。相比之下，实验者给予的可卡因剂量并未改变由食物颗粒维持的反应。因此，自我给药的可卡因对由食物颗粒维持的反应的影响与实验者给予的可卡因对由食物颗粒维持的反应的影响不同。
