According to the Multiplicative Hyperbolic Model (MHM), the value of a reinforcer is an increasing hyperbolic function of its size (q). Recently reported results indicated that dilution of a sucrose solution reduced its reinforcing value by increasing the ‘size-sensitivity’ parameter of this function and reducing its maximum. The present experiment examined whether adulterating a sucrose solution with citric acid would have a similar effect on the hyperbolic function. Rats were trained under an adjusting-magnitude schedule in which a response on lever B delivered a fixed volume of a sucrose/citric-acid mixture, while a response on lever A delivered a sucrose solution, the volume of which, q_A, was adjusted according to the rats’ choices. When B was preferred in a given block of trials, q_A was increased in the following block; when A was preferred, q_A was reduced in the following block. q_B was varied across four phases of the experiment and the corresponding indifference magnitudes of A were measured. The results failed to support the hypothesis that adulteration with citric acid resulted in devaluation of sucrose. An alternative hypothesis derived from MHM, that the value of the mixture reflected the summation of positive (sucrose) and negative (citric acid) values, is discussed.

根据乘法双曲线模型 (MHM)，强化物的值是其大小 ( q )的递增双曲线函数。最近报道的结果表明，蔗糖溶液的稀释通过增加该函数的“大小敏感性”参数并降低其最大值来降低其增强值。本实验检验了在蔗糖溶液中掺入柠檬酸是否会对双曲线函数产生类似的影响。大鼠在调整幅度计划下接受训练，其中杠杆 B 的响应提供了固定体积的蔗糖/柠檬酸混合物，而杠杆 A 的响应提供了蔗糖溶液，其体积为q _A，根据大鼠的选择进行调整。当在给定的试验块中首选 B 时，q _A在下一个块中增加；当 A 是首选时，q _A在接下来的块中减少。q _B在实验的四个阶段发生变化，并测量了 A 的相应无差异幅度。结果未能支持掺入柠檬酸导致蔗糖贬值的假设。讨论了源自 MHM 的替代假设，即混合物的值反映了正值（蔗糖）和负值（柠檬酸）的总和。