According to the Multiplicative Hyperbolic Model (MHM), an extension of Mazur's (1987) model of delay discounting, the value of a reinforcer is an increasing hyperbolic function of its size (q). This experiment tested a prediction based on a revised version of MHM (MHM-R), according to which the maximum value may differ between different reinforcers, a possibility not envisaged in MHM. Rats were trained under a discrete-trials adjusting-magnitude schedule in which a response on lever B delivered a dilute sucrose reinforcer (0.2 M) of fixed volume, qB, while a response on lever A delivered a more concentrated sucrose solution (0.4 M) the volume of which, qA, was adjusted according to the rats' choices. When B was preferred in a given block of trials, qA was increased in the following block; when A was preferred, qA was reduced in the following block. qB was varied across four phases of the experiment and the corresponding indifference magnitudes of A (qA(50)) were measured. In keeping with expectations based on both MHM and MHM-R, qA(50) increased approximately linearly with qB, and 1/qA(50) with 1/qB. The ratio qB/qA(50) increased linearly with qB with a positive intercept, a finding that is consistent with MHM-R but not with MHM.

中文翻译：

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在调整幅度计划中选择不同浓度的蔗糖：强化物特异性值最大值的证据

根据乘法双曲线模型 (MHM)，Mazur (1987) 延迟贴现模型的扩展，强化物的值是其大小 (q) 的递增双曲线函数。该实验测试了基于修订版 MHM (MHM-R) 的预测，根据该预测，不同强化物之间的最大值可能不同，这是 MHM 中没有设想的可能性。大鼠在离散试验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 qB 的稀释蔗糖强化剂 (0.2 M)，而杠杆 A 的响应提供了更浓缩的蔗糖溶液 (0.4 M)其中，qA 的体积根据大鼠的选择进行调整。如果在给定的试验块中首选 B，则在下一个块中增加 qA；当首选 A 时，qA 在接下来的区块中减少了。qB 在实验的四个阶段发生变化，并测量了 A (qA(50)) 的相应无差异幅度。与基于 MHM 和 MHM-R 的预期一致，qA(50) 与 qB 近似线性增加，1/qA(50) 与 1/qB 近似。比率 qB/qA(50) 随 qB 呈正截距线性增加，这一发现与 MHM-R 一致，但与 MHM 不一致。