Division of Psychiatry, University of Nottingham, UK.
Behav Processes. 2022 Jan;194:104551. doi: 10.1016/j.beproc.2021.104551. Epub 2021 Dec 3.
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, was adjusted according to the rats' choices. When B was preferred in a given block of trials, q was increased in the following block; when A was preferred, q was reduced in the following block. q 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.
根据倍增双曲线模型（MHM），强化物的价值是其大小（q）的递增双曲线函数。最近的报告结果表明，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强化价值。本实验研究了柠檬酸对蔗糖溶液的掺杂是否会对双曲线函数产生类似的影响。大鼠在调整幅度方案下接受训练，其中在杠杆 B 上的响应会输送固定体积的蔗糖/柠檬酸混合物，而在杠杆 A 上的响应会输送蔗糖溶液，根据大鼠的选择，q 根据调整。当在给定的试验块中 B 被优先选择时，q 在随后的块中增加；当 A 被优先选择时，q 在随后的块中减少。q 在实验的四个阶段中变化，并且测量了相应的 A 的无差异幅度。结果不支持柠檬酸掺杂导致蔗糖贬值的假设。从 MHM 得出的替代假设是，混合物的价值反映了正（蔗糖）和负（柠檬酸）值的总和，对此进行了讨论。
