Carroll M E, Carmona G G, May S A
Department of Psychiatry, University of Minnesota, Minneapolis 55455.
J Exp Anal Behav. 1991 Sep;56(2):361-76. doi: 10.1901/jeab.1991.56-361.
Six rhesus monkeys were trained to self-administer orally delivered phencyclidine (0.25 mg/mL) and saccharin (0.03% wt/vol) under concurrent fixed-ratio 16 schedules. In Condition 1 the fixed-ratio requirement for phencyclidine was changed from 16 to 4, 8, 16, 32, 64, 128 and 16 while the fixed-ratio requirement for saccharin deliveries remained constant at 16. In Condition 2 the fixed-ratio value for saccharin was systematically altered while the fixed-ratio requirement for phencyclidine remained at 16, and in Condition 3 the fixed-ratio requirements for both phencyclidine and saccharin were altered simultaneously. Water was then substituted for saccharin, and the series of fixed-ratio manipulations was replicated. The phencyclidine concentration was reduced to 0.125 mg/mL and Conditions 1 and 3 were repeated. When the fixed-ratio requirement for phencyclidine was increased and the fixed-ratio requirement for saccharin or water remained fixed at 16, phencyclidine deliveries decreased when saccharin (vs. water) was concurrently available. The magnitude of the decrease ranged from 20% to 90% (of the concurrent water condition) as the fixed-ratio requirement for phencyclidine increased from 4 to 128. When the fixed-ratio requirement for phencyclidine remained at 16 and the fixed-ratio requirements for concurrent saccharin or water varied between 4 and 128, phencyclidine deliveries decreased by 30% to 40% due to the concurrent availability of saccharin (vs. water). This decrease occurred only at the three lowest fixed-ratio values when saccharin intake was relatively high. When the fixed-ratio requirements for both phencyclidine and concurrent saccharin or water were varied simultaneously, phencyclidine deliveries were reduced from 20% to 45% when saccharin (vs. water) was concurrently present. There was little effect of reducing the phencyclidine concentration when the data were analyzed in terms of unit price (responses per milligram). Thus, changes in the fixed-ratio requirement or drug concentration were functionally similar, and unit price of phencyclidine was the variable that was influenced by the presence of concurrent saccharin. These data indicate that drug-reinforced behavior is substantially reduced when the environment is enriched with an alternative nondrug reinforcer. The economic context in which these substances are presented is an important determinant of drug-reinforced behavior.
六只恒河猴被训练在同时进行的固定比率为16的实验安排下，自行口服给予苯环利定（0.25毫克/毫升）和糖精（0.03%重量/体积）。在条件1中，苯环利定的固定比率要求从16依次变为4、8、16、32、64、128，然后再变回16，而糖精给予的固定比率要求保持在16不变。在条件2中，糖精的固定比率值被系统地改变，而苯环利定的固定比率要求保持在16，在条件3中，苯环利定和糖精的固定比率要求同时改变。然后用水替代糖精，并重复这一系列固定比率操作。苯环利定浓度降至0.125毫克/毫升，并重复条件1和条件3。当苯环利定的固定比率要求增加且糖精（相对于水）同时可用时，糖精（相对于水）同时存在时，苯环利定的给予量减少。随着苯环利定的固定比率要求从4增加到128，减少幅度在（同时给予水的条件下）20%至90%之间。当苯环利定的固定比率要求保持在16，同时给予糖精或水的固定比率要求在4至128之间变化时，由于糖精（相对于水）的同时存在，苯环利定的给予量减少了30%至40%。这种减少仅在糖精摄入量相对较高的三个最低固定比率值时出现。当苯环利定和同时给予的糖精或水的固定比率要求同时变化时，当糖精（相对于水）同时存在时，苯环利定的给予量减少了20%至45%。当根据单位价格（每毫克的反应次数）分析数据时，降低苯环利定浓度几乎没有影响。因此，固定比率要求或药物浓度的变化在功能上是相似的，苯环利定的单位价格是受同时存在的糖精影响的变量。这些数据表明，当环境中富含替代非药物强化物时，药物强化行为会大幅减少。呈现这些物质的经济背景是药物强化行为的一个重要决定因素。
